ML20029A478
| ML20029A478 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 02/19/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20029A474 | List: |
| References | |
| NUDOCS 9102250056 | |
| Download: ML20029A478 (4) | |
Text
_
((e ueg'o,j -
UNITED STATES
~
NUCLEAR REGULATORY COMMISSION
,j W ASHING TON, 0. C. 20555 g
+....
SAFETY EVALUATION BY THE OFFICE Of t'UCLEAR REACTOR REGULATION GPU NUCLEAR CORPORATION AND JERSEY CENTRAL POWER A LIGHT COMPANY OYSTER CREEK NUCLEAR GENERATING STATION DOCKET NO. 50-219
1.0 INTRODUCTION
The NRC audit team led by G. Bagchi (NRR), visited the Oyster Creek site and the Gpu Nuclear corporate office on October 31 and November 1,1990, respectively.
The purpose was to evaluate concerns identified in Section 2.3.5 of HRC Inspection Report 88-202 (Reference 1) regarding the seismic design adequacy of safety related piping outside the Reactor Building, specifically the buried Emergency Service Water line (ESW).
2.0 THE CONCERNS The following sumarizes the specific concerns, which are descri_ bed in greater detail-in Section 2.3.5 and Appendix C (under Item D-3 and D-4) of the Inspection Report (References 1 and 2).
1.
The piping specification which delineates the design criteria for
_ piping outside the reactor building stipulated that.the seismic loads be based on a ground acceleration of 0.05g horizontal and zero 1
vertical. This is_ inconsistent and less stringent than the seismic criterf a specified in the final Safety Analysis Report (FSAR), which 3
specifies a maximum horizontal ground acceleration of 0.229 for the Safe Shutdown Earthquake (SSE), and a simultaneous consideration of a vertical component equal to 2/3 of the-horizontal.-
2.
The stress allowable of 3S used in the ESW-seismic reanalysis report forthecaseoftheupsetEonditionwasdrawnfromaversionofthe AStiE code that was 'later than the licensee's Code of Record. According.
.to FSAR Section'3.7.3.2, the requirements of ANSI B31.1-1983 shall be met. -;The upset condition stress allowable according to B31.1 is 1.2S
- Furthermore, the calculated maximun stress of 62.52ksi even exceeded h the 35, limit of 48ksi.
3.0- EVALUATION During the site visit and the subsequent meeting, the NRC staff discussed with the-licensee the issues of concern, performed a-walkdown of the ESW piping, audited relevant documents, and interviewed select licensee personnel. The findings are summarized below:
9102250056 910219 hDR ADOCK 05000229 PDR
- - - -. - _ -... -. - - -.. - _. -. -. -. ~.. - -.... -,,... - _.. _. -.. -.,.. -.
-l
-2
- 1.
For Concern No. 1:
The -licensee indicated that the seismic load corresponding to 0.05g horizontal and zero vertical was delineated in Burns & Roe Specification S-2299-48 in 1965 for-non-seismic-piping, and that its intent was further clarified in Specification S-2299-60.
For seisnic category I piping, the FSAR criteria were actually used (Reference 2, Item D-4).
The staff audited relevant documents and found the following:
The Oyster Creek plant was designed in the mid-60s.
In its original a.
FOSAR, Section 3.1.1 and 3.1.2 of Reference 3, the design of seismic category 1 piping for the SSE was based on a ground motion of 0.22g with a simultaneous vertical _ motion equal to 2/3 the horizontal. A 0.279 Housner Spectrum was used.
b.
Specification S-2299-60-A,B,C stated that dynamic analyses shall be performed for all _ seismic category I piping 10".and larger. For piping smaller than 10", design coefficients for peak accelerations of 0.439 horizontal and 0.299 vertical shall be used (Page 11-51, Reference 4).
c.
In 1977, NRC initiated the Systematic Evaluation Program (SEP).
Two years later, NRC Bulletin 79-14 " Seismic Analysis for As-Built Safety-Related Piping Systems" was issued. Piping and seismic considerations for older plants including Oyster Creek were reevaluated to ensure adequacy. -In 1983, NRC issued-the Oyster Creek Integrated Plant Safety Assessment (IPSA) report which concluded.the Oyster Creek systematic evaluation program (SEP) efforts (Reference 5).
For issues related to seismic category 1: piping, only 10 and smaller piping remained open.
However, the open issue was subsequently closed in 1989_.(Reference 6).
Although both the SEP and Bulletin 79-14 efforts reevaluated only
. selected. piping systems, the staff found that the seismic-design adequacy of seismic category I piping systems in_ the Oyster Creek plant was accep_ table (Reference 6).
d.
During the SEP review in'1981, the staff accepted-the site specific spectrum for the Oyster Creek plant (Reference 7). That spectrum
._ reduced the maximum ground acceleration from 0.229 to 0.165g.
-The NRC-staff audited the licensee's original earthquake analysis of e.
