ML20148G229

Responds to Transmitting CA Snow Concerns Re Safe Operation of Facility During Activity of Mount St Helens.Affidavit of RB Mcmullen Re Impact of Volcanic Activity on Safety of Facility Encl

ML20148G229
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/29/1980
From:	Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Jackson H SENATE
References
TAC-41023, NUDOCS 8011100351
Download: ML20148G229 (3)

Text

{{#Wiki_filter:, .-~ fEK# z. N; augk - UNITED STATES ~ L y d NUCLEAR REGULATORY COMMISSION lh 'f WASHING TON, D. c. 20555 - e g, 1q OCT 2 919so Docket Mo..50-344 a tt ' The Honorable Henry M. Jackson United States Senator ~ ~ ) 802 United States Courthouse - Seattle, Washington 98104 l 8

Dear Senator Jackson:

This is 'in response to your letter of' September 5,1980 regarding Carol. A. Snow's -letter' to you of July 29,.1980,1 which expressed concerns about Mount St. Helens. [ and the Trojan Nuclear Plant. Those same concerns were raised recently by a . member of the public' who filed a formal request, under.10 CFR 2.206 of the NRC's regulations, that the'NRC issue a show cause ' order and require the Trojan 1 ~ Plant-to be snut down because of the activity of Mount St. Helens. After an i . evaluation,.it' was' determined that there was no need to shut down the Trojan l i Plant and that reauest was denied in a decision issued by.the Acting Director of the Office of he. lear Reactor Regulation on August 13,1980(DD-80-26). j o' In response to'Ms. Snow's concerns. I am enclosing a technical report which discusses in detail the possible im?act of volcanic activity at Mount St. Helens -l on the safety of Trojan. The report. is in the' form of an affidavit which was l filed.with the Atomic Safety and Licensing Board in the Trojan spent fuel pool proceeding. ;Although this report was filed prior. to the recent volcanic activity, it' is with few exceptions considered an accurate assessment today. Exceptions to the report include (1) the. underestimation of the volume of debris i associated with a potential mudflow, (2) exclusion of a discussion of volcano-I induced earthquakes, and (3) the statement that historic data indicates that the volcano has been subi.tantially more active in the 19th century than the 20th century. Notwithstanding the above exceptions, the report's conclusion thatz the Trojan site is suitable from a volcanic hazards point of view remains accurate. The recent massive eruption of May 18 1980 exceeded that envisioned by the Nuclear Regulatory Commission and by our advisors, the U. S. Geological Survey. Nevertheless, the effects of the recent volcanism (mudflows, earthquakes i . and ashfall) at the Trojan site have-been minimal. Mudflows in the Toutle, D sama, and Lewis River valleys have not compromised the safety of the Trojan j Aant. Volcanic-induced earthquakes have been small.and have neither been j felt ~nor recorded instrumentally at the site. Ashfall at the Trojan plant ') resulting from the May 25, 1980 eruption has been slight (not exceeding 1/8 j of an inch) and: fell at the site in the fonn of a muddy rain or mist. The 1 only.other indication of esh occurred on April 29, 1980 when a thin' coating of the ash was noted at the Trojan site. 'IHlS DOCUMENT CONTAIN P MUAUTY PAGES' 8011100 3 9 g = A -.i-

t -t Senator Jackson - -2, According to? University of Washington seismologists, the volcanic-induced ' earthquakes. mentioned previously have not exceeded Richter Magnitude 5.1 and. have been concentrated in an area roughly coincidental with the volcano crater-I which is 35 miles northeast of the Trojan plant. None of the larger events (Magnitude 5.0 and above) have occurred closer.than 35 miles to the plant. I - For the most part, the volcanic earthquakes have occurred at shallow depths . and have consequently been felt only in the immediate vicinity of the seismic event. However, there have been unconfirmed reports of volcanic-related earth- - quakes (originating at Mount St. Helens) being felt in the Longview-Kelso, Oshington area, roughly five miles north of the Trojan plant. Apparently, those feeling the tremors were located in areas where soil overlies bedrock. The plant is designed to safely withstand seismic levels of 0.259 peak ground acceleration.. This corresponds to earthquake levels many times greater than A those generated by the volcano-induced earthquakes. The potential impact of volcanic activity on the safety of.the Trojan facility was investigated thoroughly by government geologists (Atomic Energy Commission and the~ U.' S. Geologi, cal Survey) before the plant' was allowed to be constructed where it is. This investigation and reassessment of volcanic-related hazards has continued as attested by the enclosed affidavit. We have been in constant contact with numerous state,' governmental agencies, and university scientists since initiation of earthquake activity and subsequent volcanic activity in the vicinity of Mount St. Helens on March 20, 1980. This surveillance and accumulation of information will continue as long as the volcano remains active. As to~ evacuation under severe ashfall conditions, this can cause transportation problems somewhat similar to those produced by road icing or heavy snowfall. The first protective action to be taken following a radiological emergency at a nuclear facility is to alert the public to take shelter and await further instructions. Seeking shelter in homes is an effective protective measure under most circumstances. A decision to evacuate is based on an assessment of the potential injury to the.public from the accident and must be balanced against the risk to the public from the evacuation 'itself and against the conditions that prevail at the time. Seeking shelter would have to be given greater weight under ashfall conditions, depending on its severity. Therefore, if an accident occurred in combination with transportation difficulties due to severe volcanic ashfall, effective protecting measures can'still be implemented, albeit with greater difficulty. The probability of these two events occurring simultaneously is, however, extremely low. Our conclusion, based upcn an evaluation of volcanic phenomena prior to con- .struction, coupled with an assessment of the effects of the activity beginning March 20, 1980, is that the Trojan site remains suitable from a volcanic 1 i f I > l i. J . l

fi 47: 9 . Senator: Jackson. - 3'- . hazards-viewpoint." - Nevertheless,'we will-continue to monitor, accumulate, and assess ^information related-to the renewed activity at Mount St. Helens q. as it.might apply to.the. safety of the Trojan Nuclear Plant.- ] ) . Sincerely, '(stened)7. A.Rehm g William J. Dircks 5 ' Executive Director for I-i Operations ( Enclosu're:. 1. Affidavit of R. B. McMullen '2. Letter, Carol A. Snow to ' Senator Jackson, dated - July 29, 1980 t s L p t ,y P L z

