ML17332A710
| ML17332A710 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 03/31/1995 |
| From: | John Hickman NRC (Affiliation Not Assigned) |
| To: | Fitzpatrick E AMERICAN ELECTRIC POWER SERVICE CORP. |
| Shared Package | |
| ML17332A711 | List: |
| References | |
| TAC-M74398, TAC-M74399, NUDOCS 9504050241 | |
| Download: ML17332A710 (4) | |
Text
Hr.
E, E, Fitzpatric~Vice President Indiana Michigan Pow~ompany c/o American Electric Power Service Corporation 1 Riverside Plaza
- Columbus, Ohio 43215
SUBJECT:
REVIEW OF D.C.
COOK INDIVIDUALPLANT EXAMINATION SUBMITTAL INTERNAL EVENTS (TAC NOS.
H74398 AND M74399) n
Dear Hr. Fitzpatri ck:
We have essentially completed our review of your Individual Plant Examination (IPE) for internal events and internal flood.
While our review to date indicates that the IPE is, in general, satisfactory, the Human Reliability Analysis (HRA) portion of the IPE has significant weaknesses.
We recognize that sensitivity analyses were performed by you which indicate that significant vulnerabilities were not overlooked and that you intend to update the IPE by revising its HRA. It is for this reason that we are providing, as an enclosure, an evaluation of your HRA to assist you in your update of the IPE.
This update, provided it properly addresses the staff's concerns, will significantly increase the future usefulness of your IPE in other applications.
Should you have any questions, please contact me at (301) 415-3017.
Sincerely, ORIGINAL SIGNED BY John B. Hickman, Project Manager Project Directorate III-1 Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos.
50-315 and 50-316
Enclosure:
HRA Evaluation w/attachment cc w/encl:
See next page DISTRIBUTION w/encl:
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Mr. E.
E. Fitzpatrick Indiana Michigan Power Company CC:
Regional Administrator, Region III U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Attorney General Department of Attorney General 525 West Ottawa Street Lansing, Michigan 48913 Township Supervisor Lake Township Hall Post Office Box 818 Bridgman, Michigan 49106 Al Blind, Plant Manager Donald C. Cook Nuclear Plant Post Office Box 458 Bridgman, Michigan 49106 U.S. Nuclear Regulatory Commission
'Resident Inspector's Office 7700 Red Arrow Highway Stevensville, Michigan 49127 Gerald Charnoff, Esquire
- Shaw, Pittman, Potts and Trowbridge 2300 N Street,,
N.
W.
Washington, DC 20037 Mayor, City of Bridgman Post Office Box 366
,Bridgman, Michigan 49106 Special Assistant to the Governor Room 1 State Capitol Lansing, Kichigan 48909 Nuclear Facilities and Environmental Monitoring Section Office Division of Radiological Health Department of Public Health 3423 N. Logan Street P. 0.
Box 30195 Lansing, Michigan 48909 Donald C.
Cook Nuclear Plant Mr. S. Brewer American Electric Power Service Corporation 1 Riverside Plaza
- Columbus, Ohio 43215 Dccanbcr 1993
EVALUATION OF THE HUMAN RELIABILITYANALYSIS OF THE INDIVIDUALPLANT EXAMINATION FOR DONALD C.
COOK NUCLEAR PLAN UNITS I AND 2 Regarding the Human Reliability Analysis (HRA) portion of the Individual Plant Examination (IPE), the staff has identified several significant weaknesses with American Electric Power Service Corporation's (AEPSC) application of the post-initiator HRA model in using the Technique for Human Error Rate Prediction (THERP) process and with AEPSC's treatment of time available for operator action.
AEPSC's model (a fault tr ee approach) resulted in incorrect applicatiens of THERP values.
For example, the diagnosis model in THERP pertains to the entire control room crew;
- however, diagnosis events are reduced by other "recoveries" which is inappropriate.
Performance shaping factors were discretized to a level that is not justified and beyond the current state-of-knowledge, and therefore, overcredited.
Dependencies and conditionalities are not considered; therefore, operator performance is assessed independent of the accident sequence.
The time available to the operators versus the time required to diagnose and perform the necessary activities are,not appropriately treated.
These various weaknesses resulted in the vela low human error probabilities (HEPs) seen in the D.C.
Cook IPE.
The staff %ad the HRA portions of the Cook IPE reviewed by a contractor (Alan D. Swain)
'This report is attached.
AEPSC conducted several sensitivity studies to indicate that significant vulnerabiiities were not overlooked.
The HEPs were increased and the core damage frequency (CDF) requantified.
Although the CDF increased, new dominant accident sequences and contributors did not appear and the relative ranking of accident sequences and contributors (i.e.,
X contribution) did not change.
Based on these sensitivities, the staff has concluded that significant vulnerabiIities were not overlooked and that AEPSC has met the intent of Generic Letter SS-20, "Individual Plant Examination for Severe Accident Vulnerabilities."
However, the staff believes the weaknesses in the HRA will substantia'lly limit any future use of the IPE.
AEPSC has noted its intention to revise the HRA with the following modifications: (I) human reliability action specific to sequences, (2) dependence
- modeling, (3) performance shaping factor in diagnosis, (4) explicit consideration of time, (5) consistent use of second person checking, and (6) training performance shaping factors.
While the staff'grees with AEPSC's intended modifications, these changes need to address the specific issues raised above.
In additien, the staff believes that, although AEPSC's peer review process provided assurance that the IPE effort had been properly documented, the review process did not assure that the IPE analytic techniques had been correctly applied.as noted by the staff's findings regarding the weaknesses of the HRA.
The staff'ncourages
- AEPSC, as part of its intended revision to the HRA, to perform an independent peer review that includes HRA experts to ensure that HRA techniques are correctly applied in the revision.
ENCLOSURE