1DAWACReport - International Atomic Energy Agency · PDF fileArtificial chemistry brain WACOL...

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DAWAC DAWAC

IAEA Coordinated Research ProgrammeIAEA Coordinated Research Programme

20002000--20052005

Nuclear Fuel Cycle and Material SectionNuclear Fuel Cycle and Material Section

Water Chemistry ProgrammeWater Chemistry ProgrammeIAEA Coordinated Research ProgrammesIAEA Coordinated Research Programmes

1.1. CCI: CCI: Investigation of Fuel Cladding Interaction with Water Coolant Investigation of Fuel Cladding Interaction with Water Coolant in Power Reactors. 1981in Power Reactors. 1981--1986.1986.

2.2. WACOLIN: WACOLIN: Investigations on Water Chemistry Control and Investigations on Water Chemistry Control and Coolant Interactions with Fuel and Primary Circuit materials in Coolant Interactions with Fuel and Primary Circuit materials in Water Cooled Power Reactors. 1987Water Cooled Power Reactors. 1987--1991.1991.

3.3. WACOL: WACOL: High Temperature OnHigh Temperature On--line Monitoring of Water line Monitoring of Water Chemistry and Corrosion. 1995Chemistry and Corrosion. 1995--2000.2000.

4.4. DAWAC: DAWAC: Data Processing and Control Technologies for Water Data Processing and Control Technologies for Water Chemistry and Corrosion Control in Nuclear Power Plants. 2000Chemistry and Corrosion Control in Nuclear Power Plants. 2000--2005.2005.

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Water Chemistry ProgrammeWater Chemistry Programme

Coolant technologyChemistry experience

and requirements

Plantinformation

Regulatoryrequirements

Models anddatabases DAWAC

WACOLINGuidelinesSpecifications

Diagnosis module:Artificial chemistry brain

WACOL

Output

Dataevaluation

Dataacquisition

Plantdata

AlgorithmsCalculations

New methodssensors

Conventionalanalysis


DAWAC Coordinated Research ProgrammeDAWAC Coordinated Research Programme

The major objective of the CRP is to improve the Processing Technologies and Diagnostics for

Water Chemistry and Corrosion Control in Nuclear Power Plants.

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DAWAC Coordinated Research ProgrammeDAWAC Coordinated Research Programme

17 Participating teams from 16 countries.

Each team has its own research focus, but all are working to improve water chemistry measurement, monitoring and control.

Both Primary and Secondary Circuits are considered and some work has been done on pond storage.


DAWAC Coordinated Research ProgrammeDAWAC Coordinated Research ProgrammeParticipants from:

INRNE, Bulgaria BARC, IndiaCRL, Canada Tohoku Univ., JapanCIAE, China Ministry F.&E., UkraineINR, Czech Republic INR, RomaniaVTT, Finland VNIPIET, Russian

FederationEdF, France Bohunice NPP, SlovakiaAreva, Germany Studsvik, SwedenPaks NPP, Hungary EPRI, USA

Penn. State Univ., USA

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Water Chemistry ProgrammeWater Chemistry ProgrammeDAWACDAWAC

The aim of the IAEA is that the participants of a CRP exchange information and experience. The participants benefit from mutual support and the structure provided by a well defined programme.

There have been three meetings of the DAWAC CRP where each participant has made a report of progress. The most recent was held in Beijing, August 2004.

A final report, prepared as an IAEA TECDOC, will be produced in 2005 to provide a comprehensive overview of the work performed and the lessons learned.


There are two main areas of work: There are two main areas of work:

1. Diagnostic systems for water chemistry and control

2. Methods of on-line water chemistry monitoring and control

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1.1. Diagnostic systems for water chemistry Diagnostic systems for water chemistry and controland control

An example is the work carried out in Japan, modelling whole plant behaviour from detectors placed at carefully chosen locations throughout the plant.

Location of monitoring equipment, Japanese PWR

control rod drive

reactor core

steam generator

separatordryer

high pressure heater

low pressure turbinedynamo

condenser

moisture separator

low pressure heater

high pressure turbine

hot-wellheater drain

condenser tubes

tubing

pressurizer

sampling*

in-line automatic analysis [[H2], conductivity, pH]

16N detector [CsI scintillation counter]

on-line ion chromatography

pH

CE [O2]

CE

sampling*

pH CE [O2]pH

CE

pHCE

CE

RN

: conductivity: radioactive nuclei

* chemical analysis at laboratory

RN

control rod drive

reactor core

steam generator

separatordryer

high pressure heater

low pressure turbinedynamo

condenser

moisture separator

low pressure heater

high pressure turbine

hot-wellheater drain

condenser tubes

tubing

pressurizer

sampling*

in-line automatic analysis [[H2], conductivity, pH]

16N detector [CsI scintillation counter]

on-line ion chromatography

pH

CE [O2]

CE

sampling*

pH CE [O2]pH

CE

pHCE

CE

RN


CE

RN


* chemical analysis at laboratory

RN

Research Co-ordination Meeting on DAWAC (23-27, Aug., 2004, Beijing ), Tohoku University, S. Uchida

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Modelling of the oxidation potential in a Japanese BWR. A model of water radiolysis.

