ML20213E421
| ML20213E421 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 04/28/1983 |
| From: | Rolonda Jackson Office of Nuclear Reactor Regulation |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| CON-WNP-0586, CON-WNP-586, RTR-NUREG-0800, RTR-NUREG-0892, RTR-NUREG-800, RTR-NUREG-892 NUDOCS 8305090248 | |
| Download: ML20213E421 (5) | |
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APR 2 8 E33 GSB RDG t'Ef'OPAtiDU ' FOR:
Al Schwencer, Chief Licensing Branch t'o. 2, DL FR0ft:
Robert E. Jackson, Chief Geosciences Branch, DE SUPJECT:
GEOSCIENCES BRAf?CH REVIEW /C0f!CURREilCE OF UNP-2 SSER #3 Attached is the draft of the WNP-2 SSEP. #3 sent to us for concurrence on Section 2.5.1.
Please note that in accordance with your memorandum of April 26 to J. Knight, a statement has been added to relate the review to appropriate sections of the SRP (t'llPEG-0800). Othenvise Section 2.5.1 is acceptable as written.
If you have further questions, please contact Dr. Ina B. Alternan, Geologist, on x27856.
"y bld C J u.1. I p'Pebe.rt E. Jacksan, Chief
.- Geosciences Branch Division of Engineering i
Attachment:
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1 2 SITE CHARACTERISTICS
- 2. 5 Geoloay. Seismolocy, and Geotechnical Engineering 2.5.1 Basic Geologic and Seismic Information 2.5.1.3 Volcanic. Hazards 2.5.1.3.1 Ashfall In the SER-OL, Supplement No.1 (SSER-1) Appendix G, the staff and the United States Geological Survey (USGS) indicated that the FSAR estimates of the uncompacted thickness of ashfall and the rate of fall fell short of more recently developed estimates by the USGS based on experience with the May -
1980 Mt. St. Helens eruption.
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Although the compacted design thickness chosen (7.4 cm or 3 inches) was con-sidered conservative, the uncompacted thickness was based on earlier estimates of 20% to 40% compaction of loose ash.
As was pointed out by the USGS (SSER-1, page G-11), a compaction factor of up to 75% was measured for the May 18, 1980 Mt. St.'.Helens eruption.
Although the validity of this latter figure had not been determined when SSER-1 was written, it was considered pru'ent to use a d
more conservative estimate than 20% to 40%--somewhere between 50% to 60%.
This higher estimate would result in a maximum of 18.5 cm (7.4 inches) of loose ash.
The rate of ashfall for a 20-hour period, based on the earlier FSAR percent compaction estimates of 0.37 cm/hr (0.15 inches /hr) would result from the compacted thickness of 7.4 cm (3 inches).
Therefore a higher rate based on the more recent unccmpacted ash estimates was suggested, the average being 0.92 cm/hr (0.36 inches /hr) and the maximum 1.1 cm/hr (0.44 inches /hr) for the Katmai volcano rate.
04/22/83 2-1 WNP-2 SSER 3 SEC 2
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I Based'on these differences between the ap lit ant's estimates on the one hand, I
and those of the NRC staff and the USGS. cQ e other, the applica'nt committed to set up a task force to evaluate and recommend a plan to incorporate the new information.
On October 4, 19,82, the applicant submitted an'FSAR supplement using the maximum compacted (3. inches) and uncompacted (7.4 inches) ashfall thicknesses and the average and maximum rates (0.35 inches /hr and 0.44 inches /hr, respectively) for the design-basis ashfall. The c.T f i
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Jhe new figures have,sresulted in proposed, revisions to p.
nt oper ting pqce-s fications.7 As rhrted in Sect' n 2.5.1.3.
of SS R 1, dure and equipment mo hfall thi sness and the U.S. Geological Surve- (USGS) estimates bot ose ption exchded the a li-ulation in the e ent of a volcanic, rate of accu Nate g' x
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nintheFina(SafetyAna'ihysis eport (FSAR) (or the event.
w cant ( estim letter Ofhbec 4,1902, -%e-WPoss proposed several plant procedures 10 it The NRC staff has reviewed the submittal and and equipment modifications.
concludes that the applicant has adequately addressed the consequences of a
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volcanic event with respect to ash loading on the ventilation system and the Section 9.5.8 of this supplement addresses the effect of ash spray pond.
loading on the emergency diesel engine combustion air intake and exhaust system.
The NRC staff agrees with the applicant that the proposed plant procedures and equipment modifications will provide adequate assurance of safe plant operation This resolves confirmat'ory item 24.
and shutdown following such an event.
WNP-2 SSER 3 SEC 2 04/22/83 2-2
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In accordance with NUREG 0800 (SRP). Section 2.5.1, concerning OperatingLicense(0L)rehiews,allnewinformationoftheregional andsitegeologydehelopedsubsequenttotheconstructionpersit(CP) safetyehaluationreportmustbeincludedandehaluatedinthe determination of site suitability and design criteria. The applicant, therefore,wasaskedtoehaluatethefollowingash-fallconsiderations.
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