ML19254E496

Status Summary Rept on Resolution of Issues Raised by 1978 IAEA Safety Mission to Philippines.

ML19254E496
Person / Time
Site:	05000574
Issue date:	03/31/1979
From:	Willis C INTERNATIONAL ATOMIC ENERGY AGENCY
To:
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ML19254E490	List: ML19254E489 ML19254E493 ML19254E496
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NUDOCS 7911010240
Download: ML19254E496 (41)

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r 4 t-STATUS SUil!ARY REPORT CN IC2:12:0N OF ISSUES RAISED 3Y THE 1978 IAEA SAIETY MISSION TO THE PHILIPPINES k Charles. A. Willis E ABSTRACT The 1978 IAEA Safety Mission raised several issues cencarning the siting cf PNFP-1. These issues involve the safe shutdcrn earthquake, the threat of volcanian and foundatica engineering. The Philippine Aconic Energy Commissics (PAEC) has required the Applicant to address k these issues. The Applicant has provided responses to several issues and is addressing the others. PAEC has reviewed these respenses and

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established additional requirements. In reaching these positiens PAEC has utilized qualified local ecusultants. Where local censultants lack the necessary experience and expertise, IAEA assistance is being scught.

It is concluded that while the work is progressing less rapidly than was reco== ended, PAEC is acting in a responsible mer to ensure the safety of the plant.

-Noee-This report is based on the author's cwn expertise and dccs not engage the IAEA in any way nor imply any co=mitment en the part of the IAEA.

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STATUS

SUMMARY

REPORT ON RESOLUTION OF ISSUES RAISCD '

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3Y THE 1978 IAEA SAFETY MISSION TO THE PHILIPPINES c

g 3ACKGROUND n.

Die first Philippine Nuclear Power Plant (PNPP-1) is a 621 MWe

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Westinghouse 2-loop PWR. It uses Krsko, Yugoslavia plant as a reference design aad is in the line of development including KoRi, Angra-1, Kewaunee Prairie Island, Point Beach, etc. The plant is being constructed on a An "turrkey" basis by Westir 3house International Projects, Co. (WIPCO) .

extensive site investigation was perfor=ed by the owner, National Power A Preliminary Corporatien (NPC) and its consultant, E3ASCO Services, Inc. W Safety Analysis Report (PSAR) was prepared in accordance with the US N

Nuclear Regulatory Cc= mission (NRC) " standard format" and submitted to k Seven tho Philippine Atomic Energy Con: mission (PACC) in July 1977.

volumes of the PSAR are devoted to t.he site study. .

l 1977 and by ,

, Review of the PSAR by an IAEA Safety Mission in Ju y the PAEC Staf

• indicated that this spp sred to be the most comprehensive site investigation and PSAR ever provided in a developing country.

These reviews also resulted in a nu=ber of questions and requirements for further investigations. Pending resolution of thest isme.s (and com-plation of the Environmental Report *) the issuance of the Construction Permit was delayed, with construction work continuing on the authority a

'PN?P-1 is designed to comply with US requirements as per 10 CFR 50 A Appendix I. Due to changes in Philippine law, the Environmental Report A is no longer a factor in PAEC licensing action. The ER vill be reviewed in accordance with PD 1151. Two')hasa=" (7 volu=es) of the ER have been [

t subnit:ed; the remaining "phane", due in Sept.1979, will include con- 7 sideration of chemicals, biocides, and sanitary wastes along with the cost- p ber.efit analysis.

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of a linited work authorization (LWA) issued 3 October 1977.

(The integrity pressure test of the containment vessel was completed 5 March 1979.)  !

f In recognition of the importance of the site-related issues, PAEC i requested the assistance of an IAEA Safety Mission that would concentrate l on the geotechnical considerations. The mission was sought in the fall of ,

1977 but actus,11y reached the Philippines in May 1978. The EBASCO and  !

'JIPCO experts were not present for discussions with the Mission in May so i the Mission was re-convened in Vienna in July 1978. Based on the inform- I acion in the PSAR and supplementary materials (Table 1) as well as the discussions with E3ASCO, WIPCD and NPC experts, the mission concluded that i

certain additional efforts were needed. The Applicant (NPC) was directed i t

by PAEC to perform the necessary investigations and respond to the issues j raised in six areas. This work is in progress. Each of the Mission's t

concerns and the status of the associated investigations are discussed in I the folloding paragraphs. *

• i  ;

i VIERATORY GROUND MOTION AND SURFACE FAULTING.

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Two of the mission's concerns were in this area. They will be discussed  ;

separately. The Mission's first conclusion was :

1. "*he Safe Shutdown Earthquake should be re-evaluated considering a '

possibly higher nagnitude random shallow earthquake postulated to .

I occur beneath the site and a high magnitude earthquake postulated I to occur on the subducting slabs beneath the site at its closest approach to the site. A third event postulated to occur in a zone of possible off shore faulting, is judged to be of lower risk level so long as these two earthquakes are reconsidered." E E

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T*"I.E 1 g RErf.RENCE MATERIALS PROVILLD TO THE IAEA SAFETT MISSION 03 GEOLOGIC HAZARDS AND GEOTEC*rCIICAL ASPECTS OF PNPP-1.

1. PNPP-1 Preliminary Safety Analysis Report (especially Chapters 2 & 3 on

,L Site Characteristics and on Design of Structures, Components, Equipment  !

. and Systems; 8 volumes) July 1977. -

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. 2. PNPP-1 PSAR Amendment No. 3 and Amendment 3 Information Sheet. (Undated

• but prepared in 1978)

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3. Site Confirmation Report, January 1976. ,'y

4. Engineering Report No. 1, February 1976.

5. Addendum to Engineering Report No.1 no date. k

6. Engineering Report No. 7, April 1976.

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7. Addendum to Engineering Report No. 2, Vibrato 1;.' Ground Motion, May 1976. h

8. Engineering Report No. 3, (2 volumes), September 1976.

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9. Engineering Rcpor t No. i, February 197 /.

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10. Engineering Report No t, :Sy 19 78. as,

11. ' Responses to PAEC Lettet Di.ted 20 Dee.cmber 1976, no date.

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12. Responses to PAEC Letter Dated 21 May 19 77, no date (unbound) .

13. Geologic Hazards or PNFP Unit 1 July 1977.

14 PNPP-1 Volcanic-Seismic Sut ve.1114nce hogt .u.. no date. E

l h 15 . Scismic Risk Analysis f or P'!PP-1 3 data. , I.

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16. Geology of Unit 1 Excavation, February 19'/6.

17. Seis=ic Analysis of ?WPP-1, WCAP-9137, February 19 78.

13. PNPP-1 Additional Satety Re~ ated Data, 30 June 1978. '

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19. Sing:aphical Data o f F? r sennt1, c.o da te , nabotrd.

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1. a . Random Earthouake The Applicant followed US NRC criteria. Every earthquake in the e

gr province with cagnitude exceeding 4.5 and with known locatien was asso-N e ciated with a tectonic feature. It was thus concluded that the random

• earthquake at the site, used to determine the SSE, should be of magnitude 4.5.

The Mission recognized the seismological work as state-of-the-art and consistant with US practices, but felt this was not sufficiently ccuservative.

Specifically, the Mission proposed that the West Luzon Trough be considered inactive and that the two earthquakes of :nagnitude 6.25 associated with the Trough be considered floating earthquakes. The Mission also recenmended that the issue be f'r-ther investigsted by (1) preparing a complete epicenter

=ap, (2) providing a co=posite earthqucks catalog, (3) considering relocation of the epicenters of sarthquakes of ingsrest or, alternately, (4) selecting  %

W and evaluating a new randem earthquake with =agnitude in the range of 6.0 and h

5 depth less than'30 km, (5) developing a strong technical basis for this choice a .d (6) thoroughly studying the duration and high frequency centent of this earthqua'se as they affect the shape of the design response spectra.