Japanese BWRResearch Co-ordination Meeting on DAWAC (23-27, Aug., 2004, Beijing ), Tohoku University, S. Uchida

Differential equations Calculation path

• 12 radiolytic species

H2O, O2 , H2, H2O2 ,

O2- , HO2

- , H+ , HO- ,

eaq-, H, OH, HO2

• 35 reactions

• transfer of gaseous species

to steam

• H2O2 surface decomposition

feed waterriser

boiling channel

jet pump

bypass channel

down comer

PLR

lower plenum

core support

PLR exit

bypass outlet

Differential equations Calculation path

• 12 radiolytic species

H2O, O2 , H2, H2O2 ,

O2- , HO2

- , H+ , HO- ,

eaq-, H, OH, HO2

• 35 reactions

• transfer of gaseous species

to steam

• H2O2 surface decomposition

feed waterriser

boiling channel

jet pump

bypass channel

down comer

PLR

lower plenum

core support

PLR exit

bypass outlet

feed waterfeed waterriser

boiling channelboiling channel

jet pump

jet pump

bypass channelbypass channel

down comerdown comer

PLRPLR

lower plenum

core support

PLR exit

bypass outlet

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1.1. Diagnostic systems for water chemistry Diagnostic systems for water chemistry and controland control

A final example is the work carried out in France, modelling whole plant behaviour from a minimum of detectors placed at carefully chosen locations throughout the plant. A central facility monitors many Reactors.

List of on-line monitors in the secondary system of French PWRS

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French coolant monitoring

List of on-line monitoring – Explanation Primary coolant

Boron : safety concern, nuclear regulation (+ grab sample cross-checking),

Hydrogen : semi continuous control. No reliable and easy grab sampling.

Lithium : an on-line monitor for lithium is under development in France but not yet available. It should be of specific interest for plants with load follow, in order to better permanently adjust Li target value to the calculated pH 300°C.

French coolant monitoring

Steam-water system

Conditioning control :. pH and hydrazine in feedwater.

Pollution control : the target value Cation conductivity (+ sodium in some plants) in condenser

for high pollution detection with early action. Cation conductivity in each condenser section for leak location. Oxygen in condenser for air ingress control. Cation conductivity in steam and MSR drains for turbine protection

pollution diagnosis, organic acid pollution detection.

SG Blowdown resin purification system Conductivity after cation exchange resin for proper operation and the

moment of exhaustion with alkaline reagent in order to get a closer look onpurity at mixed bed outlet (cation resin is operated after exhaustion with alkaline reagent) . Sodium + cation conductivity after mixed bed for recycled water purity

control.

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Water Chemistry ProgrammeWater Chemistry ProgrammeExpert and SemiExpert and Semi--expert Systemsexpert Systems

Full Expert Systems for water chemistry control are possible in those countries with large programmes and centralised facilities.

For countries with single or few units, a simpler, semi-expert system is found to be more appropriate, with a minimum of parameters measured and monitored.

Water Chemistry ProgrammeWater Chemistry ProgrammeExpert and SemiExpert and Semi--expert Systemsexpert Systems

Trending for early problem identification (from EPRI)

0.0

0.5

1.0

1.5

2.0

5/12 6:00 5/12 12:00 5/12 18:00 5/13 0:00 5/13 6:00 5/13 12:00

SG

Sod

ium

, ppb

SG1 SG25/12 14:35 SG2 Na >0.75 ppb

5/12 14:52 SG1 Na >0.75 ppb

5/12 14:58 SCW Engineer Email

0.00

0.02

0.04

0.06

0.08

0.10

5/12 6:00 5/12 12:00 5/12 18:00 5/13 0:00 5/13 6:00 5/13 12:00

Sod

ium

, ppb

0

50

100

150

200

250

SG

Blo

wdo

w, g

pm

FFW CPD

Sodium Intrusion

5/12 17:00 BD Flow Increased

0.0

0.5

1.0

1.5

2.0

5/12 6:00 5/12 12:00 5/12 18:00 5/13 0:00 5/13 6:00 5/13 12:00

SG

Sod

ium

, ppb

SG1 SG2

5/12 19:38 'Small Condenser Leak' Call

5/12 22:46 'ETA Loss' Call

5/13 00:54 SG1 Na >0.75 ppb Cleared

5/12 09:00 SG Na Started Increasing

5/12 14:35 SG2 Na >0.75 ppb

5/12 14:52 SG1 Na >0.75 ppb

5/12 14:58 SCW Engineer Email

0.00

0.02

0.04

0.06

0.08

0.10

5/12 6:00 5/12 12:00 5/12 18:00 5/13 0:00 5/13 6:00 5/13 12:00

Sod

ium

, ppb

0

50

100

150

200

250

SG

Blo

wdo

w, g

pm

FFW CPD

Sodium Rinse by Rain

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2.2. Methods of onMethods of on--line water chemistry line water chemistry monitoring and controlmonitoring and control

Work focussed on developing new types of sensors, such as Electrochemical Potential (ECP) measurement devices. Such high temperature, on-line devices are not suitable for routine water chemistry control on a Power Plant, but can be extremely useful to experts developing whole plant models.