~. I g'., UlIlltU-%iAlu'Ur.. ;daLA JCCLEAR REGULATORY.C0%'415SION. BEFORE THE ATO:41C SAFETY A.'!D LICE!1SI!!G SOARD In'the Matter of PORTLAND' GENERAL ELECTRIC COMPANY, ~ Docket' No. 50-344 ET AL1 (Proposed' Amendment to Facility ~ - ~ ~ ~ Operating License HPF-1 to Permit. l., rcjanNuclear' Plant)' ' Storage Pool Modification) 5 AFFIDAVIT OF RICHARD B. McMULLEN STATE 0F' MARYLAND ) SS n ^ [V COUNTY OF MONTGOMERY. ) Y I, Rich'ard 'B. McMullen, being duly sworn, depose and state. 1. I am a Geologist in the Geosciences Branch of the Office of Nuclear 7 a P.eactor Regulation, U.S. Nuclear Regulatory Co.7;nission, !!ashington, D.C. 20555. 2.- I have prepared the statement of Professional Qualifications attached hereto, a'nd, if called u,pon, would testify as set forth therein. 3. I have prepared the a'ssessments on landslides and volcanism attached , hereto'in response to the Atomic Safety and Licensing Board's Order of January 9,1978 and I hereby certify that the statements made l herein are true and correct to the best of my knowledge. I 808 M8ME 1-Richard B. McMullen. l Subscribed & sowrn to +-" 'hefere me this \\ @ day l . of April,.1978 l 0-- Q C\\ M L 3

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49 RfCllARD H. McMULLEN-PROFESSIONAL QUALIFICATIONS GEOSCIENCES BRANCl! DIVISION OF SITE SAFETY AND ENVIRONMENTAL ANALYSIS NUCLEAR REGULATORY CO:ttISSION I am a geologist in the Coosciences Branch, Division of Site Safety and Environmental Analysis, Nucicar Regulatory Commission. My present duties in this position include: (1) the evaluation.of.the geological i aspects of sites for nucicar power generating facilities; (2) analyzing ~ and interpreting the geological data subnitted to the NRC in support of applications for constr'ction and operation of nuclear facilities; u (3) developing critoria; and acting as consultant to the. Regulatory staf f on c'ngineering and ~ construction matters. Af ter completion of three years in' t.he Marine Cerps I attended the University of Florida and graduated in 1959 with a B.S. degree in Geology. During my pro-fossional employment, I completed correspondence courses in soils engineering and quarrying sponsored by the Army Engineer School at Ft. Belvoir, Va., and short courses in the effects of ground motions on structurcs, and airphoto interpreting. I am a registered Geologist and Engineering Coologist in the State of California. ~ Af ter graduation I worked as a field geologist with the Corps of Engineers in Florida conducting field geological investigations for flood control structures, icvees, canals, military installations, radar sites, and missile launching complexes. I evaluated and wrote reports concerning the stratigraphy, geologic structure, groundwater conditions, ~ and foundation engineering aspects regarding these facilities in Florida, Puerto Rico, Bahama Islands, several of the L'est Indies Islands, and Panama. In 1963 I was assigned to the Corps of Engineers Canaveral District of fice at Cape Kennedy, Florida, first as a staff engineering geologist, and later ne D strict Geologist. My duties were to plan, direct and evaluate the x sults of geological and foundation studies for nissile launch pads and associated facilitics for the NASA Manned Lunar Landing Program,. the Air Force, and the Navy. I acted'as con-sultant to other government agencies and architectural engineers in developing design features of structural foundations, monitored the performance of foundations during and after construction, and recommended and monitored necessary foundation treatment techniques such as vibra-flotation, grouting, surcharging, dewatering and compaction. I wrote reports on the investigations,' geology, foundation design, and construction regarding these projects, l l In 1967 and 1968 I spent 6 months and 1 month respectively participating in the geological investigations for proposed sea level canal routes f in Panama. The region investigated consisted of complex structures of volcanics and folded and faulted sedimentary strata. ' Among the tech-niques employed in this study were field geologic mapping, geophysical surveying, bore hole photography, and core borings. .In 1968, I was 4 e 4 e

+; .,1 t transferred to the Huntsville, Alabc a Corps of' Engineers Division which was' re1ponsitic for' the siting, design and construction of 15 to 20 (later reduced to 4) safeguard antibalistic nissile installations throughout the United States. !!y dutics there were to plan, direct .and participate in in/estigations to determine the suitability of these sites for construction of the missile complexes. I performed geological studies and some soil mechanics work to develop design parameters f or - fcundations ' and' excavations I also served as technical consultant during design.and construction to other government agencies. architectural engineers, and contractors.. I have been a me:.ber of. the Regulatory staff since January 1971 and have participated in licensing activities for at least twenty-five nuclear f acilities including Summer, Nine->!1le Point, Washington Nuclear 2, Pebble Springs, and Indian Point. These activities con- .sisted of' review of the scological aspects of the sites as presented 3 - by applicants and usually an independent evaluation conducted by a i review of the most pertinent literature, site visits, and conversations with knowledgeable individuals or agencies. I ~ l I - l I 1 I 5 1 l i t i I i i l --ua aw. y ,y.-, p.. m._,._ y

s ?, A. L.andsl ides 1. !!RC Ponit ions Af ter CP knd OL Reviews In it's Fafety' Evaluation Report (SER)-for: the' Trojan site dated Octo-ber 19,1970, the staff concluded that " Based on the evidence provided by the' applicant and field observations of our geologists and our ~ geologien1 consultants, we have concluded-that the existing geological structure is acceptable fo'r the construction.and operation of the proposed plant at the Trojan site.". The U. S. Geological Survey conclud6d that, i'the applicant proposes to found all major plant structures in the volcanic rocks. Boring-logs and test data indicate that the' rocks are sound and will provide an adequate foundation for j the proposed facility." In its SER following the OL review, the J staff reaffirmed its originalaconclusions. 1 l 2. _Cu_rrent Staff Positions It is the staff's position-that landsliding in the site area does not present a threat to the Trojan plant. This conclusion is based on our review of several recent publications on landsliding in the region and the j results of geological investigations in the site area including borings, scismic profiling, surface geologic mapping and the geophysical investi-cations that were supervised and evaluated by the Trojan Geophysical Advisory Ponrd comprised of Dr. Peterson, Dr. White and Mr. Dodd. The results of these studies indicate that the immediate site area does not j have the characteristics which typify large landslides along the Colur.;bia River. e e e -e w .,f .q-,, -e -.n-p..