The Applicant chose the first approach. "as composite catalog (item J.)

and the composite map (item 2) have been prepared. (9) Seven earthquakes were relocated,(') including those cited by the Missien. The Appli; ant finds t i

no basis for selecting 4 higher ugnitude for the random earthquake, p PAEC finds the Applicanc's ncthods and conclusions gensis;aqq with r NRC criteria. Pt.rther, PAEC has reviewed the data and ccafirmed that at hn w

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be least all " strong" earthquakes (6 or greater magnitude) in the province ,

are associated with tectonic structures other than the trough, see Appendix 3. PAEC notes that a shallow earthquake cf local magnitude 6 g in the Stat.es corresponds to an epicentral intensity or VIII on the

Modifi~e d Mercalli (MM) scale; see Murphy and O'Brien(2) , for exac:ple.

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. The associated peak acceleration would be about 0.16 g in the Western CSA and slightly less in Japan; the = ore conservative Trifunac and Brady relationship yields 0.25 g (see Figure 1) . As stated by Rood et al ,

US NRC require =ents are met by a peak acceleration of 0.25 g where the rando= earthquake intensity is MM VIII. Thus, the present PNPP-1 design value of 0.4 g appears sufficizatly conservative to accet=nodate any reasonable uncertainty in the rander earthquake.

1.b. Earthauake on the Subducting Slab The Applicant again followed US NRC criteria. The largest historical i

carthquake associated with each fault was deter =ined. Using published length-nagnitude relationships, and taking the rupture length as 40% of the fault length as recon:= ended by Denton('} , a "=axi==" =agnitude was calculated for each tectonic structure. The use of a 50% rupture length as suggested by Mark ( would not significantly change the results. In every case, the calculated magnitude exceeded or equaled the largest historic =agnitude. Each of these "=axi=um" events was assumed to occur

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near the earth's surface at the fault's closesc approach to tha site. *

. Seven published relationships between =agnitude, distance and peak acceleration were used (Appendix A) and the larges: calculated .p.

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acceleration was a'ssumed in each case. After questions vara raised concerning the methods used in preparation of the PSAR, both magnitudes and accelerations were re-:alculated using more recently published relaticas' nips, and the PSAR values were confirmed. See Table 2.

P Again, the Mission was concerned that the approaches used were I not sufficiently ecuservative. Slightly higher magnitudes were suggested for each of the tectonic structures. In themselves, these i L

magnitude changes would =ake no significant differences; the largest b increase suggested is from 7.4 to 7.8 for the San Antonio Fracture Zone and this weald increase the calculated peak acceleration to only 1 0.36 g. However, the major concern is with the location of these h g

events; the Mission rect .t= ends plac:ng the Manila Trench earthquake at the top of the subducting slab directly beneath the site. I 4

I Specifically, they recor:=end a =agnitude S event at a depth of 50 to 7d km beneath the site. Again, this new assumption would in itself f

k i= pose no new requirements because the applicable magn.tude-distance-acceleration relationships yield peak accelerations less than 0.4 g. I i

The Kataya=a(6) for=ulation, for exa=ple, gives 0.21 g for 70 km and  :

j 0.31 g for 50 km. The problem arises fron the paucity of acceleraticn h

data near epicenters and the need to consider near field effects.

3e Mission reco~ ends the use of "some type of scaling approachd.

w IM Applicant has submitted material which centends that no 9p P

technical justification can be found for considering the top of the 5

>se slab to be less than 70 kn below the site.. The largue earthquake IL

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IE.A83H.i.0 TABLE 2-FNFP-1 EARTHOUAKE DATA

SUMMARY

Length Estance Magnitude Calculated Fm to site,km Historic Calculated Acceleration

• g imila Trench 500 100 6 . 75 7.9 .35 lest Luzon Trougn 220 35 7<6.0 7.55 .35 im Antonio FZ 160 32 5.75 7.4 .34 Linila Bay FZ 125 30 6.25 7.35 .34 Da Fractures Zcne 100 60 5.7 7.3 .23 faal Fracture Zone 1000 125 5.5 8.2 .2

?hilippine Fault 1500 160 7.8 8.4 .18 7erde Island Passage 350 95 7.8 7.8 .16 Philippine Trench 900 650 8.3 8.3 .02 J

'tui=um acceleration at the site calculated from historic carthquakes is '.12 g.

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.- in the trench slab was magnitude 6.75 co assuning anythine, higher than 7.0 directly beneath the site would be inappropriate Also calculations were reported scaling 16 response spectra from 11 earthquakes that may correspond to the PNPP-1 situation.(9) These calculations j indicate that the 0.4 g design value =ight be exceeded with an earthquake b'

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- ry of magnitude 8 at.50. Icn depth but not for a magnitude 7 event at 70 km. !1 l:)

Some of the scaled spectra fell within the design criteria in both cases - 'l i

but scaling the spectrum obtained at Oly= pia Stationiom the earthquaka '

I-at Puget Sound 29 April 1965 to magnitude 8.0 at 50 km suggests a design ,

requirenent of 2. g.

PAEC has concluded that (1) there is justification for assuming that a the slab is at least 70 km beneath the site, and (2) it is sufficiently conservative to postulate a magnitude 7.0 event directly beneath the site. Thus, the present design basis is found to be acceptable.

' l . c ., Of f-Shore (Shore-Parallel) Faulting .

I PAEC reviewers noticed in the PSAR figures, indications of a possible fault running parallel to the shoreline off Napot Point. The Applicant has provided docu=entation contending that (1) de indications are slu=p f eatures, ' " I: e not a cectonic f ault and (2) even if there were a tectonic fault in the

• indicated location, it would necessarily be too short to produce a streng -

enough earthquake to increase the Safe Shutdown Earthquake (SSE) . The -

I Ession considered the data obtained with the single-channel system to be ,

I of too low quality to conclusively preclude the existence of the poss:.ble l t.

fault. 6 i

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. .'eQ' fd n .M E s' J PAEC has concluded that no further work in this area is required 6

because the acceleratien that a =ar.i=um earthquake on this possible fault 8 would produce would be less than the present SSE value. .

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( The Mission's second conclusion was:

4 g 2. " Additional investigation and analyses are required to resolve I concern with evidence for a shore normal fault running parallel

= to and i=r:cdiately south of the Napot Point Peninsula."

The topography i==ediately south of the site, as revealed by I

the Marine Geological Survey, SI.AR, Landsat data, etc. caused ccucern en the part of both PAEC revicuers and the Mission about a possibic tectonic fault. Such a fault within -a km of the site could af f er.t the SSE.

The Applicant has responded to PAEC require =ents by digging appropriate trenches and mapping the area utilizing road cuts, cu.

The trenches have been investigated by ?AEC censultants. The final report, which cencludes that no capable f'ault e.xists, was submitted recently. It is being revicued by PACC and its consultants, To ensure r

an adequate basis for judge =ents; PAEC has required an additi

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seismic survey of the area.

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= VOLCANISM Three of the Mission's concerns were in this area and they are in W discussed separately in the paragraphs following the background infermati:n d

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Eastround .

Volcanism has roccived little attentien in past nuclear siting e:iu , ,'

in part gt least because of the relatively low volcanic activity in r...

!i continental USA. Recently, volcanic hazards have been considered for the ig Pebble Spring and the Skaget plants in the States. Of course, Japan has 5

considerable volcanic activity. Philippine volcanic activity is high -

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(Table 3); only Indonesia and Italy have experienced more volcanic ,

disas tars . Nash, for example, lists 17 disastrous volennic cruption: --

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the Philippines since 1591( ) . These disasters are all associated w* &

3 volcanoes; (Taal, Mayon and Hibok-Hibok), but other Philippine vol :r t >

n . nor.sidered active. Taal, little more than 60 niles away, is the j L

active volcano closest to the site (Table 4). Mt. Pinatubo is c:nsid.: : {

inactive because it has not erupted in his oric times. However, i: ci: I g

erupt some 635 years ago so it cannot be ignored; Pinatubo is little r.::= i E

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than 35 miles frem the site. All these volcanoes could affect the sitt by f i

causing heavy ash f all.

k The principal cencerns about volcanic activity are asscciate.d .m ':

inactive but nearby peaks; Natib and Mariveles. Mariveles is about 12 nilas [

from the site and so presents the possibility of very heavy ash-fall. Na ib"+ i closest crater is less than 6 =iles frem the sita and it is ::ncei f:1 -

a new fissure en the western slope could threaten the site with gir.wic e, E!

avalanche, etc. Natib last erupted about 67,000 years ago and is ::r. ict:;: . f, by some to be extinct. For comparisen, in the US, caly those volcances sn:.rh l had crupted in the last 15,000 years were considered in the evaluatien .i ii Febble Spring and of Skaget. I 1284 J75 .

