ML19309B432
| ML19309B432 | |
| Person / Time | |
|---|---|
| Site: | Vallecitos File:GEH Hitachi icon.png |
| Issue date: | 03/21/1980 |
| From: | Nelson C Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19309B433 | List: |
| References | |
| NUDOCS 8004040142 | |
| Download: ML19309B432 (2) | |
Text
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NUCLEAR REGULATORY COMMISSION
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March 21, 1980 Docket No. 50-70 LICENSEE:
Gsneral Electric Company (GE)
FACILITY: General Electric Test Reactor (GETR)
SUBJECT:
SUMMARY
OF MEETING WITH GE REGARDING THE GETR SEISMIC REVIEW On January 31, 1980, a meeting was held in Bethesda, Maryland, to discuss the probability analysis proposed by GE to support restart of the GETR.
In additior, the combination of offset and ground acceleration; the recent earthquakes in the Livermore Valley region; NRC staff questions regarding the GETR eigineering analysis and additional >icensee work in the landslide stability area were discussed.
The NRC staff, GE staff and their respective consultants attended.
A list of attendees is enclosed as Enclosure 1.
1.
GE Probability Analysis The probability analysis of surface rupture beneath the GETR was presented for discussion. A similar presentation was made at the ACRS subconunittee meeting in November 1979 and a copy is enclosed as Enclosure 2.
The NRC staff and its consultants questioned tne assumed independence of offsets between the known shears from the known shears.
In addition, the probability of offset was based on a distribution which did not correctly consider the period since the last known offset. Also the comment was made that the model used had not demonstrated its acceptability by comparison to known events.
A copy of the NRC staff's comments are Enclosure 3.
The NRC staff indicated it would explore, with the assistance of consultants, quantification of an acceptable value of probability for fault offset.
The only available guidance is that set forth in the siting criteria,10 CFR Part 100, Appendix A, which is not explicitly based on probabilistic considerations.
GE agreed to review the concerns raised during the meeting and supplement its probability analysis as necessary.
2.
Combined Offset and Vibratory Ground Motion The validity of separating (in time) peaks of strong ground motion from surface offset was discussed.
The licensee reiterated arguments made in previous sub-mittals to support separation (in time) of the two events.
The staff and its consultants recommended consideration of a realistic rupture-ground motion model as a possible way to better define the time relationship between peak ground motion and offset. The staff also noted that in some events shaking increases as the rupture passes which supports its position of coincidence.
3.
Recent Earthquakes in the Livermore Valley Region The licensee presented records obtained from seismic recorders at GETR during 8 004 0 4 6 d2 -
- v.
. earthquakes which occurred on January 24 and 26, 1980.
These records were not of a quality to reproduce for this report. The licensee was informed that any use of near field data to develop a site specific response must consider this data as well as other near field data such as from the Imperial Valley and the Coyote Lake, 1979 events.
GE agreed to review the potential use of near field data.
4.
Engineering Questions The NRC staff provided a list of engineering questions based on its review of the most recent GE submittals regarding the GETR structures. A copy of these ques-tions are enclosed as Enclosure 4.
GE committed to answer these questions.
5.
Landslide Stability Additional slope stability calculations to satisfy NRC concerns about the assump-tions in GE's Landslide Stability Report, July 1978, were discussed.
These cal-culations might involve:
a.
varying the shape of the assumed failure plane, b.
reducing the cohesion used in the shear strength properties, and c.
considering variations in hillside groundwater flow conditions.
In addition the need for a limited drilling and lab testing program to support the calculations was discussed.
The licensee acknowledged the usefulness of slope deformation monitoring equipment for future seismic events and plans to evaluate installing such equipment.
Conclusion Subsequent to the discussions above, the NRC and GE staffs discussed the schedule for the next ACRS subcomittee meeting with the ACRS staff.
It was proposed that this meeting be rescheduled from February 22, 1980, to the week of March 31, 1980.
A/Cb kk Chris Nelson, Project Manager Operating Reactors Branch M Division of Operating Reactors
Enclosures:
1.
List of Attendees
'2.
Prob. Analysis of Surface Rupture Offset 3c
" NRC Comments 4.
NRC Questions on GETR Structures cc w/ enclosures:
See last page
GETR MEE_ TING - January 31, 1980 EARTH F.'IENCE NRC GE ASSOCIATES Chris Nelson Dwight Gilliland Richard Meehan Sandra Wastler Robert W. Darmitzel Dick Harding Robert E. Jackson Gary L. Crellin Roland Sharpe Joseph Martore Ed Firestone John T. Greeves Kevin P. Gallen B. D. Liaw E. G. Igne W. P. Gamill H. R. Denton LAWRENCE LIVERMORE N_ATIONAL LAB & TERA CORP.
R. L. Tedesco M. Wohl Don Bernreuter S. A. Treby Larry Wight Daniel Huang Marshall Payne R. W. Reid W. Veseley W. Burkhardt Dan Swanson USGS Philip S. Justus Ina B. Alterman Robert H. Morris Leon Reiter James F. Devine Darrell Eisenhut i
.