ML19254E493

Rept of IAEA Safety Mission on Geological Hazards & Geotechnical Aspects.

ML19254E493
Person / Time
Site:	05000574
Issue date:	07/31/1978
From:	Harsch W, Muzzi F, Rizzo P INTERNATIONAL ATOMIC ENERGY AGENCY
To:
Shared Package
ML19254E490	List: ML19254E489 ML19254E493 ML19254E496
References
NUDOCS 7911010235
Download: ML19254E493 (21)

Text

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REPORT h

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THE I. A.E. A. SAFETY MISSION 9$

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GEOLOGICAL HA7JRDS & GECTECHNIC AL ASPECTS W

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E P?EAP3LE W

At the request of the Philippine Atomic Energy Coc=icsion (PAIC) ]

i acting for and on behalf af the Governcent of the Philippines, the International Atomic Energy Agency (IAEA) provided the advisory services l

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e of 2 dafety Mission for a review of certain geologic.1 and geotechnical ~ it aspects of the site and its environment for the Philippine Nuclear Power ,

Plant !!o.1 (P!TPP-1). The Mission visited the Philippines from 1 to 9 g

't May 1971 and =st in Vienna from 3 to 7 July 1978.

The Director General of the IAEA would like to place on record his  :

understandng that, upon ecmpletion of its work, the Mission has for=ulated such recoc=endat e:ns as the Mission, to the best of it s judge =ent , considers desirable for the attention of the Philippine authorities with respect to the ceasures that should be taken for ensuring tne safety of the plant, the 4 plant personnel and the public. The Mission wishes, however, to point out that only a s=all part of the safety aspec.s were considered by it , and that such ccncideration was limit ed to geological and geot echnical matt er=.

It should be noted that the Mission's conclusions and recommendations cet out in this report t (a) are based on the documentation and inforcation made available to -

it by the Philippine authoritles and are =ade on the ' Mission's collective expertise without endaging the individual responsibility of any of its members or the Missien's liability whatsoever 1 (b) do not engage the IAEA in any way ner imply any guaran:y or legal responsibility on the part of the IAEA. .

In view of the nature of the info:=ation contained in this report , it s dist ribution is strictly restricted and subject to the discretion of the -

Philippine au:horities. ,

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IlfrRODUCTION l

3ACKGROUND -l SCOPE OF REVEd VI3RATORY CROUND MOTION AND SURFACE FAULTINO VOLOANISM CE0 TECHNICS CONCLUSION ANNEX 1 List of participants durf-g the visit to the Philippines

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UCGX 2 Itinerary ANNTX 3 List of additional documents presen*.ed for the meeting in Vienna 3 - 7 July 1978 ANNEX 4 List of experts who attended the meeting in Vienna ,

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PREAM3LE l

I!iTRODUCTION BACKCROUND

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SCOPE OF REVIEW VI3RATORh CROUND MOTION AND SURFACE FAULTING

\DLCANISM CEOTECHNICS CONCLUSION ANNEX 1 List of participants during the visit to the Philippines ANNEX 2 It inerary ANNEX 3 List of additional docu:,ents presented for the meeting in Vienna 3 - 7 July 1978 )

A!CEX 4 List of experts aho attended the neeting in Vienns ,

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IN?RODUCTION ,

The IAEA safety mission composed of the following experts: -

r MM. W. Harsch - Swit ze rland  ;

F. Muzzi - It aly ,

P. Rizzo - United States of America h

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J. McCullen, IAEA staff member g E. Iansiti, IAIA staff member J- @

-  ; i, visited the Philippines during the period 1 - 9 May 1978 sad had discussions hh with the experts and repnsentatives of t' e nPhilippine Atomic Energy Commission b (PAEC), Nuclear Pewer Corporation (NPC) and Westinghouse. A list of the h persons met during this period is enclosed as Anne i and the itinerary is T

present ed in Annex 2. During this visit , it was not possible to have discussion a P

with the experts who have prepared the Preliminary Safety Analysis Report r k (PSAR) and performed the seismic analysi's. At the request of the Covernment f of the Philippines the Mission was reconv*ned wit'a the same participants with f[

the exception of Mr. McCullen who was ill at this time, in Vienna from 3 - 7

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July, 1978. t 1ll:

The members of the Mission received during and lafore the meetira a y substantial amount

( f additional materials whose list la enclosed as Annex 3 On 3 July, the experts of the Mission discussed the additional mate rial with [

the experts of PAIC, Mr. Ibe, Mr. Santos and Mr. Willis (IAEA Technical I

. Assistance expert ).