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us fii~LA,u 5 ~p;n i -,h Rhd TABLE 3 10RLD VOLCANO DISTRIBUTION

[ Eastern Pacific Islands

• 45'%

Western Americas 17%

Indenesia 14%

. Atlantic Islands 13%

, Continental ** & Mediterranean 7~

Central Pacific Islands 3%

Indian Ocean Islands 1%

Including the Philippines Principally the East African Rift Valley I

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liELASMEi TABLE 4 VOLCANOES IN THE PNPP-1 AREA g Di FROM SITE C0&. INT p_ STERN ZONE (Theoleitic) Activity 0.6 to 7 Mybp

Mt. Natib Calderia 9 youngest west flan) feposit 40.000 years.

, Mt. Santa Rita 22 Mt. Na=iranlac 32.5

! Mr. Balakibok 33 r Mr. Subic 33.6

';INTRAL ZONE (Cale-Alkalic) Activity 600 ybp to 7 Mybp

' 3 Mt. Natib , Eas t Vent 14 Pyroclastic deposic (7.5 km') about 67,000 ybp Mt. Mariveles 21 190,000 ybp lava, more recent activity older than last Natib eruption Mt. Samat 21.5 Mt. L1=ay 23.5 Mariveles Harbor 28 Or:ca 29 Cc:regidor 39 M:. Pinatubo 57 Pyroclastic flew 600 ybp; 7.5 km3 terphra Cavite-Batangas Highlands 60 Mt. Cariliao 75 Mt. Satulao 84 D3 TERN ZCNE (Shoshonitic) Active O to 2 Mybp M:. Arayat 79 Taal .

101 active; =ost destructive recent eruptiens (MDRE) 1754, 1911, 1965 C4ccces Mt. I 105 M:< Makiling 110 Mt. Mapinggen 116 M:. Nagearlang 124 Mt. Malepunyo 126 Mt. Ati=bia 126 M:. San Cristobal 136 censidered active, associated with Balungao M:. Bangcay 136 M:, Cuyapo 136 M:. 3anahao 142 no activity since 1909, MDRE: 1730, 1743, 1909 M 3alungao 143 M:. A=orong 144 CSIANT ACTIVE VOLCANOES Mt: Mayon 407 active, MDRE 196 8,1928,1914,1897, etc.

M:. 3clusan 471 Erupted 1978 Eibok-Hibok 507 Destructive eruptiens 1950 & 1951; l

84 & 248 killed.

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i.;w L .. . J The Applicant perf ormed investigations (later said by the Mission to be extensive, indepth, and state-of-the-art) and obtained review and counsel from sone of the world's nost eminent volcanologists. The con-clusions reached were that during the life of the plant, eruption in v

l the Philippines are virtually certain and that the expulsion of a large

- quantity of ejecta is not highly i= probable. Thus, the plant is designed to withstand a linited anount of ash fall. An eruption on the Bataan peninsula, on the other hand, is considered highly i= probable. Furthermore, historic trends and geochemical considerations indicate that even if Natib were to erupt, the eruption would occur at the su=mic areas or on the eastern side so the plant would not be threatened by glowing avalanche and the like. The youngest volcanic deposit on the western flank is 600,000 years old. The Applicant proposed a volcano monitoring system to ensure adequate warning should Natib again becoce active.

The Mission's third conclusion was: ,

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3. "The eruptim of Mt. Natib is a credible event which should be taken into account. This requires consideration of excassive ash fall, glowing avalanche, and gas accu =ulation as well as laharic slides."

The Mission recogni:ed the high quality of the work that had been done but cencluded first that there remained considerable uncertainty about renewal of volcanic activity at Natib and second, that an eruption on the western slope could not be dee=ed incredible.

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l The Applicant has provided additional information on the volcanic 5

threats. Clearly local topography protects the site from most of these s

threats unless a new fissure develops and a flank eruption occurs, r

I essentially at the site. The Applicant deems such an eruption incredible.

W

. Even if an eruption were to occur at or near the summit nearest the site, e

gravity would channel flows away fron the site, protecting the plant from 3 pyroclastic flows, laharic flows, and lava flows. The plant is considered r

b safe from direct i= pact of ejected missiles by reason of first, distance a

and second, t.he absence of a volcanic doce at Natib. Volcanic shock waves and earthquakes would be f ar smaller than the design bases. The amount of ground tilt considered credible at this distance from the summit should pose no threat to the site. These phenonena should not directly damage the plant but could isolate the site, according to the Applicant's evaluations.

Direct i

volcanic threats to the plant are provided by ashf all and gases, The App icant has estimated that dangerous levels of gases at the site

.tuld be limited to 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> or less. The ash fall esti=ates are that a Kat=ai-like eruption (Table 5) at Natib would result in between 4 and 22 feet of ash at the site while an eruptien at Pinatubo wculd produce 0.1 to 4 feet of ash at Napot Point (Figure 2). WIPCO has shewn that 10 inches of ash f all at the site vould be acceptable.

PAEC has directed the Applicant to extend the investigatien of beth

. ash f all and volcanic gases. The threat of volcanic gases was emphasized

• by the recent disaster in Indonesia. The Applicant has been directed to t

provide the available information en kinds and arou=ts of gasas which =ight 1284 979 ykgngq

v. ubu.a e ee e

Oi TABLE 5 QUANTITY OF EJECTA AND ENERGY RELEASES FROM SOME MAJOR VOLCANO ERUPTIONS DATE LOCATION VOLUME,km ENERGY, MT l 7000 ybp Mazama, Oregen 63.

, 1932 Quizapu, Chile 20.

[ 1912 Kat=ai*, Alaska 20.

1815 Ta=bora,*** Indonesia 20. 20,000 f

. 1835 Cosiguina, Nicaragua 8.3 24 g 1902 Santa Maria, Guatemala 5.5 1883 Krokatoa, Indonesia 5. 240 1964 Shiveluch, Kamchatka 1.5 1958 Pezymianny, Kamchatka 1. 570 1929 Komagatake, Japan 1.

1888 Bandaisan, Japan 1.

1669 Etna, Italy 0 .76 1911 Taal, Philippines 0.5 1947-48 Hekla, Iceland 0.4

,1902 Pales, Martinique 0.1 1919 f Kalud, Java 0.1 1843 Guntur, Java 0.008 1.6 1968 Mayon, Philippines 0.004 1898 Una Una, Celebes Island 0.002 0 .43 or Mt. Novarupta

• • no Megatens TNT; 1 Mr = 4.2 x 10' ergs 3

The volu=e of ejecta from Tambora also has geen given as 40 km and the PSAR in one place mentions 20 miles 1284 980 UNC'_A8370

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be emitted in a najor eruption. Also cricualtions are required of concentrations and integrated exposures at the site from eruptions at Natib, Pinatubo and Taal.

PAEC cannot accept the position that an eruption on the western slope of Natib is " incredible". The distance involved seem too small ,

to justify the implied large difference in probabilities for western and eastern slope eruptions. Therefore, the Applicant has been directed to calculate probabilities for (1) a western slope eruption and (2) a western slope eruption without adequate advance warning.

Further, the Applicant has been directed to evaluate the consequences of an eruptica such as .he 1911 eruption of Taal, if the eruption were to occur on the western slope of Natib; this ev .luation should include a determination of the eruption locations from which the " base surge" would not reach the plant.

PAEC has directed the Applicant to include in its August 1970 report assurance that the plant is designed to be safe despite (1) an ash fall of 4 feet in 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> without prior warning and (2) A 22-foot ash f all af ter shutdown follewing an advance warning. (Note: the first conditica correspords to maxi =un ash fall frem a Kat=ai-type eruption at Pinatubo and the second conditien corresponds to maxinum ashfall from such an eruption at Natib) .

