ML20203D354
| ML20203D354 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 12/10/1997 |
| From: | Eaton R NRC (Affiliation Not Assigned) |
| To: | Roche M GENERAL PUBLIC UTILITIES CORP. |
| References | |
| TAC-M836652, NUDOCS 9712160172 | |
| Download: ML20203D354 (5) | |
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D:cember 10, 1997 t
-Mr. Michael B. Roche Vice President-and Director GPU Nuclear Corporation Oyster Creek Nuclear Generating Station Post Office Box 388 Forked River, NJ 08731
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING OYSTER CREEK NUCLEAR GENERATING IPEU' SUBMITTAL (TAC rl0. M83652)
Dear Mr. Roche:
Based on the NRC staff and contractor reviews of your Individual Plant Examination of External Events (IPEEE) submittal dated December 29. 1995, the enclosed questions were developed.
To facilitate our review schedule, we are requesting a 60-day response to the enclosed request.
If you have questions regarding this request please contact me on (301) 415-3041.
Sincerely.
Original signed by Ronald B. Eaton, Seninr Project Manager Project Directorate 1-3 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Decket No. 50-219
Enclosure:
Request for Additional Information cc:
See next oage DISTRIBUTION Docket File PUBLIC PDI-3 Rdg.
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B. Boger J. Zwolinski A. Rubin RES R. Eaton R. Hernan I
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H. Roche Oyster Creek Nuclear GPU Nuclear Corporation Generating Stction CC:
Ernest L. Blake Jr.. Esquire Shaw. Pittman. Potts & Trowbridge 2300 N Street. NW Washington. DC 20037 Regional Administrator. Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia. PA 19406-1415 BWR Licensing Manager GPU Nuclect Corporation 1 Upper Pond Road Parsippany, NJ 07054 Mayor Lacey Township 818 West Lacey Road Forked River. NJ 08731 Licensing Manager Oyster Creek Nuclear Generating Station Mail Stop:
Site Emergency Bldg.
P.O. Box 388 Forked River. NJ 08731 Resident inspector c/o U.S. Nuclear Regulctory Commission P.O. Box 445 Forked River. NJ 08731 Kent Tosch, Chief New Jersey Department of Environmental Protection Bureau of Nuclear Engineering CN 415 Trenton. NJ Eo25
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April 1997 l
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REQUEST FOR ADDITIONAL INFORMATION ON THE OYSTER CREEK NUCLEAR GENERATING STATION IPEEE SEISHIC 1.
Provide a discussion of how operator actions were incorporated into the analysis, including a table of the most important acticns identified.
Also, describe how the human error probabilities were derived and the method used and the basis for quantification.
2.
Provide a discussion of offsite power recovery via the combustion turbines modeled in the analysis, including:
Operator actions required cad needed instrumentation:
fragility analysis calculations for the Combustion Turbine Fuel Oil Tank, as well as soil-related structurcl failure:
routing of combustion turbine power (if routed via the 4kV emergency switchgear, additional discussion of how the switchgear fragility was incorporated into '.he model for off-site power recovery is needed).
3.
Provide a discussion of the procedure used for the evaluation of LOCA pathways in the analysis and drawings of the recirculation pump support structures.
4.
Provide the cutoff threshold values of fragility curves; and the results of sensitivity studies, if any, on the effects of the cutoff of lower tails of fragility curves.
E.
Provide the references 3-2. 3-3 and 3-8 which contain the results of the fragility analyses referred to in the IPEEE submittal.
FIRE 1.
In the detailed evaluation, use of a fire severity factor was applied for five of the eight zones that had not been screened up to this point of the analysis. The formulation and application of the fire severity factor is considered to have technical flaws. The formulation of the factor is based on fire events that have been recorded in the EPRI Fire Events Data Base. Consideration of the extent of automatic or manual fire suppression on mitigation of these events was not addressed-in the formulation of the severity factor. (It is anticipated that these types of suppression were employed in some of the events, thereby limiting severity.) Because the frequency associated with the fire can not be totally independent from the fira severity factor. use of the factor ENCLOSURE
artificially decreases the fire frequency. When the fire severity factor was applied in an area where fire suppression was credited, the fire severity factor was only applied to the scenario where fire suppression was unavailable; thi is inconsistent with the formulation of the factor. The engulfing fire assumed when using the fire severity factor is not always the limiting case; i.e., a smaller fire of higher frequency could pose as much if not more risk. The use of the fire severity factor is considered to be technically unsubstantiated, therefore, assessment of fire damage is warranted.
For the five zones mentioned above, in which fire severity factors were used. please model fire suppression and propagation to determine the probability that the fire will damage the critical targets before it. is suppressed, and provide the results of the analysis.
