ML20141D978
| ML20141D978 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 06/24/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20141D977 | List: |
| References | |
| NUDOCS 9706300167 | |
| Download: ML20141D978 (4) | |
Text
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,j NUCLEAR REGULATORY COMMISSION
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WASHINGTON, D.C. 20565 4001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.106 TO FACILITY OPERATING LICENSE NO. NPF-42 WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NO. 50-482
1.0 INTRODUCTION
By letter dated March 21. 1997, as supplemented by letter dated April 15, 1997. Wolf Creek Nuclear Operating Corporation (the licensee) requested changes to the Technical Specifications (Appendix A to Facility Operating License No. NPF-42) for the Wolf Creek Generating Station. The proposed changes would revise the reactor coolant pump (RCP) flywheel inspection schedule specified in technical specifications (TS) 6.8.5.b and delay the 10-year examination for the "D" RCP.
A typographical error in TS 6.8.5.c would also be corrected.
2.0 BACKGROUND
The function of RCP in the reactor coolant system (RCS) of a pressurized water reactor (PWR) plant is to maintain an adequate cooling flow rate by circulating a large volume of primary coolant water at high temperature and pressure through the RCS.
A concern regarding overspeed of the RCP and its potential for failure led to the issuance of Regulatory Guide (RG) 1.14
" Reactor Coolant Pump Flywheel Integrity" in 1971.
Since then, licensees for PWR plants, with very few exceptions, have adopted the guidelines of RG 1.14 to conduct their RCP flywheel examinations.
These requirements are normally specified in the individual plant's TS as is the case for Wolf Creek and specify in part, that (1) an in-place ultrasonic examination of the areas of higher stress concentration at the bore and keyway should be performed at approximately 3-year intervals, and (2) a surface examination of all exposed
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surfaces and complete ultrasonic volumetric examination should be performed at l
approximately 10-year intervals.
In Westinghouse Topical Report. WCAP-14535. " Topical Report on Reactor Coolant Pump Flywheel Inspection Elimination." information intended to eliminate examination of the RCP flywheels was provided.
The staff reviewed this report as documented in a safety evaluation report (SER) forwarded by a letter from Brian W. Sheron (USNRC) to Mr. Sushil C. Jain dated September 12, 1996.
" Acceptance for Referencing of Topical Report WCAP-14535. ' Topical Report on l
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9706300167 970624 PDR ADOcK 05000482 P
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. Reactor Coolant Pump Flywheel Inspection Elimination'." This SER concluded that a revised inspection schedule was justified for (1) flywheels made of SA 533 B material that do not belong to Group 10 and 15 and for (2) flywheels made of SA 533 B material that belong to these two groups if justified by some l
additional analyses.
To justify a change in the flywheel inspection interval l
for flywheels not made of SA 533 8 material, an assessment must be made using i
a methodology similar to that in WCAP-14535.
In addition to changing the RCP flywheel inspection schedule as specified in TS 6.8.5.b. the licensee also requested to delay the 10-year examination for the "D" RCP and to correct a typographical error in TS 6.8.5.c.
i 3.0 EVALUATION The RCP flywheels at Wolf Creek are-fabricated from SA-533 B material and do not belong to Group 10 and 15. As a result, the revised RCP flywheel inspection schedule specified in the September 12, 1996, letter is applicable to Wolf Creek. This revised inspection schedule requires conducting a qualified in-place ultrasonic-testing (UT) examination of the volume from the inner bore of the flywheel to the circle of one-half the outer radius or conduct a surface examination (magnetic particle (MT) and/or liquid penetrant (PT)) of exposed surfaces of the removed flywheels once every 10 years.
As a result of a change to the RCP refurbishment schedule, the 10-year examination of the RCP "D" flywheel as specified in RG 1.14 (i.e., the requirement in 31 ace prior to this amendment) was not performed prior to the completion of t1e 10-year inservice inspection interval, including the extension allowed by Section 11 of the American Society of Mechanical Engineers Code (ASME Code). As discussed above, this 10-year inspection involves a surface examination of all exposed surfaces and complete ultrasonic examination.
During an NRC inspection conducted in October 1996, the NRC indicated that this exception should have been reviewed and approved by the NRC as a change to the TS.
For the RCP "D" flywheel, the licensee would still not meet the inspection recuirements specified in TS 6.8.5.b even with the new requirements being proposec with this amendment request.
As a result, the licensee has proposed an exception to the currently proposed TS 6.8.5.b examination requirements until the Fall 1997 refueling outage at which time the 10-year volumetric and surface examination will be completed for the RCP "D" flywheel (this 10-year requirement would be per the revised inspection schedule discussed above).
Although the 10-year examination specified in RG 1.14 (which is referenced in the TSs) was not performed, the 3-year examination specified in RG 1.14 was completed as scheduled in September 1994 with no indications identified. This 3-year examination was a volumetric examination of the higher stress areas and was aerformed from the gage holes to the bore and keyways. The radius of the flywieel is 37.5-inches and the gage holes are 14.5-inches from the center of the flywheel. This 3-year examination. therefore, covered slightly less than
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the circle of one-half the outer radius as would be required by 'N currently however, the inspections proposed revision to TS 6.8.5.b. as discussed above:
Jerformed were concentrated on the areas of higher stress concentration at the
) ore and keyway. To justify delaying the performance of the examination of the RCP "D" flywheel until the Fall 1997 refueling outage, the licensee cited the NRC SER dated September 12, 1996, the low probability of RCP motor flywheel failure as documented in WCAP-14535, and oerformance of the 3-year examination (as specified in RG 1.14) on the RCP ")" flywheel in September t
1994.
The staff concludes that the licensee's proposal to delay the 10-year l
volumetric / surface examination for the RCP "0" flywheel to the Fall 1997 refueling outage is acce) table based on industry inspection results to date l
and the performance of tie 3-year examination specified in RG 1.14 in l
September 1994.
The licensee also requested to correct a typographical error in TS 6.8.5.c on l
the Containment Tendon Surveillance Program.
Specifically the licensee l
recuested to correct the date of Oraft Revision 3 of RG 1.35. The licensee incicated that this regulatory guide was issued in April 1979 rather than April 1989, the date in the TS.
The staff finds the proposed change ac:eptable.
The staff has determined that the proposed revisions to the TSs are The revisions include a change to the overall RCP flywheel acceptable.
inspection schedule, a one-time exception to the requirements of the inspection for the RCP "D" flywheel, and correction of a typographical error.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Kansas State Official was The State official had no notified of the proposed issuance of the amendment.
comments.
5.0 ENVIRONMENTAL CONSTDERATION The amendment changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative The Commission has previously issued a occupational radiation exposure.
proposed finding that the amendment involves no significant haz 27803). Accordingly, the amendment meets the eligibility criteria for Pursuant to 10 CFR categorical exclusion set forth in 10 CFR 51.22(c)(9).
51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
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6.0 CONCLUSION
The Commission has concluded, based on the consideraticas discussed above.
that:
(1) there is reasonable assurance that the heelth and safety of the public will not be endangered by operation in the proposed manner. (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Centributor:
K. Karwoski I
Date:
June 24, 1997 i
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