The Missien's fourth conclusi:n was:

4 '%e i=nediate installation of a sophisticated and well maintained volcano surveillance system in ccebination with well defined base line criteria and subsequential procedures and action plan cencerning the operatien and/or shutdewn of the plant is strongly reco ended."

h.[f[].a ~ )

^ '

h This recom=endation reflects the imperrane: placed by the Mic:sion en the volcano surveillance system. This feeling ic shared by PAF.C and the Applicant is retponding appropriately. A plan has been developed

' and is being it:plemented. According to the schedule, the system will be in operation by 1 September 1979.

The Mission's fif th conclusion, was:

5. "One possible solution to mitigate against a radioactive release in the event of . a eruptien of Mt. Natib is the removal of the fuel to an off-site storage location upon advmice warning of a surveillance system. The Mission believes that this alternative as well as other possi_ ~.e alternatives, deserve consideration in developing the procedures and action plan ment ioned above."

This statement indicates the Mission's concern th:st the detection of volcanic activity at Natib would serve littic purpece unicss proper procedures for responding to these warmings were developed and imple-mented. PAEC agrees and has required. the Applicant to develop and justify appropriate procedures, including conaiceui ion ot~ fuel reo: oval.

The Applicant has not completed work in this aren. 'nte schedule calls for these procedures at.' their justification to be submitted for PAEC review in August 1979.

1284 983 e

ly n p - -m l 0 ,s N J.n .i uu

me . . . .

FO lOATION ENGINEERINC Sixth conclusion:

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 effects on vibratory ground motion, design response spectra, natural slope stability-and cut slope stability should be properly investigated; soil-str'ucture interaction should also be revised accordingly if appropriate. Clarification is needed with respect to the shear moduli and " strain sof tening" cil characteristics used in the dynamic analysis presented to date."

The concern about topographical and local effects result from the

, fact that the Napot Point site differs significantly (perhaps more than othert real sites) **om the " infinite plane" presumed in postulating a free field acceleration and spectrum. The site is a small peninsula rising rather sharply from the sea floor. On the landward side is a significant motmtain. WIPCO agreed to perform analyses to evaluate these phenomena if so directed by the Applicant.

The Mission seriously questioned the shear modulus-strain function emerimentally obtained by E3ASCO and used by WIPCO in WCAP-9187. Th e inaa is Oe reduction n the modulus at high strain. In Vienna, WIPCO untended, and agreed to verify, that the dynamic strains do not exceed about 10 . The variation in shear modulus at such icv strains is so small that an error in the iunction would be uni =portant.

1284 184 D7dMUIM- .

e

k 6.a. Tocograehical and I.ocal Effects i

,- In response to PAEC questions, the Applicant has reported that VIPCO T

finds the requested analyses to be beyond the state-of-the-art. Therefore, 4, the Applicant is unable to supply the requested information.

5 PAEC then directed the Applicant to provide a report justifying the g methods used, considering the inability to handle topographical and local e

p effects. The Applicant has not yet provided this report. However, WIPCO ir

, has indicated that the methods used neat US NRC criteria, including the I

regulatery guides and the Standard Review Plan. WIPCO comments also P

indicate that the methods include conservatism to ce=pensate for these li=itations in the analysis.

Although PAEC cannot make a jydec=e:n until the full report is t

,' reviewed, satisfactory resolution seems probable.

d.b. Initial Shear :toduli and " Strain-Softeninn" The Applicant ha; performed the re-evaluation and, as a result, has

' revoked the sot soil case (of WCAP-9137) and has added, a new parametric t

-0 a case of soil modulus. The strains were found to be less than 2. x 10  ;

I

, thus, the modulus remains in the flat region.

t PAEC has reviewed this response internally and feels that it is E

adequate. Recogniting its limited capability in this area, however, I

l PAEC is submitting the report to IAEA for further review.

e I

t 1284 185 9

C. h. ? ". 9 ",

J a.a N -

6.c. Cut and Natural Sloce Stability The slope stability question has been evaluated by the Applicant's consultant, E3ASCO. PAEC Staff has reviewed and found the result accept-s t

able based on the present SSE. However, in this area also, PAEC is k seeking IAEA support to ensure adecuate review.

b COMMENT AND CONCLUSION r

The work has progressed more. slowly clian was reco= mended. The cause of this delay has not been fully established. Field investigations, of course, require time to plan and execute. I suspect also that difficulty in the reorganization of NPC has been an important factor.

Responses received and reviewed to date have varied greatly in quality. This suggests co==unication proble=s. To i= prove con =xnications ,

frequent staff-level meetings between PAEC and NPC have been arranged, i

An inportant factor in the PNPP-1 situation is the ability and willingness of PAEC to act to ensure the safety of the planc. An example is the recent PAEC order stopping work in one area until PAEC is convinced that adequate provisions have been :.ade for the repair of defective concrete therein. PAEC inspection teams are now at the site every second week and the frequency is expected to be increased to every week. One full audit of the subcontractors has been performed and others are planned. Several me=bers of the regulatory staff have foreign education (to the Ph.D. level) and training (on-the-job quality assurance, for example) . The Philippine regulatory situation is vastly superior to that in =any other developing countries.

1284 986 6 ,** i In tv E d . e =F

~

i). i,;blNa While geotechnical proble=s are = ore difficult in the Philippines than in =sev other areas, there is evidence that appropriate precautions are being taken. It is noteworthy that the site selected appears to be the best possible on Luzon and that exceptionally thorough site invest-I *

igations have been conducted. USA criteria have been used and

[ conscientious efforts are being =ade to resolve the issues raised by the 1978 IAEA Safety Mission. Generally, my recomnendations have been f

well received and additional IAEA assisrance is being sought. In total, the situation is encouraging.

It is recom= ended that IAEA nake special efforts to provide the technical assistance that is needed in the Philippines. This will provide a hi;;h degree of assurance that PNPP-1 will constitute no undue hazard to the public.

I US criteria are nore detailed and explicit than the IAEA (draf t) guides in -Jiese areas .

1284 987 1 4 A Q yL' UV:s a'.

V a REFERENCES i

,I 1. " Reactor Site Criteria", Code of Federal Regulations, Title 10 Part 100, US Nuclear Regulatory Co==ission, Washington, D.C. Jan.1978

2. J.R. Murphy & L.J. O'Brien, " Analysis of a Worldwida Strong Motion i Data Sample to Develop an I= proved Correlation Between Peak Accele-ration, Seismic Intensity and Other Physical Parameters", US Nuclear Regulatory Commission Report NUREG 0402, January 1978.

, 3. H. Rood, et. al., " Report on TVA Seismic Issua by NRC Staff Working Group", Unpublished US Nuclear Regulatory Com=ission Report. May, g 1978.

p

4. H.R. Denton, "Selecticu of Safe Shutdown Earthquakes: Atomic Industrial Forum Workshop on Reactor Licensing and Safety", San Diego, Calif.1974

5. Robert K. Mark, " Application of Linear Statistical Models of Earth-quaka Magnitude Versus Fault Length in Esti=ating Ph E:rpectable Earthquakes", Geology, v.5., p. 464-466, August 1977.

6. T. Katayama, " Fundamentals of Prebabilitic Evaluation of Seismic Activity and Seismic Risk", Monthly Journal of Institute of Industrial Science, Tokyo Univ.1975 (as cited in the NPC/EBASCO Report of 23 Nov.1978) .

7. J.R. Nash, " Darkest Hours", Pocket Books, Inc., New York,1976.

' 8. " Volcanic Hazard Study; Potential for Volcanic Ash Fall, Pebble Springs

~

Nuclear Plant Site, Gilliam County, Oregon", Shannon. & Wilson, Inc.

Unpublished Report, Rev.1 May 17,1976.

9. " A Report on the Actions Taken Regarding the PAEC/IAEA Site Safety Reco==endations", Unpublish National Power Corporation Reporr, Manila, Nove=ber 1978.

1284 088 QNE.A8$fid E

IJ APPENDIX A EXPRESSION USED IN EVALUATING PNPP-1 SSE MAGNITUDE AND ACCELEPaTION Marnitude as a Function of Ruoture Len ph, Tocher

} :

M = 0.98 Log 10 L + 5.65 . . . M > 6.5 Iida( }  : M = 0.76 Log 10 L + 6.07 Press ( }  : M = 1.06 Log 10 L + 5.53 ... M > 6 ,

Wyss & Brune('}  : M = 1.9 Log 10 b+ *0 Ecusner(5) : M = 1.15 Log 10 L + 5'.1 ... M > 6.5

) : M = 1.182 Log 10 L + 5.15 2 . .. world wide data Sle== ens NOTE: The use of the nest conservative of the Sle:x: ions functions in each case would not increase the magnitude postulated in the PNPP-1 PSAR.

