PWR secondary water chemistry guidelines in Japan - Purpose and technical background

Progress in Nuclear Energy 114 (2019) 121–137

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PWR secondary water chemistry guidelines in Japan - Purpose and technical
background

T

Hirotaka Kawamuraa,∗, Yasuhiko Shodab, Takumi Terachic, Yosuke Katsumurad,
Shunsuke Uchidae, Takayuki Mizunof, Yusa Muroyag, Yasuo Tsuzukih, Ryuji Umeharai,
Hideo Hiranoj, Takao Nishimurab
a

Central Research Institute of Electric Power Industry, Japan
Mitsubishi Heavy Industry, Ltd, Japan
c
Institute of Nuclear Safety System, Inc, Japan
d
University of Tokyo, Japan
e
Tohoku University, Japan
f
Mie University, Japan
g
Osaka University, Japan
h
Japan Nuclear Safety Institute, Japan

i
Japan Nuclear Safety Institute, Japan
j
Central Research Institute of Electric Power Industry, Japan
b

A R T I C LE I N FO

A B S T R A C T

Keywords:
Guidelines
PWR
Secondary water chemistry
System component integrity
Steam generator
Stress corrosion cracking
Flow accelerated corrosion

In the more than 40 years of operational history of pressurized water reactors (PWRs) in Japan, sustainable
development of water chemistry technologies has resulted in the world's highest secondary system component
integrity; additionally, secondary system components, especially steam generator (SG) tubing, with excellent
material integrity have been developed to prevent leakage of radioactive contamination from the primary to the
secondary system and to maintain the heat removal function of the secondary system. Although reasonable
control and diagnostic parameters for water chemistry are utilized by each PWR owner, the specific values are
not shared.
To ensure reliable PWR operation and to achieve the highest safety level, relevant members of the Standards
Committee and the related committee organized by the Atomic Energy Society of Japan (AESJ) decided to
establish water chemistry guidelines for PWRs. The Japanese PWR secondary water chemistry guidelines provide
strategies for improving material integrity and the heat removal function. The guidelines also provide reasonable

“action levels” for control parameters and “control values” and “diagnostic values” for multiple parameters, and
they stipulate the responses when these levels are exceeded. Specifically, “conditioning parameters” are adopted
in the guidelines. Good operational practice conditions are also discussed with reference to long-term experience.
This paper introduces the purpose, technical background and framework of preliminary secondary water
chemistry guidelines for Japanese PWRs. Addition, the differences in bases of parameter settings between the
Japanese and overseas guidelines are discussed.

1. Introduction
To increase the safety and reliability for the operation of light watercooled nuclear power plants, careful and reliable water chemistry
control is one of the key issues. For this, plant water chemistry should
be controlled by the water chemistry experts based on the suitable
water chemistry guidelines. There are many water chemistry guidelines

∗

prepared by many organizations, e.g., Electric Power Research Institute
(EPRI) in US (Fruzzetti, 2004), Vereinigung der Groβkesselbesitzer
(VGB) in Germany (Neder et al., 2006) and Électricité de France (EDF)
in France (Odar and Nordmann, 2010).
On the other hand, the major features of a plant's water chemistry
depend on its' unique construction materials and operational histories
This means that the water chemistry guidelines should include common

Corresponding author.
E-mail address: (H. Kawamura).

/>Received 28 October 2018; Received in revised form 20 December 2018; Accepted 25 January 2019
Available online 14 March 2019
0149-1970/ © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
( />

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H. Kawamura, et al.

features while ensuring the flexibility required for each plant.
In the Standard Committee of the Atomic Energy Society of Japan
(AESJ), the water chemistry guidelines have been prepared. Those for
BWR water chemistry and PWR primary water chemistry are now in
press. Those target values and technical background have been introduced in the previous paper (Kawamura et al., 2016).
The water chemistry guidelines for PWR secondary water chemistry
is now on the final stage of editing processes, which will be published
after public review. One of the major objectives and roles of PWR
secondary water chemistry control are to ensure the secondary coolant
system components integrity, especially steam generator (SG) tubing, to
prevent leakage of radioactive contamination from the primary to
secondary systems and to maintain the heat transfer efficiency for
steam generation. In the PWR secondary coolant system, the structural
materials contact with the secondary water under a high-temperature
and high-pressure environments. Degradation in the system component
are due to corrosion affected by the following secondary water parameters, e.g., pH, conductivity, presence of impurities, and dissolved
oxygen content. Notably, if inappropriate water chemistry management
occurs for a prolonged time, stress corrosion cracking (SCC) propagates
through the wall of the SG tubes, and coolant with radioactive species
may leak from the primary system to the secondary system in the SG
and potentially leak out of the station. Some of corrosion products
might accumulate on heater tube surface, which results in decreasing
heat transfer efficiency and then decreasing plant efficiency. In addition, wall thinning of secondary coolant pipes caused by flow-accelerated corrosion (FAC) is an important safety issue for plant workers
because wall thinning will cause possible large amount of steam leakage
from the secondary coolant piping.

However, changes in water chemistry as a material corrosion control technique often result in change in the integrity of the various
secondary system component materials due to different corrosion mechanisms. Thus, the various issues must be solved harmoniously
through a comprehensive understanding of the plant system. Due to the
complexity of the water chemistry, which affects several corrosion
mechanisms of secondary system components, various sustainable developments and improvements in water chemistry technologies have
been applied to commercial PWRs based on plant systems, material
design and operational experiences to achieve high-reliability performance of secondary system components and highly effective heat-exchange performance. Those backgrounds are also involved in the PWR
secondary water chemistry guidelines.
“Control values”, “diagnostic values” and “action levels” for multiple parameters are also provided in the Japanese PWR secondary
water chemistry guidelines. The concept of these values are same as the
Japanese PWR primary water chemistry guidelines (Kawamura et al.,
2016). Specifically, the concept of a “conditioning parameter”, such as
the hydrazine (N2H4) content and pH of the feed water, is adopted in
the Japanese PWR secondary water chemistry guidelines. These
guidelines lead to the optimum water chemistry parameters and protocols for Japanese PWRs to assist in self-discipline and sustainable
safety improvements and to provide strategies to improve material integrity and heat-exchange performance. A further goal is to create more
human resources for developing water chemistry experts, including
those of the next generation.
This paper introduces the purpose, technical background and framework of the secondary water chemistry guidelines for Japanese
PWRs. Additionally, the differences and the bases of parameter settings
between the Japanese and the EPRI and VGB guidelines (Fruzzetti,
2004), (Neder et al., 2006) are discussed.

supplemented with chemical additives. To scavenge dissolved oxygen
and maintain an adequate reducing condition in the secondary coolant
system, hydrazine (N2H4) is added to the secondary water. Ammonia or
ethanol amine (ETA) is also injected into the coolant to maintain a
suitable pH and increase the corrosion resistance of the secondary
system components.
Recently, sophisticated chemical injection control has been carried

out using multiple pH-control agents such as ETA, dimethylamine
(DMA) and 3-Methoxypropylamine (MPA) in US PWRs to ensure the
long-term integrity of the secondary system material. However,
Japanese PWR utilities emphasize reliability rather than efficiency, and
therefore simple operation using single pH-control agents has been
carried out. Concurrent achievement of reliability and efficiency is
targeted by eliminating copper-based alloys and adapting high pH operation.
2.2. Objectives of water chemistry
PWRs have experienced various corrosion problems, such as intergranular attack (IGA), SCC of nickel-based alloy tubing in the SG and
stainless steel piping, and FAC of carbon steel.
To overcome these problems, it has been widely recognized that
secondary water chemistry is very important for the safe and reliable
operation of PWRs.
The primary objectives of PWR secondary water chemistry control
are as follows:
(1) To mitigate coolant-assisted corrosion and ensure the material integrity of the secondary system components
(2) To maintain heat exchange performance
2.3. Necessity of water chemistry guidelines
PWR secondary system management is charged with generating
safe, reliable, and low-cost electric power. Management is periodically
faced with a choice of either keeping a unit available to generate power
to meet short-term system demands or maintaining good control of
chemistry to help ensure the long-term integrity of the secondary
system components, and to improve power generation and balance-ofplant (BOP).
Based on the PWR operational history of more than 40 years in
Japan, Japanese PWR utilities have made huge efforts to maintain reactor and component integrity and improve power generation as well as
to pursue corrosion risk reduction.
Japanese PWR utilities have voluntarily implemented secondary
water chemistry precautions to obtain the highest reliability. In the
implementation process, secondary water chemistry experts have discussed the operating rules for PWR secondary water chemistries based

on state-of-the-art scientific understanding as well as the field experiences of Japanese PWRs.
To ensure secondary system safety, assurance of the material integrity of the secondary system components, particularly, the SG tubing
integrity, to prevent radioactive contamination from the primary to
secondary leakage and to maintain the heat-removal function of the
primary system are related strongly to the nuclear safety principles of
“confining sources of radiation risks” and “protecting people and the
environment from radiation”. Pipe wall thinning control is related to
labor safety principles. Both sets of principles are important to the
operation of PWRs from the viewpoint of safety and reliability.
Therefore, to ensure nuclear safety, continuous integrity of the secondary system component material based on appropriate water chemistry control techniques is required.
However, changes in the water chemistry as a material corrosion
control technique should be performed to maintain the integrity of the
various different secondary system component materials, which have
different corrosion mechanisms. Thus, the various issues must be solved

2. PWR secondary water chemistry guidelines
2.1. PWR secondary coolant
The secondary water in the PWR is an alkaline solution
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controlled water chemistry and should be factors that are likely to
affect the corrosion performance of secondary system materials.
● The concentrations of impurities, iron and copper in secondary
water should be kept to practical and achievable minimum levels.
● All action levels should be consistent with the technical specifications of the plant, and should be based on quantitative information

about the effects of the water chemistry on the corrosion behavior of
components. In the absence of quantitative data, prudent and
achievable action level values should be determined by expert
consensus.

harmoniously through a comprehensive understanding of the plant
system.
Standardized water chemical guidelines from the viewpoints of
secondary system safety and reliability have not yet been established. In
the guideline establishment process, it is important that experts in the
nuclear safety, plant life management (PLM) and water chemistry fields
share information and discuss the guidelines to ensure consistency with
each other's knowledge and thereby ensure PWR secondary system
safety, maintenance of coolant system component integrity, and highpower-generation effectiveness.
The goal should be to extend the operating life of the secondary
system components and maintain heat exchange performance while
providing an acceptable level of unit availability.