p.j t ,mz l H 1 ,y ); e U ~ i,op z. U.l roi.me reilt y or 1.lirm. l.:ni,ijhil.tr l'n t he colorahin River Corco - 3.s f h i - Palmer (1977) studied'several large : landslides' that have occurred within f the Columbia ' River Gorge. These' slides were in an area t characterined by steep ~ terrain with relief on the -order of 1200 1 l l meters, high rainfall- (250. cn/yr.), exposure of water saturated

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pinstic clay layers under permeable', rock maraes, and regional l E dips of roc'k strata lfrom 5* to 30' into the gorge. I A. thick ' stratigraphic section of the Iocene ' to '011gecene. 0hanapecosh formation underlies the area studisd by Palmer. This. formation is i made-up of varied claystone to pebble conglomerate of'both sedimentary and volcanic materials. Portions of this rock have.been weakened by l-weathering. .An' angular unconformi.ty in.the Miocene-cauged the develop- !4 ment of a zone of soft clay rich saprolite on top of the chanapecoch i L fuer4 tion. The "iocene Eagle Creek formation overlies the Chanapecoche i. The Ecgic Creek is similar in compositson to the Ohanspecosh but is j less wuathered and contains larger rock fragments. On the Washington i . side of the river, the strata within these formations dip toward the Columbia Gorge, while on the Oregon side they dip away from it. Easale i overlies the Eagle Creek formation. i River banks were overst eepened as the Columbia River cut through the basalt into the week Eagic Creek and Chanapecosh, formations. Most large scale Pleistocene and Holocene landsliding occurred on the !I L'ashington shore vhnro overstcopened' slopes intersected the bedding plancs of erJposed incoripetent rock,,ehich dip to toe south into the gorge.

1. esser slides are found on tho. Oregon shore where several thousand feet of l

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a ~:o : ~ 3 s ^ 9 i y bannit overlic the clay'of the Eagic Creek and chanapecosh l formation whtch ' dip away f rum the gorge. The combination of ~ -exposure by.croglon 'of the clays and the weight of the basalt-caused squeezing' updip of tbc clays, eventually undermining the ' bas. sit and enusing large rook fa11s.(Palraer.1977). 4 Coolony and,_ Topography of the Site Bedrock bcncath the Trojan site consists'of volcanic rocks of the 4 Upper Eocenc Gobic series.. Boring, seismic, and laboratory test data show that the rock is relatively sound and composed of tuff, j flow breccia, tuf f breccia, agglomerate, and basalt. Bodding planes i withir. the rock are poorly developed, but those that have been mapped generally dip toward the west-southwest or-southwest, away from the ' Columbia River. Coophysical data indicate that the volcanic rock also underlic's the Colunbia. River cast of the site thus precluding the exposure to crosion of continuous clay strata like those described in the Columbia River Corge (Palmer,1977). The topography along the river valleys in the site region is characterized by many steep arcuate features. The Trojan site is located on a bedrock ridge just cast of one of these steep arcuate features within the Columbia River Valley. This valley was subjected to intense flooding during post glacial time (Srctz 1969). It is likely, based on geologic evidence at the site, that the arcuate feature is the result of river.. bank scouring and erosion from rapid flood stage flow through a since-6 9 t - eme en

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(., l 4 3 .c- 'u-' 1 . !t abandoned channel of the Columbia ?.iver, rath'r than lands 1fding. 1 e JSimilar abandoned channels ucre reported by Piteau (1977) following Lhis study of landslides.in -the Fraser River Valley' in southern British - Columbia. Piteau also presented evidence to show that the major single-cause of' landslides in that area was the presence of_ alluvial fans or 4 carlicr: landslide debris on the opposite s1de of.the river, which i deficceed thel river laterally and caus,ed undercutting and oversteepening of sinpes. Such' processes are not active at the site. 5. Bases for Staff Position ' Although landslides are evident in the site region, landsliding is not likely to pose a hazard to the Trojan site. The staff concludes

that' the Trojan site is not susceptible to landsliding for the following reasons:

1. Available data indicate'that t*r.e volcanic bedrock in the site area is continuous from the hills vest of the site, beneath the alluvial valley, through the site ridge, beneath the Colur.bia River, and on to the h'ashington side, and is not an active slide block. 2. Interpretive seisnt: profil.es show that the surface of the bedrock bencath the alluviated channel is secothly rounded, as vould be expected in a rapidly ernded bedrock channel, and not sharp and angular an would characterize a relatively recent and unstable slide block. f 6 .m 2(+., y_ w ...-m ,w 9- - - .~<,--+#-,y o e,--%y,--..,,,.. w- ,,,,-.-.7..er--n e

\\ '6-5 f ~ 3. Rock strata bancath the, site and the area around the site on Ithe Oregon-shore dip, with. relative consistency, southwest or vest-soutlwastc away from the River; and data presented by the applicant -16dicate that joints and shear zones are either not continuous cr dip at-steep angles, thus precluding the existence of a votential slido plane sloping toward the river. Geologic maps of the site vicinity o'n both sides of the Columbia a. River show that bedding dips either I:Ln a s'outherly or westerly ~ direction. b. Figure 2.5-16 in the FSAR, which is the Geologic Map of Final Foundations, shows that joints and shear zones are either dis-continuous, dip away from the river, or dip at a high angle such1 that a projection of that dip would not intersect the river valley. c. Correlation of bedding from boring to boring and interpretation of geophysical data show that, locally, bedding plancs below foundat. level are generally horizontal or dip away from the river, d. On a broader scale, based on geophysical data and surface mapping, the site lies on the eastern flank of a northwest trending syncline within which the bedding dips to the west, away from the river. Dips of strata benesLh the site show no evidence of rotation of e. beds as would be expected within a landslide mass. l 4 j i ~~