Earthquake nagnitude is M and L is rupture length in 's::::. For PNPP-1 es.:h of these expressions was tried and the one giving the highest sagnit':de for each specific fault was used.

Acceleration-Distance-Marnitude Relatienship

1. Gutenberg & Richter  : Log 10 ** " ~ * + * '

) + ) + 0.81 M-0.027 M

2. 31u=e  : Log 10 a. = -(

a = a. LI+ (D/H) 7 ~

3

3. Kani  : a,, = (1/T) 10

~

B = 0.16 M - L1. 66 + 3. 6 /R7 Lo g 10 * '

2 4 Milne & Devenport( 0)  : a = ( . 006 9 e . 64 M) 7 (1, g ,1.1 M , 3 )

0

. " . Esteva(11) -

a = Q 25 e .8 M) / (R + 25)

6. Cicud & Perez(1 )  : Log 10 a = 3.5 -2 Log 1 0 ( .62D - 80) ... M L 7.0

7. Schnabel & Seed (1 ) : curves given (Figure A~.) l 0 -1.32

3. Donovan (l4)- a = 1.1 e .5 M (R - 25) ,

• . . . 036 M) i

): Log 10 **

9. Cka=oto

• e I

^-t 1284 989

'dN@.A3I.U .

e.

k l. hGd,:M

) : a = 0.411 M - 0.6d31 - 1.637 ug10 (R + 30)

10. Kat. . , Log 10

a. = peak epicentral acceleration, g a = peak acceleration, g

, M = nagnitude 8 b = site factcr t

D = epicentral distance, km g

H = focal depth, km f

P a = baserock peak acceleration, g 5 r

= predominant period T

R = distance to hypocenter, ics For PNPP-1, functions 3, 4, 5, 6, 7, 8, 9 and 10 were tried and in each case the function used was that which gave the largest acceleration.

In Amend =ent 3 to the PSAR, the method of U=e=ura et. al. was considered and found to give acceleration values lower than those previously presented -

in the PSAR. The peak acceleratien (in cm/sec') was found to average 11 ti=es the maxi =um velocity (V en/sec) with a standard deviation of 1.8.

Thus the mean plus one standarE*de,viation acceleration is given by*:

< 11. , C=ecura(18) : a = 12.5 Vnax/980

' V = 10 C = 0.61 M -(1.66 + 3.6/R) Log 0 R - 0.631 - 1.83/R

• What appeared to be an error in the PSAR formulative has been corrected so the equations are consistant with the graph in the PSAR am. ndment, Figure A2.

1284 990 A-2 3 pcTH k3 1b, y ub l e .)

~ # 3=,,

LM".n;4ghe,isi bi.ho m

C.S I .

t 0.7

• 0.6, ,

s s\ g, I

m

\N g I,,_

s.:

l N N s

.a i M - 8.5 E-' d - #

5 ~~ ___ _

$ th \s a

i 7 -l - _l ___ _u_, M - 7.6 lN s s

._! c .,

y l N v s

_ s.

's 2

l 6--~___, _ _ _ M-es N s y L.

l l '

l

'N. N s m\

j s.

s s(s g I ' 5 J,~~~

' M

• S.6 's N \

l

{ i ~% '

y s g Ns (

. l l ~s  ! Ns N\

oh 3 N w s 0 5 -

1 2 4 6 10 20 40 60 100 Distance from Causrive Fault - miles S:nnabel and Seed (!973)

~ ~ ~ -~ ~ ~ Mcu:ner , TSGS) 1284 ')91 IJ30!.AE;3lf![5

.gf *g g'71Q ,Lmendment No. 3 f.,.9j, Q.7 M:y 1978 Figure A2

~  :.1. ..  %

i *

' 05 O.4 0~3 '

i. . . NNgt.x I N

\

'..\W.k. %

,, I .

3 0.07

. 5 ,O.05

, i i X . 's n N NNN i i  !

> 5 ,,, I i \ . il.%NN\\l i I

< 0.02 i

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I i

i I

I i

i 1

%\ -Xs.

. vt \\i\

NN\ 41 N \N o, I  ! I I 1.Xi- \\\ i\ Nw\

0.002 \

. 's N 't N \

0.001 1

s

' l\

I s

\\ l l i\ \ i  :

2 5 13 20 E0 100 200 500 1000 2000 OlSTANCE (kml

- Eastern U.S. after Algermissen and Perkins (19).

~--~~~~-- Western U.S. after Algermissen and Perkins 0.9 ).

. .. . . . . .... .. . Japan. after Seed and others ( 20)and Kanai ( 9 ).

Japan. after Umemura and others 0.5).

1284 192 PSAR FLGURE 2.5.L-2 ACCELERATIOfJ ATTENUATION CURVES BASED ON U.S. AND JAPANESE DATA a ~~  % be i?-

O

n .,...,m JLN b2Isb REFERENCES *

1. Tocher, D.,1958, Earthquake energy and ground breakage: Seismological Soc. America Bull., v. 48, p. 147-153.

2. Iida, K.,1965, Earthquake =agnitude, earthquake faulu and source dimension: Earth Sciences Jour. , Nagoya Univ. , v.12, p.115-132.

3. Press, F.,1967, Dimensions of the source region for small shallow earthquakes, in, Proceedings of the VESIAC Cenference on the Source Machanism of Shallow Seis=ic Events: VESIAC Report 7585-1-x, p.155-164 4 Wyss, M. , and Brune, J.N. , N Seis=ic moment, stress and source dimensions for earthquakes in :ne California-Nevada region: Jour.

Geophysical Research, v. 73, p. 4681-4694.

5. Housner, G.W.,1969, Engineering esti=ates of ground shaking and maxi =um earthquake =agnitude: Proceedings of the 4th World Conference en Earthquake Engineering, Santiago, Chile, p.1-13.

6. Gutenberg, B., and Richter, C.F. ,1956, Earthquake =agnitude, intensity, energy and acceleratien (2nd Paper): Seismological Soc. Arerica Bull . ,

v. 46, p . 105-145.

7. Blume, J.A.,1965, Earthquake ground motion and engineering procedures -

for i=portant installation near active faults: Proceedings of the 3rd World Conference on Sarthquake Engineering, New Zealand, v.4, p. 53-6 7.

3. Housner, G.W. ,1965 Intensity of ground shaking near the causative fault: Proceedings of the 3rd World Ccnference en Earthquake Engineering New ::ealand, v.1, p .94-115.

9. Kanai, K.,1966, I= proved e=pirical for=ula for characteristics of stray earthquake motions: Proceedings of the 2nd Japan Earthquake Engineering Sy=posiu=, Tokyo (in Japanese) p.1-4.

10. Milne, W.G., and Davenport, A.G.,1969, Distribution of earthquake risk in Canada: Seismological Soc. A= erica Bull. , v. 59, p. 729-754.

11. Esteva, L.,1970, Seismic risk and seis=ic design decisions, in Hansen, R.J. (ed.), Seismic Design for Nuclear Power Plants, M.I.T. Press, *

p. 142-182.

12 . Cloud, W.K. and Perez, V.,1971, Unusual accelerograms recorded at Li =

Peru: Seis=ological Soc. America Bull. , v. 61, p . 633-640. ,

13. Schnabel, P.3. and Seed, H.B.,1973, Accelerations in rock for earthquakes i in the western United States: Seis=ological Soc. A= erica Bull., v. 63.

p . 501-516.  ;

I 1

A-5

)h3 cr a ss a  :

e

~

UNCLA38lBL9 14 Donovan, N.C.,1973, A Statistical evaluation of strong motion data including the February 9,1971 San Fernando earthquake: Proceedings of the 5th World Conference on Earthquake Engineering, Rome p.1252-1261.