Water chemistry parameters in the start-up and shutdown processes
are also defined in the guidelines in addition to power operation because the secondary system component integrity and heat exchange
improvement are influenced by the deposition and release of corrosion
products which are affected by changes in coolant temperature and
reactor pressure.

2.4. Guideline definitions and philosophy
The objectives of the secondary water chemistry guidelines are to
simultaneously assure the material integrity of the secondary system
components and improve the heat-exchange performance. To achieve
these objectives, suppressing material corrosion in the secondary
system and reducing corrosion product release and deposition on the SG

tubes are key issues.
The AESJ PWR Secondary Water Chemistry Guidelines are applicable only to the recirculating SG and cover the secondary coolant
system and make-up water system. Fig. 1 shows the targets of the PWR
secondary water chemical system in the guidelines. Similar definitions
are used for the chemistry parameters in all systems. The parameters
can be categorized as control, conditioning, and diagnostic parameters,
and they are set for all PWR operation modes.
The following framework was used to establish the parameters.

2.4.1. Plant status of PWR
With respect to the water chemistry parameters, these guidelines
define the plant status in the four operating modes shown in Table 1,
and they consider the thermal and hydraulic conditions and their effects
on the chemical environment. Typical plant status modes and operations in Japanese PWRs are shown in Fig. 2.
2.4.2. Concept of control, conditioning and diagnostic parameters
As mentioned above, the key purpose of the secondary water
chemistry is the elimination of impurities except for chemical additives
to reduce corrosion product and to ensure secondary coolant system
component integrity.
Fig. 3 shows an example of the concept of control, conditioning and
diagnostic parameters for the SG blowdown water and feed water and
at the outlet of condensate water during power operation according to
the PWR secondary water chemistry guidelines. The concept of control,
conditioning and diagnostic parameter definitions are the same as that
in the PWR primary water chemistry guidelines (Kawamura et al.,

● Each control parameter has three action levels that are defined to
ensure the long-term integrity of the secondary system materials.
● The conditioning parameter is defined by the hydrazine (N2H4)
content and pH of the feed water.

● The diagnostic parameters are defined to complement the overall

Fig. 1. Targets of the PWR secondary water chemical system in the guidelines.
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Table 1
Operational status modes in a PWR secondary coolant system.
Plant Status

Reactor Condition

Remarks

Start-up
Power Operation
Shutdown
Outage/Wet Layup (Clean-up)

Critical to power operation
Reactor critical
Power descent to shutdown
Shutdown to coolant temperature < 100 °C

Covers the period of increasing pressure before power operation.
Covers the period from power up to the beginning of the shutdown process.

Covers the period from power descent to heat removal using an SG.
Covers the period from shutdown to start-up.
Purification of the feed water and condensate water systems and deaeration before start-up are
also included in this period.

chemistry guidelines (Kawamura et al., 2016). When the water chemistry parameters deviate from the action levels, water chemistry experts
should ensure that the optimal water chemical conditions are recovered
within the set time. Requirements for the action levels are the same as
that in the PWR primary water chemistry guidelines (Kawamura et al.,
2016).

2016). In the guidelines, the ideas of recovering from deviations in the
control parameters are the same to ensure secondary coolant system
component integrity and to improve heat-exchange performance.
2.4.3. Control parameters
The control parameters are selected to ensure that overall water
chemistry allows optimal plant operation, and the parameters are the
water quality limits for ensuring the long-term reliability of the materials. In addition, the control parameters are selected based on their
importance according to the state-of-the-art scientific understanding
and extensive Japanese PWR field experience. Moreover, the parameters are selected based on the availability of detection methods that
are reliable, sensitive and accurate when used in PWR secondary systems. When the water quality is outside the safe limits, suitable countermeasures should be taken to maintain plant system reliability. For
the control parameters, the following values are defined.

(2) Recovering from Action Levels and Requirements
The basic concept of recovering from the secondary water chemical
deviations is the same as that in the PWR primary water chemistry
guidelines (Kawamura et al., 2016). If it is foreseeable that the values
will go down immediately within Action Level 3 by a power descent,
then the operating status can be continued.

2.4.4. Conditioning parameters
Conditioning parameters are key parameters associated with chemical additives, such as the pH and N2H4 used to maintain appropriate
feed water quality. Conditioning parameters are not stipulated in the
EPRI and VGB guidelines (Fruzzetti, 2004), (Neder et al., 2006).

(1) Action Levels
Three action levels are defined as the chemical conditions that require immediate evaluation and corrective actions. The definitions of
the action levels are the same as that in the PWR primary water

Fig. 2. Typical plant status conditions and operations for Japanese PWR secondary systems.
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Fig. 3. Example of the concept of control, conditioning and diagnostic parameters in the PWR secondary water chemistry guidelines.

Action levels 1 and 3 are not stipulated for pH because the direct effect
of protons in the secondary coolant has not been clarified. When the pH
does not recover from action level 2, impurities must be identified, and
remedial action should be taken. The monitoring frequency is weekly
because the pH depends on the feed water pH, which is checked daily,
as shown in Table 4.
The secondary coolant properties can affect intergranular attack and
stress corrosion cracking (IGA/SCC) and pitting corrosion in the presence of small amounts of oxygen and/or oxidant. IGA/SCC has appeared on the secondary side of nickel-based alloys within SG tubes/
tube support plate (TSP) crevices and SG tubes/tube sheets (TS) because sodium and sulfate ions (Na+ and SO42−) are concentrated in the
crevices (Tsuruta et al., 1995), (Shoda et al., 1996), (Kawamura and
Hirano, 2000). The impurities are slightly dissolved in the secondary

coolant due to ion exchange resin degradation in the condensate polisher. Sodium and chloride can also be present in the secondary coolant
due to sea water ingress from a leaking condenser tube. Chloride can
form acid chlorides in crevices, and acid chlorides may be a major
factor in the denting of SG tubes and pitting corrosion on ferric materials (EPRI, 1983a), (EPRI, 1982), (Von Nieda et al., 1980). The presence of oxidants can promote the formation of acidic conditions in
crevices. Thus, the sodium, sulfate, and chloride concentrations are
stipulated as control parameters because they are harmful species that
adversely affect the long-term integrity of the nickel-based alloys used
for SG tubes and other structural materials.
According to the crevice calculation code provided by Mitsubishi
Heavy Industry, the relationship between the pH300C and sodium concentration for crevice concentration factors of (a) 107 and (b) 105 at a
simulated SG tube support plate crevice is shown in Fig. 6. The sodium
concentrations are 5 μg/L and 50 μg/L for concentration factors of 107
and 105, respectively, at a drilled-type and a broached egg crate (BEC)type TSP crevice with pH300C = 10, respectively. Based on Figs. 4 and 6,
action levels 1 and 2 for sodium are set to > 5 μg/L (> 5 ppb) and >
50 μg/L (> 50 ppb), respectively. Action level 3 is set to > 300 μg/L
(> 30 ppb) for concentration factors of 105 at a BEC-type TSP crevice
with pH300C = 10.5, which was calculated considering thermally
treated alloy 600 (alloy TT600). Even if condenser leakage occurs, the
feed water can be demineralized within 24 h after sodium detection
using a condensate demineralizer system. On the other hand, sodium
contamination has been caused by human error during chemical

2.4.5. Diagnostic parameters
The concept of diagnostic parameters is the same as that in the PWR
primary water chemistry guidelines (Kawamura et al., 2016).
2.4.6. Recommended values
The concept of recommended values is the same as that in the PWR
primary water chemistry guidelines (Kawamura et al., 2016).
2.4.7. Monitoring frequency
The concept of monitoring frequency is the same as that in the PWR

primary water chemistry guidelines (Kawamura et al., 2016).
2.5. Example of PWR secondary water chemistry guideline values and
settings for control parameters and recommendations
As mentioned previously in the paper, action level 1 and recommended values are defined for self-disciplined safety improvement.
In this section, some examples of action levels and recommended values
are shown for PWR power operation.
2.5.1. SG blowdown water during power operations
Table 2 shows the control and diagnostic parameters and recommended values for SG blowdown water during power operations.
pH can be a harmful parameter that adversely affects the long-term
integrity of secondary system components via general corrosion and
FAC of the carbon steel used for the SG support plates, feed water
systems, and bleeding and drain lines, and corrosion product release
and deposition due to material corrosion in the secondary system.
Ammonia attack of condenser tubes made of copper alloy has been
observed.
Fig. 4 shows SCC initiation mapping for SG tubing made of alloys
MA600 (mill-anneled alloy 600), TT600 (thermally treated alloy 600),
and TT690 (Yashima, 1995). SCC initiates at pH300C < 5 or
pH300C > 10. Fig. 5 shows an example of the effect of pH on magnetite
(Fe3O4) dissolution. Fe3O4 easily forms on the surface of carbon steel
and stainless steel under the reducing conditions present in a PWR
secondary system. The dissolution of Fe3O4 increases at pH < 9.8 at
25 °C, as shown in Fig. 5. Based on the data, action level 2 for pH is set
to < 8 at 25 °C, as shown in Table 2. The pH represents the balance
between the anion and cation concentrations in the secondary coolant.
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Table 2
Control and diagnostic parameters for SG blowdown water during power operations in the Japanese, EPRI, and VGB guidelines.
Period

