ML16342A494
| ML16342A494 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 05/04/1994 |
| From: | Peterson S Office of Nuclear Reactor Regulation |
| To: | Miraglia F, Russell W, Thadani A NRC |
| References | |
| NUDOCS 9405100253 | |
| Download: ML16342A494 (18) | |
Text
Docket Nos.
50-275 and 50-323 May 4, 1994 MEMORANDUM FOR:
W. Russell F. Miraglia A. Thadani L. Reyes D. Crutchfield W. Travers F. Gillespie S.
Varga J.
Calvo G. Lainas J.
Roe J. Zwolinski E.
Adensam B. Grimes B. Sheron B.
D. Liaw A. Thadani M. Virgilio C. Rossi R.
Zimmerman B. Boger C.
Thomas F.
Congel E. Butcher V. McCree, EDO M. Slosson Operations Center R. Cooper, RGI E. Merschoff, RGII E.
- Greenman, RGIII A. Bill Beach, RGIV THRU:
FROM:
SUBJECT:
DATE 5 TIME:
LOCATION:
Theodore R. quay, Director Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation Sheri R. Peterson, Project Manager Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation DAILY HIGHLIGHT FORTHCOMING MEETING WITH PACIFIC GAS AND ELECTRIC AT DIABLO CANYON POWER PLANT May 9, 1994 ll:30 am 1:30 pm Diablo Canyon Power Plant Training Building Avila Beach, California To discuss plant status PURPOSE:
PARTICIPANTS:*
UTILITY W. Fujimoto W. Crockett C.
Newman K. Oliver T.
Leserman Original signed by:
Theodore R.
Quay for Sheri R. Peterson, Senior Project Manager Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation NRC A. Thadani, NRR E. Adensam, NRR M. Tschiltz, RIV 9405100253 940504 R PDR ADOCK 05000275 P
'PURE OGG003 cc:
See next page CONTACT: S.
Peterson 504-1325 Pgg Hg CER
- Meetings between NRC technical staff and applicants or licensees are open for interested members of the public, petitioners, intervenors, or other parties to attend as observers pursuant to "Open Meeting Statement of NRC Staff Policy," 43 Federal Receister
- 28058, 6/28/78.
OFFICE NAME DATE PD IV-3/LA DFoster-Curseen 94 PDIV-3/PM SPetetson S/+
94 PDIV-3/D Tquay~
5 /4/94 OFFICIAL RECORD COPY:
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Docket Nos.
50-275 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0003 May 4, 1994 and 50-323 MEMORANDUM FOR:
WE Russell F. Miraglia A. Thadani L. Reyes D. Crutchfield W. Travers F. Gillespie S.
Varga J.
Calvo G. Lainas J.
Roe J. Zwolinski E.
Adensam B. Grimes B. Sheron B.
D. Liaw A. Thadani M. Virgilio C. Rossi R.
Zimmerman B. Boger C.
Thomas F.
Congel E. Butcher V. McCree, EDO H. Slosson Operations Center R. Cooper, RGI E. Herschoff, RGII E.
- Greenman, RGIII A. Bill Beach, RGIV THRU:
FROM:
SUBJECT:
DATE Imt TIME:
LOCATION:
Theodore R. quay, Director Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation Sheri R. Peterson, Project Manager Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation DAILY HIGHLIGHT FORTHCOMING MEETING WITH PACIFIC GAS AND ELECTRIC AT DIABLO CANYON POWER PLANT Hay 9, 1994 ll:30 am - 1:30 pm Diablo Canyon Power Plant Training Building Avila Beach, California PURPOSE:
PARTICIPANTS:*
To discuss plant status NRC A. Thadani, NRR E.
- Adensam, NRR H. Tschiltz, RIV UTILITY W. Fujimoto C.
Newman T. Leserman W. Crockett K. Oliver cc:
See next page CONTACT: S.
Peterson 504-1325
.7/sSM~ ~Zv ~ +
Sheri R. Peterson, Senior Project Manager Project Directorate IV-3 Division of Reactor Projects Office of Nuclear Reactor Regulation
- Meetings between NRC technical staff and applicants or licensees are open for interested members of the public, petitioners, intervenors, or other parties to attend as observers pursuant to "Open Meeting Statement of NRC Staff Policy," 43 Federal Receistev
- 28058, 6/28/78.
I Jg A
Pacific Gas and Electric Company Diablo Canyon CC:
NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.
Box 369 Avila Beach, California 93424 Dr. Richard Ferguson, Energy Chair Sierra Club California 6715 Rocky Canyon Creston, California 93432 Ms.
