ML20133B363

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Forwards Rev 0 to TR 024, Evaluation to Increase Normal Drywell Temp Operating Limit. Requests Review of Increasing Entry Condition for Bulk Drywell Temp to 150 F.New Algorithm for Determining Drywell Temp Developed
ML20133B363
Person / Time
Site: Oyster Creek
Issue date: 08/01/1985
From: Fiedler P
GENERAL PUBLIC UTILITIES CORP.
To: Zwolinski J
Office of Nuclear Reactor Regulation
Shared Package
ML20133B367 List:
References
NUDOCS 8508060149
Download: ML20133B363 (2)


Text

. , 9-d GPU Nuclear Corporation Nuclear ='3=:;388 Forked River,New Jersey 08731-0388 609 971-4000 Writers Direct Dial Number:

August 1,1985 Mr. John A. Zwolinski, Chief Operating Reactors Branch No. 5 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Zwolinski:

Subject:

Oyster Creek Nuclear Generating Station Docket No. 50-219 License No. DPR-16 Drywell Temperature Analysis for Design Basis Loss of Coolant Accident GPU Nuclear has reconsidered the maximum allowable drywell temperature prior to the design basis loss of coolant accident and two other events for Oyster Creek. Based on detailed analyses we have determined that 1500F, at the commencement of these events, poses an insignificant reduction in safety margin for the containment in withstanding the events described. Raising the subject temperature does not present any concern relative to the drywell's steel and concrete structural components. We will be evaluating the aging effect on environmentally qualified components inside containment.

Accordingly, we have concluded that it is acceptable to raise the Emergency Operating Procedure (EOP) entry condition for bulk drywell temperature to 1500 and to permit normal plant operations up to this value. We request your review of this matter since it represents a change to the design bases of the plant.

We recognize that previously docketed information with the Commission reflects a 1350F limit. Enclosed for your review is Topical Report 024 that describes the analytical work used to arrive at the new limit. However, pursuant to 10CFR50.73(a)(2)ii(B), we will be reporting to USNRC Region I that we have and are operating in excess of the original 1350F limit to drywell temperature as calculated. This constitutes being outside of the design basis of the plant. Amendment 15 to the FDSAR (The Primary Containment Design Report) had originally established the limit of 1350 USNRC Region I personnel are aware of the condition.

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'i GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation

Mr. J:hn A. Zwolinski US Nuclcar R:gulatory Commission v/ Page 2 In addition to the analytical work involving design basis events, GPUN has developed a new procedure and algorithm for more accurately determining drywell temperature. The new algorithm which incorporates additional thermocouple readings in the vicinity of the recirculation pumps is in use.

Based on a physical review of the HYAC system routing, and use of additional thermocouples, the new algorithm will provide greater accuracy in determining l

actual drywell bulk temperature. l l

GPUN has determined that such a temperature increase poses an unreviewed safety question to the staff since it does have a very small, albeit inconsequential effect on the margin of safety. However, the probability of occurrence Of any accident previously reviewed is not increased and no new type of accident or malfunction is introduced. The GPUN procedure LP-004, used for updating Licensing basis document, has been implemented. This process will result in a change to the updated FSAR pending your approval.

The application review fee of $150.00 will be submitted under separate cover letter.

In the event that any comments or questions arise, please contact Mr. Drew Holland, Oyster Creek Licensing Manager at (609)971-4643.

Very truly yours, A n1 Vice President and Director Oyster Creek PBF/DH/ dam

(#0026A) cc: Dr. Thomas E. Murley, Administrator Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 Mr. Jack N. Donohew, Jr.

U.S. Nuclear Regulatory Comission 7920 Norfolk Avenue, Phillips Bldg.

Bethesda, MD 20014 i . Mail Stop No. 314 I NRC Resident Inspector l Oyster Creek Nuclear Generating Station Forked River, NJ 08731