ML20210J573

Safety Evaluation Denying Relief Request for Plant Third 10-yr Interval Program for Inservice Testing of Pumps. Request Not in Sufficient Detail to Justify Proposed Alternative

ML20210J573
Person / Time
Site:	Cooper
Issue date:	08/13/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20210J570	List: ML20210J565 ML20210J573
References
NUDOCS 9708180145
Download: ML20210J573 (3)

Text

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p.ur p- .k UNITO STATES

.  :; NUCLEAR REEULATCRY CEMMISSIEN WAeHINGToN, D.C. 30046 4001 k ....+

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TES11NG PRMBM NEBRASKA PUBLIC POWER DISTR!fd COOPER NUCLEAR STATION DOCKET NUMBER 50-298

1.0 INTRODUCTION

The code of federal Regulatfons,10 CFR 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Bof fer and Pressure Vessel Code (the Code) and applicable addenda, except where alternatives have been authorized or rellef has been requested by the licensee and granted by the Commission pursuant to Sections (a)(3)(1),

(a)(3)(ii requesting),orrelief, (f)(6)(1) theoflicensee 10 CFRmust 50.55a.

demonstrate t1at:In pro)osing (1) the proposedalternatives or alternatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for its facility. Section 10 CFR 50.55a authortzes the Commission to approve altsrnatives and to grant relief from ASME Code requirements upon making the necessary findings. Guidance related to the development and implementation of IST programs is given in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," issued April 3,1989, and its Supplement 1 issued April 4, 1995. Also see NUREG-1482, " Guidelines for Inservice Testin Clarifications, gand at Nuclear GuidancePower Plants,"Requests on Prepart.1g and NUREG/CR-6396, for Relief from Pump " Examples, and Valve Inservice Testing Requirements."

The 1989 Edition of the ASME Code is the latest edition incorporated by reference in paragraph (b) of Section 10 CFR 50.55a. Subsection IWV of the 1989 Edition, which gives the requirements for IST of valves, references Part 10 of the American National Standards Institute /ASME Operations and

1. aintenance Standards (OM-10) as the rules for IST of valves. OH-10 replaces s)ecific recuirements in previous editions of Section XI, Subsection IWV, of tie ASME Coc e. Subsection IWP of the 1989 Edition, which gives the requirements for IST of pumps, references Part 6 of the American National Standards Institute /ASME Operations and #afntenance Standards (OM-6) as the rules for IST of pumps. OH-6 replaces specific requirements in previous editions of Section XI, Subsection IWF, of the ASME Code.

By letter dated October 25, 1996, the Nebraska Public Power District (licensee) submitted a relief request, RP-05, for Cooper Nuclear Station, third ten-year interval program for inservice testing of pumps. RP-05 is evaluated below. The Cooper Nuclear Station IST Program was developed to the 1989 Edition of ASME Section XI for the third ten-year interval that began March 1, 1996.

ENCLOSURE 9708180145 PDH 970813 E P

ADOCK 05000298 PDR

l l 2.0 RELIEF REQUEST RP-Db RP-05 requests relief from DM-6 Table 3b, with regard to the differential pressure acceptance criteria for vertical line shaft pumps. This relief request pertains to service water pumps, SW-P-A, B, C, and D.

l 3.0 LICENSEE'S RASIS FOR REQUEST The licensee provided the following basis for the relief request:

Previous experience has shown that the high silt content of Missouri River decreases the life of the service water pump internals. Under the rules of the 1981 ASME Code (Section XI), pump differential pressure was allowed to degrade to 0.90$P before corrective action was required.

Whenthisconditionwasreached,thepumpliftwasadjusted,the baseline was re-established, and the pump was returned to service. The OM Code requires corrective action when the differential pressure is

<0.95[0.93]AP.r The average differential pressure after a lift adjustment is 63 psid.

The required action level would-be <58.6 psid. However, the service water pump can meet their design basis required flows of 5500 g>m with a minimum differeatial pressure of 56.2 psid. The new limit in tie ON Code results in more frequent pump maintenance. The difference in the acceptance criteria between the 1981 ASME Code and the 1988 OMa Part

. 6 is only 35. This difference is insignificant when compared to the cost of manpnwer required to perform pump maintenance without providing a compensating increase in the level of quality and safety.

4.0 PROPOSED ALTERNATE TESTING The licensee proposed the following:

The low alert level for the service water pumps differential aressure will be 0.90 to <0.936P,. The low required action level shal; be

<0.906P,. A pump differential pressure <56.2 psid at 5500 gpm will not be acceptable for continued operation.

5.0 EVALUATION OM-6, Table 3b, has tighter acceptance criteria for flow and differential pressure than those included in earlier editions of Section XI for vertical line shaft pumps (.93 versus .90). NUREG/CP-0111. " Proceedings of the Symposium on Inservice Testing of Pumps and Valves," states that this change came about because of inherent deficiencies in vibration testing of vertical line shaft pumps and positive displacement pumps. Also, a discussion of this issue .is found in NUREG-1482, Section 5.9.

The licensee has requested relief from the OM-6, Table 3b, alert range of (0.93 to 0.95)oP, and the required action values of <0.92P,. The-proposed

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3 alternatives ([0.90 to 0.93 for required action values The difference) arethe less restrictive, based on}AP,1981 edit range and <0.906P, for alert in the applicable acceptance criteria between the 1981 and 1989 ion o Code editions is 3%. The licensee stated that this difference is insignificant when compared to the burden of performing the test, without i prov' ding a compensating increase in the level of quality and safety.

It is not evident from the infonnation presented that the difference of 3% in the acceptance criteria is insignificant when com)ared to the hardship involved in performing the test. The statement t1at " previous experience has shown that the high silt content of Missouri River decreases the life of the service water pump internals" may justify additional testing, not less as proposed by the licensee. Also, meeting the minimum pressure differential of 56.2 psid at 5500 gpa is a system requirement that is generally not acceptable as a justification for relaxing the component level acceptance criteria used in inservice testing. Further, the basis does not address areas considered to be relevant to this relief request, such as (1) past test and maintenance data, including those related to adequacy of vibration testing, (2) details of the hardship involved (3) the acceptability of the proposed testing, considering the discusston on vertical line shaft pumps contained in NUREG-1482, Section 5.9, and (4) manufacturer's technical specifications and recommendations. The basis for relief, as presented, is not sufficient to justify the proposed alternative. Relief is therefore denied, f

6.0 CONCLUSION

Based on the determination that the relief request is not in sufficient detail to justify the proposed alternative, relief as requested is denied.

Principal Contributor: K. Dempsey Date: August 13, 1997 w w i %. +=aww y .ww w< .._.m.we