ML20212M241
| ML20212M241 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Diablo Canyon |
| Issue date: | 12/24/1975 |
| From: | Parr O Office of Nuclear Reactor Regulation |
| To: | Boyd R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20150F500 | List:
|
| References | |
| FOIA-86-391 NUDOCS 8608250422 | |
| Download: ML20212M241 (1) | |
Text
{{#Wiki_filter:- vm .,~.a... w - a,s.~.e.r,.. - m,-- v -~vm w.~ msma~~ ~ w 'i g;g -y '7 q FLASH NOTE / December 24, 1973 l l l R. S. Boyd, Acting Director, Division of Reactor Licensing, NRR l THRU: R. C. DeYoung, Assistant Directer for Light Water Reactors Gmg 1,DE i DIABLO CANTON GEOLOGY The draft USGS report is due to us today. Preliminary indications are that the USGS will, once again,,recosamend rejecting the proposed -. design basis earthquake.for.this plant (which is already built).
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p ..,n. y4 We are planning to meet with USGS to discuss their draft report on J December 30, 1975., Their final report is expected in mid to late ~ s . Gp;.c. January 1976.. Since,any further; delay,at this time (to obtiin -t g 1ggg 3 additional information) would.mean.further delay in operation of hgjMIh " M^ w.g'1. ;the plant, we will:need'atmanagementidecision on how to proceed 4 .m dc .-after the meeting of Dece'abErj30lfl975;.n. v.- ., h,_ i d..d ;w .g q q,yj g g g C-4( N,.ygiereco==amtthatmanagement[ contin'usutifollow#this case closely gff m %gand, 'if possiblepparb.icipite'stiU'.thh!Decemberx30- meeting. with1USG8lAsm p M m..'. M. %g;pjg j~.0 O
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~ l j ,.K 1... g.Q,l "',S, Shg,3,-,a, ppy.,,.,., ;.._.. 3 -~ " h h.h ' t .g. j, [..;'.. I ' '."'-fdijM [.[.bi MN[I N$)M th.hE,$$, 1, ' ' ' b,. }.! l: A ~.,e ~. MIU D ~ ~~ s/. ~" < ? M.E' :- '.4.;1. ' ".I ' .3 , F,. i f, ' 2..?. 6 ' "(Z 1 r ~ . -T.' [N,'" d, '{,k,:ri?'p. 0 4 JAN 5 1976 ., g l,: . i. l Doeket Bos 50-27 50-323 Roger Boyd, Acting Director, Division of Resctor Licensing DIABID CANTON We strongly recommand that immediate meetings be held with upper management to initiate actions to promptly develop a firm basis for = miring a decision on Diablo Canyon. Our m1 preliminary thoughts are provided in the enclosure. Urfginal signed by R. C.DeYounit R. C.. DeYoungg Assistant Director _, M 2-N ' - *.< w w,,-.y. ,.,(,;...,, for Light Water Reactors Group 1 Division of Reactor Licensing
Enclosure:
Diablo Canyon Geology-Seismology ec w/ enclosure: R. Heineman F. Schroeder H. Denton R. Hofmann C. Stepp O. Parr D. Allison Distribution JARicket File RCDeYoung g p* RCDe. Young's Rdg g
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e c .a.s. iN ,'h' ? f ~ 'f . i ',' .}.g 1-4, ~ !A.., DIABLO CANYON GEOLOGY-SEISMOLOGY 1 l 4 I. GEOLOGY-SEISM)IAGY SITUATION Based on USGS draft report, Renner Hofmann's assessments to date, as discussed with Dennis Allison, and the meeting of December ~30, 1975, between the staff and USGS, we understand the geology-seismology situation is as follows: 1. USGS believes that the 1927 event might have occurred on the Hosgri Fault so we should place a magnitude 7.0 to 7.5 earth-quake on that fault. The published magnitudes for the 1927 avant are in that range. This would lead to a calculated peak acceleration much higher than 0.5g using standard methods. The USGS position is suspect. Renner Hofmann of the staff has reviewed the felt effects of the 1927 event and they'seem to
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"' - tvM i 1927 event was either much farther out to sea or was much smaller. Either way, the plant, which is adequately designed for 0.5g using standard techniques, could take the effects of this earthquake when it is moved in an appropriate manner. We do not have a direct verification of the magnitude determination r at this time. Renner Hofmann has reviewed the location data, which indicate that the 1927 event was or could be on the Hosgri Fault, and considers them to be of very poor quality, capable only of determining the location to be somewhere off the coast of Central California. The USGS expressed a villingness to take another look at this aspect of the geological situation taking into account Renner l Hofmann's and Carl Stepp's counsents made at the meeting on l December 30, 1975. 2. The USGS believes that the Hosgri Fault is more than 90 miles long and may even be coupled with the San Simeon Fault at the northern end of the ilosgri Fault. This is a somewhat incongruous statement because it appears that one must add the San Simeon fault length to the Hosgri Fault on the north, as well as a few miles on the south, in order to get a 90-mile length. Neverthe-less, what we believe they are saying is that other interpretations (FFICs > eusmaus > oara > Forms AEC.318 (Rev. 9 5H ABCM 0240 W u. s. oovenwassar reewnne orrecas sers.sae.see
.a w ..;=--....:. ...u.... .. -. =. = . = :..- %.4-L.,.,:.. 4.,,.. ~. 2 3 t,-_ .g .w q. ,.E :? %.c*r ^ F, ' ~:: .u. ' f.::.' ; 6 \\'? ' .~ q3 l ,.3 / than the applicant's can be placed on the geologica.1 evidence of fault length. Furthermore, with these other interpretations, the fault length is unknown, except that it is greater than 90 miles. It is not at all clear where we are going here. This is a question we must deal with even if USGS is convinced of our position with respect to item 1 above. Unfortunately, we do not have a specific earthquake recommendation from USGS based on fault length to deal with. A. Renner Hofmann is looking at the seismic profiles but the USGS opinion (that another interpretation is possible) will probably hold water. Ferhaps the fault length could be limited to 90 miles or a little more with additional field work. A fault length of up to 120 miles would give a 0.5g peak acceleration, amataning mostly strika slip motion and.a rupture length of one half the ~+af,,yg. length'. ~ We feel that there are'irEasonabinhetssptions"f6r " " this site, but the USGS may well disagree. 