Parameters

Japanese Guideline

EPRI Guideline (Fruzzetti, 2004)

VGB Guideline (Neder et al., 2006)

Start-up to 100% Reactor Power

> 30% Reactor Power

100% Reactor Power

Action Levels

pH at 25 °C

Cation Conductivity, mS/m (μS/cm)

Sodium, μg/L

Sulfate, μg/L

Chloride, μg/L

Level

Value

1
2
3
1
2
3
1
2
3
1
2
3
1
2

–
<8
–
-a
-a
-a
> 5b
> 50b,c
> 300b

> 10
> 100b,e
–
> 10
> 100

Recom-mended value

Frequency

–

Weekly

–

–

≤1

Dailyd

≤2

Dailyf

≤2

Dailyd

Action Levels
Level

Value

1
2
3
1
2
3
1
2
3
1
2
3
1
2

–
–
–
–
>1
>4
>5
> 50
> 250
> 10

> 50
> 250
> 10
> 50

3

> 250

1
2
3

–
–
–

Frequency

Action Levels
Level

Value

–

Normal operating values:
< 9.5

Continuous

1
>1
2
>2
3
>7
1
> 50
2
> 100
3
> 500
Normal operating values:
< 10

Continuous

Daily

Daily

Normal operating values:
< 10

–

1
2
3

b

3

> 2000
b

Total Radioactivity, Bq/cm

3

1
2
3

–
–
–

–

Monthly

g

–
–
–

Note.
a
In Japanese PWRs, Na, SO4 and Cl concentrations in SG secondary water should be monitored instead of cation conductivity because cation conductivity reflects
the sum of the effects of impurities.
b
These values are defined based on experimental corrosion data.
c
When the value is over action level 2, the cause should be sea water ingress. If ingress can be detected and the leakage line can be isolated, the polluted secondary
water can be cleaned up by condensate demineralizer within 24 h.
d
Continuous monitoring should be recommended if a continuous monitoring system is implemented. Ion chromatography is semicontinuous monitoring and an
optional analysis method. The frequency should be increased if evidence of sea water ingress is noted.
e
Action level 2 of sulfate is treated in the same manner as for chloride.
f
Continuous monitoring should be recommended if a continuous monitoring system is implemented. Ion chromatography is semicontinuous monitoring and an
optional analysis method.
g
Continuous monitoring should be adopted if using an SG blowdown water monitor.

dependent on the feed water pH and conductivity, as shown in Table 3.
Additionally, to check the water quality trend, continuous monitoring
should be recommended if an on-line monitoring system is implemented. The frequency should be increased if sea water ingress into
the secondary system is noted.
According to the crevice calculation code provided by Mitsubishi
Heavy Industry, the relationship between pHt and sulfate concentration
for 105 as a concentration factor at a simulated SG tube support plate
crevice is shown in Fig. 7. As shown in the figure, the sulfate concentration is 120 μg/L (120 ppb) for a concentration factor of 105 at
crevice pH300C = 5. The maximum concentration factor of sulfate is
estimated to be 105 in the test solution with sulfuric acid (Tsuruta et al.,

1995), (Shoda et al., 1996), (Kawamura and Hirano, 2000). Based on
Figs. 4 and 7, action level 2 for sulfate is set to > 100 μg/L (> 100 ppb).
Action level 1 is set to 1/10 of action level 2, i.e. > 10 μg/L (> 10 ppb).
Action level 3 for sulfate is not stipulated because the effect of sulfate
on SG material corrosion is not clear. When sulfate does not recover
from action level 2, it is necessary to identify the impurities, and take
appropriate remedial actions. The recommended value for sulfate
is ≤ 2 μg/L (≤2 ppb) because there are no data showing an adverse
effect on coolant system component integrity at this level. The monitoring frequency of sulfate is daily for the same reason as for sodium.
Fig. 8 shows the effect of chloride on the corrosion rate of alloy 600
using a boiling heat transfer test loop. In Japanese PWRs (Atomic
Energy soceity Of Japan, 2000), pitting corrosion cannot easily occur
because the SG secondary side is maintained under reducing conditions.
Even if some oxidants are present in the SG secondary side, the effect of

Fig. 4. SCC initiation region for SG tubing (Yashima, 1995).

additive injection, leading to a rapid increase in the sodium concentration in the SG blowdown water and plant shutdown in some
overseas PWRs. Large amounts of sea water leakage can be detected by
a salt detector. When the sodium concentration does not recover from
action level 2, appropriate remedial actions should be taken. The recommended values for sodium are ≤1 μg/L (≤1 ppb) because data do
not show an adverse effect on the coolant system component integrity
at this level. The monitoring frequency is daily because sodium is
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Fig. 5. Relationship between the Fe ion concentration and pH (JIS B 8223: 2015).

necessary to identify the impurities and take remedial action. The recommended values for chloride are ≤2 μg/L (≤2 ppb) because there
are no data showing an adverse effect on the coolant system component
integrity at this level. The monitoring frequency of chloride is daily for
the same reason as for sodium.
Total radioactivity is an important parameter and can be used as an
index to check primary coolant leakage. The total radioactivity is

chloride ions on alloy 600 corrosion is very small with a maximum
chloride level of 0.1 mg/L (0.1 ppm). On the other hand, the possibility
of pitting corrosion increases for chloride levels over 2 mg/L, as shown
in Fig. 8. Based on the test results, action levels 2 and 3 are set to >
100 μg/L (> 100 ppb) and > 2000 μg/L (> 2000 ppb), respectively.
Action level 1 is set to 1/10 of action level 2, i.e., > 10 μg/L
(> 10 ppb). When chloride does not recover from action level 2, it is

Table 3
Control and diagnostic parameters for feed water during power operations in the Japanese, EPRI and VGB guidelines.
Period

Parameters

Japanese Guideline

EPRI Guideline (Fruzzetti, 2004)

VGB Guideline (Neder et al., 2006)

Start-up to 100% Reactor Power

> 30% Reactor Power

100% Reactor Power

Action Levels
Level

Hydrazine, μg/L

Dissolved Oxygen, μg/L

Copper, μg/L

Lead, μg/L

pH control agent, mg/L

Conductivity, mS/m (μS/cm)

Iron, μg/L

Dispersant, μg/Li

1
2
3
1
2
3

1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3

Recom-mended value

Frequency

Action Levels

Value
< 50
–
–
–

>5
–
> 1c
–
–
> 10
–
–
–
–
–
–
–
–
–
–
–
–
–
–

–

Daily

–

Weeklyb

–

Weekly

–

Monthlyd

Plant-specifice

Appropriate

a

f

Plant-specifice

Dailya

≤5h

Weekly

–

–

Level

Value

1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3

< 8xCDP [O2] or < 20
–
–
>5

> 10
–
>1
–
–
–
–
–
Plant-specific
–
–
–
–
–
>5
–
–
Plant-specific
–
–

Frequency

Action Levels
Level

Value

Continuous

Normal operating values:
> 20

Continuous

1
2
3
1
2
3
1
2
3
1
2
3
Normal operating
> 1.5 (> 15)g

>5
> 20
> 100
–
–
–
–
–
–
< 9.8

–
–
values

1
2
3
1
2
3

–
–
–
–
–
–

Weekly

–

Daily

–

Weekly

Daily
–

–

Note.
a
Continuous monitoring should be recommended. Inlet water monitoring at a deaerator is an alternative analysis method.
b
Weekly monitoring is enough to detect the water quality changes because the vacuum in the condenser, the temperature of the deaerator, Do in the condenser
pump, and the hydrazine concentration at the outlet of the high-pressure feed water heater are monitored daily.
c
If copper alloys are used in the secondary system, such as condenser tubes.
d
Lead material is not used in Japanese PWR systems, although it is known to be the cause of PbSCC.
e
Plant-specific administrative limits should be established. Values are defined based on the plant design, component material and water chemistry.
f
Required as appropriate during power operation.
g
Cation conductivity is set to > 0.2 μS/cm in the VGB guidelines.
h
Value is defined based on the plant design, component material and water chemistry.
i
Dispersant is not employed in Japanese PWRs.
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Table 4

Conditioning parameters for feed water during power operations.
Conditioning Parameters
pH at 25 °C
Hydrazine, μg/L

Conditioning Value
a

Plant-specific
Plant-specificb

Frequency
Dailyb
Dailyb

Note.
a
Plant-specific administrative limits should be established. Values are defined based on the plant design, component material and water chemistry.
b
Continuous monitoring should be recommended. Inlet water monitoring at
the deaerator is an alternative analysis.

