ML20138D911
| ML20138D911 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 04/18/1997 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BY97-5087, GL-88-20, NUDOCS 9705010292 | |
| Download: ML20138D911 (2) | |
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Commonwealth Edison Company liyron Generating Station o
4 650 North German Church Road Hyron; 11. 610l n9"'94 Tel 814234 5 6 4 L.
April 18,1997 LTR:
BY97-5087 FILE: 2.01.0207 (GL 88-20, Sup. 4)
Office of Nuclear Reactor Regulation
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U.S. Nuclear Regulatory Commission i
Washington, DC 20555-001 i
Attention:
Document Control Desk
SUBJECT:
Transmittal of Page 5-1 of the Byron Station Individual Plant Examination of External Events Submittal Report Byron Nuclear Power Station Unit (s) 1 and 2 Facility Operating License (s) NPF 37 and NPF-66 NRC Docket No(s). 50-454 and 50-455
REFERENCES:
(1)
U.S. NRC Generic Letter 88-20, Supplement 4, " INDIVIDUAL PLANT l
EXAMINATION OF EXTERNAL EVENTS (IPEEE) FOR SEVERE
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ACCIDENT VULNERABILITIES - 10CFR50.54(f)", dated June 28, i
1991.
(2)
K. L. Graesser to NRR letter dated December 23,1996.
a The purpose of this letter is to transmit Page 5-1 of the Byron Station IPEEE Submittal Report. The subject report had been previously transmitted as part of Reference (2) in response to NRC Generic Letter 88-20, Supplement 4," Individual Plant Examination of a
External Events (IPEEE) for Severe Accident Vulnerabilities - 10CFR50.54(f)", dated June 28, 1991 (Reference (1)). Page 5-1 was inadvertently omitted from the December 23,1996 transmittal (Reference (2)). Please insert the attached copy of Page 5-1 into your copies of 4
the Byron Station IPEEE Submittal Report.
If there are any additional questions, please contact Marcia Lesniak. Nuclear Licensing Administrator, at (630) 663-6484.
Sincerely, K. L. Graesser Site Vice President I
Byron Nuclear Power Station b,
Attachments cc:
A. B. Beach, NRC Regional Administrator - Rill G. F. Dick, Jr., Byron Project Manager NRR S. D. Burgess, Senior Resident inspector - Byron Office of Nuclear Safety-IDNS lllllhlfllll 9705010292 970418 PDR ADOCK 05000454 P
PDR A l'nicom Company
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I 8
O 5.
HIGH WINDS, FLOODS, AND OTHER EXTERNAL EVENTS l
5.1 Introduction The external events considered in this section include those applicable to Byron Station except for fire and seismic events which are covered in other sections of this document. While a multitude of potential extemal events have been cited in the literature such as NUREG/CR-2300
[5.1], the primary focus is on high winds, external floods, transportation accidents and accidents at nearby facilities. The methodology for assessing these events differs from those established for other aspects of the overall IPE/IPEEE program efforts in keeping with the general perception of the potential risk contribution of these events.
5.2 GeneralMethodology Supplement 4 to the NRC's Generic Letter 88-20 [5.2] and the related NUREG-1407 [5.3]
requested specific evaluations be performed based on a progressive screening approach. The first step in the general process is to establish a list of initiating events to be considered. This effort is to be based on the open literature, the requirements of the fPEEE program itself and any site specific extemal hazards of a unique nature. A general screening of events upon j
completion of the list is in order. This may eliminate certain postulated initiators as not relevant 1
to a given site or as being so very unlikely as to warrant dismissal.
The second step in the process consists of performing evaluations of each of the hazards i
(initiating events) retained using the progressive screening approach noted above. The steps in the progressive screening approach involve a series of eva'uations in ever increasing detail, g
effort and resolution. Figure 5.1 of Reference 5.3 illustrates these e,aluations. Each of these evaluations, as they apply to the Byron IPEEE effort will be d5cassed.
The first evaluation involves a review of the plant specific UFSAR [5.4] hazard data and plant 1
licensing bases. This effort will, on a hazard by hazard basis, delineate those postulated hazards which were considered in the plant licensing basis and the hazard level or magnitude associated with each included hazard. It will also delineate the frequency with which the hazard is expected to manifest itself at the site where such information is appropriate and available. For i
example, the UFSAR for a site might well define a specific tomado design basis for the plant in terms of rotational and translational air velocities and in terms of specified missiles and associated missile velocities. The frequency of tomado occurrence on site may also be j
provided in the UFSAR. The design provisions and features incorporated into the plant to effectively cope with the design basis tomado and associated missiles would also be described l
in detail. Special analyses, such as structural analyses of doors, hatches, etc., might also be described to illustrate the efficacy of the design. The IPEEE review would note all of these points for all hazards discussed in the UFSAR.
The second evaluation cited in Figure 5.1 of Reference 5.3 is the identification of changes since the operating license (OL) issuance. The actual UFSAR itself should provide a very high level of assurance that significant changes have been identified and accounted for. Specifically, if the UFSAR is compared to the relevant OL documents such as the basic FSAR and the NRC's i
SER, those changes which affect the licensing basis will readily be noted. In practice, this is l
more valuable than walkdowns since the changes which might affect the licensing bases for typical external initiators are more likely to be structural or major architectural changes which will i
Byron Station IPEEE Submittal Report December 1996 page 5-1
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