15. Oka=oto, S.,1973, Introduction to earthquake engineering: New York, John Wiley & Sons, 571 p.

' 16. Slemmons, D.B.,1977, State of the Art for Assessing earthquaka hazards in the United States: faults and earthquake magnitude: '

. Miscellaneous Paper 5-73-1, Report 6, US Ar=y Engineer Waterways

. Experiments Station Corps of Engineers, Vicksburg, Mississippi.

17. Katayama, T.,1975, Fundamentals of Probabilities evaluaticu of seismic ,

activity and seismic risk (in Japanese) SEISAN-KENYU: Moa.thly Journal of Institute of Industrial Science, University of Tokyo, 27-5, p.1-11.

18. Umemura, H., Pen:ien, J., Oshaki, Y. and Watabe, 1977, An Approach to the Modeling of 3-Dimensional Strong Motions. Sixth World Conference on Earthquake Engineering, New Delhi, India.

19. Alger=issen, S.T. & Perkins,1976, A Probabilistic Esti= ate of Fnimu:n Acceleration in Rock in the Contigous United States: U.S. Geol. Survey Open-File Report,76-416.

20. Seed, H.3., Indriss, I.M. & Kiefer, F.W.,1969, Characteristics of

, Rock Motions During Earthquakes: Jour. Soil Mechanics and Foundaticus Div., Proceedings A=arican Soc. Civil Engineers, v. 95, p.1199-1218.

J

21. Nuttli, 0.M.1973, Dasign Earthquakes for the Central United States, Misc. Paper S-73-1, U.S. Ar::7 Waterways Experi=ent Station, Vicksburg, Mississippi.

• Largely as given in the PNPP-1 PSAR and supplementary =aterials. -

6

,o A-6 1284 094

$Ei1 Elf!E

J APPENDIX 3 f

r EARTEQUAKZ ACTIVITY IN THE SITE REGION I.

}

The Central Luzon Tectonic Province is bounded by the Philippine  !' ,

l.L Fault, the Taal Fracture Zone and the MaMia Trench. Appendix C lists g the province' high intensity events and the text gives the -w4 - -j historic =agni vl2 for each fault. This Appen/iz lists the strong ii b earthquakn, =agnit ,le 6 or = ore, in the province and the region around .

}

it (Table 31). g .

,- d p y

. This Table was compared to the PAGASA (Philippine Weather Bureau) .. m t

catalog. Some minor differences were noted but generally the agreement F was good. One event was added to the Table which was not positively identified in the NPC/E3ASCO composite catalog. This event's occurrence.

fI seems well established because it reportedly wrecked a sub-standard r apartment building, thereby killing so=e 300 people in Manila. This [

event is of no special significance in the PNPP-1 evaluation. Three

(

other earthquakes listed in PSAR Table 2.5 F-3 as having nagnitvde-

, )

v greater than 6.0 were not so listed in the composite catalog and were g not included in Table 31; these are events 212, 253 and 538 with t magnitudes 6.75, 6.5 and 6.5 located in TFZ, CZZ, and NLEZ, respectively, .4 f The " structure" listed was not provided by the Applicant but is =y own I assessnent.

3 A map (Figure 31) is included which shows the approximate location '[.

of each of the =ajor tectenic structures. Several events are associated ' 4" with the Manila Trench even though the epicenters is =any kilematars I ft from the Trench. This is appropriate because the Trench.is produced ' ?

oy a slab which subducts at about 45 degrees and u=derlies the Province.

Thus, event 183 is associated with the Itench even though its epicenter '>

j, is in the West Luzon Trough and sece 50 b from the Trench. Event 133 Ii

,I occurred at a depth of 100 b and so was in the slab associated with p the MaM1 = Trench. .

1284 #)95 [

3-1 I

H M A00C U JLFAW L '

l I

MTIT'h D'*f?

~ x3 W $ 0sk- w

'Otl le fil

-2 STn0!;G c.A3Y:a!UAIO:S Ili TI'F. P:!P"-1 ';1Tr. PF.0TW1 (From clic .':L'C/1:P.ASCO Coryosite Cat:tlog,1 l throuCt i 1977, !!agnitude 6, Latitude 12 to ,

17 N, Iongitude 118 to 123 E) ae Degrecs ._- Depth,. St m ture Catalog . . Magnituda -

• North; East ,.,,; , Ic= . . , , . , , , .

Ntre.ber ,  ; Body Wave.,

~ Local j 12.5 .10 7.0 l '.5 June 1928 121.5 T SMEZ~. ' .- }

l 25 May 1925 12.5 ,. 122.5, -  ; SNEZ., 18 . ., : . . J .~25 ,

j

Feb. 1970 12.6 l ~ 122.1 . . 11 SEZ, 25 6.0 6.5 ,

i i July .1931 12.0 12 3.0 - SMEZ 30

6.5 31'

~

' 6.9 5 Nov. 1941 12.5 " ~ 123.0 ~ - SMEZ - i

" Oct. 1956 13.6 120.6 '- 115 VIP - 34 -

6.25*

Iti.io 1964 April 1972 13.6 13.4 120.3 120 .3 56 50 VIP VIP 51 09 6.5 6.2

- g, 7.3

.O Sept 1933 13.0 121.0 100 SMEZ 150 -

6.5

0 May 1936 13.5 121.5 160 VIP 15 1 -

6.0

• 6 May 1939 13.5 121.25 110 VIP 15 2 - 6.5

• 3 April 1942 13.5 121.0 25 VIP 15 3 -

7.8

• 7 Feb 1935 13.5 122 . 75 -

PF 16 8 -

6.0(c*) ,

17 March 1973 13.4 122 .8 33 PF 175 5.6 7.5 21 March 191' 13.0 123.0 50 PF 182 -

6.5

• July 1932 14.0 12 0 . 0 100 MT(s. 183 184 6.0g),

6.25 g,

.itmo 1933 13.0 120.4 76 VIP /Fr(s) -

M 1914 13.8 120.6 79 VIP /MT(s) 185 - 6.25

. March 1940 14.5 120.0 200 MT(s) 186 -

6 .75 *

'O Aug 1937 14.5 12 1.5 -

TFZ/PF 209 -

7.5 *

.. Dec 1719 . 14.0 122.0 25 PF 220 -

7.8 *

^ Sept.1941 14.0. 123.0 -  ? 229 - 6 .75

'urch 1933 15 .5' 120 0 120 IFZ 231 -

6.5 *

.M y 1959 15 .5 120.5 150 Mr(s) 235 -

6.63*

1953 15 . 7 120.1 C9 MT(s) 240 6.3

• mt:1 1970 15 .7 121.7 36 CEZ 233 6.4 '7.5I ') I

' pr il 19 70

. 15 .4 121.8 33 CZZ 315 5.7 6.3  :

' ~ April 1970 15 .1 122 .1 24 EZC 373 5.9 7.0 15 April 1970 15.1 122 .7 12 BEC 350 5.6 6.0

'. 3 April 1977 16.0 120.5 140 Mr(s)/?F 408 -

6.25*I")

April'1927 16.0 120.5 140 MI(s)/PF 409 -

6. 75 * (* ) ','

spril 1927 16.0 12 0 .0 100 Mr(s) 410 -

6 .75*

Aug 1937 16.5 120.5 -

NIEZ 411 -

6.25

.J Nov 19f 3 16.0 121.0 -

NLEZ 424 -

6.0 6 Feb 1962 16.1 121.6 32 NLZZ/CEZ 427 -

6 .1

2 May 19 72 16.6 122.3 34 CEZ 470 5.7 6.9 4

'1 May

. 1975 16.2 122.2 64 CEZ 493 4.8 6.5 i:

.3 March 1977 16.8 122.3 37 CEZ 494 6.2 7.0 21 July 1977 16.9 122.4 33 CEZ 533 ' 6 .1 6.8 5 Aug 1928 16.0 119.5 -

Mr 602 - 6.25*

Aug 1968 16.5 122.3 - CEZ (d) - 7. 3

-2 1284 99o' l stime h.wy LjG%1%g i

( .

M A W .Fi D

• These 22 events were within, or on structures bounding the i I

Central Luzon Tectonic Province.

)

(a) PAGASA lists this as 6.4 (b) PAGASA ducs not list a local magnitude l .

g (c) PidAsA lists this as 7.0 ,  ;

.. :. . c.

o

. . .'(ii) ' From' the PAdASA listi nay correspond '.. .to event 445,or 450 in. '

. .. :the.NPC/EBASCO catalog,' both of .i.9 body wave magnitude' + " - e t i 1 ..

