ML20004A984
| ML20004A984 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 05/01/1981 |
| From: | William Jones OMAHA PUBLIC POWER DISTRICT |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-79-01B, IEB-79-1B, NUDOCS 8105270071 | |
| Download: ML20004A984 (7) | |
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Omaha Public Power District 1623 HARNEY e O M A N A. NEsRASMA 68102 a TELEPHONE b56-4000 ARE A CJDE 402 May 1, 1981 Mr. K. V. Seyfrit Directcr U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011
Reference:
Docket No. 50-285
Dear Mr. Seyfrit:
Omaha Public Power District's letter to the Commission dated February 1, 1981, provided a revised response to IE Bulletin 79-01B. 1 to that letter identified several open issues related to IE Bulletin 79-01B.
Item 5 to Enclosure 11 detailed the District's commit-ment to further the need for qualification of Power Operated Relief Valves (PORV's), block valves, and pressurizer heaters as discussed in 9 to the February 1,1981, letter. The District has com-pleted this follow-up evaluation of PORV's, block valves, and heater environmental qualifications and has determined that these components are not required to achieve a cold shutdown. Accordingly, Enclosure 19 has been revised and is forwarded herewith.
The applicable qualifi-Cdtion sheets have been deleted (pages 6-110 and 6-113b), the master list has been updated (page 4-90), and Enclosure 13 has been revised to reflect these changes also.
Sincerely,
- N7 W. C ones Divisipn Manager Production Operations WCJ/KJM/TLP:Jmm Enclosure cc:
U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Washington, D.C.
20555 LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, D.C.
20036 810526007l
Y 9 Power Operated Relief Valves PORV Block Valves Pressurizer Heaters The PORV's and their associated block vales were included in the IE Bulletin 79-01B submittal as part of the 9quipment referenced in the plant emergency procedures. The District's follow-up evaluation shows that these valves are not required to be operable to place the plant in cold shutdown after a LOCA.
Under the emergency procedures, the PORV's and/or block valves are used in two different situations.
The first is as a possible source of a LOCA in which the PORV may open and fail to close.
If this should occur, the acoustic position indication and quench tank capacity coupled with block valve operation should provide adequate protection to miti-gate this accident. The block valves are qualified to 2500F, 25 psig.
If the PORV's cannot be isolated, the accident would be handled as a small break LOCA.
The second use of the PORV's in an emargency procedure is that of backup to the steam generators for long term cooling when the primary system is above 700 psia. This would require the failure of the re-dundant auxiliary feedwater system. The auxiliary feedwater system as it stands, and as it will be upgraded to as part of the TMI modifi-cation. provides an adequate redundant source for cooling of the core.
Therefore, PORV's are not required for long term cooling.
No further qualification effort is planned. The District will continue I
to reference the PORV's and block valves in the emergency procedures to i
provide the operator with the maximum amount of flexibility in miti-gating an accident. The District has also connitted to identifying all qualified electrical equipment on the control boards so that the re-liability and use of the equipment may be determined.
The pressurizer heaters are referenced in the emergency procedures as a system for use in mitigating a LOCA anc, as required by IE Bulletin 79-01B, LOCA qualification must be evaluated.
The pressurizer heaters are to be used to insure natural circulation and subcooling following a LOCA only if pressurizer inventory is maintained. However, unavail-ability will not precluce achieving shutdown. No qualification test data has been located by the District.
The calculations and assumptions for the heaters were originally based on hot standby loss of offsite power conditions (CE NPSD-133) to account for heat and leakage losses, not for LOCA mitigation.
This insures natural circulation can be achieved. Should the heaters not work, the ECCS will be used to maintain subcooling.
l It is the Distric:'s intention to continue to reference the heaters in the emergency procedures as a potential mitigation system.
There are no further plans to upgrade qualification.
The qualification of this equipment will be identified in the control room.
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Reference 6:
Deleted - Reference Not Used Reference 7:
See Enclosure 19 Reference 8:
These components are required to function once during the first few seconds of a LOCA or MSLB and remain in
" Normal" room conditions until recirculation occurs.
No work sheets are required.
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