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The USGS reviewer examined the excavation for the plant on 1 October.11970, and reported that alth'ough no. rcal bedding - t t plance were visibic, some nearly horizontal, crude separations were observed that were consistent with observations cade in natural l exposures' of these rocks nearby. j 4. Based on a projection from mapped outcrops, the volcanic rocks underneath the site rest on the Cowlitz formation, which is described by the Applicant as well compacted but sometimes loosely. cemented sandstones and siltstones. i Sandstones or siltstones are generally less suceptible'to landslide i development than clays, such as those described (Palmer 1977) as being j part of the-Eagle Creek and Ohana;ecosh formations. It is possible that there are clay zones in the Cowlitz formation beneath the site, either from deposition or weathering. However, the Cowlitz formation was subjected to the same deformation as the overlying volcanics, f and bedding planes would likely dip in a westerly direction, away from i I the Columbia River Valley in contrast to the bedding in other parts of the gorge where large landslides have occurred. e { 5. Aeromagnetic and gravity profies show no anomalous break that might be l t associated with bedrock sliding. 3 i 6. A major landslide upstream could teaporarily block the Columbia River; i however, the site intake facility is located at a sufficiently low elevation relative to sea level, that'the source of en.ergency cooling i water would not be cut off. 6 l i l l I i 1 J

7-7.. In its report entitled " Geologic Hazards Review Trojan fluclear Power Plant Site Columbia County, Oregon," the Oregon State Department of Geology and liineral Industries concluded that '"available geophysical data and geologic information collectively indicate that the site area is underlain by continuous bedrock andtNatdeepmassmovementisnotafactor". it is t$erefore our conclusion that landslides do not pose a potential threat to the site including the Spent Fuel Pool Facility. e 4 4

.o - - J References for Part_s, Landslides 1. Breti, J.li., 1969, The Lake Missoula #1tods and the Channeled Scabland. Jour. Geology, V. 77, No. 5, p. 505-543, 2. Pal.,er, L.,1977 Large Landslides of the Columbia Rive r Gorge, Oregon and t!achington, Geological Society of America, Reviews in Engineering Geology, Volume 111, pp. 69-83. 3. Peterson, R. A., J. E. White & R. K. Dodds,1972, Geophysical Survey Report Trojan Nuclear Power Plent Site; Prepared by the Trojan Geophysical Advisory Board for the U. S. Atomic Energy Commission, August, 1972. 4. Piteau, D. R., 1977 Regional Slope - stability Controls and Engineering Geology of the Frazer Canyon, British Columbia; Geological Society of America Reviews in Engineering Geology, Volume III 1977. 5. Portland General Electric Company,1973, Final Safety Analysis Report, Volume 1. 6. Portland General Electric Company,1969, Preliminary Saf ety Analysis Report, Trojan Nuclear Plant, Volume 1. 7. State of Oregon Department of Geology and Mineral Industries, 1978, Geologic Hazards Review Trojan Nuclear Power Plant Site Columbia County, Oregon, Open File Report 78-1, March 14, 1978. 8. U. S. Atomic Energy Comnission,1974, Safety Evaluation Report Trojan Nuclear Plant, Docket No. 50-344, October 7,1974. 9. V. S. Atomic Energy Commission,1970, Safety Evaluation Report by the Division of Reactor Licensing, US AEC, In the Matter of Portland General Electric Company, City of Eugene, Oregon, Pacific Power and Light Co., Trojan Nuclear Plant, Docket No. 50-344, October 19, 1970. 1. F I l$ I

~ = + o - B. Volcanism, y 1. Staf f Position Af ter CP and OL Reviews and Current NRC Ppsitiot: following - In its Safety Evaluation Report dated October 14, 1970, the Construction Permit review, the' staf f concluded that: The applicant has evaluated potential lava flows, mud. flows, and volcanic ash falls and determined. that they would not adversely af fect the safe operation of the Trojan' reactor. We and our consultant.s, USGS, 'have reviewed the applicant's evaluations. We conclude that the assumptions and evaluation techniques used by the applicant were reasonable and we agree 5 ( with the applicant's conclusion." In the' Safety Evaluation Report (October 7,19 74), af ter' reviewing the. Final' Safety Analysis Report, in support of the application for an operating license, the staff concluded that: " based on this review, . we c'onclude that investigatifons condue ted since the issuance of our Safety Evaluation Report dated October 19, 1970, have disclosed nothing that would alter our original conclusion regarding the suitability of the Trojan Plant Site." Since publication of the SER, new information has become available. We have reviewed these data and we sco no reason to change our original conclusion. 2. Basis for the Staff's Conclusions Following the CP and OL Review During the review for the Trojan site the following potential volcanic hazards were evaluated as to their significance to the Trojan site: -ash f all, mud flows, pyroclastic. flow, flooding, and lava. Crandell and 9 e r e ,+-,-,,,m,- ,,,a-<, c w-ew,....y.-- y,, s,-, ,-,...-w,4-,y-. ,,mw,, v.-,,+,w..y w.w. w.e, ,-,,r,.m#,y, --,r p -w n

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• e Waldron- (1969) ' indicate that if one of the Cascade volcanoes ' erupts',

"we believe ' that ash' eruptions and mudficus are ' the two greatest hazards."' i a. . Volcanic Ash. Ash is made up of fine volcanic particles that d ' have been blown high'into the air by explosions in a volcano. The extent and thickhess of ' ash fallout is in'fluenced by the altitude ri to which it has been erupted, sizes of the particles, the directions i and velocities of the winds, and other meteorologic condit(ons. Mount St. Helens is the closest (33 miles east northeast) and most likely source of ash that could affect the site. The applicant stated in the PSAR that even if the ash fall from the Crater Lake eruption vera superimposed over Mount St. Helens, the resulting ash fall would not have damaged the plant, nor caused interruption of i the cooling water supply. Crater Lake is located in the Cascade Mountains in southern Oregon and was formed by violent eruptions of a volcano (Mt. !bzsua) about 7003 years B.C. The staff agreed with that conclusion on the bases that : (1) dhe site lies near the maximum extent of ashfall when the contours showing the distribution of ash from the Mt. Mazara eruptions according to ' i Williams (1942) are superitposed on Mount St. Helens and other nearby volcanoes (PSAR Figure 2.8-16); (2) the prevailing winds blow away from the plant toward the volcano most of the time and ] t apparently have done so for thousat ?s of years; and (3) tha. source of c=ergency cooling water is the Colu=bia River. e e, m v w w- --r, v grv -- >--,-r n-- rv- -,

