ML16342D049
| ML16342D049 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 09/06/1995 |
| From: | Stone J NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| TAC-M83614, TAC-M83615, NUDOCS 9509140263 | |
| Download: ML16342D049 (14) | |
Text
September 6,
1995 Hr. Gregory M. Rueger Pacific Gas and Electric Company NPG Hail Code A10D P.O.
Box 770000 San Francisco, California 94177
SUBJECT:
INDIVIDUALPLANT EXAMINATION OF EXTERNAL EVENTS, REQUEST FOR ADDITIONAL INFORMATION, DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1
AND 2 (TAC NOS.
M83614 AND H83615)
Dear Hr. Rueger:
During the NRC staff's continuing review of the Diablo Canyon Individual Plant Examination of External Events (IPEEE) submittal and its associated documentation, the need for additional information has been identified.
The request for additional information (RAI) is detailed in the enclosure.
The RAIs is related to the external event analyses in the IPEEE, including the seismic analysis, the fire analysis, and the analyses of the effects of high winds, floods, and others (HFOs).
In order to meet our schedule, it is requested that you provide written responses to the RAI within 60 days of receipt of this letter.
This requirement affects nine or fewer respondents and, therefore, is not subject to the Office of Management and Budget review under P.L.96-511.
If you have any questions, please contact me at 301-415-3063.
Sincerely, Docket Nos.
50-275 and 50-323 ORIGINAL SIGNED BY'ames C. Stone, Senior Project Hanager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
Enclosure:
Request for Additional Information cc:
See next page DOCUMENT NAME:
DCIPEEE.RAI DISTRIBUTION:
Docket File ACRS(4),
TWFN PUBLIC PDIV-2 Reading JRoe
- OGC, 015B18 EAdensam
- KPerkins, RIV/WCFO WBateman
- JDyer, RIV RHernan DChamberlain, RIV JStone EPeyton
- JChen, RES/PRAB
- HDrouin, RES/PRAB OFC PD IV-2/LA PDIV-2/PM NAME 6 eye>
JStone:pk DATE 9/Q /95 9/
/95 OFFICIAL RECORD COPY 9509i40263 950906 ',
PDR ADQCK 05000275 P
- PDR,
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September 6, i995 ii Mr. Gregory M. Ruege Pacific Gas and Electric Company NPG Mail Code A10D P.O.
Box 770000 San Francisco, California 94177
SUBJECT:
INDIVIDUALPLANT EXAMINATION OF EXTERNAL EVENTS, REQUEST FOR ADDITIONAL INFORMATION, DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1
AND 2 (TAC NOS.
M83614 AND M83615)
Dear Mr. Rueger:
During the NRC staff's continuing review of the Diablo Canyon Individual Plant Examination of External Events (IPEEE) submittal and its associated documentation, the need for additional information has been identified.
The request for additional information (RAI) is detailed in the enclosure.
The RAIs is related to the external event analyses in the IPEEE, including the seismic analysis, the fire analysis, and the analyses of the effects of high winds, floods, and others (HFOs).
In order to meet our schedule, it is requested that you provide written responses to the RAI within 60 days of receipt of this letter.
This requirement affects nine or fewer respondents and, therefore, is not subject to the Office of Management and Budget review under P.L.96-511.
If you have any questions, please contact me at 301-415-3063.
Sincerely, ORIGINAL SIGNED BY:
James C. Stone, Senior Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket Nos.
50-275 and 50-323
Enclosure:
Request for Additional Information cc:
See next page DOCUMENT NAME:
DCIPEEE.RAI DISTRIBUTION:
Docket File ACRS(4),
TWFN PUBLIC PDIV-2 Reading JRoe OGC, 015B18 EAdensam
- KPerkins, RIV/WCFO WBateman
- JDyer, RIV RHernan DChamberlain, RIV JStone EPeyton
/95 OFFICIAL RECORD COPY
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205554001 September 6,
1995 Hr. Gregory M. Rueger Pacific Gas and Electric Company NPG - Mail Code AlOD P.O.
Box 770000 San Francisco, California 94177
SUBJECT:
INDIVIDUALPLANT EXAMINATION OF EXTERNAL EVENTS, REQUEST FOR ADDITIONAL INFORMATION, DIABLO CANYON NUCLEAR POWER PLANT, UNITS 1
AND 2 (TAC NOS.
H83614 AND H83615)
Dear Mr. Rueger:
During the NRC staff's continuing review of the Diablo Canyon Individual Plant Examination of External Events (IPEEE) submittal and its associated documentation, the need for additional information has been identified.
The request for additional information (RAI) is detailed in the enclosure.
The RAIs is related to the external event analyses in the IPEEE, including the seismic analysis, the fire analysis, and the analyses of the effects of high winds, floods, and others (HFOs).
In order to meet our schedule, it is requested that you provide written responses to the RAI within 60 days of receipt of this letter.
This requirement affects nine or fewer respondents and, therefore, is not subject to the Office of Management and Budget review under P.L.96-511.
If you have any questions, please contact me at 301-415-3063.
Sincerely, Docket Nos.
50-275 and 50-323
Enclosure:
Request for Additional Information James C. Stone, Senior Project Manager Project Directorate IV-2 Division of Reactor Projects III/IV Office of Nuclear Reactor Regulation
7
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Hr. Gregory H. Rueger cc w/encl:
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 1100 11th Street, Suite 311 Sacramento, California 95814 Hs.
Nancy Culver San Luis Obispo Mothers for Peace P. 0.
Box 164 Pismo Beach, California 93448 Hs. Jacquelyn C. Wheeler P. 0.