.ut'%. * *Rf;,R? .;,,."*.o .

.'*~.; .

~~ ~ (e) PAJASA lists'both of theseras 6.5 magnitude T ~. .. "'-~:-^

P "

,. 7 ,._ ., g ,u

q. . . g .. 7,. ; ,

(f) These events have been relocated (at the IAEA Mission's l auggestion) from 14 N by D,0 E and unknown depth. >

I

( .. - - * - ..~. . -..

e , .

g

l SMEZ : South Mindoro Earthquake Zone ll l ,

VIP : Verde Island Passage i ,

t'

! PF  : Philippine Fault  ! 'f I I1 WLT : West Luzon Trough 1 l

.t l

i-Mr t. MmM1a Trench; (s) indicates the associated slab .

I

! TFZ : Taal Fracture Zone '. r i tt

)e 8 *

?  : Undetermined, remote from CLT Province i ' l; TFZ  : Iba Fracture Zone i .

!. r l

CEZ  : Casiguran Earthquake Zone ..

. i.

. BEZ  : Baler Earthquake Zone NLZZ : North Luzon Earthquake Zone I

L.284 297 l

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j 4 + ** %4 7 g. M I *e . , * * . , y #m .a , , , , , ,

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SAN ANTONIO . ..

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MARIK]NA GRABEN i , -.

g'ji 5., #- E '~ @- 1 J )k 84 *- C yay tj gay , i FRACTURE 20M sw ? .s, . VERDE . ISL,'_ NO: PASS E ~+

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sie* s'a o* tat' i z* I 3* 1 4*

Ly 0 10 0 200 300 1' SCALE IN KILondETEits f FIGURE B1 1284 198 ,

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_ _ 7 . - .7 :- .3 h h.pp,:-w. :: u :  :" .

M kkO 99hehet:rl=s .

APPENDI:~ C i

!1 i,

DISCUSSION OF THE PAEC FIQUIREMENTS ii I

I In response to the IAEA Safety 'tissica recom=endations, PAEC has i

':ablished additional requirement for PNPP-1. These requirements are  !

intended to ensure the safety of the plant and to cet:plet.4 the public o

acord. The requirements are stated and discussed briefly in the body of this report. This appendix provides further discussion and clarifi-e requirements. . l>

catten of ll

' . . Randon Earthcuake l;  !

Earthquakes so=etimes occur where there is no known causitive structure. The location of sucn " random" or " floating" earthe;uakes ,

cannot yet be reliably predicted. For nuclear plant design purposes, it is assunad that the ::ost severe historic random earthquake in the ,

tectonic province will occur directly beneath the site. With this e approach, random earthquakes have become the controlling events fcr several nuclear plants in less seismically active parts of the U.S. ,

t I

Randos earthquake considerations night not be expected to dominate

? !PP-1 design because of the proximity of known faults. Actually the ,

Applicant's selection of a 0.4 g design basis was not influenced by a ,

randce earthquake. All earthquakes with known epicentral location and Ir '

=agnitude exceeding 4.5 were associated with tectenic structures so the random earthquake magnitude was taken as 4.5. Earthquakes with magni:m between 4 and 5 are considered " feeble shocks" where damage is not usually  ; ,

reported. Such an event is not a factor in the ?'TPP-1 design.

,'; i t

While the approach used was reasonable, I vc9 cenetreed cbcut O ' .b c mc of such a mild random event for a seist ically active arca while auch stren:;cr i i .

r:.nden earthquakes are being used in relatively inactive areas in the U.5;  ; ,

M,,-.

35 l '!

(2) the failure to consider a niaber of high intensity historic .

events (Table C.1) beer.use the epicenter locations were not kar.,wn; l, and (3) the limited accuracy in locating earthquakes (the co= mon '

uncertainty of 50 km exceeds the distance between knetm f aults) . j Thus, further consideration of the random esrthquake sear.ed l appropriate. .

I Key considerations are (1) The random earthquake is mild becrae .$

r; known faul:s are nearby. (2) The selection cf a low-eaguitude random iI earthquake did not result in a "sof t" design. The historic high intensity events are readily accounted for by the structure underlying Manila and the proximity of active faults, particularly the Marikina Graben and the danila Bay Fracture ZeTe (20 km) and the highly active '

Verde Island Passage (90 km). A ceasure of the soil anplification in .

Manila is provided by the 1963 event wherein def ective construccico r,

co.:bined with a =agnitude 7.3 event ser.e 250 km away to kill 3C3 people.

The Appl $ cant has been asked to provide an assessment of the early high intensity e';en.s to complete the public record but this is no: ,

likely to alter the carthquake risk evaluation.

2. Earthcuakt en Subducting Slabs ,

i Two slabs are said to underly the site. Tha sich associated  !

it wi:h the Manila Trench is subductir;g. "'he slab associated with the l!

I West Luzon Trough is said to be no longer subducting. (A PAEC l ,

'i C '~

l284 100 xa, l b b

W.

_ . - . , o +

ae .5 I

if .

%) (QlTT dt'3 fJUI[i$d ,

1 TtJ,LE C.1 '

i I

hIGd II;TENSITI FJ.RTdQUAICS IN TdE CC: TRAL LU':CU IECTC'IIC PROVINCE .

(From the PAGASA Catalog) i Date IntensitJ Location Remarks 21 June 1599 VIII Manila {

l Jan. 1601 II Manila 30 Nov. 1645  % Manila 500 killed

. 'I 20 Aug, 1658 IX Manila Few killed ,[ j ,

7 Dec. 1677 IX Manila 2 or 3 killed I:!

iI 23 Feb. 1687 VIII Luzon i ,

2 Feb. 1771 VIII Manila ' ',

i Oct. 1796 VIII Manila .

26 Oct. 1824 VIII Manila i 13 Ja. 1830 II Manila 16 Sept.1852 IX Manila O July 1862 VIII Manila , l 3 June 1863 X Manila 320 killed 1 Oct. 1869 VIII Manila

'8 July 1880 j X Manila 20 killed u 17 March 1892 X Dagupan Area 19 March 1931 VIII Lu:ca-foulong Magnitude 6.9 ,

30 Aug. 1937 VIII Alabat M = 7.5 at 14.5'N & 121.5'E 1;

2 Aug. 1968  ? Marila (300 killed) M= 7.3 at 16.5'N & 122.3*E i t-l.

t Ihe original Rossi-Torel Scale of 10 intensities vts used up to 1934. '!g hereaf ter the adapted Rossi-Forel Scale of 9 intensities was used. It j;j ,

Eas been suggested that, en the original RF Scale, RF VIII corresponds .,

o MM VII or VIII; RF IX corresponds to MM VIII or IX; and RF X corresponds

o MM X through XII. The two nast recent events in this list were considered n the previous analysis. ,

l c _3 1284 101 1 i +

N! I' E

[AkkbS._b

$;

4 a

. I i

g,c oa c gget . .u . G. C.tnios , doub t=, cae oniscence of this s' lab). I I

It is agreed that both the Trench and the Trough are seismically J active. However, the slab location is determined by the location t, of earthquake focal points so the slab associated with the Trough ,[

evidently is inactive. -

{ p

.l .) ,

The published relationships (Appendix A) between magnitude, f

v distance and peak acceleration are in considerable disagreement. For p

. m.

present purposes the most important disagreement concerns the accele- F ration close to the event. Japanese results show great variation in _

i k acceleration with cagnitude whereas Acarican results show relatively l

licele =agnitude effect. (See Appendix A Figure 2). Even so, if the i h

cost conservative of these relationships (where focal depth is con- J sidered) is used in each case, the 0.4 g design basis is not exceeded by the "=aximus" events on the slabs.

$se,.