Fig. 8. Relationship between the corrosion rate of alloy 600 and the Cl concentration (Atomic Energy Society of Japan, 2000).

recommended if using an SG blowdown water monitor.
Table 2 also shows the control and diagnostic parameters for SG
blowdown water during power operation in the EPRI (Fruzzetti, 2004)
and VGB guidelines (Neder et al., 2006).
The pH is not stipulated within control parameters in the EPRI
guidelines and is stipulated as normal operating values, i.e. < 9.5, in

the VGB guidelines because multiple pH control agents such as ETA,
dimethylamine (DMA) and 3-methoxypropylamine (MPA) are employed in US and EU PWRs. In these guidelines, the cation conductivity
should be stipulated as the control parameter instead of pH monitoring
and monitored continuously. In Japanese PWRs, on the other hand,
cation conductivity is not stipulated as a control and/or diagnostic
parameter, and action level 2 for pH is stipulated based on the SCC
initiation mapping for the nickel-based alloy (Fig. 4) and the effect of
pH on Fe3O4 dissolution (Fig. 5). When the pH is over action level 2, the
cause should be sea water ingress and impurities in the chemical additives because sea water is used as the condenser coolant in all Japanese PWRs. pH monitoring is also categorized in the Japanese guidelines to check for the ingress of impurities other than sodium, sulfate
and chloride into the secondary coolant.
Ingress can be detected using a salt detector at the condensate hot
well. When sea water leaks into the secondary coolant system from the
condenser tube, the leakage line should be isolated and the polluted
secondary water should be cleaned up using condensate demineralizer
within 24 h.
In the VGB guidelines, the sodium concentration was stipulated as
the control parameter, and both sulfate and chloride in SG secondary
water were set as normal operating values, i.e., < 10 μg/L (< 10 ppb).
On the other hand, in the EPRI and Japanese guidelines, the impurity
concentrations should be monitored separately, i.e., sodium, sulfate and
chloride, instead of cation conductivity because cation conductivity
reflects the sum of the effects of the impurities, and it is difficult to
separate the effects of each impurity. In the EPRI guidelines, the action
levels of sodium, sulfate and chloride are stipulated based on the field
experience in US PWRs. In the Japanese guidelines, the action levels of
sodium and chloride are larger than those in the EPRI guidelines, but
they are defined based on many kinds of experimental corrosion data
(Figs. 4, 5, 7, and 8). The Japanese guidelines stipulate daily checking
frequencies for sodium, sulfate and chloride for SG blowdown water,
and continuous monitoring should be recommended using some kinds

of semicontinuous monitoring, such as ion chromatography and optional analysis. The monitoring frequency should be increased if evidence of sea water ingress is noted.
In the Japanese guidelines, the total radioactivity is stipulated as a
diagnostic parameter and should be monitored continuously using the

Fig. 6. Relationship between the pH300C and Na concentration for concentration factors of (a) 107 and (b) 105 at a simulated SG tube support plate crevice.

Fig. 7. Relationship between the pHt and SO4 concentration in a NaOH solution
for a 10−5 mist carry-over rate at a simulated BEC-type tube support plate
crevice.

stipulated as a diagnostic parameter because it does not affect secondary system material integrity. The monitoring frequency is monthly
for the same reason. However, continuous monitoring should be

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Fig. 9. Effect of hydrazine on the corrosion potential of alloy 600 (Fruzzetti, 2000).

SG blowdown water monitor. In the EPRI and VGB guidelines, the total
radioactivity is not stipulated within the control parameters and/or
diagnostic parameters.
2.5.2. Feed water during power operations
Table 3 shows the control and diagnostic parameters and recommended values for the feed water during power operations. The
water is sampled at the outlet of a high-pressure feed water heater.
Hydrazine is stipulated as a control parameter because hydrazine is
injected into the PWR secondary coolant as an oxygen scavenger to

reduce oxygen levels in the secondary coolant and to suppress SG tube
corrosion. Fig. 9 shows the effect of hydrazine on the corrosion potential (electrochemical corrosion potential, ECP) of alloy 600
(Fruzzetti, 2000). Based on the data, action level 1 is set to < 50 μg/L
(< 50 ppb) because this value is the limit to suppress oxidant formation
in the secondary system. Action levels 2 and 3 and recommended values
are not stipulated. The monitoring frequency is daily because reducing
conditions should be maintained during power operation. Continuous
monitoring should be recommended if an on-line monitoring system is
implemented. Inlet water monitoring at the deaerator can be an alternative analysis method.
The dissolved oxygen (DO) content is set as a control parameter
because it is a harmful parameter that adversely affects IGA/SCC and
pitting and crevice corrosion of SG tubes by increasing the corrosion
potential of nickel-based alloys, as shown in Fig. 10 (Kishida et al.,
1987). Action level 2 is set to > 5 μg/L (> 5 ppb) because this concentration is the monitoring limit of the implemented continuous
monitoring system. Action levels 1 and 3 and the recommended values
are not stipulated. The monitoring frequency is weekly to check the
reducing conditions. Continuous monitoring should be recommended if
an on-line monitoring system is implemented.
The copper concentration is also stipulated as a control parameter
because copper ions and copper oxide increase the ECP of carbon steel,
stainless steel, and nickel-based alloys as oxidants, and copper is a
harmful species that adversely affects the long-term integrity of these
materials. Based on test results (Kishida et al., 1987) and Japanese PWR
operating experiences, action level 1 is set to > 1 μg/L (> 1 ppb). The
value may be stipulated if copper alloys are implemented in the secondary system. Action levels 2 and 3 and recommended values are not
stipulated. The monitoring frequency is weekly because the concentration changes in copper are very small during power operation.
Continuous monitoring should be recommended if an on-line monitoring system is implemented.
A control parameter for lead is also stipulated to monitor contamination in the SG even though lead-induced SCC (PbSCC) has not
been experienced and lead materials are not installed in Japanese

Fig. 10. Effect of oxidant on the ECP of alloy 600 (Kishida et al., 1987).

PWRs. On the other hand, PbSCC has been experienced in some overseas PWRs due to lead shielding blocks left in the secondary system
after a refueling outage. Experimental data for PbSCC indicate that lead
levels should be as low as possible (Takamatsu et al., 1997), (Staehle,
2005), (Fruzzetti, 2006a), (Fruzzetti, 2006b). However, the effect of
lead on the SCC has not been clarified. The lead level should be recommended to be as low as possible. Fig. 11 shows the effect of lead on
SCC of nickel-based alloys (Staehle, 2005). A lead concentration <
0.1 mg/L (< 0.1 ppm) is not harmful for PbSCC. In an SG crevice, the
concentration factor of lead is estimated to be 5 for 1% of the SG
blowdown rate in a commercial Japanese PWR. In the guidelines, the
concentration factor is set to 10 as a conservative estimate. Based on
this knowledge, action level 1 is set to > 10 μg/L (> 10 ppb). Action
levels 2 and 3 and recommended values are not stipulated. The monitoring frequency is monthly because the dominant changes in lead
concentration are caused by leaving lead shielding blocks in place after
periodic inspections. The lead concentration in the feed water should be
checked when the NH3 chemical additive is changed to another manufacturing lot because lead may be present in the additive.
The concentration of a pH control agent such as ammonia (NH3) or
ethanol amine (ETA) is stipulated as a diagnostic parameter because an
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Fig. 11. Effect of lead on the SCC of a nickel-based alloy (Staehle, 2005).

guidelines.
Lead is not stipulated as a control parameter in the EPRI and VGB

guidelines because the lower limit of the lead concentration that affects
the PbSCC of nickel-based alloys has not been clarified. Lead is not
included as an additive in any materials in Japanese PWR systems.
However, a negligible amount of lead may be included in the NH3
chemical additive when the additive is changed to another manufacturing lot.
The pH control agent is stipulated as a control parameter in the EPRI
and VGB guidelines to check the concentration of the injected pH
control agent. In the Japanese guidelines, on the other hand, the pH
control agent is stipulated as diagnostic parameter because the pH
control agent should be selected according to the plant design, component material and water chemistry.
Conductivity is not stipulated as a control and/or diagnostic parameter in the EPRI guidelines. In the VGB guidelines, on the other hand,
conductivity is stipulated as a control parameter to check the concentration of the injected pH control agent. In the Japanese guidelines,
conductivity is stipulated as a diagnostic parameter to monitor the
concentration of the injected pH control agent.
Iron is stipulated as a control parameter in the EPRI guidelines to
check the iron concentration. In the Japanese guidelines, on the other
hand, iron is stipulated as a diagnostic parameter because the value is
defined based on the plant design, component material and water
chemistry, and the recommended value, i.e., ≤5 μg/L (< 5 ppb), is the
same as in the EPRI guidelines. In the VGB guidelines, iron is not stipulated as a control and/or diagnostic parameter.
The dispersant is stipulated as a control parameter in the EPRI
guidelines because the dispersant is employed in US PWRs. In the
Japanese guidelines, on the other hand, the dispersant is not stipulated
as a diagnostic parameter because dispersant is not employed in
Japanese PWRs.
The conditioning parameters in these guidelines are original and are
not stipulated in the EPRI and VGB guidelines. The pH and hydrazine
concentration are stipulated as conditioning parameters because they
are additives in the secondary coolant and should be controlled based
on the plant design, component material and water chemistry.

Table 4 shows the conditioning parameters for the feed water during
power operations.
pH is a parameter that adversely affects the general corrosion and
FAC of the carbon steel used for the feed water system and bleeding and

adequate concentration is needed in the feed water. The pH control
agent should be selected according to the plant design, component
material and water chemistry. The recommended value should also be
defined as a plant-specific administrative limit based on the plant design, component material and water chemistry. The monitoring frequency should be appropriate to check the concentration of the pH
control agent injected into the secondary coolant during power operation.
Conductivity is stipulated as a diagnostic parameter to monitor the
concentration of the injected pH control agent. The recommended value
should be defined as a plant-specific administrative limit according to
the plant design, component material and water chemistry. The monitoring frequency is daily to check the concentration of the pH control
agent injected into the secondary coolant. Continuous monitoring
should be recommended at the inlet of the deaerator. Inlet water
monitoring at the deaerator is an alternative analysis method.
Iron oxide affects the heat transfer of SG tubes via scale adhesion on
the tube surface and scale blockage within the TSP crevice. A diagnostic
parameter for iron is stipulated to suppress the above phenomenon. The
recommended value is set to ≤5 μg/L (< 5 ppb), and the value is defined based on the plant design, component material and water chemistry. The monitoring frequency is weekly to check the iron concentration in the feed water.
Table 3 also shows the control and diagnostic parameters for the
feed water during power operation in the EPRI (Fruzzetti, 2004) and
VGB guidelines (Neder et al., 2006).
Hydrazine is stipulated as a control parameter in the EPRI and
Japanese guidelines. However, action level 1 for hydrazine is higher in
the Japanese guidelines than in the EPRI guidelines because < 50 μg/L
(< 50 ppb) is the limit to suppress oxidant formation in the secondary
system. In the EPRI guidelines, action level 1 for hydrazine is set to
maintain reducing conditions and to maintain hydrazine at greater than

eight times the condensate dissolved oxygen in the condensate polisher
demineralizer (CDP) or 20 μg/L (< 20 ppb). The value is set based on
field experience in US PWRs. On the other hand, hydrazine is stipulated
as normal operating values, i.e., > 20 μg/L (< 20 ppb), in the VGB
guidelines.
Action level 2 for DO in the Japanese guidelines is set to > 5 μg/L
(> 5 ppb) and is more conservative than in the EPRI and VGB guidelines.
Action level 1 for copper is the same value in the EPRI and Japanese
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Table 5
Control and diagnostic parameters for condensate water during power operations in the Japanese, EPRI and VGB guidelines.
Period

