ML20133G946
| ML20133G946 | |
| Person / Time | |
|---|---|
| Issue date: | 01/14/1997 |
| From: | Scott Flanders NRC (Affiliation Not Assigned) |
| To: | Newton R WESTINGHOUSE OPERATING PLANTS OWNERS GROUP, WISCONSIN ELECTRIC POWER CO. |
| References | |
| PROJECT-686 TAC-M96110, NUDOCS 9701160234 | |
| Download: ML20133G946 (6) | |
Text
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January 14, 1997
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i Mr. Roger A. Newton, Chairman LCM /LR Working Group Westinghouse Owners Group Wisconsin Electric Power Company 231 West Michigan Milwaukee, WI 53201
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING THE WESTINGHOUSE OWNERS GROUP TOPICAL REPORT WCAP-14574 (TAC NO. M96110) 1
Dear Mr. Newton:
1 By letter dated July 3,1996, the Westinghouse Owners Group (WOG) submitted Generic Technical Report (GTR) WCAP-14574 Management Evaluation For Pressurizers," j " License Renewal Evaluation: Aging Revision 0, July 1996, to the Nuclear Regulatory Commission for review and approval. The staff has completed its initial review of WCAP-14574 and concluded that additional information'is neeced to complete the staff's review.
l Enclosed is the staff's request for additional informafion (RAI).
I't should be noted that as the staff's review progresses, additional RAIs maybe issued.
Please review the request and provide, responses in a timely manner.~ If you have any questions please call me at (301) 415-1172.
4 This requirement affects less than ten (10)" respondents, and therefore is not subject to Office of Management and Budget review under Public Law 96-511.
Sincerely, Origi_nal signed by:
Scott C. Flanders, Project: Manager License Renewal Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation
Enclosure:
As stated i
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WESTINGHOUSE OWNERS GROUP (WOG) l Project No. 686 cc: Mr. Gregory D. Robison Ad Hoc Technical Group Coordinator LCM /LR Working Group Westinghouse Owners Group Duke Power Company P.O. Box 1006 Charlotte, NC 28201 Mr. Sumner R. Bemis Westinghouse Owners Group Project Office Westinghouse Electric Corporation, ECE 5-16 l
P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Theodore A. Meyer Westinghouse Program Manager for WOG LCM /LR Program Westinghouse Electric Corporation, ECE 4-22 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Gordon M. Vytlacil Westinghouse Lead Engineer for WOG LCM /LR Program Westinghouse Electric Corporation, ECE 4-22 P.O. Box 355 Pittsburgh, PA 15230-0355 Mr. Roger A. Newton Chairman, LCM /LR Working Group Westinghouse Owners Group Wisconsin Electric Power Company 231 West Michigan Milwaukee, WI 53201
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1.
With respect to Step 1 of the Proposed Industry Position on Fatigue Evaluation for License Renewal (the " Position") in Subsection 4.2, the staff requests the following:
a.
Subsequent to the evaluation of the current and projected transients for the license renewal ters, the WOG should implement the recommendation for license renewal contained in SECY-95-245,
" Completion of the Fatigue Action Plan." The staff's Fatigue Action Plan (NUREG/CR 6260) evaluated components whose usage factors were calculated with fatigue curves that included environmental effects, and resulted in high usage factors.
For these components, the WOG should also perform an evaluation, using the most current environmental fatigue effects, for the period of extended operation.
As applicable to the pressurizer, provide a specific commitment, in the discussion of the " Position" that this will be done either generically or plant specifically.
b.
Step Id in the " Position" discusses future reconstitution of surge line piping load transients resulting from plant-specific application of the WOG program for pressurizer insurge-outsurge transients mitigation. The WOG program is identified as report number MUHP-5060/5061/5062 in Subsection 2.6.1.
Provide more detailed background information on this program. Discuss the relationship of this program to the NRC Bulletin 88-11.
2.
Step 2 in the " Position" states that any changes to the existing inservice inspection (ISI) program from future risk-based considerations should be included in the pressurizer aging management program. A clarification is needed in Step 2 and in all other applicable sections of this repcrt to emphasize that the-ISI program should be based on the 1989 Edition of American Society of Mechanical Engineers (ASME)
Section XI, and that any deviation from this standard should be reviewed and endorsed by the staff.
3.
In reference to Step 2.of the " Position," describe how the proposed ISI program will provide a fatigue aging management program that will l
prevent failure of the pressurizer under current design-basis loads for the period of extended operation, consistent with the requirements in 10 CFR 54.21(c)(1).
4.
The last paragraph in Step 3 of the " Position" states that based on the general status published by the PVRC and the expected PWR water chemistry, it does not appear that environmental effects in fatigue will be a significant issue for the pressurizer.
It should be emphasized in Step 3 that the staff has not endorsed Ref. 17.
Revise Step 3 to eliminate the reference to the PVRC report.
5.
WCAP-14574, Page 14 states that the pressurizer surge line nozzles are carbon steel but the Nuclear Management and Resources Council (NUMARC)
Report 90-07, October 1990, Pages 4-12, states that surge line nozzles on Westinghouse and CE pressurizers are cast stainless steel.
