ML060950277

GALL AMP: XI.M2, Water Chemistry (Audit Worksheet, GALL Report AMP)

ML060950277
Person / Time
Site:	Vermont Yankee
Issue date:	03/22/2006
From:	Morgan M NRC/NRR/ADRO/DLR/RLRC
To:	Office of Nuclear Reactor Regulation
morgan M NRR/NRC/DLR/RLRC, 415-2232
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Download: ML060950277 (8)

Text

AUDIT WORKSHEET GALL REPORT AMP PLANT: ______________________________

LRA AMP: __________________________ REVIEWER: ______________________

GALL AMP: XI.M2, Water Chemistry DATE: __________________________

Program Auditable GALL Criteria Documentation of Audit Finding Element Program A. The main objective of this program is to mitigate damage Consistent with GALL AMP: Yes No Description caused by corrosion and stress corrosion cracking (SCC). The Document(s) used to confirm Criteria:

water chemistry program for boiling water reactors (BWRs) relies on monitoring and control of reactor water chemistry based on industry guidelines such as the boiling water reactor vessel and internals project (BWRVIP)-29 (Electric Power Comment:

Research Institute [EPRI] TR-103515) or later revisions. The BWRVIP-29 has three sets of guidelines: one for primary water, one for condensate and feedwater, and one for control rod drive (CRD) mechanism cooling water. The water chemistry program for pressurized water reactors (PWRs) relies on monitoring and control of reactor water chemistry based on industry guidelines for primary water and secondary water chemistry such as EPRI TR-105714, Rev. 3 and TR-102134, Rev. 3 or later revisions.

The water chemistry programs are generally effective in removing impurities from intermediate and high flow areas. The Generic Aging Lessons Learned (GALL) report identifies those circumstances in which the water chemistry program is to be augmented to manage the effects of aging for license renewal.

For example, the water chemistry program may not be effective in low flow or stagnant flow areas. Accordingly, in certain cases as identified in the GALL Report, verification of the effectiveness of the chemistry control program is undertaken to ensure that significant degradation is not occurring and the components XI.M2 Water Chemistry 1

Program Auditable GALL Criteria Documentation of Audit Finding Element intended function will be maintained during the extended period of operation. As discussed in the GALL Report for these specific cases, an acceptable verification program is a one-time inspection of selected components at susceptible locations in the system.

1. Scope of A. The program includes periodic monitoring and control of Consistent with GALL AMP: Yes No Program known detrimental contaminants such as chlorides, fluorides Document(s) used to confirm Criteria:

(PWRs only), dissolved oxygen, and sulfate concentrations below the levels known to result in loss of material or cracking.

Comment:

B. Water chemistry control is in accordance with industry Consistent with GALL AMP: Yes No guidelines such as BWRVIP-29 (EPRI TR-103515) for water Document(s) used to confirm Criteria:

chemistry in BWRs, EPRI TR-105714 for primary water chemistry in PWRs, and EPRI TR-102134 for secondary water chemistry in PWRs.

Comment:

2. Preventive A. The program includes specifications for chemical species, Consistent with GALL AMP: Yes No Actions sampling and analysis frequencies, and corrective actions for Document(s) used to confirm Criteria:

control of reactor water chemistry. System water chemistry is controlled to minimize contaminant concentration and mitigate loss of material due to general, crevice and pitting corrosion and cracking caused by SCC. For BWRs, maintaining high water Comment:

purity reduces susceptibility to SCC.

3. Parameters A. The concentration of corrosive impurities listed in the EPRI Consistent with GALL AMP: Yes No Monitored/ guidelines discussed above, which include chlorides, fluorides Document(s) used to confirm Criteria:

Inspected (PWRs only), sulfates, dissolved oxygen, and hydrogen peroxide, are monitored to mitigate degradation of structural materials. Water quality (pH and conductivity) is also maintained in accordance with the guidance. Chemical species and water Comment:

quality are monitored by in- process methods or through sampling. The chemical integrity of the samples is maintained and verified to ensure that the method of sampling and storage will not cause a change in the concentration of the chemical XI.M2 Water Chemistry 2

Program Auditable GALL Criteria Documentation of Audit Finding Element species in the samples.