Electrochemical PotentialElectrochemical PotentialNoise measurements can be made on the electrochemical signals from corrosion. Such measurements can detect the onset of pitting and stress corrosion in experimental conditions. Below is an example of pitting corrosion.

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Water Chemistry ProgrammeWater Chemistry ProgrammePrimary Coolant activity monitoring (tool for Primary Coolant activity monitoring (tool for

DIWA Expert System)DIWA Expert System)Primary coolant activity monitoring is used for identification of failed fuel.

133Xe and 135Xe monitoring will show the onset of failed fuel

133Cs and 137Cs measurements during power drops can provide information on failed fuel burnup

239Np can show severe degradation

Primary Coolant activity monitoringPrimary Coolant activity monitoring

1,0E+7

1,0E+8

1,0E+9

1,0E+10

1,0E+11

25.08 08.09 22.09 06.10 20.10 03.11 17.11 01.12 15.12 29.12 12.01 26.01 09.02 23.02

Xe 133Xe 135

[Bq/m³]

Identification of failed fuel onset

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Primary Coolant activity monitoringPrimary Coolant activity monitoring

Limitations of an expert / diagnostic system• Total number of defective fuel rods

• Distinction between primary and secondary defects

• Type of defect

• Burnup of defective fuel rods

• Estimation of the date of defect initiation in case of several incidents during the cycle

Conclusion• The implementation of fuel failure estimation in an expert /

diagnostic system is a good tool but cannot substitute the experience of experts


Primary side crud and corrosionPrimary side crud and corrosion

A coolant circuit in a Nuclear Power Plant is manufactured from many different materials which will experience different conditions of pressure, temperature and irradiation damage. The water chemistry needs to minimise corrosion and damage throughout the circuit.

The Romanian participants have examined the corrosion behaviour of a CANDU primary circuit.

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Corrosion

MATERIAL

-Chemical composition-Microstructure-Mechanical properties-Surface condition

ENVIRONMENT

-Chemical composition-Temperature-Flow rate-Crevices-Potential (galvanic contact)

Parameters that influence corrosion

Corrosion

Water Chemistry ProgrammeWater Chemistry ProgrammeCorrosion database

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Water Chemistry ProgrammeWater Chemistry ProgrammeCorrosion database

Techniques used have included

• Corrosion kinetics

• Visual and microscopic examination of oxide layers

• Gravimetric analysis

• Electrochemical analysis

• XRD and XPS analysis

Contents of the DAWAC ReportContents of the DAWAC Report

1. 1. Executive Summary (Onufriev, Makela, Nordmann)2. Introduction and Background (Ullberg, Onufriev)3. Approach to Water Chemistry and Corrosion Control

a) Grab Sampling (Smiesko, Nordmann)b) On-line Monitoring (Ye, Uchida, Makela, Smiesko, Nordmann)c) Data Storage (Delse, Smiesko, Turner)d) Data Processing, Trending and Analysis (Turner, Smiesko, Delse)e) Quality Assurance of Data (Uchida)f) Updating Chemistry Specifications (Nordmann, Arkhipenko, , Kritski)

4. Plant Operation Supporta) Diagnostic Approach (Narasimhan, Smiesko, Turner, Zeh, Nordmann, Delse)b) Users of Diagnostic Results (Kritski, Smiesko, Nordmann, Delse)

Operators, Chemistry Staff, Plant Management5. Plant Chemistry Improvements

a) R&D Support (Dobrevski, Zmitko , Pirvan)b) Development of Models (Kritski, Ullberg, Turner, Macdonald, Uchida)c) Plant Verification (Arkhipenko, Narasimhan, Nordmann)

6. Recommendations on Monitoringa) Chemistry Monitoring (Zmitko, Uchida, Smiesko, Schunk, Nordmann)b) Radioactivity Monitoring (Schunk, Zmitko, Uchida, Smiesko, Zeh)c) Corrosion Monitoring (Pirvan, Makela, Zmitko, Ye, Ullberg, , Turner, Schunk, Macdonald)

7. Conclusions and future development (Makela, Nordmann, Onufriev)

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Future plans Future plans –– a new CRPa new CRPThere are still problems with corrosion control and crud deposition, particularly with high burnup fuel and aging plants that have seen varied chemistry over life.There are new techniques and ideas, such as zinc passivation for the primary side of steam generators, that are being introduced to help control corrosion and circuit activity, and hence operator dose.


Future plans Future plans –– a new CRPa new CRP

The IAEA is proposing a new CRP, FUWAC, which is intended to follow up from the original WACOLIN CRP, to examine new specifications and ideas for water chemistry, particularly to control corrosion and crud in the primary coolant.

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