Parameters

Japanese Guideline

EPRI Guideline (Fruzzetti, 2004)

VGB Guideline (Neder et al., 2006)

Start-up to 100% Reactor Power

> 30% Reactor Power

100% Reactor Power

Action Levels
Level

Cation Conductivity, mS/m (μS/cm)a

1

Recom-mended
value

Frequency

Value
> 0.03 (> 0.3)

–

Continuousc

Action Levels
Level

Value

1

–

2

–

3
1
2
3
1
2
3

–
–
–
–
> 10
> 30
–

Frequency

Normal operating values

–

< 0.02 (< 0.2)

–

–

Continuous
–
–

< 0.02

b

2

> 0.05 (> 0.5)
b

Sodium, μg/La,b

Dissolved Oxygen, μg/Ld

3
1
2
3
1
2
3

–
> 10

> 20
–
–
–
–

–

Continuousc

–

Daily

Note.
a
At least one of the parameters should be selected based on the implemented monitors in each plant.
b
If sodium is monitored continuously, sodium should be > 10 μg/L at action level 1 and > 20 μg/L at action level 2.
c
Continuous monitoring should be recommended. During monitoring sensor maintenance, a salt detector at the condensate hot well or manual analysis should be
used as an optional analysis method.
d
In the EPRI guidelines, dissolved oxygen in condensate water is monitored adequately during < 5% reactor power operation. It is a diagnostic parameter if
copper alloys are not implemented in the secondary system.

monitoring for cation conductivity should be adopted. Sodium is
monitored continuously if a salt detector is implemented. During
monitoring sensor outage for maintenance, a salt detector at the condensate hot well or manual analysis should be used as an optional
analysis method.

Dissolved oxygen (DO) is stipulated as a diagnostic parameter because the DO monitor is effective for checking air in-leakage at the
vacuum area in the condenser. The recommended value is not stipulated, as shown in Table 5. However, to maintain an appropriate level
of DO in the condensate water, a recommended value should be considered if copper alloys are implemented in the vacuum area of the
condenser and/or low-pressure feed water heaters. The monitoring
frequency is daily to check for air leakage into the secondary system.
Table 5 shows a comparison of the diagnostic parameters for condensate water during power operations in the Japanese and EPRI
guidelines.
Cation conductivity is not stipulated as a control and/or diagnostic
parameter in the EPRI guidelines and is stipulated as normal operating
values, i.e., < 0.02 mS/m, in the VGB guidelines. In Japanese PWRs, on
the other hand, cation conductivity and sodium are stipulated as control parameters, to detect sea water leakage and flow to the SG.
DO is stipulated as a control parameter in the EPRI guidelines and as
normal operating values, i.e., < 0.02 μg/L (< 0.02 ppb), in the VGB
guidelines. In Japanese PWRs, on the other hand, DO is stipulated as a
diagnostic parameter to monitor the water sampled at the outlet of a
high-pressure feed water heater and to check air leakage into the secondary system.

drain lines. The pH adversely affects ammonia attack on the condenser
tube if copper alloy is implemented. Hydrazine should be controlled to
reduce the condensate and SG blowdown system polisher loads and to
maintain the SG heat-transfer effectiveness. The pH and hydrazine
concentration are monitored at the outlet of a high-temperature feed
water heater. The monitoring frequencies for pH and hydrazine are
daily because the pH is an important index of adequate injection of
chemical additives and hydrazine is injected to maintain reducing
conditions during power operation. Continuous monitoring is preferable if an on-line monitoring system is installed. Inlet water monitoring
at a deaerator can be an alternative analysis method.

2.5.3. Condensate water during power operations
Table 5 shows the control and diagnostic parameters and recommended values for condensate water during power operations. The

water is sampled at the outlet of the condensate pump.
Cation conductivity is affected by sea water leaking from the condenser tube. The cation conductivity is set as a control parameter because SCC and pitting corrosion may be caused by a large amount of sea
water leakage and flow into the SG. In this case, the ruptured tube
should be plugged and in extreme cases, power descent may be needed.
Action levels 1 and 2 are set to > 0.03 and > 0.05 mS/m, respectively, and 0.03 mS/m corresponds to the detection limit for changes in
cation conductivity. The value 0.05 mS/m corresponds to the sum of
0.03 mS/m and the maximum increase in cation conductivity of
0.02 mS/m caused by organic acid formation under high pH operation
conditions with ETA. Cation conductivity is also affected by the sodium
chloride concentration in the feed water. Therefore, for continuous
sodium monitoring, the sodium concentration should be > 10 μg/L
(> 10 ppb) at action level 1 and > 20 μg/L (> 20 ppb) at action level
2. Action level 3 for the cation conductivity and sodium concentration
are not stipulated because the cation conductivity includes the effect of
dissolved carbon dioxide and impurity contamination in the condensate
water, and the effect of contamination is difficult to eliminate. When
the cation conductivity or sodium concentration does not recover from
action level 2, the impurities must be identified, and remedial action
should be taken. The recommended values for cation conductivity are
not stipulated because data do not show an adverse effect on the
coolant system component integrity at this level. Continuous

2.5.4. Make-up water during power operations
Table 6 shows the diagnostic parameters and recommended values
for make-up water in the storage tank during power operations. The
make-up water is sampled from the storage tank.
Conductivity is stipulated as a diagnostic parameter because water
purification in the make-up water treatment system is maintained by
controlling the make-up water. The possibility of exceeding the range of
conductivity may be very small when the purification of make-up water

is controlled adequately. The recommended value is set to ≤0.1 mS/m
based on the effect of dissolved carbon dioxide (CO2). The monitoring
frequency is monthly because the possibility of exceeding the
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Table 6
Diagnostic parameters and recommended values for make-up water at the storage tank during power operations.
Period

Japanese Guideline

EPRI Guideline (Fruzzetti, 2004)

VGB Guideline (Neder et al., 2006)

Start-up to 100% Reactor Power

> 30% Reactor Power

100% Reactor Power

Parameters

Recommended Values

Frequency

Recommended Values

Normal operating values

Conductivity, mS/m (μS/cm)
Sodium, μg/L
Sulfate, μg/L
Chloride, μg/L
Dissolved Oxygen, μg/L

≤0.1 (≤1)
≤5
≤10
≤10
–

Monthly
Monthly
Monthly
Monthly
–

–
–
–
–
–

–
–
–
–
–

2.5.5. Condensate demineralized water during power operations
Table 7 shows the control and diagnostic parameters and recommended values for condensed demineralized water during power
operations. The water is sampled at the outlet of the condensate demineralizer.
Conductivity is stipulated as a control parameter to monitor the
clean-up capacity of the condenser and feed water quality. Action level
1 for conductivity is set to > 0.01 mS/m because the water quality can
be recovered within that conductivity level, and the level has no adverse effect on the secondary system based on field experience in
Japanese PWRs. Action levels 2 and 3 and a recommended value for
conductivity are not stipulated because no data show an adverse effect
on the coolant system component integrity at this level. The monitoring
frequency is daily to check the clean-up capacity of the condenser and
feed water quality. Continuous monitoring for conductivity should be
adopted if an on-line monitoring system is implemented. During monitoring sensor maintenance, a salt detector at the condensate hot well or
manual analysis should be used as an optional analysis method.
The sodium, sulfate and chloride concentrations are selected as diagnostic parameters because their concentration changes in the makeup water can be detected by on-line conductivity monitoring, and a
plant operational change is not needed even when these impurities
increase in the make-up water storage tank. The recommended values
of sodium, sulfate and chloride are set to ≤0.06 μg/L (≤0.06 ppb),
≤0.15 μg/L (≤0.15 ppb) and ≤0.15 μg/L (≤0.15 ppb), respectively,
based on field experience in Japanese PWRs. Although chloride may
accelerate pitting corrosion of alloy 600 during the layup process (EPRI,
1983b), chloride is defined as a diagnostic parameter because chloride

conductivity level may be very small when the make-up water purification is controlled adequately.

Conductivity is not stipulated as a control and/or diagnostic parameter in the EPRI guidelines. In the VGB guidelines, conductivity is
stipulated as a diagnostic parameter, and the value is set to < 0.1 mS/
m.
The sodium, sulfate and chloride concentrations are stipulated as
diagnostic parameters because their concentration changes in the makeup water can be predicted from on-line monitoring data of conductivity,
and a plant operational change is not needed even when the concentration of impurities increases in the make-up water storage tank.
Although chloride may accelerate pitting corrosion of alloy 600 during
the shutdown process, chloride is defined as a diagnostic parameter
because pitting cannot easily occur under reducing conditions (Staehle,
2005). The recommended values of sodium, sulfate and chloride are set
to ≤5 μg/L (≤5 ppb), ≤10 μg/L (≤10 ppb) and ≤10 μg/L (≤10 ppb),
respectively, which are the same as action level 1 for SG blowdown
water during operation. The monitoring frequencies are monthly because their low levels should be monitored. To check the trend of their
concentrations, continuous monitoring should be recommended if an
on-line monitoring system is implemented.
These impurities are not stipulated as control and/or diagnostic
parameters in the EPRI guidelines.
DO is not stipulated as a control and/or diagnostic parameter or
recommended value in the EPRI and VGB guidelines. In Japanese
PWRs, on the other hand, DO is not stipulated as a control and/or diagnostic parameter because DO should be controlled in the feed water.