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i i l 'j -3 I a ? e b. Mudflhws. "Mudflows7are casses.of water saturated rock debris j whie'. novo downslope in a manner resembling the flowage of wet ' cr,cr e te." (Crandell,'1976). Mudficgs have been known to move j l nany tens'of kilometers down-valley floors at speeds of 35 km/hr: t or more (Crandall,19 76). The possfLilief of a mudflow. from Mount St. Helens endangering the site was considered during the CP stage. t . The applicant concluded ~ that, "A large mudflow on Mount St. Helens. t = would likely move either dern the Kalama River Valley or the Lewis l River Valley. The mouth of the Kalama River 1,s. close to the Trojan 'l ~ It does not-site, but on the opposite side of the Columbia River. r seem credible that a' debris flow'down the Kalama would evea reach { ' he Columbia River, let alone that it could block it. If it t reached the Columbia River, f.s probable worst ef fect would be to i muddy the river downstream as the Columbia removed and diluted the j flow of debris emptying into it. The slopes are so flat at the j ) point where the Kalama discharges into the Columbia that a mudflow extending that far would be moving very slowly." The staff also -{ concluded that nudflows did not constitute a hazard to the plant. [ l c. rioods. Floods can be caused by melting of snow on the flanks of a volcano. These floodwaters can carry large amounts of rock j debris which can be deposited many kilometers from the volcano. An analysis of the flooding potential due to volcano eruption was t b t I j I i I

. i. ~ .4-made by. PGI duri.ng the CP stage of the licensing process. The vorst case situation was failure of dans and reservoirs along the ' Lewis River. 'It was concluded that flooding from the Lewis River reservoirs would not raise the Columbia River enough to inundate th'e plant. A similar analysis was not done by the staff; however, the staff's hydrological engineering analysis showed that the plant was safe ' from flooding' even assuming the failure of upstream dams including Grand. Coulee Dam. Any flooding caused by volcanic activity would j be less severe than the failure of upstream dams on the Columbia River. d. Pyroclas tic floir. As defined by Crandell (1976), pyroclastic flow is a mass ef hot, dry rock debris that roves rapidly down the flanks of volcanoes. Because of the distance that Trojan lies from the nearest volcano, and the topography, pyroclastic flow was not regarded as a hazard to the site. e. Lava Flows. According to Crandell (1976) lava flows generally erupt quitely, but can be proceeded by explosive activity. Lava flows ~ are usually confined to the is.ediate slopes and toe of the volcano. In order for lava to reach the site it cust be highly fluid and o f-sreat volu e. This is not characteristic of Mount St. Helens and there is no evidence that lava from this volcano reached the ( t 4 e 7 e. ag9 ,,4.- -%,3 ,p

Columbia River. For these reasons lava flows were considered not to present a hazard to the Trojan site. 3. Variation of Volcanic Activity in the Pacific Northwest _ The staff finds 'no evidence indicating that there has been a recent increase in activity of Cascade volcanoes. Evidence is that future a activity will continue much as it has in the past 10,000 years. The volcanoes nearest to the Trojan site: Mt. St. Helens, Mt. Rainier, I and Mt. Hood are considet.d active volcanoes. The available evidence indicates that activity has been essentially constant though episodic for at leas t thu lest 10,000 years. Historic data show that Mount St. Helens was substantially more active during the 19th Century than during the 20th Century. The enclosed figure is a compilation of known activity of several Cascade volcanoes including.those most significant to the Trojan site. The illustration is base ~d on data published by several' investigators, which was presented in Portland Cencral Electric's report entitled " Volcanic Hazard Study, Potential for Volcanic Ash Fall, Pebble Springs Nuclear Site, Gilliam County, Oregon." It can be seen from this illustration that Mt. Rainier and Mt. Hood have undergene sporadic activity for at least the last 10,000 years and Mount St. Helens for 4,000 years. This type of activity is expected to continue in the future. L'orldwide data on plate tectonic activity support this interpretation. .,The volcanic activity is related to processes at the plate boundary in i 1

.. j.. this region. Data indicate that plate tectonic activity in the United States Pacific Northwest is either continuing at a relatively slow rate as co=paredi to cest tectonically active regions around th6 world, or i .has stopped co pletely. This would explain the relative inactivity of the Cascade volcances, when compared to' world wide data. For example, i 'in the vicinity of.the Aleutian Trench,. where 'the Pacific Plate is actively subducting beneath the Alaskan Plate, volcanoes have erupted far more~ frequently historically and with greater' violence than in the N.' S. Pacific Northwest. It is not possible to absolutely rule out that Mt. Hood, Mt. Rainier, f 1 or Mt. St. Helens could experience similar eruptions like those that l forced Crater -Lake. Crater Lake was created after violent eruptions S of Mt. Mazama about' 7000 years B.C. Houever, such an occurrence is i considered to be very unlikely within th'e.next few centuries (Crandell i and "allineaux, 1975). It would represent a complete change in activity from that deconstrated' during the last 10,000 years for Mt. Hood and Mt. Rainier and 4000 years for Mount St. Helens. Such an eruption at one of these volcanoes occurring simultaneously with the wind blowing l l teward the site is extremely remote. Therefore it is reasonable to assuna that the worst events that have occurred in the geologic past { i L at a specific volcano could occur there again. l i l I e

