ML19318A755
| ML19318A755 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 06/11/1980 |
| From: | Nelson C Office of Nuclear Reactor Regulation |
| To: | Clark R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8006240113 | |
| Download: ML19318A755 (2) | |
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'o, UNITED STATES 8
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Docket No. 50-70
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MEMORANDUM FOR: Robert A. Clark, Chief, Operating Reactors Branch #3, DL FROM:
Chris C. tJelson, Project Manager, Operating Reactors Branch #3
SUBJECT:
GETR ACRS SUBCOMMITTEE MEETING (JUNE 16 & 17, 1980)
A.
GETR ACRS Concerns Following the GETR ACRS subcommittee meeting in November 1979, the ACRS requested that the staff discuss a number of topics at the next subccmmittee meeting on this subject. Two of the topics are:
1.
A specification by the staff of what probability of surface faulting they would deem sufficiently low to be ignored.
2.
A discussion by the staff of the influence that overall facility risk has in their specification of acceptable seismic criteria.
Based on the conduct of the staff's review to date, I propose the following responses:
1.
The staff cannot ignore the potential for surface faulting at the GETR site based solely on a low value of probability. Although the proba-bility analyses and/or their results have received favorable reviews, the sparsity of data needed to establish geologic input assumptions; '
the limited knowledge of rupture location preference within a' capable fault zone;'and the absence of testing the analysis methods against well known examp,les of surface faulting contribute to a lack of staff confidence in probability analyses deciding if~ surface faulting should or should not be a GETR design basis.
The results of the probability analyses were considered in arriving at the staff's position of one meter offset beneath the facility.
2.
WhentheOrderwasissued(October 24,1977) it had been determined that the consequences of a seismic event more severe than the GETR design basis could exceed the exposure guidelines of 10 CFR Part 100.
This determination, that there is some risk, has-cuided the staff in its specification of the proper design bases. No additional consideration of overall facility risk has been proposed or evaluated in arriving at acceptable seismic criteria.
B.
NRC Review of Structures and Systems The NRC staff has not issued its evaluation regarding the adequacy of GETR's systems and structures during the design basis seismic events.
In fact, since the design bases specified in our May 23, 1980 SER are more severe than used in 8 0062.4 0 l1.3 0
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Robert A. Clark GE's structural-analyses, additional information is needed to complete our review and.will be requested this week. Despite the lack of staff SER, GE will make a four hour presentation regarding this topic to the ACRS followed by an hour staff presentation of its revi.ew status.
GE hopes by doing this, to avoid. future subcommittee meetings.
It is my intent to remind the ACRS at the start of the meeting that although the review of systems and analyses has been favorable thus far the staff has not issued its evaluation on the adequacy of the facility and has requested additional information regarding this subject.
I will also state that the staff presentation will be a status of the review of analysis methods and criteria.
ft should be noted that there is still the issue of landslide hazard to be analyzed by GE and evaluated by the staff as part of the seismic design bases determination. This is likely to be the critical path for completing the staff's SER for GETR.
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Original :;nad by Chris C. Nelson, Pro, ject Manager Operating Reactors Branch #3-Division of Licensing cc:
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