ML17056A874
| ML17056A874 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 05/15/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17056A873 | List: |
| References | |
| GL-88-01, GL-88-1, NUDOCS 9006060245 | |
| Download: ML17056A874 (6) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 ENCLOSURE F 1 SAFETY EVALUATION-BY-THE-OFFICE-OF-NUGLEAR-REACTOR.REGULATION EVALUATION.OF-NRC GENERIC-E.ETTER-88-01.RESPONSE NIAGARA-MOHAWKPOWER CORPORATION N INE - MILE-PO INT.NUCLEAR-STATIQN UNIT-NO.
1 DOCKET.NO.-SQ-22Q
1.0 INTRODUCTION
Niagara Mohawk Power Corporation, the licensee, submitted its response to NRC Generic Letter (GL) 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping" for Nine Mile Point, Unit 1 by letter dated July 28, 1988, and additional information requested by the staff was provided by letters dated August 25, September 6 and November 30, 1989.
GL 88-01 requested Licensees and construction permit holders to resolve the IGSCC issue for BWR piping made of austenitic stainless steel that is 4 inches or larger in nominal diameter and contains reactor coolant at a temperature above 200 degrees Fahrenheit during power operation regardless of Code classification.
The licensee was requested to address the following:
1.
The current plans regarding pipe replacement and/or other measures taken to mitigate IGSCC and provide assurance of continued long term integrity and reliability.
2.
The Inservice Inspection (ISI) Program to be implemented at the next refueling outage for austenitic stainless steel piping covered under the scope of this letter that conforms to the staff positions on inspection schedules, methods and personnel, and sample expansion included in GL 88-01.
3.
The Technical Specification change to include a statement in the section on ISI that the ISI Program for piping covered by the scope of this letter will be in conformance with the staff positions on schedu les, methods and personnel, and sample expansion included in GL 88-01 (See model BWR Standard Technical Specification enclosed in GL 88-01).
It is recognized that the Inservice Inspection and Testing sections may be removed from the Technical Specifications in the future in line with the Technical Specification Improvement Program.
In this case, this requirement shall remain with the ISI section when it is included in an alternative document.
4.
The confirmation of your plans to ensure that the Technical Specifications related to 'leakage detection wi 11 be in conformance with the staff positions on leak detection included in GL 88-01.
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The plans to notify the NRC in accordance with 10 CFR 50.55a(g) of any flaws identified that do not meet IWB-3500 criteria of Section XI of the Code for continued operation without evaluation, or a change found in the condition of the welds previously known to be cracked and your evaluation of the flaws for continued operation and/or your repair plans.
2.0 D ISCUSS ION The licensee's response to NRC GL 88-01 has been reviewed by the staff with the assistance of its contractor, Viking Systems International (VSI).
The attached Technical Evaluation Report (TER) provided is VSI's evaluation of the licensee's response to NRC GL 88-01.
Although the submittals of August 25,
- 1989, and November 30, 1989, are not included in the "Documents Evaluated" section of the TER, these two submittals have been considered in the staff evaluation.
The staff has reviewed the TER and concurs with the evaluations, conclusions, and recommendations contained in the TER with the exception as follows:
TER Section 2.6 and recommendation No.
6 in Section 4.0 of the TER are not applicable to Nine Mile Point I as the current Technical Specification (TS) Amendment No.
107 issued July 7, 1989, has already incorporated the requirement of GL 88-01 regarding TS change to include an ISI statement in the TS.
This TS amendment was not part of the documents reviewed by VSI.
In the review of the licensee's GL 88-01 submittal, the staff has found the following positions to be unacceptable:
1.
The licensee s position in classifying welds between non-conforming materials and high carbon stainless steel castings as IGSCC Category A.
2.
The differences between the licensee's original submittal dated July 28,
- 1988, and RAI response dated September 6, 1989, with regard to the number of welds in each of the IGSCC categories and the number of inaccessible welds; e.g., listing several welds as inaccessible for inspection although these welds were also listed as having been inspected and/or scheduled for inspection and classified as IGSCC Category D welds.
3.
The licensee's inspection schedules for IGSCC Category D and Category G
welds and the omission of inspection plans for welds in the RWCU piping outboard of the isolation valves.
The licensee's position to exclude from the scope of applicability of GL 88-01 the welds in that portion of the RWCU system piping outboard of the isolation valves is not acceptable as it does not comply with the requirements of GL 88-01.
As a minimum, the licensee should prepare an inspection plan of the RWCU system piping outboard of the isolation valves on a sampling basis with justification for the selected sample size.
For a detailed discussion of these items refer to the TER attached to this Safety Evaluation.
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The NRC staff has reevaluated the frequency of leakage monitoring.
After discussions with several BWR operators the HRC staff concluded that monitoring every four hours creates an unnecessary administrative hardship to the plant operators.
- Thus, RCS leakage measurements may be taken every eight hours instead of every four hours as required in GL 88-01.
As a reminder, GL 88-01 requires that if any cracks are identified that do not meet the criteria for continued operation without evaluation given in Section XI of the Code, HRC approval of flaw evaluations and/or repairs in accordance with IWB-3640 and IllA-4130 is required before resumption of operation.
Please note that weld overlay repair is considered as a non-Code repair, which requires NRC approval.
ASME Code,Section XI, IWB-3640 states that piping containing a flaw exceeding the allowable flaw standards of IWB-3514.3 may be evaluated to determine its acceptability for continued service in accordance with the evaluation procedures and acceptance criteria of IWB-3641 or IWB-3642.
The evaluation procedures and acceptance criteria are subject to approval by the HRC.
3.0 GONCLUSION Based on the review of the licensee's NRC GL-88-01 response the staff concludes that the response as evaluated is acceptable with the exception of the licensee's positions as identified above.
The staff requests that the licensee address the GL 88-01 exceptions as identified above and resubmit inspection plans for IGSCC Category G and D welds as required in GL-88-01.
The plans should also include inspection of welds in the RWCU piping outboard of the isolation valves.
The staff also concludes that the proposed IGSCC inspection,and mitigation program will provide reasonable assurance of maintaining the long-term structural integrity of austenitic stainless steel piping in the Nine Mile Point Nuclear Power Plant, Unit I.
Dated:
PRINCIPAL - CONTRIBUTORS:
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