7 It is.' the staff's position that any increase in volcanic activity 1 that fis pose,ulated, based on a study of the activity of the Cascade volcanoes for the past 10,000 years is not likely to present a hazard to the Trojan site. We believe that there vill be no increase in activity based,on the experience of the past 10,000 years. Evidence . from the plate tectonic theory supports this position. 4. Data Subsequent to the SER's Considerable additional studies have been made of the volcanic hazards of the Pacific Northwest since publication of the Safety Evaluation Re po r ts'. Many of these studies have been conducted in' regard to the si'ing of nuclear power plants, such as the Washington Public Power i Supply Sys tem (WPPSS) Nuclear Project 3.and 5, the Puget Power Skagit site; and the Portland General Electric Pebble Springs site. The data included in the reports supporting license applications for these sites are compilations of data from many investigators. The USGS has published studies of volcanoes in the Pacific Northwest, among which are volcanic tazard assessment maps (Crandell,1G76 and Mullineaux, 19 76). The analysis of volcanic hazard for the WPPSS 3 and 5 site, which is 80 miles from the nearest volcano (Mt. Rainier and Mount St. Helens) indicated that only ash could affect the site. It forther s'howed that less t sn 2 inches of ash would fall at the site even if the assumption b is made that a Mt. Mazama type eruption occurred at Mt. Rainier or !tount St. Helens. t 8 --,w ,,.mr--..,,, -e -...c., m_-

8 Based on a recommendation from the USGS, Puget Power postulated that a mudflow sirdlar to the Osecola nudflow from Mt. Rainier could occur at !!t. Baker, which is about 22 rdles east of the Skagit site. The analysis showed that such a mudflow would not adversely affect the site. Ashfall is believed to be the only form of eruption that poses a direct hazard to the Skagit site (USGS, 1977). The Skagit sit'e is located about 56 miles from Glacier Peak, the nearest volcano with an explosive' history. Based on the superposition;of the 1912 Katmai Alaska eruption on. Glacier Peak, about 2 inches of ash would fall at the site. The Applicant assumed a maximum ash accumulation of 6". The staff and the USGS concluded that this was a conservative approach. Unlike the WPPSS 3 and 5, Skagit and Trojan sites, the Pebble Springs site is located east and downwind of the Cascade volcanoes. 5 During ".e review of the volcanic hazard for the Pebble Springs site, j it was our position, and that of the U. S. Geological Survey, that a l conservative and reasonable estimate of a maximum potential ash fall at the site should be modeled after the Yn esh layer which was erupted from Mt. St. Helens between 3,000 and 4,000 B.C. This analysis resulted in the assumption of a thickness of 81/2 inches of uncompacted ash at the site, which is located 80 miles and 105 miles east of Mt. Hood and ~ Mount St. Helens respectively. Since publication of the SER's the USGS has published 2 Volcanic Hazards Maps (Crandell,1976 and Mullineaux, 1977). The former designates zones in the state of Rashington within

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9-which' specific volcanic hazards are possibic. The latter shows volcante hazard ' zones in the western United States, The USGS also open filed a report entitled Potential Hazards from Future Eruptions of Mount St. Helens Volcano, Washington (Crandell and Mullineaux,1976). 5. Impact of Subsequent Data on original Conclusions 9 Based.on the data that' the staff is. aware of, which has come to light since the CP & OL proceedings, the only form of volcanic eruption - that could directly affect the Trojan site is ash fall. 'However,'new information has become available regarding several of the other potential hazards. These will be addressed first, followed by a discussion of -ashfall. Crandell (1976) and Figure 2.5.18 of the WPPSS Nuclear Project No. 3 Preliminary Safety Analysis Report, which is based on data presented by Crandell (1973), shows mud flow deposits just north of Longview, Washington in the Cevlitz River Valley, During its evaluation of this phenomenon PGE concluded that because of the distance from the volcano, and consideration that the intersection of the Cowlitz a'nd Columbia Rivers was located downstream from the plant there was no potential hazard to the Trojan plant. Crandell (1976) also shows a potential mudflow hazard within the' Kalama River Valley extending to I about 8 miles from its ' intersection with' the Columbia River. This does not present a threat to the Trojan site. Much larger mudflows have occurred in the region such as the Osceola mudflow from Ht. Rainier, 4 e D ,....J.

n.. a l h i .+ / .10"- . i + Shich u.s'~ uced rs a model for the caxine:s possibic radflow during ~ the Ska git 1 site. review. However,. since Mount St. Helens is a relatively l . young and un=1: eked volcano, one would not expect such large cuantities of potential cudflev material to be available on its flanks as on .j i those of the older' altered volcanoes like Mt. Rainier and Mt. Baker. j 4 t According to Crandell and Mullineaux (1976), "The absence of an I appreciable an unt of clay in mudflows from Mount St. Helehs suggests that.large areas of hydrothermally altered rock did not exist.on' the - } I - volcano in the past; nor are they present today. For this reason, I mudflows as large as the largest from Mount Rainier volcano (Crandell, e 1971) are not'likely to occur in the foreseeable future at Mount St. l l Helens." Because of the distance from the Trojan site to the volcano, the nature of the' intervening topography, the site being outside of I the mudflow hazard zone specified by Crandell (1976), and the youthfulness '{ o f Mount St. Helens, we consider our earlier conclusion that mudflows i do not constit;te a threat to the Trojan site, as being still valid. Crandell (19~6) shows the potential for volcano induced flooding E at the Kalaca 2nd lewis Rivers. As stated earlier, flooding from these i sources would te itss than the assu=ption of failure of upstream dams on-the Colcibia ?.iver. The site is considered to be safe from such f events. t L A i l. i l- ) i ~_

f e 4 1he distribution and thickness of ash deposits cast of the Caucode volcanoes are relatively well documented, at 1 cast those that originated within the last 10,000 years. The distribution of ash to the west of the volcanoes is not 'well documented, partly because the prevailing winds blow mostly toward the cast, therefore, most ash has been trans-ported in that direction; and partly because investigations have not been conducted west of the volcanoes to the extent that they have to the cast. According to Crandell (1976) "No significant amount of tephra has fallen in the western sector beyond the base of the source volcano during the last 4,000 years at Mt. St. Helens, or during the last 10,000 years at the other large volcanoes in Washington." Crandell (1976) and Mullineaux (1976) selected the respective tephra hazard zones west of each volcano to be 25% as great as those in the eastern sector, although the few ash beds known to exist west of their source vents are less than 10% of the distance that similar beds extend east of the source vents (Mullineaux 19 76). This number is not completely arbitrary as it is based on the knowledge that not only do the prevailing winds blow to the east most of the time, but on the rare occasions when they are blowing to the west, velocities are significantly less. This is demonstrated by atgeched tables 3 and 4 from Crandell and Mullineaux (1976). The Trojan site is near the outer boundary designated as zone B by Mullineatot (1976), and described as an area subject to 5 cms or more a 6 h e