Nancy Culver San Luis Obispo Mothers for Peace P. 0.
Box 164 Pismo Beach, California 93448 Ms. Jacquelyn C. Wheeler P. 0.
Box 164 Pismo Beach, California 93448 Managing Editor The County Telegram Tribune 1321 Johnson Avenue P. 0.
Box 112 San Luis Obispo, California 93406 Chairman San Luis Obispo County Board of Supervisors
, Room 370 County Government Center San Luis Obispo, California 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Rm.
4102 San Francisco, California 94102 Diablo Canyon Independent Safety Committee ATTN:
Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D
Monterey, California 93940 Mr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94234 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Mr. Peter H. Kaufman Deputy Attorney General State of California 110 West A Street, Suite 700 San Diego, California 92101 Christopher J.
- Warner, Esq.
Pacific Gas
& Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. John Townsend Vice President and Plant Manager Diablo Canyon Power Plant P. 0.
Box 56 Avila Beach, California 93424 Mr. Gregory M. Reuger Nuclear Power Generation, B14A Pacific Gas and Electric Company 77 Beale Street, Room 1451 P, 0.
Box 770000 San Francisco, California 94177
a.
,DISTRIBUTION Meetin Notice Hi hli ht Docket File NRC 8 Local-PDRs PD IIV-3 Reading T. quay S.
Peterson D. Foster-Curseen A. Chaffee, OEAB OGC E. Jordan Receptionist, OWFN NRC Participants ACRS (10)
OPA NRR Mailroom, PMAS, 12/G/18 (must be handcarried)
G. Zech, RPEB J. Mitchell, EDO K. Perkins, WCFO J. Gilliland, Region IV
0 A
Docket Nos.
50-275 and 50-323 MEMORANDUM FOR:
FROM:
SUBJECT:
April 8, 1994 Kenneth E. Perkins, Jr., Director Region IV Walnut Creek Field Office Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
RESPONSE
TO TASK INTERFACE AGREEMENT (94-TIA-007)
REGARDING SAFE SHUTDOWN EARTHQUAKE REQUIREMENTS FOR DIABLO CANYON POWER PLANT (M88859)
Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation In response to your request for technical assistance dated February 25,
- 1994, enclosed is a discussion of the seismic design and capacity of the Diablo Canyon Power Plant.
The plant was designed and constructed prior to implemen-tation of 10 CFR Part 100, Appendix A using a double design basis earthquake with a horizontal peak ground acceleration of 0.4g, in accordance with the practices prevalent at that time.
Following the discovery of the Hosgri fault zone the plant was reanalyzed and modified to show that it could withstand the Hosgri event.
The plant was further reevaluated under the Long Term Seismic Program (LTSP) to satisfy a condition in the Unit 1 operating license.
There are no differences between the NRR and licensee definitions of the safe shutdown earthquake for Diablo Canyon.
The staff's position and the licensee's position are that the safe shutdown earthquake for the plant is the original 0.4g peak ground acceleration.
In addition, the Diablo Canyon Updated Final Safety Analysis Report, Sections 3.2. 1 and 3.7.6 correctly define the licensee's commitments with regard to the Hosgri fault and the LTSP.
All modifications or additions to the facility, subsequent to the Hosgri reanalysis, are to use both the original design basis ground motion and the Hosgri ground motion for design.
Furthermore, all modifications or additions to the facility subsequent to the LTSP reevaluation are to meet the license condition and to assure that the seismic margins established during the LTSP program are not reduced.
+OgiiiO+7+cygOgOg]Original signed by CF ADOCK 05000275 CF
Enclosure:
As stated cc w/enclosure:
R. Cooper, RI ED Herschoff, RII E.
- Greenman, RIII B. Beach, RIV DISTRIBUTION:
'ocket File, Pl-22 JRoe
- SVarga, 14E4 HMiller EAdensam
- BSheron, NLN368 TQuay DFoster-Curseen PDV Plant File
- KPerkins, RV TKing, NLN368 SPeterson OFFICE LA:PDIV-3 NAME DFoster-Curseen PH:PDIV-SPeterson (n /94 9
('o/94 DATE OFFICIAL RECORD COPY'ILENAME: A:DCTIA PD'PDIV-3 Tg nay
+y4 94 AD IV-3 +~~
EAd sam 94
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Docket Nos.
50-275 r
and 50-323 MEMORANDUM FOR:
FROM:
SUBJECT:
April 8, 1994 Kenneth E. Perkins, Jr., Director Region IV Walnut Creek Field Office Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
RESPONSE
TO TASK INTERFACE AGREEMENT (94-TIA-007)
REGARDING SAFE SHUTDOWN EARTHQUAKE REQUIREMENTS FOR DIABLO CANYON POWER PLANT (M88859)
In response to your request for technical assistance dated February 25,
- 1994, enclosed is a discussion of the seismic design and capacity of the Diablo Canyon Power Plant.
