ML20211R071
| ML20211R071 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/22/1986 |
| From: | Wilson R GENERAL PUBLIC UTILITIES CORP. |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| 3526F, 5000-86-0961, 5000-86-961, NUDOCS 8607280090 | |
| Download: ML20211R071 (4) | |
Text
)
GPU Nuclear U
a si pany, e Je s y 07054 201 263-6500 TELEX 136-482 Wnter's Direct Dial Number.
July 22, 1986 5000-86-0961 Mr. John A. Zwolinski, Director BWR Project Directorate No.1 Division of Boiling Water Reactor Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Zwolinski:
Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 Request for Additional Infonnation Concerning Safety Relief Yalve (SRV) Discharges to the Suppression Pool In our letter dated October 31, 1985, GPU Nuclear (GPUN) requested cancellation of two modifications associated with the Mark I Containment Long-Term Program.
The two modifications were to 1) provide suppression pool temperature monitoring local to the safety relief valve (SRV) discharge quenchers and, 2) improve thermal mixing within the suppression pool.
My staff and yours have discussed the issues concerning the cancellation request in subsequent telecons and during the April 10, 1986 meeting. The purpose of this letter is to address the open issues and respond to the request for additional information forwarded by your letter dated May 5, 1986. The specific response to the information request is attached.
GPUN provided the NRC staff with a status summary of Mark I modifications which were already made or proposed for the future by letter dated June 29, 1981.
In that letter a thermal mixing modification was indicated.
- However, in subsequent analysis, no credit was taken for thermal mixing enhancement.
The NRC staff consultant, Brookhaven National Laboratory (BNL) found the pool temperature analysis acceptable.
The BNL report, together with the NRC staff SER, was forwarded to us by NRC letter dated January 13,1984, Mark I Containment Long-Tenn Program - Pool Dynamic Loads.
Therefore, GPUN does not consider the thermal mixing modification to be part of the scope of work j
required by the Order dated January 19, 1982.
In retrospect, this modification should not have been included in the October 31, 1985 cancellation request.
8607280090 e60722 ADOCK0500g9 DR g000 3526f GPU Nuclear is a part of the General Pubhc Utihties System g
. 4 The proposed. local temperature monitoring system was reviewed by BNL and found acceptable. Subsequently, GE, for the BWR Owners Group, analyzed SRV discharge performance with quenchers. The conclusion reached in the resultant report (NED0 30832) was that unstable steam condensation is not a concern when quenchers are installed on SRV discharge piping. As a result, the local temperature limit specified in NUREG 0661 is no longer considered appropriate. Based upon our review of the NED0 report, we concluded that installation of a local temperature monitoring system is no longer necessary.
The BWR Owners Group requested the NRC staff to review NED0 30832.
It is our understanding that this review has not been completed, nor will it be completed in time to support our cancellation request. The local temperature monitoring modification is currently required by Order for installation during our current refueling outage which we intend to complete in October 1986.
Therefore, we request that a deferment be granted to the Cycle 12R outage or until such time as the cancellation issue can be resolved.
V y t uly yours, T
C
. F. W lson Vice President Technical Functions RFW/pa 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 Commission 7920 Norfolk Avenue Phillips Building, Mail Stop 314 Bethesda, MD 20014 NRC Resident Inspector Dyster Creek Nuclear Generating Station Forked River, NJ 08731 3526f
ATTACHMENT Response to Request for Additional Information The specific information request, for which a response below is provided, was forwarded by letter dated May 5,1986 and is stated as follows:
Is the Acceptance Criteria on safety relief valve discharges in Appendix A to NUREG-0661, Mark I Containment Long-Term Program, applicable to these modifications and does Qyster Creek meet the Acceptance Criteria without the modifications.
This includes the use of the Monticello test data to obtain the 43*F as the maximum local-to-bulk torus water temperature difference for Qyster Creek.
Has anything changed such that Qyster Creek is outside the assumptions made hy the staff's two safety evaluations dated January 13, 1984, on the Mark I Containment Long Term Program.
Response
The Acceptance Criteria (AC) in NUREG 0661, Mark I Containment Long-Term Program, which are applicable to the cancellation request dated October 31, 1985 are contained in Section 2.13.P, Suppression Pool Temperature Limits.
As indicated in the technical evaluation report (BNL No. 04243) hy Brookhaven National Laboratory, the NRC staff consultant, Qyster Creek did not meet the AC for the analysis of the suppression pool temperature limit. However, the alternate approach employed was considered acceptable.
The BNL report and NRC SER were forwarded to GPUN by letter dated January 13, 1984, Mark I Containment Long-Term Program - Pool Dynamic Loads. The conclusion which was reached, based upon the information provided, was that the suppression pool local temperature would not exceed the AC limit during the severe transients analyzed.
No credit was taken for enhanced suppression pool circulation (the thermal mixing modification). For Qyster Creek, the Monticello test data without RHR operation was employed. This corresponds to the 43*F maximum local-to-bulk suppression pool temperature difference.
It has already been concluded that the alternate approach employed for Qyster Creek satisfies the AC for the suppression pool temperature limit. This is discussed in Section 3.3 of the BNL report. As such, the inclusion of the thermal mixing modificatfor. in the cancellation request, in retrospect, was inappropriate.
GPUN does not consider the thermal mixing modification to be within the scope of work required by the Order dated January 19, 1982.
The second modification for which cancellation was requested is the installation of a suppression pool local temperature monitoring system. The proposed system which BNL reviewed provided enhanced suppression pool bulk temperature monitoring as well as sensors positioned to assess temperature local to the quenchers. As the AC local temperature limit is not expected to De exceeded, which is discussed in the BNL evaluation, local temperature monitoring is not deemed necessary.
Currently, two pairs of thermocouples, each pair diametrically opposed in the suppression pool, provide indication 3526f
4 of suppression pool bulk temperature. Additional sensors will be installed during a future refueling outage to enhance suppression pool bulk temperature measurement and comply with the requirements of Regulatory Guide 1.97.
As stated previously, the NRC staff Safety Evaluation Report (SER) which is applicable to the modifications under discussion is that forwarded by NRC letter dated January 13, 1984, Mark I Containment Long-Term Program - Pool Dynamic Leads. The only change which will be made, which is different from the assumptions made in the SER, is the final design configuration for sensor placement during the upgrade of the suppression pool temperature monitoring system.
Sensors which provide pool temperature local to the quenchers will not be installed. The exact number and placement of additional sensors for enhanced bulk temperature measurement has not been finalized at this time.
Our October 31, 1985 letter formally endorsed the General Electric report NED0 30832, " Elimination of Limit on BWR Suppression Pool Temperature for SRV Discharge with Quenchers", December 1984. This report concluded that unstable steam condensation is not a concern when quencher devices are installed on SRV discharge piping and that the AC suppression pool temperature limit in NUREG 0661 should be eliminated.
In our review of the NED0 report we concluded that the NUREG 0661 suppression pool temperature limit is not appropriate for Oyster Creek. Thus, the requirement for local suppression pool water temperature measurement at the SRY quenchers is no longer valid.
l 3526f
_ _ _ _ _, _ _