1 i . 12'-- of ash 'f rom a;"large" ' eruption: similar to the "3unt St.' Helens eruption - . f about 3,400 yccrs ago. The site is located in an ' area' designated by-Crande11.(1976) as one of very low to low potential hazard to known human: life and health, and one' of ' probable-taxicum tephra thickness of iless; tha'n 5 cms. With regard to the spent. fuel'huilding, the weight F of 5 cm' of uncompacted ash on the fuel building roof would impose ' loads well within the design 1imits of the roof. (FSAR. Table 3.8-2 ~ g . gives live. load design'11mits for facility roofs.) - The staff ' concludes that informatios that has become available i since publication of the SER's does not cause us to alter our original. q conclusions that the site is suitable fron' a volcanic hazards stand-poidt including the spent fuel pool. . 6. Conclusions a. It is the -staf f's position that there is no present increase in volcanic activity in the Cascade volcanoes. Available evidance a indicates that activity has been relatively consistent over the past 10,000 years. The historic record shows that Mount St. Helens was far more active during the 19th Century than during the 20th Century. Future activity is expected to be similar to that which has occurred during the past 10,000 years. A very large eruption, like the Crater Lake eruptions, of one of the larger Cascade volcanoes cannot be completely ruled out. However, such an -occurrence sinultaneous with "high altitude winds blowing toward - a S we. og 4 e -rwr-- -,~.A-y.,. ,, y a ..q,. ,1,w.r, ,m,. e w wwr 9--**--veve 4-v - - s' we -r 5 -N 5

13 .the ~ site is considered to be extremely remote. Any increase in volcanic activity that is postulated, based on the activity of the Cascada volcanoes for the past 10,000 years is not likely-to present a hazard to the site.

b. 'Because the. Trojan site was shown to be safe from a more severe hydrologic event Gailure of upstream damc on the Columbia River, including Grand Coulee Dam), floods caused by volcanic activity will not present a hazard to the site.

t c. Due to the distance of the Trojan site from the Cascade volcanoes and the topography, pyroclastic and lava flows do not pose a threat to the site. d. Mount'St. Helens is a young, unaltered volcano; therefore, large . quantities of potential mudflow material are not likely to be avail- ~ able on its flanks. We conclude that mudflows are not likely to threate e site. e. Ashfall is considere represent the greatest potentia 1' hazard in this part of the Northwest. It is u ely that any ash will fall I on the. Trojan Plant because the prevailing winds w away from the plant and toward the volcano; and even during those rare t t when s they blow toward the plant, velocities are significantly lower. 'ss Superposition of the ash distribution from the Mt. Mazama eruptions at Mount St. Helens would not adversely af fect the safe shutdown capabili'ty of the site. e 4

l ( - l f. In its March 18, 1978 report to the State Departr.ent of Energt entitled " Geologic Ha::ards Review Trojan Nuclear Power Plant Site, Colu:nbia County, Oregon," the State of Orc,on Department of Geology and Mineral Industries concluded that "no new evidence has come to light to require modification of conclusions regarding volcanic hazards as they are presented in the FSAR." The Applicant committed in the SAR's to take the necessary steps g. to mitigate the ef fects,of a volcanic eruption including shutting down the plant. Ref erences in items (a) through (e) to the " site" include the spent fuel pool. Based on the above, the staf f reaf firms its conclusion following the licensing reviews, that the Trojan site, including the spent fuel pool, is suitable from the volcanic hazards point of view. l l

i o I l 'EFL nCES FOR PahT B - VOLCANISM 1. Crandell, D.R'.,1971, Postglacial lahars from Mount Rainier volcano, l Washington U. S. Geological Survey Professional Paper 677, j 75 pages. 1 i 2. Crandell, D. R.,1976, Preliminary Assessment of Potential Hazards from Future Volcanic Eruptions in Washington, U. S. Geological Survey Misc. Field Studiec Map MF-774. 3. Crandell, D. R.,1973, Map Showing Potential Hazards from Future Erupt. ions of Mount Rainier, Washington, USGS tbp I-836. 4 Crandell, D. R., and H. H. Waldron,1969, " Volcanic Hazards and the Cascade Range," Of fice of Emergency Preparedness, Region Seven, Geologic Hazards and Public Problems Conference Proceeding, Santa Rose, Calif. (May 27-28, 1969). 5. Crandell, D. R., and D. R. Mullineaux,1976, Potential Hazards from Future Eruptions of Mount St. Helens, Volcano, Washington, U. S. Geological Survey Open File Report 76-491. 6. Mullineaux, D. R.,1976, Preliminary Map of Volcanic Hazards in the 48 conterminous United States, MF-786. 7 Portland General Electric Company,1973, Final Safety Analysis Report, Volume 1. 8, Portland General Electric Company,1969, Preliminary Safety Analysis Report, Trojan Nuclear Plant, Volume 1. 9. Puget Sound Power and Light Company,19 73, Preliminary Safety Analysis Report Skagit Nuclear Power Project, Volume No. 4. 10. Shannon & Wilson, Inc.,19 76, Volcanic Hazard Study Potential for Volcanic Ash Fall Pebble Springs Nuclear Plant Site, Gilliam County, Oregon, Revision 1, Iby 17,19 76, Report to Portland i Ceneral Electric Company. 11. U. S. Atomic Energy Commission,19 70, Safety Evaluation Report by the Division of Reactor Licensing, US AEC, In the Matter of Portland General Electric Co., City of Eugene, Oregon. Pacific Power & Ligh t Co. Trojan Nucicar Plant, Docket No. 50-344, October 19, 1970. 12. U. S. Atomic Energy Corsission, 1974, Safety Evaluation Report Trojan Nuclear Plant, Docket No. 50-344 October 7, 1974 m i l 5 _. - - - - - - - - - - - - - - - - - - - ^ - ~ - - - ^ ^ ' ~ ~ " " '