In the following days, from 4 to 6 July, the subject was discussed ',

under the chair =ansh!n of Mr. Ibe with expert s from PAEC, NPC, Ebasco, ,

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Westinghouse as well as independent exper:s (see Annex d) invited by Ebasco and NPC. Mr. M. Ros en and Mr. A. Karbassioun, st aff = embers of the -

' Agency, and Mr. C. Willis t ook part also in the discussion. A list of all b participants in the meetings is enclosed as Annex 4.

The peesent repo rt was prepared by :he Mission and includes discussion -

and recommendations on specific technical items on geological hazards and >-

geotechnics as finalized during both periods. It supersedes the preliminary 'i I draft repor: prepared at the end of the visit in the Philippines in May 1978 and it represent s the best assessment possible of the situation within the 1tmited time available to the Mission. $

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5ACCRC'JN D The PNPP-1 is locat ed at Napot Point , Bataan peninsular. A reorgani:stion has taken place in the Philippines since the previous safety review =ade by the P.A.E.C. with an IAEA Safety Mission during 5 - 22 July,1977 New the De part =ent of Energy has overall responsibility for the nuclear programmes, it and both the P. A.E.C. and the N.P.C. are in this Lepartment. o l!

The P. A.E.C. is the compet ent national authority responsible for i' licensing and regulating nuclear projects including PNPP-1. All regulatory ,,

activities are the responcibility of the . Nuclear Regulation and Safeguards Depart ment (NRSD). The N.P.C. is the utility company directly responsible through its Special Project s Croup - for the PNPP-1. ,

PHPP-1 is a turnkey project with Westinghouse International Project Corporation serving as the general cont ractor; =ajor sub-cont ractors include ,

Burns & Roe as architect / engineer and Chicago Bridge & Iron as containment vessel supplier. E3ASCO serves as general consultant to NPC as well as for directing the sit e work and providing relat ed part s of the PSAR.

ACENOWLEDGE'E.NT

'he M'ission wishes to express its thanks to the P.A.E.C. and the Philippine

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Ecbacsy for their kind hospitality and support during the Missio~n's stay in the Philippines and the =eeting held in Vienna. Further= ors, the Mission expresses its thanka to N.P.C. who made a room and secretarial services available in its downtcwn office in Manila. Finally, the Mission wishes to acknowledge the kindness of both Westinghouse and their local cont racters P.C.I. who made available two helicopters for visiting the sit e and its surroundings.

, SCOPE CP TIC RE 7IEW  !

The Mission visit ed the site and observed const ruction activities and ,

local site conditions in May 1978. During the course of the visit in the Philippines and meeting in Vienna, the experts held meetings and discussa.cna i ,

with P.A.E.C., N.P.C, Westinghouse and Ebasco (the latt er was present for discuss:.on in Vienna only), reviewed and studied material provided by the

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applican; in the PSAR as well as the Supplementary Mr.erial provided by ,

t P.A.E.C., Ebasco and Westinghouse and PNPC dealing with vibratory ground .

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P00RORGNAL i"

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tion, geological hazards including surface faulting and volcanism, 6 i

foundat ion engineerin; and seismic analysic. At the conclusion of the g

visit to the Philippines and of the meetings in Vienna, this report t' was prepared which includes ce= ents en the safety of the site from the [

oint of view of geological hazards and foundation engineering. y m

IIr VIERATORY CROUND POTION A!!D SURFACE FAULTIl!G g 4

The . review of related sections of'the PSAR and of the additional data t a rr combined with the discussions held in July 1978 indicates that a comprehensive 9 series of investigations hate been conducted towards establishing suitable y seismic design bases and considering the need to design for surface faulting. I is The techniques and =ethods used in the investigation are generally regarded as st at e-o f-t he-art and consist ent with those used in the United States, 4 4

Europe and elsewhere. However, several conceptual / interpretational issues a have developed during our review process which might impact on the design of F 1

the plant. These issues are enumerated as follows:  ;*,

(1) The approach and judge =ent used to postula n the =axamus earthquakes [

for deter =ining the level of the safe Shutdawn Earthquake (SSI). In [

addition, we have concern with the approach used in considering the }

seismic risk associat ed with the eastward deccending subducting slab i; beneath Luzon. ',.'