Table 7
Control and diagnostic parameters for condensate demineralized water during power operations in the Japanese, EPRI, and VGB guidelines.
Period

Parameters

Conductivity, mS/m (μS/cm)

Sodium, μg/L

Sulfate, μg/L

Chloride, μg/L

Japanese Guideline

EPRI Guideline (Fruzzetti, 2004)

VGB Guideline (Neder et al., 2006)

Start-up to 100% Reactor Power

> 30% Reactor Power

100% Reactor Power

Action Levels
Level

Value

1
2
3
1
2
3
1
2

3
1
2
3

> 0.01 (> 0.1)
–
–
–
–
–
–
–
–
–
–
–

Recom-mended value

Frequency

–

Dailya

≤0.06

Appropriateb

≤0.15

Appropriateb

≤0.15

Appropriateb

Action Levels
Level

Value

1
2
3
1
2
3
1
2
3
1
2
3

–
–
–
–

–
–
–
–
–
–
–
–

Frequency

–

–

–

–

Action Levels
Level

Value

1
2
3
1
2
3

1
2
3
1
2
3

–
–
–
–
–
–
–
–
–
–
–
–

Note.
a
To check the trend of water quality, continuous monitoring should be recommended if a continuous monitoring system is implemented.
b
It is required as appropriate when the conductivity of the secondary water at the condenser outlet is increased and the impurity concentration in the SG water
changes greatly during power operation.
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Table 8
Diagnostic parameters and recommended values for SG blowdown water during
the start-up process.
Diagnostic Parameters

Recommended Values

Frequency

Cation Conductivity, mS/m (μS/cm)
Sodium, μg/L
Chloride, μg/L
Lead, μg/L

≤0.2 (≤2)
≤50
≤100
≤100

1
1
1
1

Table 9
Diagnostic parameters and recommended values for feed water during the startup process.

timea
timea
timea
timea

Note.
a
Check the recommended values prior to parallel in.

Diagnostic Parameters

Recommended Values

Frequency

pH at 25 °C
Conductivity, mS/m
Hydrazine, μg/L
Dissolved Oxygen, μg/L

Plant-specifica
Plant-specifica
≥50
≤5

Appropriateb
Appropriateb
Appropriateb
1 timec

Note.
a
Plant-specific administrative limits should be established. Values are defined based on the plant design, component material and water chemistry.
b
Required as appropriate based on the power generation during the start-up
process.
c
Check the recommended values prior to parallel in.

is monitored in the SG. The monitoring frequencies are appropriate to
evaluate the root cause of concentration changes. To check the trends of
their concentrations, periodic monitoring should be recommended if an
on-line monitoring system is implemented.
Table 7 Also shows the control and diagnostic parameters for condensed demineralized water during power operation in the EPRI
(Fruzzetti, 2004) and VGB guidelines (Neder et al., 2006).
Conductivity is not stipulated as a control and/or diagnostic parameter in the EPRI and VGB guidelines. In the Japanese guidelines, on
the other hand, conductivity is stipulated as a control parameter to
check the clean-up capacity of the condenser and feed water quality.
Sodium, sulfate and chloride are not stipulated as control and/or
diagnostic parameters in the EPRI and VGB guidelines. In the Japanese
guidelines, on the other hand, the concentrations of these impurities are
stipulated as diagnostic parameters.

drain system, and SG. The recommended values of pH and conductivity
should be defined as a plant-specific administrative limit according to
the plant design, component material and water chemistry. The monitoring frequencies are appropriate for checking the values during the
start-up process.
Hydrazine is injected into the PWR secondary coolant as an oxygen
scavenger to suppress SG tube corrosion. Hydrazine is stipulated as a
diagnostic parameter to control adequate reducing conditions in the

secondary side of the SG. The recommended value of hydrazine is set to
≥50 μg/L (≥50 ppb), which corresponds to action level 1 of hydrazine
in the feed water during power operation as shown in Table 3 to reduce
oxygen to an adequate level in the secondary coolant. The monitoring
frequency of hydrazine is appropriate for checking the value during the
process.
DO is also stipulated as a diagnostic parameter to check for adequate DO in secondary coolant reduction during the start-up process.
The recommended value of DO is set to ≤5 μg/L (≤5 ppb), which
corresponds to action level 2 of feedwater during power operation
(Table 3). The monitoring frequency of DO is one time prior to parallel
in to check the recommended value of DO in the secondary system.

2.5.6. SG blowdown water during the strat-up process
Table 8 shows the diagnostic parameters and recommended values
for SG blowdown water during the start-up process.
Cation conductivity, sodium, chloride and lead are stipulated as
diagnostic parameters to the ingress of impurities into the SG during the
start-up process. During the parallel in from the step of the secondary
coolant filling up the SG, it is difficult to concentrate impurities into SG
crevices such as the tube support plate crevice and tube sheet crevice
because the heat flux of the SG tube is very small during the process.
The recommended value of cation conductivity is set to ≤0.2 mS/m,
which corresponds to ≤100 μg/L (≤100 ppb) as chloride and other
impurities. The recommended values of sodium and chloride are set to
≤50 μg/L (≤50 ppb) and ≤100 μg/L (≤100 ppb), respectively, which
correspond to action level 2 for sodium and chloride in SG blowdown
water during power operation as shown in Table 2. The recommended
value of lead is set to ≤100 μg/L (≤100 ppb), which is ten times action
level 1 in the feed water during power operation as shown in Table 3.
The monitoring frequencies of cation conductivity, sodium and chloride

are one time prior to parallel in (electric power generator start-up)
because it is difficult to concentrate impurities into the SG crevice
during the process. The monitoring frequency of lead is one time prior
to parallel in (electric power generator start-up) to confirm the removal
of lead shield blocks after the periodic inspection. Lead is not contained
as an additive in any materials in Japanese PWR systems. However, a
negligible amount of lead may be found as contamination in the NH3
chemical additive. Therefore, the lead concentration in the SG blowdown water should be checked carefully when the additive is changed
to another manufacturing lot.

2.5.8. Condensate water during the strat-up process
Table 10 shows the diagnostic parameters and recommended values
for condensate water during the start-up process.
The cation conductivity of the condensate water is also stipulated as
diagnostic parameter to check salt contamination in the SG during the
start-up process. During the parallel in from the step of secondary
coolant filling up the SG, it is difficult to concentrate sea water into the
SG crevice because the heat flux of the SG tube is very small during the
process. The recommended value of cation conductivity is set to
≤0.03 mS/m. The monitoring frequency of cation conductivity is one
time prior to parallel in because it is difficult to concentrate impurities
into the SG crevice during the process. Continuous monitoring should
be recommended if an on-line monitoring system is implemented.
2.5.9. Feed water during the shutdown process
Table 11 shows the diagnostic parameters and recommended values
for the feed water during the shutdown process.
pH is stipulated as diagnostic parameter to check the adequate
Table 10
Diagnostic parameters and recommended values for condensate water during
the start-up process.

2.5.7. Feed water during the strat-up process
Table 9 shows the diagnostic parameters and recommended values
for the feed water during the start-up process.
pH and conductivity are stipulated as diagnostic parameters to
check the adequate pH and secondary water quality during the start-up
process because pH and conductivity are harmful parameters that adversely affect the long-term integrity of carbon steel, stainless steel, and
nickel-based alloys, and corrosion product release and deposition by
causing material corrosion in the feed water, condenser, bleeding and

Diagnostic Parameters

Recommended Values

Frequency

Cation Conductivity, mS/m (μS/cm)
Sodium, μg/L

≤0.03 (≤0.3)
≤10

1 time
1 time

a
a

Note.
a

Check the recommended values prior to parallel in. Continuous monitoring
should be recommended if a continuous monitoring system is implemented.
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Table 11
Diagnostic parameters and recommended values for feed water during the
shutdown process.
Diagnostic Parameters

Recommended Values

Frequency

pH at 25 °C
Conductivity, mS/m (μS/cm)
Hydrazine, μg/L

Plant-specifica
Plant-specifica
≥50

Appropriateb
Appropriateb
Appropriateb

Table 13
Diagnostic parameters and recommended values for SG blowdown water during
the outage/wet layup (clean-up) process.

Note.
a
Plant-specific administrative limits should be established. Values are defined based on the plant design, component material and water chemistry.
b
Required as appropriate depending on the power generation during the
shutdown process.

≤0.03 (≤0.3)
≤10

1 timea
1 timea

≥10
20 to 500b
50 to 500c

Appropriatea
Appropriatea
Appropriatea

–
–
–

Appropriate

Appropriate
Appropriate

With Ammonia
Only Hydrazine
(Without Ammonia)

mixture of hydrazine and ammonia to maintain alkaline and reducing
conditions.
For secondary coolant with ammonia, pH is stipulated as a diagnostic parameter to check for adequate pH during the outage/wet layup
(clean-up) process because weak alkaline conditions with ammonia are
effective to the long-term integrity of the structural material in the
secondary system. The recommended value of pH is set to > 10 to
suppress the corrosion of carbon steel, stainless steel, and nickel-based
alloys in the secondary system with ammonia. The monitoring frequency of pH is appropriate for checking the value during the outage/
wet layup (clean-up) process.
For secondary coolant with ammonia, hydrazine is also stipulated as
a diagnostic parameter to check for adequate reducing conditions in the
secondary side of the SG. The recommended value of hydrazine is set to
20–500 mg/L (20–500 ppm); 20 mg/L (20 ppm) hydrazine corresponds
to twice the substitution of 8 mg/L (8 ppm) as DO during the step of
secondary coolant parallel in the SG. The monitoring frequency of hydrazine is appropriate for checking the decrease in the hydrazine concentration during the outage/wet layup (clean-up) process.
For secondary coolant without ammonia, hydrazine is also stipulated as a diagnostic parameter to check for adequate reducing conditions in the secondary side of the SG. The recommended value of hydrazine is set to 50–500 mg/L (50–500 ppm); 50 mg/L (50 ppm)
hydrazine corresponds to 10 mg/L (10 ppm) as hydrazine during lay-up
plus 2 to 3 times (20–30 mg/L as hydrazine) for substitution of 8 mg/L
(8 ppm) as DO during the step of secondary coolant parallel in the SG.
The monitoring frequency of hydrazine is appropriate for checking the
value during the process.
Periodic analysis is recommended during the first 1–2 weeks to
confirm the decreasing trend of hydrazine. If the decreasing trend is

sufficiently small, the appropriate frequency of monitoring can be
decided.
Sodium, sulfate and chloride are stipulated as diagnostic parameters
to check for impurities in the secondary water injected into the SG.
Until the parallel in from the step of secondary coolant injection into
the SG, it is difficult to concentrate impurities into the SG crevice because the heat flux of the SG tube is very small. Recommended values of
sodium, sulfate and chloride are not stipulated because there are no
data showing an adverse effect on the coolant system component integrity under the low temperature condition. The monitoring frequencies of sodium, sulfate and chloride are appropriate for checking

Table 12
Diagnostic parameters and recommended values for condensate water during
the shutdown process.

