ML17250A348
| ML17250A348 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 06/03/1980 |
| From: | White L ROCHESTER GAS & ELECTRIC CORP. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-80-12, NUDOCS 8006300494 | |
| Download: ML17250A348 (6) | |
Text
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ROCHESTER GAS AND ELECTRIC CORPORATION
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89 EAST AYENUE, ROCHESTER, N.Y. I4649 LEON O. WHITE: JR.
VICE PRESIDENT TEI EPIIONE ARE* CODE Tld 546-2700 June 3, 1980 Mr. Boyce H. Grier, Director U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19406
Subject:
IE Bulletin No. 80-12, Decay Heat Removal System Operability R. E. Ginna Nuclear Power Plant, Unit No.
1 Docket No. 50-244
Dear Mr. Grier:
In response to Inspection and Enforcement Bulletin 80-12 dated May 9, 1980, concerning decay heat removal capability, the following information is provided.
1'.
The circumstances and sequence of events. of the Davis-Besse event of April 19, 1980 were reviewed.
The review included assignment to the Operational Assessment Group for on-shift discussions.
2.
A review of the Ginna plant history indicated a loss of residual heat removal flow during steam generator work on May 3, 1972.
On that date, while operating at low Reactor Coolant System loop level, the running residual heat removal was observed to have lost suction, and cooling flow was interrupted for about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and 10 minutes.
The residual heat removal (RHR) pump suction from refueling water was used to restore pump suction and raise loop level.
Simultaneously, cooling flow was initiated via loop drains and one of the reactor coolant drain pumps.
The Plant Operating Review Committee met shortly afterward to review the incident and provide recommendations.
These are dis-cussed further in the items below.
3.
Ginna Station has two RHR pumps with power supplied from separate safeguard buses.
The emergency power for these buses is available from two separate emergency Diesel generators.
There are al o t reactor coolant drain pumps with power supplied from separate sa e
~
guard buses.
These pumps are backup to the RHR pumps for core cooling.
8008s00 W9'y
ROCHESTER CAS AND ELECTRIC DATE June 3, 1980 To Mr. Boyce H. Grier, Director SHEET NO 2
The power source for the above-mentioned pumps is primarily from off-site circuit 767 via station auxiliary.transformer 412.
A second circuit, 4751, is also available.
As mentioned above, the emergency Diesel generators back up the off-site circuits.
Instrumentation and control reliability has been demonstrated by the historical operating record of the station.
Also, the overall reliability during refueling and cold shutdown modes of operation has been demon-strated by the historical operating record of the plant.
4., In response to the May 3, 1972 interruption, the PORC provided the following recommendations which were implemented.
a.
The minimum loop level for continuous operation was administratively limited to 10 inches above loop centerline to ensure suction to the Residual Heat Removal Pump.
b.
The hot leg temperature was to be recorded so that more comprehen-sive monitoring of loop temperatures can be attained..
c.
Residual Heat Removal flow was to be temporarily recorded to monitor any flow fluctuations.
d.
A tygon hose for level indication was established on the A loop piping.
e.
A procedure was written to describe necessary operations for oper-ating at low loop levels and if the incident occurs again.
The present procedures for refueling and draining the Reactor Coolant System require RHR system operation.
Procedure S-13B, RHR Pump Isolation, requires the testing and operability of the alternate RHR pump and both reactor coolant drain pumps before isolating an RHR pump for maintenance.
In addition to these redundancy requirements it has always been a practice during the history of Ginna Station not to perform maintenance on RHR components unless the reactor coolant system is filled and vented and containment integrity is in effect so that the steam genera-tors may provide an alternate means of decay heat removal, or unless the refueling cavity is flooded so that decay heat may be removed by circulation of the large body of water.
For the latter mode a path for borated water to the core is required in the refueling procedures.
ROCHESTER OAS ANO ELECTRlC oATE June 3, 1980
'r. Boyce H. Grier, Director SHEET NO.
3 5.
Emergency procedure E-17, Loss of Residual Heat Removal, responds to loss of RHR for all conceivable events during the following conditions:
a.
Reactor Coolant System closed.
b.
Reactor vessel head removal.
c.
Low loop levels.
Ginna Station also has an emergency procedure E-17.1, Reactor Coolant Drain Tank Pump Operation for Core Cooling.
This provides the direction to proceed in the event of loss of normal RHR system capability.
6.
Procedure changes deemed necessary to satisfactorily resolve this issue for the Gfnna plant are as follows:
a.
Amend procedur'e S-13B to insure clarity of the testing requirements apply to all modes of plant operation, and to include expediting restoration in the event of an additional loss of an RHR method, including a steam generator.
b.
Amend Operating Procedure 0-2.3.1, Draining the Reactor Coolant
- System, to include a precaution on expediting restoration in the event of an additional loss of an RHR method.
These procedure changes should be in effect by July 1, 1980.
Very truly yours, L. D. Whit, Jr.
Subscribed and sworn to me on this2 r'.
r day of June 1980.
NOTARY PUBLIC, State of ff.Y.,Monroe County catty C~trctgpires March 30, 19 +~
Division of Reactor'Operations Inspection Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555