LS (2) the conoideration of a relatively shallow, ficating earthquake in l ,,

the i= ediate vicinity of the sit e. p t'

(3) The consideration of a postulat ed earthquake on a possible shore- IP tr parallel fault approxi=at ely 15 - 20 km offshore the sit e. rr (4) The lack of adequat a consideration of a possible there-normal fault [

t-on the south side of the Napot Point Peninsula. p ks Each of these issues is more fully discussed in the following paragraphs. p.

V POSTULATED MAXIrJM EARTEUAKES Cbk b &

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Each of the postulated maxi ==.s earthquakes listed en Table 2 5 2-4 of the I I

PSAR is associated with a known capable fault in the vicinity of the site. The j sagnitucte of the =axi. us event , which is postulat ed to occur at the fault 's l closest approa:h to the sit e, has been dct er=ined by the Applicant on the

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r r-acsu=ptien of 407. of the fault 's total loncth of rupture durirs the ,

post ulat ed e vent . '

Our review of the dato presented in the PSAR as well as discussions in July 1978 coupled with data available for faults elsewhere in the world indicate that certain of the postulated maximum earthquakes should be core conservat ively int erpret ed. Firstly, we judge that a magnitude 7 5 t o 7.8 -

event can be reasonably postulated to occur on the San Antonio Fracture Zone. 2econdly, in accordance with the st ructural =odel provided in Chap.

2 51 the Mission judges that an event having a magnitude in the range of 8 can be reascnably postulated to occur directly on top of the subducting slab at its closest approach to the site,at a depth of about 50 - 70 km.

This is opposed to the magnitude 7 9 event postulat ed by the Applicant to occur at a distance 100 km west of the site. Thirdly, we judge the data =

to show that an event having a =agnitudo in the range of 7 5 could be reason-ably postulat ed to occur in the Manila Bay Fracture ZorA It appears from the above considerations coupled with the Applicant 's other postulated =azimum events that the event postulated to occur beneath the sit e on the subducting slab might control the seismic design basis for the plant . There are very little data available to the profession for assignird a "g" Value, est ablishing a complete seismic design basis or for M evaluating oth'er ground motion effects for this type of near-field event.

Conventional att enuation relationshipe, such as used by the Applicant for the other =ax1=*.:.s event s, =ay not be applicable for such a model. Rat he r, so=a type of scaling approach would appear : ore appropriate. Consequently, detailed additional work should be direct ed toward evaluating the above g postulat ed event on the descending slab from the Manila t rench as well as k the other postulated events described below.

w 1284 349 SHALLCW FicATING EARTMCUAKF.;

The Applicant considers a " floating" earthquake of agnitude 4 5 without-adequat e subst ant iat ion. The tectonic model developed by the Applicant does not adequat ely define the t ectonic st ructure i==ediately east of the Manila -

Trench, specifically the zone designat ed by the Applicant as the west Luzon Trough. ' Consequently, the Mission is not able to agree with the Applicant 's assignment of events having a magnitudo greater than 4 5 to this feature. e 300RORSNAl. 1 e

_5-Marcover the Mi:sion was unable to fully assess the pocsibility of a higher cagnitude shallow event occurring beneath the site because of the lack of a co=plete composite epicenter map and a composite earthquake catalegue.

