ML20076M077

Chronolgy of Events

ML20076M077
Person / Time
Site:	Diablo Canyon
Issue date:	06/15/1983
From:	AFFILIATION NOT ASSIGNED
To:
Shared Package
ML20076B440	List: ML20076B576 ML20076M077
References
FOIA-83-130 NUDOCS 8310110048
Download: ML20076M077 (8)

Text

1 5 . .

%g CHRONOLOGY OF EVENTS ..

Shell offshore geological investigations which confirm existence of the Hosgri fault 1965-1970 PG&E expert consultants suspect potential existence of Hosgri fault. 1967 N,

. i Application for Construc-tion Permit - Unit 1 January 1967 ssuance of Construction Permit - Unit 1 April 1968 s .

Application for Construc-tion Permit - Unit 2 June 19 68 Letter from.Dr. Curry to California Public Utility Commission suggesting possible existence of faulting off the coastline adjacent to the Diablo Canyon site. Letter 3 found in PG&E files. December 1968 .

(73 Pegulatory staff rejects USGS suggestions for additional investigation of offshore faulting. 1969-1970 (?)

f,,[,, Issuance of Construction

'.* c Permit - Unit 2 December 1970

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t Existence of Hosgri Fault '

reported in scientific literature--Hoskin and Griffith's article. January 1971 Regulatory staff to counter intervenor's contention that .

seismic hazard should be reviewed, advises Hearing ,

Board at NEPA prehearing conference for Diablo Canyon ,

that there is no new information on earthquake hazard. June 1973 Regulatory staff receives

• reference to Hoskin's and Griffith's article and requests additional information from PG&E. August 1973 Application for Operating License docketed - Units 1& 2. October 1973

, USGS begins offshore surveys. December 1973 -

PG&E begins additional 4

investigations at s'taff request. December 1973

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ASLB considers and rejects rec}uest to issue stop-work

$']+,,cruer. Staff opposes order. April 1974 v d S W.

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USGS publishes'a preliminary report concluding the Hosgri to be an active fault at least 90 miles long,.therefore capable

.of sustaining.an' event greater-than the.SSE for Diablo Canyon. -August 1974 ASLB considers and rejec,ts intervenor's second request ,

to issue stop-work order.  ;,

Staff opposes order. November 1974 . g -

Regulatory s taffj receives USGS i

conclusions: i

1. 1927 earthquake may have occurred.on Hosgri fault - magnitude 7.0-7.5 (Richter) .

s . 2. Hosgri fault.more than-

. 90 miles long.

3. Standard methods-for calculating peak ,

accelerations for fault this large and ,

close to. site are likely to lead torunderdesigned plant. ,l December 1974 Upper level management at NRC ~')

, reports to be unconvinced of merits of USGS findings. January.1975 Staff Supplement #1 to Safety -

Evaluation Report issued revising upward the Safe Shutdown Earthquake for

. .n , Diablo Canyon. Staff further I

Mtf $ concludes that although '

^ i' plant designed to an earthquake N, ' ,

rcuulting in 0.4g at the site,

• 2 the "as built" facility.

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could withstand the highest acceleration--0.5g--associated with.the larger Safe Shutdown <

Earthquake. January'1975 .

Staff meets with USGS who have revised initial estimates upward and are advocating an SSE value of 0.7g. February 1975 Staff recognizes that U9GS position will require design reanalysis, taking up to two . /'

years and perhaps more. Staff further concludes "[S)ome.

increases in capability is possible from design changes that might be undertaken, but changes sufficient to bring the design up to a 0.6g-0.7g capability are impracticable. February 1975 ACRS Subcommittee meeting on Diablo Canyon operating license. ,

Meeting explores problems of seismic design and the llosgri fault. February 1975 From position taken at ACRS rs meeting, the upper level .