The plant was designed and constructed prior to implemen-tation of 10 CFR Part 100, Appendix A using a double design basis earthquake with a horizontal peak ground acceleration of 0.4g, in accordance with the practices prevalent at that time.
Following the discovery of the Hosgri fault zone the plant was reanalyzed and modified to show that it could withstand the Hosgri event.
The plant was further reevaluated under the Long Term Seismic~
Program (LTSP) to satisfy a condition in the Unit 1 operating license.
There are no differences between the NRR and licensee definitions of the safe.-
shutdown earthquake for Diablo Canyon.
The staff's position and the licensee's position are that the safe shutdown earthquake for the plant is the original 0.4g peak ground acceleration.
In addition, the Diablo Canyon Updated Final Safety Analysis Report, Sections 3.2. 1 and 3.7.6 correctly define the licensee's commitments with regard to the Hosgri fault and the LTSP.
All modifications or additions to the facility, subsequent to,the Hosgri reanalysis, are to use both the original design basis ground motion and the Hosgri ground motion for design.
Furthermore, all modifications or additions to the facility subsequent to the LTSP reevaluation are to meet the license condition and to assure that the seismic margins established during the LTSP program are not reduced.
Original signed by:
Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/enclosure:
R, Cooper, RI E. Merschoff, RII E.
- Greenman, RIII B. Beach, RIV DISTRIBUTION:
Docket File, Pl-22 JRoe
- SVarga, 14E4 MMiller EAdensam
- BSheron, NLN368 TQuay DFoster-Curseen PDV Plant File
- KPerkins, RV TKing, NLN368 SPeterson OFFICE NAME LA:PDIV-3 Q
PM: PDIV-DFoster-Curseen SPeterson (y /94 "l (o/94 DATE OFFICIAL RECORD COPY'ILENAME':DCTIA PD:PDIV-3 TQuay~i 94 AD IV-3 4g EAd sam 94
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Docket Nos.
50-275 and 50-323 MEMORANDUM FOR:
FRON:
SUBJECT:
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205580001 April 8, 1994 Kenneth E. Perkins, Jr., Director Region IV Walnut Creek Field Office Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
RESPONSE
TO TASK INTERFACE AGREEMENT (94-TIA-007)
REGARDING SAFE SHUTDOWN EARTHQUAKE REQUIREMENTS FOR DIABLO CANYON POWER PLANT (H88859)
In response to your request for technical assistance dated February 25,
- 1994, enclosed is a discussion of the seismic design and capacity of the Diablo Canyon Power Plant.
The plant was designed and constructed prior to implemen-tation of 10 CFR Part 100, Appendix A using a double design basis earthquake'ith a horizontal peak ground acceleration of 0.4g, in accordance with the practices prevalent at that time.
Following the discovery of the Hosgri fault zone the plant was reanalyzed and modified to show that it could withstand the Hosgri event.
The plant was further reevaluated under the Long Term Seismic Program (LTSP) to satisfy a condition in the Unit 1 operating license.
There are no differences between the NRR and licensee definitions of the safe shutdown earthquake for Diablo Canyon.
The staff's position and the licensee's position are that the safe shutdown earthquake for the plant is the original 0.4g peak ground acceleration.
In addition, the Diablo Canyon Updated Final Safety Analysis Report-,
Sections 3.2. 1 and 3.7.6 correctly define the licensee's commitments with regard to the Hosgri fault and the LTSP.
All modifications or additions to the facility, subsequent to the Hosgri reanalysis, are to use both the original design basis ground motion and the Hosgri ground motion for design.
Furthermore, all modifications or additions to the facility subsequent to the LTSP reevaluation are to meet the license condition and to assure that the seismic margins established during the LTSP program are not reduced.
Enclosure:
As stated Elinor G. Adensam, Assistant Director for Region IV Reactors Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation cc w/enclosure:
R. Cooper, RI E. Herschoff, RII E.
- Greenman, RIII B. Beach, RIV
I
ENCLOSURE Seismic Design Basis of Diablo Canyon The Atomic Energy Commission (AEC), the predecessor to the Nuclear Regulatory Commission (NRC), issued construction permits (CP) for Diablo Canyon Unit 1
and Diablo Canyon Unit 2 on April 23, 1968 and December 9,
1970.