B. BWR Water Chemistry: The guidelines in BWRVIP-29 (EPRI Consistent with GALL AMP: Yes No TR-103515) for BWR reactor water recommend that the Document(s) used to confirm Criteria:

concentration of chlorides, sulfates, and dissolved oxygen are monitored and kept below the recommended levels to mitigate corrosion. The two impurities, chlorides and sulfates, determine the coolant conductivity; dissolved oxygen, hydrogen peroxide, Comment:

and hydrogen determine electrochemical potential (ECP). The EPRI guidelines recommend that the coolant conductivity and ECP are also monitored and kept below the recommended levels to mitigate SCC and corrosion in BWR plants. The EPRI guidelines in BWRVIP-29 (TR-103515) for BWR feedwater, condensate, and control rod drive water recommend that conductivity, dissolved oxygen level, and concentrations of iron and copper (feedwater only) are monitored and kept below the recommended levels to mitigate SCC. The EPRI guidelines in BWRVIP-29 (TR-103515) also include recommendations for controlling water chemistry in auxiliary systems: torus/pressure suppression chamber, condensate storage tank, and spent fuel pool.

C. PWR Primary Water Chemistry: The EPRI guidelines (EPRI Consistent with GALL AMP: Yes No TR-105714), for PWR primary water chemistry recommend that Document(s) used to confirm Criteria:

the concentration of chlorides, fluorides, sulfates, lithium, and dissolved oxygen and hydrogen are monitored and kept below the recommended levels to mitigate SCC of austenitic stainless steel, Alloy 600, and Alloy 690 components. TR-105714 Comment:

provides guidelines for chemistry control in PWR auxiliary systems such as the boric acid storage tank, refueling water storage tank, spent fuel pool, letdown purification systems, and volume control tank.

D. PWR Secondary Water Chemistry: The EPRI guidelines Consistent with GALL AMP: Yes No (EPRI TR-102134), for PWR secondary water chemistry Document(s) used to confirm Criteria:

recommend monitoring and control of chemistry parameters (e.g., pH level, cation conductivity, sodium, chloride, sulfate, XI.M2 Water Chemistry 3

Program Auditable GALL Criteria Documentation of Audit Finding Element lead, dissolved oxygen, iron, copper, and hydrazine) to mitigate steam generator tube degradation caused by denting, Comment:

intergranular attack (IGA), outer diameter stress corrosion cracking (ODSCC), or crevice and pitting corrosion. The monitoring and control of these parameters, especially the pH level, also mitigates general (for steel components), crevice, and pitting corrosion of the steam generator shell and the balance of plant materials of construction (e.g., steel, stainless steel, and copper).

4. Detection of A. This is a mitigation program and does not provide for Consistent with GALL AMP: Yes No Aging Effects detection of any aging effects. In certain cases as identified in Document(s) used to confirm Criteria:

the GALL Report, inspection of select components is to be undertaken to verify the effectiveness of the chemistry control program and to ensure that significant degradation is not occurring and the component intended function will be Comment:

maintained during the extended period of operation.

5. Monitoring A. The frequency of sampling water chemistry varies (e.g., Consistent with GALL AMP: Yes No and Trending continuous, daily, weekly, or as needed) based on plant Document(s) used to confirm Criteria:

operating conditions and the EPRI water chemistry guidelines.

Whenever corrective actions are taken to address an abnormal chemistry condition, increased sampling is utilized to verify the effectiveness of these actions. Comment:

6. Acceptance A. Maximum levels for various contaminants are maintained Consistent with GALL AMP: Yes No Criteria below the system specific limits as indicated by the limits Document(s) used to confirm Criteria:

specified in the corresponding EPRI water chemistry guidelines.

Any evidence of aging effects or unacceptable water chemistry results is evaluated, the root cause identified, and the condition corrected. Comment:

7. Corrective A. When measured water chemistry parameters are outside the Consistent with GALL AMP: Yes No Actions specified range, corrective actions are taken to bring the Document(s) used to confirm Criteria:

parameter back within the acceptable range and within the time period specified in the EPRI water chemistry guidelines. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to Comment:

XI.M2 Water Chemistry 4

Program Auditable GALL Criteria Documentation of Audit Finding Element address the corrective actions.

