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US 9,280,688 B2Granted
Apparatus and method for limiting and analyzing stress corrosion cracking in pressurized water reactors
AssigneeAreva GmbH
InventorsBrian Glenn Lockamon, William Edward Allmon, Stephen Fyfitch, John Carroll Griffith
Life of this patent
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Abstract
A method to assess and predict pressurized water stress corrosion cracking in operational nuclear power plants and the effect of adding zinc compounds into a reactor coolant system of the nuclear power plant.
Claims10
A method to evaluate an effect of applying a zinc compound to a reactor coolant system of a pressurized water reactor, comprising:
- quantitatively assessing a pressurized water reactor stress corrosion cracking initiation rate of a candidate reactor coolant system through analysis of operational eddy current testing data and pressurized water stress corrosion cracking failure history using empirical relationships;
- determining an extent of damage to the candidate system;
- quantitatively assessing pressurized water stress corrosion cracking initiation benefit for high-concentration (>10 ppb) and low-concentration (<10 ppb) zinc addition programs;
- calculating a pressurized water stress corrosion cracking initiation benefit from zinc addition at low concentrations (<10 ppb) in the candidate system;
- approximating a time T when zinc addition at low concentrations (<10 ppb) in the candidate system is needed for pressurized water stress corrosion cracking mitigation;
- and
- applying zinc acetate to the reactor coolant system at the time T at concentrations of approximately between 1 to 10 parts per billion for pressurized water stress corrosion cracking mitigation,
- wherein zinc has not previously been applied to the candidate system and wherein the applying zinc acetate to the reactor coolant system at the time T at concentrations of approximately between 1 and 10 ppb for pressurized water stress corrosion cracking mitigation is not performed until after there are pressurized water stress corrosion cracking indications in the reactor coolant system.
5 more elements
A method to evaluate an effect of applying a zinc compound to a reactor coolant system of a pressurized water reactor, comprising:
- quantitatively assessing a pressurized water reactor stress corrosion cracking initiation rate of a candidate reactor coolant system through analysis of operational eddy current testing data and pressurized water stress corrosion cracking failure history using empirical relationships;
- determining an extent of damage to the candidate system;
- quantitatively assessing pressurized water stress corrosion cracking initiation benefit for high-concentration (>10 ppb) and low-concentration (<10 ppb) zinc addition programs;
- calculating a pressurized water stress corrosion cracking initiation benefit from zinc addition at low concentrations (<10 ppb) in the candidate system;
- approximating a time T when zinc addition at low concentrations (<10ppb) in the candidate system is needed for pressurized water stress corrosion cracking mitigation;
- and
- applying zinc acetate to the reactor coolant system at the time T at concentrations of approximately between 1 to 10 parts per billion for pressurized water stress corrosion cracking mitigation,
- wherein zinc has not previously been applied to the candidate system and wherein the step of quantitatively assessing a pressurized water stress corrosion cracking initiation rate of a candidate system through analysis of operational eddy current testing data and pressurized water stress corrosion cracking failure history using empirical relationships comprises calculating a normalized degradation rate define as a number of tubes with new pressurized water stress corrosion cracking indications divided by a number of rotating coil examinations in a region of the number of tubes.
5 more elements
Dependencies are inferred from the claim text.