Cation Conductivity, mS/m (μS/cm)
Sodium, μg/L

pH at 25 °C
Hydrazine, mg/
L

Note.
a
Check the decreasing trend within 1–2 weeks during the outage/wet layup
(clean-up) process. If the decreasing trend is small, an appropriate check should
be performed during the outage/wet layup (clean-up) process.
b
Based on the field data during outage/wet layup, the initial decline in the
concentration should be set, and the value should be within the recommended
range for using ammonia.
c

Based on the field data during outage/wet layup, the initial decline in the
concentration should be set, and the value should be within the recommended
range for without ammonia.
d
When feed water is supplied from the make-up water storage tank, the
purity of the make-up water should be checked.

2.5.11. SG blowdown water during the outage/wet layup (clean-up) process
Table 13 shows the diagnostic parameters and recommended values
for SG blowdown water during the outage/wet layup (clean-up) process.
The guidelines stipulate two types of wet layup conditions. One uses
only hydrazine to maintain reducing conditions, and the other uses a

Frequency

Frequency

Sodium, μg/L
Sulfate, μg/Ld
Chloride, μg/Ld

2.5.10. Condensate water during the shutdown process
Table 12 shows the diagnostic parameters and recommended values
for condensate water during the shutdown process.
Cation conductivity is also stipulated as a diagnostic parameter to
check sea water contamination in the SG during the shutdown process.
Until the parallel in from the step of secondary coolant filling in the SG,
it is difficult to concentrate the salt into the SG crevice because the heat
flux of the SG tube is very small. The recommended value of cation
conductivity is set to ≤0.03 mS/m. The monitoring frequency of cation

conductivity is one time during the shutdown process because it is
difficult to concentrate impurities into the SG crevice during the process. Continuous monitoring is recommended if an on-line monitoring
system is implemented.

Recommended Values

Recommended
Values

d

quality of the secondary coolant during the shutdown process because a
weak alkaline condition is effective for the long-term integrity of carbon
steel, stainless steel, and nickel-based alloys in the secondary system.
Conductivity is also stipulated as diagnostic parameter to check the
adequate quality of the secondary coolant during the shutdown process
because conductivity is a harmful parameter that adversely affects the
corrosion of carbon steel, stainless steel, and nickel-based alloys in the
secondary side. The recommended values of pH and conductivity
should be defined as plant-specific administrative limits according to
the plant design, component materials and water chemistry.
Hydrazine is also stipulated as a diagnostic parameter to check for
adequate reducing conditions in the secondary side of the SG. The recommended value of hydrazine is set to ≥50 μg/L (≥50 ppb) to reduce
oxygen to an adequate level in the secondary coolant.
The monitoring frequencies of pH, conductivity and hydrazine are
appropriate for checking their values during the process.
Although chloride may accelerate pitting attack of alloy 600 during
the layup process (EPRI, 1983b), chloride is not defined as a diagnostic
parameter because pitting is not a problem (EPRI, 1983b) under reducing conditions or pH > 9.5.

Diagnostic Parameters

Diagnostic Parameters

Note.
a
Continuous monitoring should be recommended if a continuous monitoring
system is implemented.
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Table 14
Diagnostic parameters and recommended values for feed water or deaerator
tank water during the outage/wet layup (clean-up) process.
Diagnostic Parameters

Recommended Values

Frequency

Cation Conductivity, mS/m (μS/cm)
Turbidity, mg/L
Iron, μg/L
Dissolved Oxygen, μg/L
Sodium, μg/L
Chloride, μg/L

Lead, μg/L

≤0.03 (≤0.3)
≤1
≤100
≤50
≤0.5
≤0.5
≤1

1
1
1
1
1
1
1

Table 15
Diagnostic parameters and recommended values for make-up water at the
secondary high-purity storage tank during the outage/wet layup (clean-up)
process.

timea
timea
timea
timea
timea
timea
timea

Diagnostic Parameters

Recommended Values

Frequency

Conductivity, mS/m (μS/cm)
Sodium, μg/L
Sulfate, μg/L
Chloride, μg/L

≤0.1 (≤1)
–
–
–

Monthly
Appropriatea
Appropriatea
Appropriatea

Note.
a
Check the value during SG layup and at the beginning of secondary cleanup.

Note.
a
Monitoring frequency is one time during the clean-up process. Check the
recommended values prior to the step of feed water filling in the SG.

2.5.13. Make-up water during the outage/wet layup (clean-up) process
Table 15 shows the diagnostic parameters and recommended values
for the make-up water at the storage tank during the outage/wet layup
(clean-up) process.
Conductivity is also stipulated as a diagnostic parameter to check
the adequate quality of the secondary coolant during the start-up process because conductivity is a harmful parameter that adversely affects
the corrosion of carbon steel, stainless steel, and nickel-based alloys in
the secondary side. The recommended value of conductivity is set to
≤0.1 ms/m, which corresponds to the recommended value for the
make-up water at the storage tank during power operation as shown in
Table 6. The monitoring frequency of conductivity is monthly.
Sodium, sulfate and chloride are stipulated as diagnostic parameters
to check for impurities in the secondary water injected into the SG.
Recommended values of sodium, sulfate and chloride are not stipulated
because there are no data showing an adverse effect on the coolant
system component integrity under the low temperature condition. The
monitoring frequencies of sodium, sulfate and chloride are appropriate
for checking the values during the process.

the values during the process.

2.5.12. Feed water or deaerator tank water during the outage/wet layup
(clean-up) process
Table 14 shows the diagnostic parameters and recommended values
for the feed water or deaerator tank water during the outage/wet layup
(clean-up) process.
Cation conductivity is also stipulated as a diagnostic parameter to
check for impurity contamination in the secondary coolant during the
outage/wet layup (clean-up) process. It is difficult for impurities to

ingress into the SG crevice during the process because the SG is isolated
from the secondary system. The recommended value of cation conductivity is set to ≤0.03 mS/m. The monitoring frequency of cation
conductivity is one time during the process. The cation conductivity is
also confirmed to be within the recommended value prior to the step of
secondary coolant filling in the SG.
Turbidity and total iron are stipulated as diagnostic parameters to
check for the removal of rust in the feed water. The recommended
values of turbidity and total iron are set to ≤1 mg/L (≤1 ppm) and
≤100 μg/L (≤100 ppb), respectively, based on field experience in
Japanese PWRs.
DO is stipulated as a diagnostic parameter to check for low levels in
the feed water that do not affect material corrosion. The recommended
value of DO is set to ≤50 μg/L (≤50 ppb), which corresponds to ten
times the level of 5 μg/L DO at the start of heat-up, which is equal to
action level 2 for the feed water during power operation as shown in
Table 3.
Sodium and chloride are stipulated as diagnostic parameters to
check the purification of the feed water. The recommended values of
sodium and chloride are set to ≤0.5 μg/L (≤0.5 ppb), which correspond to 0.5 μg/L (0.5 ppb) as the control value at the start of heat-up.
The monitoring frequencies of turbidity, total iron, DO, sodium and
chloride are one time during the process, and sodium and chloride are
checked to ensure that they are within the recommended values prior to
the step of secondary coolant filling in the SG.
Lead is also stipulated as a diagnostic parameter to check for lead
contamination in the secondary coolant during the outage/wet layup
(clean-up) process. The recommended value of lead is set to ≤1 μg/L
(≤1 ppb), which corresponds to 1/10 of action level 1 for lead in the
feed water during power operation as shown in Table 3. The monitoring
frequency of lead is one time during the process, and lead is checked to
ensure that it is within the recommended value prior to the step of

secondary coolant filling in the SG. Lead is not contained as an additive
in any materials in Japanese PWR systems. However, a negligible
amount of lead may be present as a contaminant in the NH3 chemical
additive. Therefore, the lead concentration in the feed water or SG
blowdown water should be checked carefully when the manufacturing
lot of the additive is changed.