- ~ g( 3. g

t. T 1

~' 2 --- I l 13. U. S; Ceolegical Survey 1977, Status of Reviev ?uget Sound Power. t and. Light Co:pany, Skagit Nuclear Power. Proj ect,. Units 16 2 Proj ect No. 514, Skagit County,5:ashington, NF.C -Docke Nos.- 1 50-522 :and 50-523. - i 14. State of Oregon Departrnent of Geology and Mineral Industries,1978, " Geologic Eszards Review Trojan Nu: lear Power. Plant Site Columbia . i . County, Oregon," Open File Report 7E-1,' March 14,- 1978. l 15. U. S. Nuclear Regulatory Commissio',1973 Supple:ent No.-3 Safety.- n Evt.luation Report related : to construction of Pebble Springs Nuclear Plants. Units 1 and 2 Docket No'. 50-514 arid 50-516. s . i

16. Washington Public Power Supply. Systen,1974, ' Preliminary Safety i

Analysis Report WPPSS Nuclear Project No, 3, Volume 3. f ^ 17.c. Williams, H. ' A.,,1942, "The Geology of Crater Lake National Park, i Oregon,". Carnegie Instit0 tion of k*ashington Publication 540, 1942.- I t + h i 1 v i [ . I b l t I ' i i t l 9

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O - Table 3.---ttean winct speeds, in knots (1 knot = 1.15 mi/h or.1.85 km/h), at various altitf ;. Based on 20-year record (1950-1970) at Quillayute, Wash. (Winds Aloft Summary of thC*r Weather Service, U.S. Air Force, available from the National Climatic Center, AshevTiiE ft.C. ) FROM----- N time flE ENE E ESE SE SSE S-SSW SW WSW W WNW f."E NNW ' .TOWARD--- 5 SSW SW WSW W WNW NW NflW N NNE NE. ENE. E

ESE SE

-SSE 1 Approx. alt. .(m) 3,000 18.6 16.3 14.8 11.5 11.6 12.4 13.8 18.l' 24.2 25.7 25.4 24.2 23.5' 21.8 22.4 -21.2 C 4,300 26.7 21.7 18.7 15.1 13.7 15.5 18.2 21.5 27.2 30.7,. 31.3 31.1 31.0 29.4 '29.6 28.5 5,500 33.2 27.8 27.9 18.5 l7'.6'-16.8 20.8 22.9 32.2 36.6 38.6 38.3' 38.4 37.3 35.7 36.9 9,100 48.6 43.8 36.5 29.9 30.2 26.4 32.2 38.0 46.8 52.5 55.9 55.4 56.2 50.8 51.6-53.9 -f 12,200 40.9 31.5 30.3 14.9 19.7 16.9 18.8 28.0 35.8 43.8 48.5 50.3 50.9 46.2 -46.3 45.4 i 16,200 20.1 12.4 11.3 6.3 6.4 9.0 9.7 13.8 15.5 -21.1 23.7 '25.8 26.2 25.1 23.7. 21.4 ~ Avera9e-- 31.4 25.6 23.2 16.0 16.5 16.1 18.9 23.7 30.3 35.1 37.2 37.5 37.7 35.1 L34.9 34.6 i & m.* Gree /$, O S J **/ $). A. 09eA *reavf,

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. s. Table 4.--Percenta3e of winth. hv month, a t.tx al titudes from about 3,000 to 16,000 m averanad. lia.ett on'/0-ygir rer.ord (_T'hil'-l}'l'7[0)((atyiTTa~y~iit[,}laV_h{(ii,inds Alof t Supya,ry of the Air Ueat'en r y rvice, u.s. Air Forro, availablo from the' Na tiona l Clima tic Center,_ Asheville, N.C.). FROM----- N NNE HE ENE E ESE SE SSE 5 SSW SW. WSW-W: WNW NW flMil TOWARD--- 5 SSW SW WSW W WNW NW NNW N NME NE ENE -E .ESE SE SSE JAN------ 3.4 1.4 0.7 0.5 0.5 0.2 0.5 1.0 2.7 6.8 12.5 16.9 18.4 15.2 11.9 7.0 F F.ll- - -- -- 3.9 1.9 1.3 .6 .8 1.1 2.0 1.8 3.7 6.5 10.8 14.2 16.4. 15.2 12.3 7.4 t%R------ 4.5 2.1 1.1 .5 .9 .9 .9 1.5 4.3 U.4 12.2 14.2 15.5 '12.7 12.0 7.6' APR------ 4.2 2.7 2.1 1.4 1.2 1.3 1.6 2.6 4.8 7.0 11.9 13.4.14.8 12.2 11.3 7.C !%Y------ 4.4 2.2 1.6 1.0 1.0 1.6 3.0 3.9 6.9 8.6 13.6 '15 0 13.0 10.1 7.7 6.0 . JUNE----- 3.7 2.8 2.3-1.7 1.4 1.5 1.7 2.8 6.0 9.0 13.9 14.9 13.4 10.0 .8.6 6.2 JULY----- 3.1 1.9 1.4 1.0 .9 .9 1.1 2.2 4.0 8.6 18.9 19.8 13.8 9.4 7.5 5.7 AUG------ 3.1 2,3 1.5 1.0 1.0 1.2 1.6 2.6 5.1 9.0 15.8 17.6 14.7 10.0 8.1 5.4. SEPT----- 5.3 2.4 1.6 1.1 1.2 .8 1.2 2.2 3.2 7.9 12.2 12.7 14.7-14.7 11.3 7.7 l I OCT ----- 2.2 1.4 .7 .4 .2 .2 .5 1.1 3.8 8.7 16.6 19.9 19.2 12.5 7.8 4.6 NOV------ 3.3 1.4 .5 .2 .4 .4 .8 1.7, 3.5 8.1 .13.9 17.0 20.2 14.0 11.3 5.1 DEC------ 3.1 1.2 .4 .3 .3 .3 .5 .9 3.2 8.8 14.4 17.4 18.5 14.4 10.5 6.0 AVERAGE-- 3.7 2.0 1.3 0.8 0.8 0.9 1.3.2.0 4.3 8.1 13.9 16.1 16.1 12.b 10.1 6.4 pr,,.- cna,eleH, D. 2 --,c/ D R. Mv//ines es; M 7 6, A/enM/ No r =dr oCom 5/sre- ' Enp h'. .e of / feen / S/. He /ent Yo/ con e, w;,r/u'nyk n, W. G e / yi d Su n y Q a-, p/e Jep.ct' 76 99/ s e ~ _h.___1_ ____h_h____-- -m

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