Box 164 Pismo Beach, California 93448 Managing Editor The Count Tele ram 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 Hr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco, California 94102 Hr. Steve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94232 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower
& Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Hr. 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 Hr. Warren H. Fujimoto Vice President and Plant Manager Diablo Canyon Nuclear Power Plant P. 0.
Box 56 Avila Beach, California 93424 Diablo Canyon Independent Safety Committee ATTN:
Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D
Monterey, California 93940
~
~ E UEST FOR ADDITIONAL INFORMATION DIABLO CANYON IP E SUBMITTAL Seismic 2.
3.
Please provide a list of all elements of the Diablo Canyon seismic IPEEE which have changed since the LTSP, including changes in scope, changes in methods/analyses, changes in walkdown effort and findings, and any others changes that affect the seismic IPEEE procedures or results.
Please provide a list of any differences between Unit I and Unit 2 which may affect the seismic IPEEE.
Please indicate whether or not seismic walkdowns were performed on both units; was the scope of seismic IPEEE walkdowns the same for both units?
What differences were noted in walkdowns in terms of unit configuration and condition?
The seismic initiating event frequencies reported in the third column of Table 3-5 do not match differences in exceedance frequencies reported in Table 3-2.
Please explain the process that was used for deriving seismic interval frequencies.
Although the submittal says that DCPP is a rock site, it also suggests that some IPEEE components may be embedded in soil, or affected otherwise by soil.
For instance, the diesel generator fuel transfer tanks are said to be underground;
- hence, transfer lines may be buried in soil.
5.
What were the reviewers findings/comments related to the containment performance assessment?
What peer review was made of revisions and additions to fragility calculations?
USI A-45 6.
The DCPP IPEEE submittal states that the only source of water credited for AFW function is the condensate storage tank (CST). If this is the
- case, why isn't the CST mentioned in Section 3.2. 1 of the submittal and included in the table at the bottom of page 3-22?
Please provide the seismic fragility for the CST.
Seismic-Fire Interactions 7.
On page 4-108, the submittal states: "If one of these deluge systems were to actuate, it could result in an initiating event, but the frequency of occurrence would be small compared to the regular initiating event frequencies for these initiators."
Many factors contribute to risk importance other than the initiating event frequency.
Please provide an assessment of how actuation of the deluge systems during a seismic event would impact overall seismic risk.
This assessment should include the consideration of potential water damage in parallel with other seismic damage.
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Concerning the second paragraph on page 4-108 of the submittal, please explain the findings of the walkdown team with respect to the three walkdown goals mentioned.
According to the IPEEE submittal, relay panels are located in the cable spreading room.
Therefore, seismically-induced electrical panel fires pose a potential risk-significant fire scenario.
Were these cabinets considered as a seismically-induced fire source?
If so, please provide the analysis.
Mechanisms for diesel failure given seismically-induced actuation of the automatic COz fire protection system have been identified.
These mechanisms include diesel generator lockout due to relay chatter in the FPS controller and starvation of the diesel generator if its air intake is within the diesel generator room.
Provide an analysis of the potential for diesel generator failure given seismically-induced spurious actuation of the CO~ FPS.
Fire The study appears to claim that, because fire boundaries will act as
- rated, interzonal fires will only occur if a fire door is left ajar or if a fire damper fails to close.
This appears to be a case where an assumption can potentially drive the results.
Such an analysis is not valid unless the assumption is adequately justified and it can be demonstrated that there are no paths through the barrier for the spread of damage.
Provide such justification and demonstration for high-hazard fire areas such as the turbine building, diesel generator
- rooms, cable spreading
- rooms, switchgear
- rooms, and lube oil storage areas.
At least two fires have occurred at DCPP on the turbine building operating floor.
One occurred in 1987 due to an electro-hydraulic fuel leak.
The other occurred in 1989 due to arcing in the main electrical generator exciter housing.
The generic data used in the study was inconsistent with the actual occurrence of these fires over the plant's 10-year lifetime.
Explain how these fires were accounted for in the study.
Provide the effect on fire risk of utilizing plant-specific data for turbine building operating floor fire scenarios.
Human recovery actions are identified as the third most critical event in the fire scenario importance ranking lists provided on page 4-71 of the IPEEE submittal report.
- However, no details are provided concerning how probabilities of recovery failure were assessed.
Provide a detailed description of how fire event recovery actions were assessed, including how factors such as sequence timing, elevated environmental stressors (e.g.,
reduced visibility, impaired communications, and impaired accessibility) were accounted for. If IPE values were
- assumed, were they adjusted to reflect reduced reliability during a fire event and, if so, how were they adjusted'f IPE values were used directly, provide a
justification for not having adjusted the values.
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4.
A listing of significant walkdown findings is not documented in the IPEEE submittal.
Provide a summary of the significant walkdown findings (if any).
5.
Fire propagation scenarios within the control room cabinets (where the fire originates) have utilized fire data events from outside the control room.
Inclusion of these events can potentially result in optimistic risk estimates and mask the physical reality of fire propagation within the cabinet of origin.
Provide justification for inclusion of non-control room cabinet fire events and an analysis of the effect on control room fire-induced core damage frequency if non-control room fire events are excluded.
6.
A listing of shared systems other than ASM and vital electrical power is not documented in the submittal.
Provide a listing of shared systems.
For each item on the list provide either the justification for screening, or an analysis of dual unit fire-induced core damage scenarios, including core damage frequency contribution.
III.
Hi h Minds Floods and Others HFOs 1.
Provide a summary of the walkdown findings related to HFOs.
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