During the Diablo Canyon CP reviews, the NRC regulation that currently governs seismic
- design, 10 CFR Part 100, Appendix A, was in the 'early stages of development, and the concept of the safe shutdown earthquake (SSE) was still being developed.
As part of the CP application preparation, Pacific Gas and Electric (PG&E),
the licensee, conducted geological and seismic investigations to validate the acceptability of the site.
As a result of these investigations PG&E concluded, and the AEC concurred, that the earthquake design basis (double design earthquake) for the safety-related structures at Diablo Canyon would be a horizontal peak ground acceleration of 0.4g.
The plant was designed, and construction began based on this earthquake design value.
Subsequently, proprietary offshore geophysical information from the petroleum industry was made publicly available.
The new information indicated that a fault zone, discovered by two geologists (Hoskins and Griffith) and named the Hosgri, exists a few miles offshore from the plant.
At the recommendation of the United States Geological Survey (USGS) and in conformance with the newly issued siting regulation, the NRC established that the Diablo Canyon design should be reevaluated based on a magnitude 7.5 earthquake on the Hosgri fault, 5 kilometers (3 miles) from the plant.
The NRC established that such an earthquake could result in vibratory ground motion with a horizontal peak ground acceleration of 0.75g.
This is usually called the Hosgri ground motion.
PG&E reanalyzed and upgraded the plant to accommodate the new (Hosgri) seismic ground motion.
On page 2-4 of the Supplemental Safety Evaluation Report (SSER)
Number 7 of the Diablo Canyon Nuclear Power Station Units 1 and 2, the NRC staff stated that even though there was a disagreement as to whether the 0.4g ground motion or the Hosgri ground motion is the safe shutdown earthquake, it has no bearing on plant safety since the NRC requires that the plant design be shown to be adequate for the Hosgri event.
The staff emphasized in Section 3.7 of the SSER that in performing the reevaluation:
(1) it is not necessary to meet all of the standard acceptance criteria for new plants in order to determine acceptability and (2) that the objective of the reanalysis is to determine whether or not the plant can safely withstand the Hosgri event.
Since the plant had already been. built it was possible to evaluate specific situations, such as actual material strengths.
As a result, the evaluations were acceptable without providing the same allowances for possible variations as are included in the standard design acceptance criteria, or with the use of lower loads or methods other than the more conservative ones assumed in the original design.
During the operating license review, the Advisory Committee on Reactor Safeguards, in its 1978 letter, recommended that the seismic design of Diablo Canyon be reevaluated in about ten years taking into account applicable new information.
1
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II After public hearings before the NRC's Atomic Safety and Licensing Board and the Atomic Safety and Licensing Appeal
- Board, and Commission meetings, operating licenses were issued for both Diablo Canyon units.
The Unit 1
operating license was conditioned to:
(1) require that PG&E update the geological, seismological, and ground motion information, (2) reevaluate the magnitude of the earthquake used to determine the Diablo Canyon seismic design
- basis, (3) reevaluate the ground motion expected at the site, (4) reassess building and equipment
- response, and (5) perform a seismic probabilistic risk assessment (PRA) and deterministic studies, as necessary.
This resulted in a
- program, conducted by PG&E and reviewed by the NRC, which became known as the Long Term Seismic Program (LTSP).
The LTSP resulted in ground motion estimates for Diablo Canyon which were higher in some frequencies than the Hosgri ground motion and lower at other frequencies.
The NRC staff conducted its'eview of PG&E's PRA and deterministic analyses and found them acceptable.
The staff also concluded that the plant has adequate seismic margins, and that the license condition had been met.
The staff noted that for future design modifications, the original design basis plus the Hosgri evaluation basis, along with the associated analytical methods, initial condition, etc., will continue to be used for design.
In addition, the ground motion characterization which resulted from the LTSP should be used to verify that the high confidence of low probability of failure values for the plant remain acceptable.
In summary, Diablo Canyon Units 1 and 2 were originally designed using a
horizontal peak ground motion of 0.4g which, in the terminology of 10 CFR Part 100, Appendix A, is the SSE.
After major parts of the plant were designed and built, it was reanalyzed to the Hosgri ground motion characterization and some modifications were made.
Any changes or additions to the plant, subsequent to the Hosgri reanalysis, are to use both the original design basis and the Hosgri characterization.
Plant seismic margins were also evaluated using the ground motion characterization which resulted from the LTSP.
Any modifications or additions to the plant subsequent to the LTSP should ensure that these margins are not reduced.
The Diablo Canyon Updated Final Safety Analysis Report, Sections 3.2. 1 and 3.7.6 correctly define the licensee's commitments.
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