A CORRELATION BETWEEN operation of primary coolants at low pH /SUB T/ with steam generator channel head dose rates in Westinghouse pressurized water reactors
It is widely experienced that operation with a low primary coolant pH /SUB T/ leads to heavy deposition on fuel-pin cladding in pressurized water reactors (PWRs). This is thought to be due principally to solubilities of corrosion products exhibiting negative temperature dependencies at low coolant pH /SUB T/ , leading to precipitation from the solution onto core surfaces. Solubilities also increase at low pH /SUB T/ values and this may be an additional reason for the increased deposition. Particulate deposition may also depend on coolant pH /SUB T/ . Operation at low coolant pH /SUB T/ may thus cause increased corrosion product activity transport, leading to higher dose rates around the primary circuit. The possible correlation between low pH /SUB T/ operation and steam generator channel head dose rates was investigated, using detailed data from nine Westinghouse PWRs. The coolant chemistry was quantified by calculating both the percentage of operating time at low pH /SUB T/ and a numerical ''precipitation index'' in order to establish the extent of operation below that coolant pH /SUB T/ above which little core crud deposition is expected. Time averaged pH's were also calculated for each cycle. End-of-cycle dose rates were plotted against these coolant chemistry parameters on a plantby-plant basis and statistical tests were applied following linear regression analysis. Positive correlations were obtained and it was found that, for the limited number of plants in the survey, these correlations were between the categories ''significant'' and ''probably significant'' for cycle 1 and cycle 2 data.
- Research Organization:
- Central Electricity Generating Board Berkeley Nuclear Laboratories, Berkeley, Gloucestershire
- OSTI ID:
- 5912832
- Journal Information:
- Nucl. Technol.; (United States), Vol. 71:3
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PRIMARY COOLANT CIRCUITS
CORRELATIONS
RADIOACTIVITY TRANSPORT
WATER CHEMISTRY
STEAM GENERATORS
WESTINGHOUSE STANDARD REACTOR
CORROSION PRODUCTS
DOSE RATES
FUEL PINS
FUEL-COOLANT INTERACTIONS
PH VALUE
PRECIPITATION
REGRESSION ANALYSIS
SCALING
SOLUBILITY
TEMPERATURE DEPENDENCE
WATER
BOILERS
CHEMISTRY
COOLING SYSTEMS
ENERGY SYSTEMS
FUEL ELEMENTS
HYDROGEN COMPOUNDS
MATHEMATICS
OXYGEN COMPOUNDS
PWR TYPE REACTORS
REACTOR COMPONENTS
REACTOR COOLING SYSTEMS
REACTORS
SEPARATION PROCESSES
STATISTICS
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
220900* - Nuclear Reactor Technology- Reactor Safety