The Mission suggests two possible alternative approaches to resolvirg this quection at this point in ti=e. Firstly, a = ore thorough and detailed ,

analysis of all available earthquake data could be performed. Secondly,

• l those events within all bounds of the Central Lucon Tectonic Province shown on Figure,2 51-27 which cannot be clearly assigned to the Manila Trench, the San Antonio Fracture Zone, Manila 3ay Fracture Zene, the Taal Frac.ure Zone,  !

the Philippine Fault of the Iba Fracture Zone should be treated as random and  !

assigned to the province, and be postulat,ed to occur beneath the site. The I Mission has particular concern for at least three particular events listed j as follows:

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.i June 6,1933 N14 E 120 6.25 Unknown i Nov. 26,1934 N14 E 120 6.25 Unknown Aug. 31,1960 N13 8 E 119 9 4 75 24 k:s ,

l In developing the composite map and composite catalegue, the Applicant may encounter other events not observed by the Mission. In any case the Mission i reco== ends a, searching of the actual recordings with a view toward relocating the above events as well as other events with unclear or suspect published )

locations with a higher degree of accuracy than heretofore available. This will allow for a high level of confidence in the assign =ent of these eventa

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to a st t-ac.ure or to the province. L' l-As an alternative approach to the question, the Applicant could postulato f a randos event having a magnitude in the range of 6.0 and a challow depth I

-(less than 30 k-) to occur directly beneath the site. In considering such i I

an event the Applicant should develop st rong technical basis for his choice g of =agnitude and depth of this event and he should thoroughly study its '

duration, high frequency cont ent and other near-field effects, particularly  ;

as they affect the shape of the design response spect ra.

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1284 150  ;

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SHO?.E-PARALLEL A!*D SH0r? !;0P"AL Pt.ULTS The Mission's review of marine geophysical data in the PSAR as well as other data provided by P.A.E.C. and discussions with Dr. Sonido in May 1978 l and the Applicant 's consultants in July 1978 indicate possible shore parallel I fault system approximately 15 to 20 Icn off-shore the plant. The Nisaion understands that this =atter us also discussed with the Applicant in March "

1978. Lacking streng data, to the contrary, the Mission believes that the  ;;

quality o,f the data obtained from the single channel analog system precludes 3 firm resolution of the seismic risk associated with the possible faulting. h Consequently, we judge that this fault =cne should be taken as a source of

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a maximum earthpake in developing the sciamic design basis for the site.

However, the Mission believes that the risk associated with possible fault- 4 e

ing in this zone to be lower than acsociated with the high =agnitude event J postulated to occur in the subducting slay and the higher magnitude shallow "

random event . l-!

u With regard to shore-nor=al faulting, there are several icolated piecce,

• of data in the PSAR which, when considered together with discussions held in Jtily 1978, suggest a need to re-consider the question of chore nor=al

• faulting in more detail. Specificallyi the abrupt scarp-like bathymetry on u 4

the South side of Napet Point , the subdued manifestation of this scarp-like a topography in the acoust to basement as revealed by the Marine Ceophysical Survey, the align = ant of surface lineatiene en land, as revealed by topo- p

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graphic caps, 'SLAR, Landsat and Ther=al IR i=agery, with the scarp-like lj seaficor feature - all cont ribute to a concern that requires i nher detailed v

, consideration by the Applicant . Specifically, the Mission reN 2 ends additional -

field investigation of possible faulting in the vicinity of a line running d between p

M 1,619,000 N 1,618,0C0 N 1,617,000 (,L E 426,875 E 426,500 E 426,175 - a-b as can be plotted on Figure 2 51 - 55 of the PSAR and on Ficure 1 of * **

Engineering Report No. 4. The results of this investigation should include n conclusions regarding the i= pact on plant design and operation if the fault L

' 'i * - L 1284 ]51

• The Missics observe:i two areas on the in testigation which could have '

receive:i additianal effort and support. Firstly, tho =icreear:hqucke survey k r

was minimal and together with the lack of detailed study of low =agnitude t event s cn:1, cons:quently, :locs not prove to be highly contribu:ory to the under-

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f P00R ORIGINAL !

_7-standir.g of the seic=otectonic situation and the assesc=ent of faults and overall seis=ic risk whereas a longer, = ore detailed survey =sy have been very helpful. The invectigation of some of the linears as well as the ther=al springs is regarded as =inical and not in keeping with the quality E

of other parts of the inventigation..

VOLCANISM The #1 pot site is unique to the nuclear industry in so fa - as the i risk associated with eruption of nearby volcanoes. The only =odern plant f which is designed to account for volcanic eruption is the Pebble Spring Plant in the Unit ed Stat es. This plant is located 128 k= from the nearent ,

volcano and consequently only ash fallout is a consideration. Jt the Napet Point site, the nearest volcano is 9 k= away. Therefore, the quet.tton of volcanic eruption deserves extre=ely careful consideration at this site. I It is e=phasised that the Applicant and his Consultants have perfor=ed exter.sive and in depth investigations to answer the questions raised by thr.t volcanic threat. Moreover, the Mission believes the investigations perfor:ed .

