ML19273B729
| ML19273B729 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/21/1979 |
| From: | Utley E CAROLINA POWER & LIGHT CO. |
| To: | Stello V Office of Nuclear Reactor Regulation |
| References | |
| GD-79-1450, NUDOCS 7906120190 | |
| Download: ML19273B729 (4) | |
Text
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M# MJ Carchna Awar & L get C reany File: NG-3514(B)
May 31, 1979 SERIAL NO: GD-79-1450 Office of Nuclear Reactor Regulation ATTENTION:
Mr. V. Stello, Jr., Director Division of Operating Reactors United States Nuclear Regulatory Commission Washington, D. C.
20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-325 AND 50-324 LICENSE NOS. DPR-71 AND DPR-62 MARK I CONTAINMENT LONG TERM PROGRAM
Dear Mr. Stello:
This letter is in response to your letter dated March 12, 1979, which we received on March 16, 1979, regarding the implementation schedule for modifications required as a result of the Mark I Program.
The Load Definition Report (LDR) was issued in two sections in December, 1978 and March, 1979. We have been performing our plant unique analyses using this load definition for the various hydrodynamic loads and load combinations.
To date we have identified only one major modification that will be required at Brunswick:
the vent header daflector. We are still uncertain whether or not this deflector will be required in all bays of the torus, or only in the non-vent bays. This modification is scheduled to be implemented during the 1980 i
refueling outages which are planned in the Winter for Unit 2 and Spring for Unit 1.
Our implementation schedule is shown on Attachment 1 and the installation schedule on Attachment 2.
Your March 12 letter made reference to the requirement for installing T-quenchers in lieu of the ramshead. On April 3, 1979, we met with some members of your staff along with representatives of Georgia Power Company and Power Authority of the State of New York. At that time we stated that the defined safety relief valve loads for the Brunswick steel-lined reinforced concrete torus were in the range of 25%-30% of the allowable. The expected torus pressure during a LOCA is 33 psi. However, the steel-lined reinforced concrete torus was conservatively designed for a pressure of 62 psi.
Even with a load factor of 1.5 applied to the 62 psi (i.e., 93 psi), no rebar stress exceeds 90% of yield. Since we have not heard officially from the NRC on the outcome of the April 3 meeting, it is still our position that T-quenchers cve not necessary because the Brunswick torus is designed to withstand significant loads without exceeding yield. T-quenchers will probably be required for resolution of the anticipated transient without scram (ATWS) issue; and therefore, we will co=mit to installing T-quenchers during the Mark I program modifications. However, we consider it a minor modi-fication which may be completed beyond the December, 1980 date. We do not feel that completing this modification at Brunswick warrants extending any refueling outage for installation work. Therefore, the attached schedule reflects instal-lation of T-quenchers beginning during the 1980 outages and, if the installation is not completed, finishing during the 1981 outages. Other minor modifications, if identified as being required during the Plant Unique Analyses, will be installed during the 1981 outages.
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'Mr. V. Stello <
The attached bar chart schedules, Attachments 1 and 2, reflect the time table for our plant unique analyses and for engineering the modifications. These schedules, of course, are predicated on receiving the NRC evaluation of the Load Definition Report and the Plant Unique Analysis Application Guide by the end of May, 1979.
If this date is delayed, the plant unique analysis will also be delayed on a day-for-day basis. Further, if the NRC review requires major modification to the load definitions in the LDR, then this too will impact the completion date for our analyses and possibly the design of our modifications.
Please contact our staff if you have any questions regarding this implementation schedule.
Yours very truly, L
J E.'E.
Utley Executive Vice President Power Supply MAC/ JAM /tl Attachments 2349 165
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