3. USGS believes that the standard methods of calculating a peak acceleration and scaling a spectrten to it are not appropriate this close to large earthquakes. While they do not know what would be appropriate, they clearly te us to find a better way. Renner Hof==nn is working on two approaches which can shed some light on the subject and may indicate that the plant could take a large earthquake on the Hosgri Fault. One approach is to l P ace the magnitude 8.3 San Francisco earthquake on.the Hongri l Fault and use the felt effects to estimate the peak accelerations. i i The second involves calculations of peak acceleration based on i the fact that only the energy released in about four miles of fault length will contribute to'the peak acesleration at a distance of four miles from the fault. This type of reasoning could possibly provide a rationale for reconciling the differences of opinion with which we are dealing. 4. The quality of the USGS recomendation, as far as we can tell at this time, is poor. i a. Their specific recommendation to place a magnitude 7.0 to 7.5 earthquake on the Hosgri Fault is based on an idea which we consider not valid. However, USGS.has agreed to consider this matter further in light of our comuments to them. GFrece > \\ susnaess > ) pave > \\. ( Perse AEC.318 (Rev. 9-53) ABCM 0240-. - W u. s. novenwasswr raswruse oprics sete.sae see
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} d w -:: ~. _-qw: ,j_ -+.g.. a. b. Their recommendation does not deal with a magnitude based on fault length, which must be dealt with. Indeed, they do not say that item a above is a worst case or design case, but neither do they say that there might be a worse case. We need something better than this to work with. c. It seems that we are daaling with the opinion of one to four people and we are not sure which ones.- For exsuple, one of these persons (Holly Wagner) is highly respected but we do not even know what he thinks, much less what a consensus of top geologists would be. As.another awample. - d, Hanks, a Cal Tech professor and part-time USGS employee, published an articia stating that the 1927 earthquake was not on the Hosgri Fault, but we have no indication of whether or not this was given any weight. This is not an adequate base for a decision as important as this and is, in our opinion, the best USGS can give us. . ~;,. r,q.3.- w4 . s,;..+ w,.,g:,q., u p w g g y g........ i. A.,_ pgjig d. Holly Wagner is the highly respected geologist== king the geological interpretations, yet we have been unable to discuss the matter with him. All we have gotten is second-hand word that good people have reviewed it and this is l what they said, without meaningful discussion of the tech-niCSI reasons. II. RECOMMENDATION AT THIS TIME Clearly we can benefit from further discussions with USGS at a lower level before they send their formal recousandation. However, in light of the serious nature of the decision we must make, the innknnwn quality of the USGS reca==.andation and the extra difficulty involved in reversing a USGS opinion after it is published, we recommend contacting top management at the Department of Interior and expressing our need for an immediate accelerated reevaluation of the geologic situation, including: 1. The independent opinions of several top USGS geologists not hereto-fore directly involved in the Diablo Canyon review. 2. A clear expression of the technical reasoning which can be dis-cussed meaningfully with the staff. In addition, we should immediately retain additional top geologists directly as consultants and initiate further independent review on our own. Depending on which how quickly we take action, the results may or may not be completed in time to support the schedule for licensing. 6mce > susna e > pars > c.u. mn -
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2 ,.s. N' f l }.. 4-I l i III. POSSIBLE PUTURE OPTIONS _ .s i If we receive the USGS reconssendation as it stands now, we will have q three basic options, assimming that we will publish tho SER. Supplane.nt and take a position instead of asking further questions and slipping the schedule. The three basic, options are Leave the door open for further 1. Oppose the operating license. study, etc. Describe why. We have a poor basis for this action at this time, other than general conservatima and "PG&E hasn't done enough to make every-Such arbitrary conservatism would not be an adequate one happy." basis in this case because of the large f4= = 4=1 loss involved and the severe impact such action would have on the nuclear i industry. { etc. Describe ' 2.*E avor-the operating license.- Requira.,further study,M.e ;.# ..o.,'. g.. g=. =w -
== P why. If this is done on the basis of rejecting the USGS recom-mendation because it is poor, there would be difficulty a. justifying the action. Alternately, we could possibly accept the USGS advice and justify the action on the basis of.probabilitics of earth-b. quakes and structural and mechanical damage (creating it This would as an exception to Appendix A to Part 100). probably be coupled with requirements for plastic structural analysis, backfit, further geological study, etc., within There would be some difficulty in ~ specified time periods. justifying this approach also. Describe the Neither oppose nor favor the operrub iPs ase. 3. situation. Although the ACRS, Hearing Board, Commission, and courts will t probably all have to decide this case anyway, it is not satis-factory for us to go to them without a recommendation. ? E m..... tuan.esa > .h - ..........,,,-..,~. - -... -.}}