ML20247B341
| ML20247B341 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 03/24/1989 |
| From: | Marsh L Office of Nuclear Reactor Regulation |
| To: | Jabbour K Office of Nuclear Reactor Regulation |
| References | |
| TAC-72252, TAC-72253, NUDOCS 8903290363 | |
| Download: ML20247B341 (3) | |
Text
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UNITED STATES p
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Doc'ket No.:
50-413/414 MEMORANDUM FOR:
K. Jabbour, Project Manager Catawba Units 1 and 2
. Division of Reactor Projects III I
FROM:
Ledyard B. Marsh, Chief Mechanical Engineering Branch Division of Engineering & Systems Technology
SUBJECT:
TECHNICAL SPECIFICATION INTERPRETATION ON SNUBBER TESTING TO RESOLVE INSPECTOR FOLLOW-UP ITEM CATAWBA UNIT 1 AND 2 (TAC NO. 72252/72253)
REFERENCE:
Memorandum for Gus Lainas, NRR from A. F. Gibson, Region II Request for Clarification, Dated February 19, 1988.
INTRODUCTION In October 1987, during the second refueling outage for Catawba Unit 1, Duke l
Power Company performed functional testing of snubbers to comply with-Technical i
Specification (TS)4.7.8. The licensee used their Technical Specification interpretation (Attachment I, Reference 1) to determine the number of additional snubbers required to be tested when functional test failures were identified.
Duke Power stated that the basis for their interpretation was a November 10, 1987 discussion with NRR.
Region II has questioned the validity of the licensee's interpretation and has requested NRR for clarification.
3 1
DISCUSSIGN Licensee's interpretation, in the opinion of Regional staff, appears to be in conflict with the requirements of TS 4.7.8.e.2 and TS Figures 4.7-1.
Their interpretation calls for grouping of similar snubber functional test failures into test failure mode groups and counting each group as single failure when computing C, the total number of snubbers of a type not meeting functional test acceptance requirements. The total number, N, of snubbers required to be tested is based on this adjusted C value.
The specific problem identified during the inspection. concerns the functional testing of mechanical snubbers manufactured by Pacific Scientific Company (PSA). The capacity of the snubbers involved range from size PSA 1/2 through PSA 35.
During the outage, the licensee selected a random sample of 37 snubbers for functional testing in accordance with sample plan 2 of TS 4.7.8.e.
One PSA 3 and two of the PSA 1/2 snubbers tested failed to meet the functional test acceptance criteria.
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An additional sample of 54' snubbers was selected and tested due to these failures. Five snubbers (one.PSA 3, one PSA 1, and three PSA 1/2) failed the functional test when these' additional 54 snubbers were tested. The licensee then selected and tested an additional sample of 36 snubbers. Two more.
functional test failures (both PSA 1/2) were recorded. At this point, the licensee concluded that the seven PSA 1/2 snubber functional test failures were a result of design and/or manufacturing and declared these as a single'
.i failure mode group counting as one failure in accordance with their TS inter-pretation. The number of snubbers tested and number of test failures are shown in the table below.
TABLE l
Snubber Total Number Total Number
" Adjusted" Number l
Size (Type)
Of Size Tested Of Test Failures Of Faibres PSA 1/2 56
'7 1
3 TOTAL IFl IU T
Afterselectionofthefailuremodegroup(sizePSA1/2),thelicenseetested all (approximately 600) model PSA 1/2 snubbers installed in Unit 1.- An additional 68 PSA 1/2 snubbers failed to meet the functional test acceptance criteria. However, the licensee determined that they met'the requirements of TS 4.7.8.e.2 and Figure 4.7-1 by using C=4 for total number of failures and calculated that they were required to test a total of 109 snubbers. Since they-had tested 127_ snubbers of all sizes before declaring the failure mode.
group, the licensee concluded they complied with the TS.
Region II disagrees with the interpretation and the licensee's reasoning. The licensee appears to have substituted the words " Failure Mode Group" for the word " Type" in the TS.
Region II agrees with considering the PSA 1/4'and PSA 1/2 snubbers as a separate Type and testing all of the snubbers of this size as a separate group.
However, the number of other Type snubbers to'be tested, N, based on C=3 (one PSA 1 and two PSA 3 test failures), equals 91~(see Figure i
4.7-1).
Therefore, the licensee was required to test 91 snubbers of the Type (size) PSA 1 through PSA 35. Since the licensee only tested 71 of this Type, it appears they are in violation of their TS.
i CONCLUSION AND INTERPRETATION Based on a review by EMEB and our consultants at the Brookhaven National Laboratory we conclude that it was appropriate for Catawba to have set up a separate test group for the PSA 1/4 and 1/2 snubbers since the relatively large number of failures of that type of snubber were attributable to a " manufacturer or design deficiency." The TS (Catawba 14.7.8g and Westinghouse 14.7.9c) require that al1~ snubbers of the same type, subject to that deficiency, be functionally tested. This testing is independent of the functional testing for the rest of the snubber population.
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i Mr. K. Jabbour With regard to the reference memorandum, we concur with Region II that the PSA 1/4 and 1/2 snubbers which were tested prior to the establishment of the single failure made group should be excluded from the function test group for the general population (PSA 1-PSA 35). This group is considered by the i
definition of 14.7.8a to be one inspection type.. Since "N" is defined to be the cumulative number of snubbers of a Type tested, then this test group requtres testing of 91 snubbers for 3' failures. Therefore testing 71 snubbers in the PSA 1-PSA 35 group as done by Catawba is not in accordance with TS requirements. ASME/ ANSI OMa-1988 in 13.2.4.3 also supports this conclusion.
Original Signed By, L D. Mmb, Chief Ledyard B. Marsh, Chief Mechanical Engineering Branch l
Division of Engineering & Systems Technology 1
CC:
L. Shao J. Richardson l
G. Lainas M. Reich H. Shaw DISTRIBUTION
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