- management recognizes that "unless specific guidance is provided to the USGS geologists and seismologists,

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they will proceed with their

. ~ review basing it upon their o.- standard methods and arrive at

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a site SSE "g" value well in p -is ' ,

i "c' excess of the 0.4g value i, .>- approved for the CP and used j,

for the design of the almost

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• completed plant." Further, the,same manager concludes that "unless specific guidance, support and direction is provided promptly by the upper management levels at NRC and USGS to the " working" levels in the two organizations, positions that do not necessarily reflect the judgment of upper-level ~

management will be formulated and x T

documented to the extent that -

later modification will be difficult. February 1975 Construction on Units 1 and 2 -

have continued unabated. Unit 1 due to be ready for fuel , ,

loading within 6 months; Unit 2, about 1 year from then. February 1975 ACRS subcommittee meeting on Diablo Canyon which considers Diablo Canyon seismic problems. May 1975 Regulatory staff puts together a r~)

team of consultants to demonstrate that, assuming occurence on the Hosgri fault of an earthquake as large as the USGS review implys "

', :y (7.5) , the energy transfer to the

. :4 site would be limited to within the design capabilities of the

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nuclear plant. Concurrently, i3lp , ' the staff initiates a review to determine if a probabilistic

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, . ; f,*,'-- . basis can be established to license Unit 1 for an interim period of 3 ,,4 O

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• operation while the reviews ~

are being conducted. Additionally the Staff informs PG&E to conduct a similar analysis. In developing -

this program the Staff considers

. the following:

1. "The impact of our decisions on the nation's energy problems and prog rams. The impact of potential denial for operation of a plant

N approved for construction cannot be underestimated, especially where the basis for denial is in controversy."

2. "The impact.of our decisions

. on the meratorium before the California voters."

3. "The impact of our decisions on the viability of continued operation of plants at other

. sites with altered seismo-logical bases, such as San Onofre, Pilgrim, etc."

4. "The' impact of our decisions . s on the viability of continued operation of plants where it g is uncertain that the capability exists to withstand altered design bases in areas other than seismic design, ,

such as containment structural

'; design, pipe whip inside

f;. _ , . , containment, spurious valve failures, etc." January 1976

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2 ACRS subcommittee me'eting. ,

Staff.and PG&E begin-presen-

• tation of views on adequacy of scismic design of Diablo' ,

Canyon. May 21, 1976 ACRS subcommittee meeting.

Staff and PG&E continue ,

presentation of views-on adequacy of seismic design of Diablo Canyon. . June 1976 ,

ACRS~ subcommittee meeting

.ACRS consultants present critique of staff and -

PG&E presentation. Generally the consultants conclude: .

1) The design response ,

spectre adopted by the Regulatory Staff falls

, short by as much as 50%

in depicting the 7.5 magnitude earthquake ,

selected by USGS as the

. Safe Shutdown Earthquake.

2) The conclusions are based on poorly justified .

modifications. The process T

"makes a mockery of the seismic analyses and sets a dangerous precedent." October-1976 9',? h PG&E begins reanalysis of plant 3,/) lg ' .

design consistent with new

, ;'Ci ' ..; January 1977 3- r criteria set'by Staff..

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'"' application for an' interim operating license based on WAer==., .

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demonstrating (1) the low probability of an earthquake resulting in radioactive release at Diablo Canyon; (2) a commitment to make necessary changes;- (3) an

, evaluation of the practicality of making needed changes to a plant that has gone critical. March 1977 Unit 1 estimated to be l physically complete by -

April or May; Unit 2, by

, December 1977 March 1977 ACRS meeting scheduled June 1977 s .

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OCT 281977 '

Mr. Michael P. Carlton '

Pollution Control Section '

Land and flatural P.orources Division United States Department of Justice Washington, D.C. 20530 ,

Dear Mr. Carlton:

Please refer to your letter of October 25, 1977, received here -

today, concerning the possible failure of the Pacific Gas and Electric Ccapany to disclose to the NRC the existence of a fault near its Diablo Canyon Nuclear Power Plant.

I have requested tt.e Comission's Inspector and Auditor, Mr. Thomas

J. McTiernan, with the assistance of our Office of Inspection and -

Enforcement, as appropriate, to provide the report and information you have requested. Mr. McTiernan can be reached at telephone ,

number 492-7301.

Sincerely, Howard V., Shapar Executive Legal Director bcc:

-ChairmanHendrie(w/ incoming) DISTRIBUTION Conmissioner Kennedy (w/ incoming) ELD Reader Comnissioner Bradford (w/ incoming) NRC Central Commissioner Gilinsky (w/ incoming) Murray chron L. V. Gossick (w/ incoming) Reading file T. McTiernan (w/ incoming)d' Subj. file I&E. TFEngelhardt Genera (w/ incoming) l Counsel (w/ incoming) HKShapar Aca o >c. * . 0 ELD __l, k 1. _

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