2.5.14. Pure water at the outlet of the pure water production equipment
Table 16 shows the control and diagnostic parameters and recommended values for the outlet of the pure water production equipment. The water is used for the make-up water.
Conductivity is stipulated as a control parameter to monitor the
clean-up. Action level 1 of conductivity is set to > 0.02 mS/m because
the water quality can be recovered within this conductivity level and
the purity has no direct adverse effect on the secondary system. Action
levels 2 and 3 and the recommended value of conductivity are not
stipulated because there are no data showing an adverse effect on the
coolant system component integrity at this level. The monitoring frequency of conductivity is daily or one time at mixed bed polisher (MBP)
sampling time because pure water is used as make-up water.
Silica is stipulated as a diagnostic parameter because carryover of
silica is very small and silicate precipitation on the turbine has not been
experienced under normal steam conditions in PWRs, which is in
Table 16
Control and diagnostic parameters for pure water at the outlet of the pure water
production equipment.
Control Parameters

Conductivity, mS/m
(μS/cm)
Silica, μg/L

Action Levels

Recommended
Values

Frequency

1

2

3

> 0.02
(> 0.2)
–

–

–

–

Daily or 1 timea

–

–

≤20

Appropriateb

Note.
a
Required as appropriate during feed water treatment system operation.
b
Monitoring of the condition of the feed water treatment system and the
purity of the pure water is as required appropriate because the frequency
should be defined based on the plant design, component material and water
chemistry.
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H. Kawamura, et al.

4. Summary

contrast to observations under overheat steam conditions in thermal
power. The recommended value of silica is set to ≤20 μg/L (≤20 ppb)
based on field experience in Japanese PWRs. The monitoring frequency
of silica is appropriate for checking the value.

This paper provides the technical background and framework for
secondary water chemistry guidelines for PWRs; furthermore, this
paper provides reasonable “control values”, “diagnostic values” and
“action levels” for multiple parameters and stipulates the responses
when these levels are exceeded. Specifically, “conditioning parameters”
are adopted in the Japanese PWR secondary water chemistry guidelines. Good practices for operational conditions are also discussed with

reference to long-term experience. The guidelines provide strategies for
improving secondary system component integrity and maintaining the
heat removal function of the secondary system. In addition, the differences and the bases of the parameter settings between the Japanese
and the EPRI and VGB guidelines are clarified.
These guidelines are expected to be helpful as an introduction to
safety and reliability during PWR plant operations.

2.6. Water chemistry guidelines for improved water chemistry application
Most Japanese PWR plants have already applied high pH control in
the secondary coolant to reduce iron transportation into the SG and
feed water pipe thinning. Japanese PWR utilities have discussed high
pH control to mitigate the corrosion of secondary system materials.
3. Chemistry strategy
3.1. Long-term strategy for PWR secondary controlled water chemistry
The concept of the PWR secondary water chemistry guidelines for
self-disciplined safety improvement follows the “Roadmap on R&D and
Human Resources for Light Water Reactor Safety in Japan”, which
provides nuclear safety visions and a technical basis for reconstruction
after the Fukushima accident and was published by the Agency for
Natural Resources and Energy (Agency for Natural Resources and
Energy, 2015). A long-term strategy for controlling water chemistry had
been discussed in the “Japanese R&D Road Map 2009 for Water
Chemistry”, which was published by the Atomic Energy Society of
Japan (AESJ) (Water Chemistry Division in AESJ), and the basic strategic scenario was not changed after the Fukushima-Daiichi nuclear
accident.

Acknowledgments

3.1.1. High pH control
To ensure the long-term integrity of secondary system materials,

future challenges for PWR secondary water chemistry optimization,
such as high pH control, will be addressed.
The primary objective of high pH control with a target pH of approximately 9.8 is the reduction of iron transfer to the SG. Prior to the
application of high pH control, copper alloy must be eliminated from
the secondary system due to its high solubility in high pH conditions.
The typical pH control agent is ammonia, but some plants have chosen
ETA to reduce corrosion in the two phase flow condition. At present, 11
PWRs in Japan have already applied high pH control.

Supplementary data to this article can be found online at https://
doi.org/10.1016/j.pnucene.2019.01.027.

We gratefully acknowledge Emeritus Professor Kenkichi Ishigure
from the University of Tokyo; Yoshihumi Watanabe, Kotaro Takeda,
and Toshiya Tezuka from Hokkaido Electric Power Co., Inc.; Nobuo
Nakano from the Kansai Electric Power Co., Inc.; Nobuaki Ishihara,
Hiroyuki Manabe, and Seitaro Mishima from Shikoku Electric Power
Co., Inc.; Akira Takahashi and Yuuichi Koga from Kyusyu Electric
Power Co., Inc.; and Kenji Hisamune and Yusuke Nakano from the
Japan Atomic Power Company for their support and guidance.
Appendix A. Supplementary data

References
Roadmap on R&D and Human Resource for Light Water Reactors Safety in Japan. Agency
for Natural Resources and Energy.
Handbook of Water Chemistry of Nuclear Reactor System. Atomic Energy Society of
Japan, pp. 161.
Cause of Denting, Vol. 4 and 5. EPRI Report NP-3275.
Laboratory Program to Examine Effect of Layup Conditions on Pitting of Alloy 600. EPRI
Report NP-3012.

PWR Steam-Side Chemistry Follow Program. EPRI Report NP-2541.
Fruzzetti, K., 2000. PWR Secondary Water Chemistry Guidelines – Revision 5. EPRI
Report 102134-R5.
Fruzzetti, K., 2004. Pressurized Water Reactor Secondary Water Chemistry Guidelines
–Revision 6. EPRI Report 1008224-R6.
Fruzzetti, K., 2006a. Pressurized Water Reactor Lead Source Book: Identification and
Mitigation of Lead in PWR Secondary Systems. pp. 2–53 EPRI Report 1013385.
Fruzzetti, K., 2006b. Pressurized Water Reactor Lead Source Book: Identification and
Mitigation of Lead in PWR Secondary Systems. pp. 2-46–2-47 EPRI Report 1013385.
Japanese government, 2015. Water Conditioning for Boiler Feed Water and Boiler Water.
April.
Kawamura, H., Hirano, H., 2000. Estimation of impurity concentration factor on boiling
heat transfer surface using high temperature conductivity measurement technique.
Nucl. Technol. 129 (3), 398–406.
Kawamura, H., Hirano, H., Katsumura, Y., Uchida, S., Mizuno, T., Kitajima, H., Tsuzuki,
Y., Terachi, T., Nagase, M., Usui, N., Takagi, J., Urata, H., Shoda, Y., Nishimura, T.,
2016. BWR water chemistry guidelines and PWR primary water chemistry guidelines
in Japan - purpose and technical background -. Nucl. Eng. Des. 309, 161–174.
Kishida, A., Takamatsu, H., Kitamura, H., et al., 1987. The causes and remedial measures
of steam generator tube intergranular attack in Japanese PWR. In: Proc. 3rd Int.
Symp. On Environmental Degradation of Materials in Nuclear Power Systems-Water
Reactors, pp. 465.
Neder, H., Jurgensen, M., Wolter, D., Staudt, U., Odar, S., Schneider, V., 2006. VGB
secondary and secondary side water chemistry guidelines for PWR plants. In: Proc.
International Nuclear Plant Chemistry Conference, NPC2006, Paper 1.3, Jeju, Korea.
Odar, S., Nordmann, F., 2010. PWR and VVER secondary system water chemistry. In:
Advanced Nuclear Technology International Europe AB, ANT International.
Shoda, Y., Kadokami, E., Hattori, T., 1996. Examination of new bulk water molar ratio
index for crevice environment estimation. Water Chemistry of Nuclear Reactor
Systems, vol. 7. pp. 608 Bournemouth, UK.

Staehle, R.W., 2005. Clues and issues in the SCC of high nickel alloys associated with
dissolved lead. In: Proc. 12th Int. Symp. On Environmental Degradation of Materials
in Nuclear Power Systems-Water Reactors, pp. 1163.

3.1.2. Alternative to hydrazine
In the near future, hydrazine use will be restricted in Japan because
hydrazine is a known carcinogen. Japanese PWR utilities have begun to
discuss alternatives to hydrazine, such as carbohydrazide (CH6N4O)
and diethylhydroxylamine ((C2H5)2NOH). However, hydrazine is an
excellent oxygen scavenger and reducing agent and does not form organic species with adverse effects on the total organic carbon (TOC)
concentration. Efforts to develop alternative chemical additives should
be required.
3.2. Characteristics of the Japanese PWR secondary water chemistry
guideline establishment system
3.2.1. Review of the draft
As a technical standard of the Atomic Energy Society of Japan
(AESJ), the draft of the PWR secondary water chemistry guidelines will
be reviewed by experts not only in industry but also in academia. The
reviewing system is the same as that in the PWR primary water
chemistry guidelines (Kawamura et al., 2016).
3.2.2. Satisfaction of regulatory criteria
The revising system is the same as that in the PWR primary water
chemistry guidelines (Kawamura et al., 2016).
136


Progress in Nuclear Energy 114 (2019) 121–137

H. Kawamura, et al.

Von Nieda, G.E., Economy, G., Wootten, M.J., 1980. Denting in Nuclear Steam Generators
– Laboratory Evaluation of Carbon Steel Corrosion under Heat Transfer Conditions.
NACE Corrosion 80.
Japanese R&D Road Map 2009 for Water Chemistry. Water Chemistry Division in AESJ.
Yashima, S., 1995. Genshiryoku Kogyo 41 (No.4), 62.Further reading
“Strategic Energy Plan in Japan”, Japanese government, April 2014. cho.
meti.go.jp/en/category/others/basic_plan/pdf/4th_strategic_energy_plan.pdf#
search=%27Japanese+Strategic+Energy+Plan++Provisional+Translation%27.

Takamatsu, H., Matsunaga, T., Migkin, B.P., Sarver, J.M., Sherburne, P.A., Aoki, K., Sakai,
T., 1997. Study lead-induced stress corrosion cracking of steam generator tubing
under AVT water chemistry conditions. In: Proc. 8th Int. Symp. on Environmental
Degradation of Materials in Nuclear Power Systems-Water Reactors, pp. 216.
Tsuruta, T., Okamoto, S., Kadokami, E., Takamatsu, H., 1995. IGA/SCC crack propagation
rate measurement on alloy 600 SG tubing using a side stream model boiler. In: The
3rd JSME/ASME Joint International Conference on Nuclear Engineering, pp. 291
Kyoto, Japan.

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