=aet the stat e-of-the-art how a volcanic hazard is to be envisioned. Also, detailed, presentation of the data during the =eeting is appreciated. In i.

addition, theJ Mission acknowledged very =uch the valuable contributions :ade f

by the Volcanological Review Co=sittee in that =e et ing.

. After thorough discussion of all the geological and volcanological provided data together with the Applicant and his Consultan;s, the Mission concludes that there is still a great deal of uncertainty of renewed f r

volcanic activity at Mt. Natib. Moreover, it cannot be judged as such that I

a future eruption is confined to the east side of Mt. Natib, i.e. the t

, for:ation of new volcanic centres on the west flank of Mt. Natib is not

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considered to te incredible. More appropriat ely, the erupt ion '

of the Mt. Natib Volcano Co= plex and all of the hacards associat ed with it should be taken as an ext rs=e environ = ental loading si=ilar to the Safe l Shutdown Earthquake (SSE). Consequently, the Mission deece that the hacards I associated with such as enption, e.g. ash fall, i= pact of volcanic e;ecta, l glowing avalanches, overflowing gas-ash e=ulsions and gas accu =ulation as  ;

well ac laharic =ud flow should be taken into account.

PDDRORGNAL -

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Means should be provided to mitigate against a. radioactive release in the event of a volcanic eruption of Mt. Natib. One possible means of I

accomplishing this is ,he recoval of all fuel from the site to an off-site  ;

storage area away from the volcanic threat. This consideration recognizes  ;

the assessment made by.the Volcanological Review Committee that the renewed

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eruption of Mt. Natib can be reasonably predicted three c:enths in advance (

should a per=anent , sophisticated and well =aintained volcanic surveillance [

system be displayed. Moreover, it is necessary to establish volcanological I l

baseline. criteria gathered by the surveillance system which should initiate L k.

without delay the possible shutdown of the plant as well as a course of actions h

regarding preteetion of all fuel.

The Missions understands that the surveillance system will be int.. .lled as soon as possible in order to collect appropriate data necessary for the l

definitien of those baseline criteria before the plant will come into t I

operat ion. The Mission not es the advice given by the Volcanological Review Committ ee that the surveillance syst em should provide seismological, geodetic, gravimet ric, 7:.gnetic, and thermal data.

CEOTE0'DICS I

. The behaviour of the soil beneath and adjacent to the foundations under static and dynamic conditions has been reviewed on the basis of the related PSAR sections. During the meeting in July 1978 additional reports wers  !

analyzed. >

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SOIL INVESTIGATIONS The results of the progra==e of soil investigations perfomed at the  :

site and in the laboratory indicat e that from the st ratigraphic point of -

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, view, the Safety Class and Seismic Category 1 stmetures are underlain by g a rock-type coil or by a cont rolled backfill. The numerous stratigraphic '

borings and coophysical investigation have been found generally adequate in ,

nu=ber and in type. The foundation soil can be characterized in a very g synthetic way by a compression wave velocity varying from 1500 to Soco =t/sec i t

which allows us to classify the site as having stiff soil conditions.

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-9 Civen the gross non-homogenity of the foundation c:st orials underlying the site as determined from borings and trenches, the Mission raised a concern with respect to the reprasentativeness of the undisturbed samples used for measuring soil behaviour in the laboratory. An exceptionally high reduction l in shear modulus at high at rain levels, i.e., "st rain-softening", is indicat ed '

by the laboratory tests on samples of rock-like saprolite and weathered rock.

This concern would diminish considerably for dynamic shear strains less .

than 10~4 The Applicant should confirm that the dynamic shear st rains will be itsa than 10-4 as revealed by the final soil-structure interaction analysis.