Provide a clarification of this apparent discrepancy.
Enclosure
6.
The WOG did not identify intergranular stress corrosion cracking (IGSCC) as a potential aging effect.
For the shell/ heads, spray line nozzle, valve nozzle, manway, instrumentation nozzle, surge line nozzle and support skirt, the staff considers IGSCC a potential aging effect because it can occur during shutdown operating conditions (i.e., the water chemistry) as a result of (1) oxygen being introduced to primary coolant during cooldown to control CRUD-bursts, and (2) exposing the primary coolant to air during shutdown. Stainless steel cladding may have regions of low delta ferrite that have been sensitized during post weld heat treatment (PWHT) and thus susceptible to IGSCC; ASME Section XI requires inspection of weld and weld regions.
7.
The staff disagrees with the WOG conclusion that aging management for the cladding of the pressurizer is not needed. The staff believes that cracks in the clad could propagate into the base metal and should be addressed by an aging management program. A program to demonstrate the integrity of the cladding could be a one-time license renewal inspection of the cladding and any attachment welds to the cladding.
8.
The staff disagrees with the report's conclusion that boric acid 4
corrosion does not affect any components and that no aging management is needed.
The WOG appears to be relying on a program to mitigate the effects of boric acid corrosion so as to conclude that boric acid is not i
an aging effect. The staff considers the loss of base metal on external surfaces from boric acid wastage as an aging effect that must be managed.
Revise your report to provide for aging management of boric acid corrosion or provide justification that no aging management is needed.
9.
The report is not clear about whether the manway gasket is in the scope of license renewal.
10 CFR 54.21(a)(1)(ii) requires structures and components not subject to replacement based on a qualified life or specified time period be subject to an aging management review.
Does this gasket meet this criteria? The staff also needs more details about the seal-welded Alloy 600 diaphragm and an assessment of the need to manage the aging of this component and material.
10.
Describe the potential for (1) corrosion of the bolt holes in the carbon steel manway cover and (2) corrosion of the manway cover at the interface between the cover and insert if a leak were to occur through the gasket.
The staff considers aging management programs necessary for the bolted manway connection to ensure against cracking and loss of preload. The staff has recognized programs proposed by industry that include such elements as ASME Code Section XI " Examination Category B-G-1 & 2, (Ref.
- 2) and B-P," system leakage and hydrostatic testing, programs in response to IE Bulletin 82-02, " Degradation of Threaded fasteners in Reactor Coolant Pressure Boundary of PWR Plants," and technical specification leakage limits. Revise your topical report to include
. o aging management of the bolted connection or provide justification for not doing so.
11.
Identify components welded to the inside of the pressurizer vessel and discuss the management of cracking of these welds for the period of extended operation (If welds crack, the cracks could potentially propagate into the vessel, affecting its integrity.).
12.
Thermal sleeves have experienced age-related degradation.
Provide an evaluation of the relevant operating experience and discuss its applicability to the thermal sleeves in the scope of this report.
I 13.
The WOG does not provide any drawings or enough detail on their heater configurations and welds. The WOG (on Page 41) attributes damage to improper maintenance and states that heaters are designeri to be replaced 1
and will not impact pressurizer function.
In contrast, the industry found, and the staff agreed, that components such as stainless steel i
heater sheaths and end plugs, sleeves and partial penetration welds could crack and that cover plates are susceptible to loss of material due to boric acid wastage.
The WOG should provide more details and drawings on the heater components, indicate which parts form the pressure boundary, and discuss aging management.
14.
Describe the provisions for examining heater penetration welds.
15.
Discuss whether Inspection and Enforcement Bulletin (IEB) 79-17, which discusses pipe cracks in stagnant borated water, is applicable to stainless steel safe ends on the relief and surge line nozzles. Are any of the management programs resulting from IEB 79-17 applicable to the stainless steel safe ends or surge line nozzles?
16.
For the inspections that are intended to be performed to the ASME Code, the edition of the ASME Code the WOG is referring to should be clearly stated.
17.
To ensure the effectiveness and reliability of ultrasonic examinations performed for license renewal is it the WOG's intent to rely upon Section XI, Appendices VII and VIII? If it is not, the WOG should discuss how it will ensure the effectiveness and reliability of ultrasonic examinations.
18.
With the exception of the discussion in Section 3.2.2 relative to Generic Letter 88-05 and a reference to Bulletin 88-11 in Section 4.2, i
this GTR does not appear to include any other references to generic communications for aging effects evaluations or aging management programs. Describe the process that the WOG used for reviewing applicable generic communications and associated licensee commitments.
If any generic consnunication will be used as a part of aging management j
activities for the pressurizer, provide the basis for using such programs in Section 4.0 of this GTR.
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- 19.
Are there any small nozzles (e.g., sampling and level sensing nozzles) exempt from ASME XI examinations? If so, describe the aging management
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program for them.
j 20.
In another review, the staff agreed that cracking of the carbon steel base metal welded joints and of the stainless steel cladding are l
potential aging effects due to the possibility of having pre-service and i
service induced flaws. Discuss whether the Westinghouse pressurizer is subject to the same effects and whether it should be under an aging management program, i
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