The problem of near field effects presents difficulties, largely V

because f ew data are available for acceleraciens near the epicenter. '

7 Wile Donovan and Bornstein(1) report accelerations within 5 'cn of 'k g

the " energy center" and find this data consistent with their attenuation E

odel, the issue seems open to question. i 3 1

l -

The Applicant has presented the results obtained for events l h

,t beneath tb site using a scaling approach (as recoc= ended by the g

i Mission). However, the approach used has not yet been fully explained l; no s.;tified. Justification is being required. m

't=

i j is.

c-4 1284 102 l

. I

, .r m '

A E

6

e h@M 9 E e*]Ld)MI V J t 4 . :t', v, '

i

'l The Applicant contends that the depth of the slab associated 6 uith the .Ian11a Trench is at least 70 km below the site. PAEC finds  ; ',

no basis for disagreeing i.,ut is requiring that the justification be ,

i more fully documented.  ;

d

3. Evaluation of Poison Cases From Volcanoes  ! l l'

The poison gas hazard from volcanoes has been known at l 5 least since 70 AD when gases from Vesuvius killed Pliny the i f

Elder. The recent disaster in Indonesia has focused attention t on the problem. The gas hazard is discussed briefly in the PSAR

, but a =cre e::plicit quantitative evaluation is necessary. ,

im PAEC specifically needs to know what volcanic releases I ik night incapacitate (1) the control room personnel and (2) other i site personnel. This requires consideration of historic releases W

of volcanic gases, the type and amount of gases which might be f released and atmospheric transport processes. The Applicant .

et f6 should also consider precautionary ceasures which might be taken.

a I

4 Natib Eruction Probabilities ,P The Applicant has esti=ated the probability of Natib erupting as about 3 x 10 -5 pa but considers a western slepe eruption to be -

"incr edible" .

n b I

ri r 1284 103 'i r

.s 4 .

C-5 !r llfi

, I, I

I: j

d j i 1, l i s' I "'

P.WC ca.aws accept the "incredibic" assessnent, particularky lk when the youngest deposits on Natib are only about 10 km from the I.' l i.

western slope. It does seem reasonable that a western slope I.

eruption is less likely than eruption at the su=mit or on the eastern slope. The fact that the youngest deposit on the western l

slope is ten times as old as the youngest eastern deposit is important; nevertheless, quantitative assessment of the risk is required. l i

The information available to PAEC indicates that in alnost a.very case there are clearly recognizable warnings before a najor g volcanic eruption. Also an instrumentation system is being pro-vided to enhance the likelihood of advance warning. Nevertheless, p advance warning cannot be considered certain. Therefore, the calculation of the probability of an eruption without warning is required. The result obtained is of less interest than the basis

.b

• f or ir, including such things as kind and Sequency of observations I

nade, equip =ent reliability, etc. >

lY This calculation is intet.ded not only to verify that the situation hr s been choroughly evaluated and that the probability , ,

i is acceptably low; it will also provide the basis for surveillance requirements and for regulatory actions.

5. Consecuences of Eruction en tiestern Natib l l/1 The Applicant has argued that the site would not be directly  ;

n

~,

in the psth of nuee ardenta, etc. even if there were an eruption on j the western slope of Natib. Topographic maps and physical inspections c-6 1284 104 3

. , ,,m .

g yi

% 3 e ee eUM

= s

k ,

of the site area lead PAEC to agree that generally this assessmen is valid. 'dovever, the evaluation has not been quanticative or objective. Therefore, the Applicant has been directed to provide a quantitative evaluation. -

i Flows of materials from an erupting volcano ata complex. A t simple drainage =ap of Natib nay be a good starting point but it I .

is not sufficient; a " Hawaiian" type eruption is not to be expected ;f The flow pattern is strongly influenced by the eruption. Small {

eruptions produce little sacerial that can flow. On the other hand, T

a "plinian" type eruption can be se destructive locally that flows are of little concern. Thus, to provide a basis for evaluating local topography, the 1911 eruption of Taal was selected as a nodel.

This was one of the largest Philippine historic eruptions but it is not so violent as to nask local topographic effects. ,

6. Ash Fall Protection a

Ash f all in significant quantities is not highly improbable a p

,. k Napot Point. The Applicant's analysis is based on a Kat=ai-type .;

eruption. It shows that such an event at Natib Crater 3 could pro- ll% 1

,. - 'd duce 22 f eet of ash fall at the site and that Pinatubo could produce =

^

up to 4 feet. These results are consistent with other work  ; ,

Questionable statistical analyses are usad to select a 1.3 f eet as ..

the design basis ash fall. [

1 1284 105 ln.;'"

t**

C-7 'n t

11 E

h

T h

l

!L

, :F

' iA FAEC concludes that (1) provisions must be made to protect l"

against a celtdown even if Natib erupts and (2) the plant must be safe even if Pinatubo (or Taal, etc.) erupts without advance warning.

. Protection against a Natib eruption means protection against 22 feet of ash fall. This could be accomplished, for exa=ple, by removal of the fuel from the site. Another approach =ight be to transfer the fuel into the fuel storage pool, operate the pool cooling system as long as practicable and restart cooling af ter the eruption.  ;

Ideally, the plant would be designed so the fuel could be lefe in the reactor vessel. khatever the approach selected, the design requirements must be identified as soon as practicable.

k The volcano monitoring system will give warning only of impending Q eruptions of Natib and l'.ariveles. It would be i= practical to respond 3

%e.

to the almost daily signs of activity at Taal. Thus, the plant nust -

be' capable of withstanding the possible ash fall from Pinatubo, Taal, etc. without warning. This could amount to 4 feet of ash. There are various possible approaches. Ideally, the plant would continue to operate, having adequately protected the air intakes, cooling systems, '

etc. However, shutdown under certain conditiens =ay be appropriate.

The ecoling systems =ust continue to operate af ter shutdown, the control roca cust remain habitable, etc. ne situation must be evaluated and  ;

necessary features incorporated in the design as seen as practicable.

1284 106 J

ids

.f.

C-8 *7 i .I-

. 1 g 5 h

.G E I/[

t.

iT l

l

7. Volcano Surveillance System and Prorram The PNPP-1 site was selected and accepted on the grounds that (1) the likelihood of renewed volcanic activity at Natib or Mariveles is slight and (2) sn appropriate surveillance program will be con-ducted to ensure adequate warning should a volcanic threat develop.

There has been little disagreement on this issue.

i I

8. Procedures for Response to Volcano Warning _

The warning signs of renewed volcanism should precede any eruption of Natib or Mariveles by several months. This period of ti=a vill permit a variety of possible responses. To be ef fective, however, the " action levels" of the Warnings and the planned responses must be developed in advance. Simply shutting the reactor down for 90 days greatly reduces the potential radiclogical

, hazard by (1) virtually eliminating both the halogens and the noble gases ( ) jtsd (2) greatly reducing the residual heat rate (to perhaps ,

i

~

3 segawatts ther=al). Meltdown remains possible, however, even af ter an extended shutdown period and additienal precautionary {

i

=easures will be necessary.

The most complete protection would be provided by ce=plete removal of all fuel from the site. The Applicant has been directed to evaluate this possibility, but difficulties are evident so another approach =ay be preferred. Placing the fuel in the storage pool (with the refueling cavity flooded) =ay permit the cooling system C-9 1284 07

., ~ , r 3 W

7

__M_

N F, .

l <f tae

t

'{

co be deactivated saf ely for a period (perhaps a week) though heat *

.P ren-r.~al must be restarted soon. These possibilities nust be explored and a definita program established. .

9. Foundation Engineering  :

i ..

PAEC has required the Applicann to . address the Mission's ,

concerns in this area. IAEA assistance vill be requested in review-  !

ing the final report when they are available. g

.R .E. _F _E _R .E _N _C _E _S w

1. Neville C. Donovan & Ann E. Bornstein, "Re Problens of Uncertainties in the Use of Seisnic Risk Procedures", Unpublished Paper Presented at the ASCE Annual Meeting, October 1977.

t

2. " Volcanic Eazard Study. Potential for Volcanic Ash Fall, Pebble

, Springs Nuclear Plant Site, Cilliam County, Oregon" Revision 1, Unpublished Report, Shannen and Wilson, Inc. Portland, Oregen, i 17 May 1976. i

3. Charles A. Willis, " Photon Energy and Air Shielding in Cloud Gamma Dose Calculations", Health Phvsics Aseects of Nuclear Facility Siring, 6 1 Eealth Physics Society, Idaho Falls, Idaho, 1971. ,

1 1

1284 108 C - 10 p F

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43 l

, .P

,