Along this same line, the Mission has concern with the "zero strain" shear wave velocity data. The in situ d$ta from a single vertical boring (No. JF1) do not permit straightforward e:ctenaien to the soil profile used for analysis and design. Furthermore, it was necessary to utiliza correction factors to cause agreement between laboratory data and field data. The Ap.nlicant should review all of the "zero strain" shear wave velocity data i i

and confirm that valves actually used in the soil-structure interaction i analysis are representative of site conditions. I STABILITY OF SU3STFACE MATE 3IALS l

,In spite of the limitations of the data as described above; the Mission concludes that the subsurfacs natorials at foundation level of Class I struc-1 l tures have adequate strength and compliance ao as not to pose a threat to the safety of the plant. However, we note that the PSAR does not report specific-ally such important parameters as the design crit eria for dynamic bearirg g capacity, factors of safety, design water tables and assumed pore pressure j condit ions. We reco==end that the Applicant perform a dynamic bearing capacity [

analysis under the worst combination of SSE loading, appropriate dynamic soil paramet ers, and design wat er tables; factor of safety greater than 2 against bearing capacity failure'should be assured. I t

SLOPE STA3 LITY [

The slope stability analysis of the natural slopes and cut slopes at the site have been performed using the Simplified 31 shop method. This method

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can include the combination of the seism:c forces (vertical + hori: ental) and t assumes a slip circle as the failure surface. Fact ors o f cafety of.1 5 and 1.1 i considered accup:acle respec:ively for sta a by the 1284 054 l

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p; Owing to the interbodding of the several layers i.nd to the rocky type -

of soil, it appears that also a wedge type of failure with due consideration given to rock joint systems should be considered by the Applicant in a new analysis. Also, the new analysis as well as all previous stability analyseu for both natural and cut slopes should consider possible amplification effects of the topography. The Mission also believes that the stabi~.ity of the coast-line scarp on both sides of the plant as well as on the seaward side deserves .

additional detailed stability analys.% under extreme environmental leading condition's, again with the consideration of topographical ampli'fication effects and rock joint syste=s.

SOIL RESPONSE UNIER SEISMIC EXCITATION The particular topcgraphy of the site a steep-sided, relatively narmw peninsula graded from about elevation 35 dcwn to elevation 18 and rising up to Mt. Natib, suggests that surface ground =otion might be sevenslyaffected during an earthquake by unus tal wave propagation phenomena. Several accolo-grams recorded during the 1971 San Fa-asde canhquake showed unusually high acceleration spikes which are attributed to pa:Sicular site t.cpography. At .

sit es locat ed on slopes in Italy, high peak accelerat ions were recorded dur-ing the Friuli earthquake of 1976. Considering the distinct topegraphy of 4 this site and the relatively high Safe Sh2tdown Earthquake, the ' Mission T recoc= ends that this aspect of seismic responra he thoroughly investigated.

Moreover, the Mission points out the conditions and typerof earthquakes used in the development of design response spect ra in Regulatory Guide 1.60.

Considering the particular conditions at this site i.e. a possible nearby '.

earthquake with stiff soil conditions, the Mission is concerned with the possibility of high frequency motion having a=plitudes higher than these $

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.associr.ed with the Regulatory Guide Spectra adopted by the Applicant. g

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The Applicant should provide his design basis for nitigating against

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5 The Appl.: ant hss adopted the finite element technique for asseccing h

coil-ct ruct ure int erat. ion. Generally speaking, the .atalysis has been performed within wvitten siipulations of the regulatery guides and standard review plants conventionally used for this type of analyses. However, the analysis fails to evaluate the possible a=plifying effects (acceleration and frequency) of the peninsula topography and the possible reduction in ,

geometric damping associat ed with the topography. Further= ore, the analysis seems to suggest exceptionally high strain sofsening which should be re-assessed by the Applicant. Both issues, i.e. Topograph! cal effects and Strain Softening as well as the assumptions for the inz t tal shear moduli, should be investigated by the Applicar EARTHQUAXE INSTRUE 7PATION The Mission understands that an earthquake =onitoring syst em will be pa:t of the surveillance system to monitor preconitory signs of a future possible eruption of nearby volcanoes. In ?Ad. tion to this Surveillance Syst em the Mission :-ecommends that atrong c:otion accelcroceters also be installed i==ediate:.y at the site. These accelerometers should Le set in a series of different locations much as treefield (off peninsular), on the peninsula away frem the foundation,on the Cat egory 1 foundation =at , and in the strdcture in accordance with Standard Practice.