2.
In the detailed evaluation, for seven of the eight remaining zones, credit was given for automatic fire suppression systems in mitigating the fire after some components are assumed to be damaged.
It is not ap3arent that this method addresses all the factors that affect the licelihood of failure to suppress the fire before damage of more critical components has occurred.
In order to assume that the suppressior, systems will effectively control or extinguish a fire, the analysis must provide reasonable assurance that the systems are designed, installed and maintained in accordance with nationally recognized standards and codes.
Verify that the automatic fire suapression systems were designed and installed to meet the applicable NFPA codes.
3.
Human recovery actions are credited in the estimates of upper bound CDF where conservative assumptions were relaxed.
No detaiis are provided concerning the methodology employed to calculate the likelihood that the recovery action is unsuccessful. There are issues unique to fire situations that relate to psychological and environmental stressors (impet of smoke and suppression agents, reduced visibility, etc.).
No indication is supplied in the Oyster Creek IPEEE submittal as to whether these factors were considered.
Please provide details as to how the human error probabilities were estimated.
HF0 1.
The IPEEE submittal estimates the frequency of high winds wich speeds exceeding 168 m;;h as SE-7 per year, and estimates the contribution of straight winds to this frequency as negligible (see Figure 7 of the submittal.) However, the staff, in a letter dated February 26, 1990 (from Alexander Dromerick, Senior Project Manager, NRR, to Mr. F.
E.
Fitzpatrick, Vice President and Director, Oyster Creek Nuclear Generating Station) has estimated that the frequency of tornado wind speeds exceeding 168 mph is 7E-6 per year.
Even the frequency of straight winds with s]eeds greater than 168 mph may be greater than 1E-6 3er year.
At Seabrooc. in a memorandum from William P. Gamill to Leon Reiter, dated Aug 16, 1984 (Public Document Room Accession No.
8408240398) it is noted that windspeeds up to 150 mph may be more likely due to non-tornado phenomena.
From a figure in this memorandum, one would estimate, at Seabrook, a frequency of about 2E-6 per year for the probability that a strai #.t wind would exceed 168 mph. Ore can obtain similar results at the Oyster Creek site, by using the approach given by Batts. Cordes. Russel. Shaver and Simiu in NBS Building Science Series 124. " Hurricane Hind Speeds in the United States". May 1980.
This report finds that a Weibull distribution fits the hurricane wind speeds.
From Figure 6 of the report, one finds that, at milepost 2450 (near Atlantic City. NJ). the frecuency of exceedance of 125 mph is about SE-4 per year, for hurricane wincs. A good fit to the data in the report is given by P-exp(-uY). where u-(v+669)/660. v is the windspeed, and y=11.
This yields about 1.2E-6 per year for hurricane wind speeds greater than 168 mph.
One notes further that Changery, in NUREG/CR-7639 gives the 1000 year return period straight wind as 117 mph.
In contrast. Table 3 on page 5.1-22 of the IPEEE submittal gives a 100.000 year return period for a straight wind of 102 mph, a much more optimistic value.
Since the frequency of wind speeds greater than 168 mph can be reasonably estimated at about 1E-5 per year, one cannot screen out high winds on the basis of wind speeds exceeding 168 mph being less than 1E-6 per year.
P wever, a reasonable ap3 roach would be to show that at speeds somewnat greater than 168 mpi the probability of core damage is low. The structures of concern are the diesel generator vaults and the oil tank compartment. Therefore:
Estimate, as a function of the wind speed, for wind speeds greater than 168 mph, the probability of failure of the diesel generator vaults and the oil tank compartment: include the effects of both wind pressure and tornado missiles.
2.
NUREG-1407 requests that a licensee " perform a confirmatory walkdown of the plant.
The walkdown Lould concentrate on outdoor facilities that could be affected by high winds, onsite storage of hazardous materials, and offsite developments." Please provide a concise summary of the findings of this walkdown and resolution of any identified potentiai vulnerabilities.
In particular, please provide an assessment of the effects of failure from high winds and tornadoes of non-safety related structures and equipment on the functioning of safety-related structures, systems, and com)onents.
Supplement 1. discusses furtier the concern with failure of nonsafety-related structures affecting safety-related structures.
3.
As noted in NUREG-1407. section 2.4. the latest probable maximum a
precipitation criteria published by the National Weather Servt a call for higher rainfall intensities over shorter time intervals and smaller areas than have previously been considered: this could result in higher site flooding levels, and greater roof ponding levels.
Please assess the effects of applying these new criteria to Oyster Creek. Additional information is given in Generic Letter 89-22.
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