8. A. Following corrective actions, additional samples are taken Consistent with GALL AMP: Yes No Confirmation and analyzed to verify that the corrective actions were effective Document(s) used to confirm Criteria:

Process in returning the concentrations of contaminants such as chlorides, fluorides, sulfates, dissolved oxygen, and hydrogen peroxide to within the acceptable ranges. As discussed in the appendix to this report, the staff finds the requirements of 10 Comment:

CFR Part 50, Appendix B, acceptable to address the confirmation process.

9. A. Site quality assurance (QA) procedures, review and approval Consistent with GALL AMP: Yes No Administrative processes, and administrative controls are implemented in Document(s) used to confirm Criteria:

Controls accordance with the requirements of 10 CFR Part 50, Appendix B. As discussed in the appendix to this report, the staff finds the requirements of 10 CFR Part 50, Appendix B, acceptable to address administrative controls. Comment:

10. Operating A. The EPRI guideline documents have been developed based Consistent with GALL AMP: Yes No Experience on plant experience and have been shown to be effective over Document(s) used to confirm Criteria:

time with their widespread use. The specific examples of operating experience are as follows:

BWR: Intergranular stress corrosion cracking (IGSCC) has Comment:

occurred in small- and large-diameter BWR piping made of austenitic stainless steels and nickel-base alloys. Significant cracking has occurred in recirculation, core spray, residual heat removal (RHR) systems, and reactor water cleanup (RWCU) system piping welds. IGSCC has also occurred in a number of vessel internal components, including core shroud, access hole cover, top guide, and core spray spargers (Nuclear Regulatory Commission [NRC] Bulletin 80-13, NRC Information Notice [IN]

95-17, NRC Generic Letter [GL] 94-03, and NUREG-1544). No occurrence of SCC in piping and other components in standby liquid control systems exposed to sodium pentaborate solution has ever been reported (NUREG/CR-6001).

B. PWR Primary System: The primary pressure boundary piping Consistent with GALL AMP: Yes No XI.M2 Water Chemistry 5

Program Auditable GALL Criteria Documentation of Audit Finding Element of PWRs has generally not been found to be affected by SCC Document(s) used to confirm Criteria:

because of low dissolved oxygen levels and control of primary water chemistry. However, the potential for SCC exists due to inadvertent introduction of contaminants into the primary coolant system from unacceptable levels of contaminants in the boric Comment:

acid, introduction through the free surface of the spent fuel pool (which can be a natural collector of airborne contaminants), or introduction of oxygen during cooldown (NRC IN 84-18).

Ingress of demineralizer resins into the primary system has caused IGSCC of Alloy 600 vessel head penetrations (NRC IN 96-11, NRC GL 97-01). Inadvertent introduction of sodium thiosulfate into the primary system has caused IGSCC of steam generator tubes. The SCC has occurred in safety injection lines (NRC INs 97-19 and 84-18), charging pump casing cladding (NRC INs 80-38 and 94-63), instrument nozzles in safety injection tanks (NRC IN 91-05), and safety-related SS piping systems that contain oxygenated, stagnant, or essentially stagnant borated coolant (NRC IN 97-19). Steam generator tubes and plugs and Alloy 600 penetrations have experienced primary water stress corrosion cracking (PWSCC) (NRC Ins 89-33, 94-87, 97-88, 90-10, and 96-11; NRC Bulletin 89-01 and its two supplements).

C. PWR Secondary System: Steam generator tubes have Consistent with GALL AMP: Yes No experienced ODSCC, IGA, wastage, and pitting (NRC IN 97-88, Document(s) used to confirm Criteria:

NRC GL 95-05). Carbon steel support plates in steam generators have experienced general corrosion. The steam generator shell has experienced pitting and stress corrosion cracking (NRC Ins 82-37, 85-65, and 90-04). Comment:

Such operating experience has provided feedback to revisions of the EPRI water chemistry guideline documents.

XI.M2 Water Chemistry 6

EXCEPTIONS Item Program Elements LRA Exception Description Basis for Accepting Exception Documents Reviewed Number (Identifier, Para.# and/or Page #)

1.

2.

ENHANCEMENTS Item Program Elements LRA Enhancement Description Basis for Accepting Enhancement Documents Reviewed Number (Identifier, Para.# and/or Page #)

1.

2.

DOCUMENT REVIEWED DURING AUDIT Document Number Identifier (number) Title Revision and/or Date 1.

2.

3.

4.

XI.M2 Water Chemistry 7