6 CONCLUSION Based on infor=ation provided in the PSAR and in the supple =entary caterial as well as provided verbally during the discussions with the experts of PAEC, Ebasco, and Westinghouse, the Mission wiches to express its major concerns in the following areas and as detailed more fully in the text of the report .

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VI3RATORY GROUND MTION AND SURFACE FAULTINO

?0DR ORGINAL (1) The Safe-Shut down Earthquake should be re-evaluat ed considering a possibly higher magnitude randem shallow earthquake postulated i to occur beneath the sito and a high magnitude earthquake postulated .

to occur on the subducting slab beneath the site at 1:s closest approach t o t h o s it e. A third event postulat ed to occur in tone .

of possible offchore faulting is judged to be of a lower ris ' level so long as these two earthquakes are reconsidered. '284 256

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.---......a (2) Additional investigation and analysis are required to resolve f.

concern with evidence for a shore normal fault mnning parallel t to and i= mediately south of the Napot Point Peninsula. l l

VOLCANISM h I

(3) The emption of Mt. Natib is a credible event which should be  ;

taken into account in design. This requires consideration of I

. excessive ash fall, glowing avalanche, gas accumulation as well f

as laharic slides. '

(4) The immediate installation of a sophisticated and well-maintained volcano surveillance syst em in combination with well-defined base-line criteria and subsequential precedures and action plan concern- I ing the operation and/or shutdown of the plant is st rongly recc= mended.

L (5) one pessible solution to mitigate against a radioactive release in the event of an eruption of Mt. Natib is the removal of the fuel to an off-site storage location upon advance warning by a surveillance syst e.n. The Mission bel'ieves that this alternative, as well as other

, possible alt ernatives, deserve consideration in developing the pro-cedures and action plan mentioned above.

t >

R)UNDATION ENGINEERING F

(6) The geotechnical investigation conducted by the Applicant is

[

acceptable for the particular soil foundation characteristics. -

The site appears adequate from a static foundation engineering point of view. Topographical and local effect s on vibratory ground I motion, design reeponse spectra, natural slope stability, and cut slope stability should be properly investigated; soil-structure ,

interaction analysis should also be revised accordingly if appropriat e. r

Clarificatica is needed with respect to the initial shear moduli and i i

"st rain soft ening" soil charact eristics used in the dynamic analysis }

present ed t o dat e. >

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. L-ANEX 1 M

!b List of experts who attended various meetings in the Philippines from -

a 1 - 9 May 1978 g

w SAITTY MISSION EMEERS W. Harsh -

Swit zerland P Mu :1 -

Italy P. Rizzo -

United States of America E. Iansiti 7,y,g,g J. McCu.llen PIIILIPPINE ATOMIC EERCY COMXISSION r

Z. M. Bartolo=a - I)eputy Commissioner R. L. Palabrica -

Acting Manager

• G. Santos -

Geologist g

E. Hernande: -

Geologist NATIONAL POWER CORPCRATION R. B. Blanco -

Manager, Special Pmjects Group -

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WESTIN0 HOUSE

. J. Woeber -

Site Manager .'

W. Corcoran - Quality Assurance -

J. Xaviar -

Site Engineer IAEA exPm a

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C. Willic N

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"U . . ._ t ANNEX 2 ITINERARY OF THE VISIT IN THE PHILIPPINES 30 April 1978 -

Safety Mission nenbers arrive in Manila 1 May - Discussion on safety problems  !

2 May -

Discussion at P. A.E.C. and first review of documents  !

3 May -

Review of docu=ent s at N.P.C.  !

4 May .

- Helicopter visit to sit e, sit e review and discussions with centractors and consultants 5 May - Discussion regarding main points arising in site visit  ;

at N.R.C. l 6 - 7 May - Pirst drafting of report 8 May - Meeting with P.A.E.C. 8 i

L TIE SCHE!ULE OF ' IRE KEETING HELD IN VIENNA 3 July 1978 - Discussion in IAEA Headquarters with the experts and ,

P. A.E.C. expert s 4 - 6' July, -

Discussion with P. A.E.C. , P.N.P.C. , E2ASCO , West inghouse and other IAEA staff neebers and experts I

I 7 July -

Preparation of the report t i

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LIST CF ADDITICUAL 'ACUE!.TS PRESEUTED FCR THE WINO IN VIENNA 3 - 7 JULY 1978 PNPC - E3ASCO, Geology of Unit 1 Excavation. February 1978 PNPN - E3ASCO, Hagae Nuclear Power Plant , Site Confirmation decort ESASCO, PNPP - 1 PSAR, Amendment No. 3 .