-the ESW piping performed in 1967 (Reference 8) and the subsequent reanalysis conducted-in 1979 for the SEP (Reference 9).
In both calculations, a_ ground acceleration of 0.22g was used to calculate deflections of the buried piping under soil seismic wave motions.
2.
For Concern No. 2 The licensee indicated that their seismic reanalysis of the buried ESW piping (Reference 9), which used the 3S stress allowable for the SSE as an m
~
. operability criteria, was accepted by the NRC staff in the SEP evaluation.
Although the updated FSAR in 1984 required that seismic category I piping meet ANSI B31.1-1983 code criteria, such a requirement was not imposed for piping systems not reanalyzed under Bulletin 79-14, which included the ESW piping.
As a result of the inspection concern, the licensee has committed to amend the FSAR to include those piping systems (Reference 2, item D-3).
The following summarizes the findings:
In response to an NRC request for information during the SEP review, the a.
licensee submitted its seismic reanalysis of the buried ESW piping on June 3, 1980 (Reference 10). The subsequent final IPSA report issued by the NRC in 1983 (Reference 5), which completed the Oyster Creek SEP efforts, did not include the ESW in the list of open issues.
Thus NRC acceptance of the report (Reference 9) under the SEP review in 1983 was verified.
b.
The code of record for Oyster Creek was ANSI B31.1-1955. The original FDSAR issued in 1968 (Reference 3) did not specify seismic stress allowables for the piping design. The seismic requirements were defined more clearly in the updated FSAR in 1984 due to SEP and Bulletin 79-14 efforts, which endorsed ANSI B31.1-1983 (Reference 2). The staff agrees with the Inspection Report concern that stress allowables in the ASME code should not be used in the ANSI design, and that the allowable of 35 for Cisss 1 piping is a faulted plant condition instead of an upset coEditionasindicatedintheconcernoftheInspectionReport (Reference 2, Item D-3), and that Oyster Creek was a plant constructed to a Code that did not specify seismic stress allowables, the SEP acceptance of a more relaxed stress allowable of 35,(instead of 2.4S )
is understandable.
h c.
The NRC staff' concurs with the licensee that the stresses calculated in the reanalysis of the buried ESW (Reference 9) were within the limit of 35,when the less stringent site specific spectrum was used.
d.
During the walkdown of~the ESW piping, the NRC staff did not observe any unusual ground settlement in the area adjacent to the ESW piping, since any such settlement may adversely constrain the buried pipe, e.
A senior licensee engineer who was interviewed during this audit indicated that, to the best of his knowledge, he did not recall any recorded or observed settlement in the adjacent areas of the buried ESW piping.
4.0'~ CONCLUSIONS Based on evaluation stated above, the NRC staff concludes that:
(1) Consistent and adequate seismic inputs were apparently incorporated in the design of seismic category I piping at the Oyster Creek plant; and that l
l l
l
>> s
~ (2) :The staff concurs that the seismic design of the buried ESW piping, including the SSE stress allowable,_was reviewed and accepted in the
= previous SEP review. No compelling evidence was uncovered during this audit that revealed a significant safety-concern which would justify
_thejreopening of this issue. However, the licensee should take
-appropriate action to ensure that the updated FSAR criteria will be consistently implemented _in all cases of reanalysis of seismic category 1-piping systems, and not just for those which were reanalyzed under Bulletin 79-14
-5.0' PEFERENCES
-1.
-NRC Inspection Report 88-202, February 17, 1989 2.
Letter, GPU-Nuclear Corporation to NRC, " Safety Systems Outage Modification Inspectior., Response to Report 88-202", 500-89-1772, May 31,-1989
-3.
Oyster Creek original _ FOSAR,1968 4.
Specification S-2299-60-A,B,C, " Phase 1 - Piping,. Reactor Building, Main Mechanical Equipment-Installation and Miscellaneous Equipment Specification"
'S.-
HUREG-0822', " Final Report - Integrated Plant Safety Assessment,
_ Systematic Evaluation Program, Oyster Creek Nuclear Generating Station", January 1983 6.
Letter, A. W. Dromerick (NRC)1to E. E. Fitzpatrick (GPUN),
August 30,_1989 y
i 7.-
Letter,_D. M. Crutchfield to all SEP owners, " Site Specific Ground Response-Spectra for Plants Located in the Eastern United States",
i June.8719811
-8.
Report, John A. Blume & Associates, " Seismic Analysis of Underground Emergency' Service Water Lines", November 20, 1967
-.9. -
Report, URS/ John A.__Blume & Associates, " Seismic Reanalysis of_ the Buried Emergency Service Water Lines", December 19, 1960 10.< Letter, Y.- Nagai (GPUN) W. A. Paulson (NRC), _"SEP-Topic 11-6,
.-Seismic-Considerations", June 3, 1980
-Principal Contributor:
S. Heu -
Date:1 February 19, 1991