EBASCO, Seismic Risk Analysis for the Philippine Nuclear Power Plant Unit No. .l.

ESASCO, Seismic Velocity Data-Philippine Nuclear Power Plant. December 1976.

ESASCO, Vibratory Ground Motion Addendum 1, Engineering Reput No. 2, -

May 1976.

E3ASCO, Philippine Nuclear Power Plant , Unit 1. Response to letter of 20 December 1976.

'E3ASCO, PNPP 1, Additional Safety Related Data. June 30, 1978.

E3ASCO, Philippine Na*ional Power Corporation. Philippine Nuclear Power Plant Unit No. 1, Volcanic-Seismic Surveillance Progrs==e.

E3ASCO, Geolcgic Ha:ards to PNFP Unit 1. July 1977 E3ASCO, PNPP, Additional Safety Relat ed Data. June 30, 1978.

E3ASCO, PNPP ,1 PSAR, A=end:ent No. 3 E3ASCO, Philippine National Power Corporation, Philippine Nuclear Power Plast. Engineering Report Number 1. February 1976.

E3ASCO, Addendum to Engineering Report No.1, Philippine Nuclear Power Plant.

E3ASCO, Philippine National Power Corporst:en, Philippins. Nuclear Power Plant Unit No. 1. Engineering Report Number 2. April 1976.

ESASCO, Philippine National Power Corporation, Philippine Nuclear Power Plant ,

' Unit No. 1. Engineering Report No. 3, Volu=e I . September 1976.

ESASCO, Philippine Nuclear Power Plant , Unit 1. Engineering Report No. 3. Voluso I:

Sept ember 1976.

E3ASCO, National Power Corporat ion, Philippine Nuclear Power Plant , Unit -

No. 1. Ingineering Report No. 4 February 1977

(

e.,

u-E3ASCO, National Power Corporation, Nuclear Power Plant , Unit No. 1.

Engineerir,g Repor: No. 5 May 1978.

J 28ll ]6) [!'

WESTINGHCUSE, Seismic Analysic-Philippines Nuclear Power Plant Unit No. 1.

February 1978.

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LIST OF EXPERTS '..TO AME::DED tnt ' TIE:'.:A 22C?ING 3 - 7 JiluY 1978 P.A.E.C Mr. L. D.' Ibe Mr. C. Santos N.P.C.

Mr. A. Alcara:

Mt. H. H. Ibarra Mr. J. C. Torres WESTI?lCHOUSE 4

Mr. T. E. CampbcIl 1

Mr. F. Loceff , '

Mr. J. W. Minogue Mr. W. S. Wilgus E3ASCO SERVICES Mr. J. Cilmore Mr. J. L. Ehas:

Mr. J. Ferguson Mr. I. N. Cupt a g

Mr. F. Snider i Mr. N. R. Tilford Mr. C. F. Whit ehead Mr. P. Ragland Mr. A. McDirney - Cent er for Volcanos Mr. A. L. Odum - The Florida Stat e University {T Mr. J. de Boer - The Wesleyan University '

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IAEA i

Mr. W. M. Harsh - Mission Expert Mr. Ha Vinh Phuong Mr. E. Iansiti - Mission Expert IAEA Legal Counsel to the Mr. A. Earbassioun Mission Mr. F. P. Mu::i - Mission Expert j} ,} l Mr. P. C. Ri::o - Mission Expert 6 t

Mr. M. Cosen . . , ..

Mr. C. A. Willis {

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5 V

g SIAIUS

SUMMARY

EPORT ON ESOLUTION OF ISSUES RAISED ' .

BY THE 1973 IAEA SAFETY MISSION TO THE PHILIPPINES 5 M

b E

CHARLES A. WILLIS I.

Nuclear Reactor Safety Expert d E

International Accmic Energy Agency I t:,

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