ML17054B372
| ML17054B372 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 01/22/1985 |
| From: | Vassallo D Office of Nuclear Reactor Regulation |
| To: | Hooten B NIAGARA MOHAWK POWER CORP. |
| References | |
| TASK-2.K.3.18, TASK-TM NUDOCS 8502050228 | |
| Download: ML17054B372 (6) | |
Text
Docket No. 50-220 January 22, 1985 Mr. B.
G. Hooten Executive Director, Nuclear Operations Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202
Dear Mr. Hooten:
SUBJECT:
CLOSE OUT OF TMI ACTION PLAN ITEM II.K.3.18, "ADS LOGIC MODIFICATION" FOR ISOLATION CONDENSER BOILING WATER REACTORS Re:
Nine Mile Point Nuclear Station, Unit 1 In a letter from T. J.
Dente to D.
G. Eisenhut dated October 28, 1982, the BWR Owners Group proposed a response to TMI Action Plan Item II.K.3.18, "Modification of ADS Logic."
The staff approved two of the options proposed.
The first option removes the high drywell pressure permissive from the logic
'nd adds a manually operated inhibit switch.
The second option adds a timer which begins on low water level, and when timed out, bypasses the high drywell pressure, permissive.
A manually operated inhibit switch is also
'ncluded in the second option; All BWR licensees were requested to implement one of the approved options.
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In a letter from C.- V. Mangan (Niagara Mohawk Power Corporation to D. B.
Vassallo (NRC) dated March 6, 1984, the staff received additional informa-tion regarding the impact of'the approved options on plants with isolation condensers.
It was indicated that certain events would be adversely impacted by either of the approved options.
These events involve the loss of high pressure makeup capability and are normally readily mitigated by the operation of the isolation condenser.
During these events, all ADS initiation signals are present except for high drywell pressure.
Bypassing the high drywell pressure permissive (as'n both approved options) would, therefore, result in actuation of the ADS.
Vessel depressurization greatly reduces the effectiveness of the isolation condenser and can defeat its function.
The modifications which the staff has approved are intended to provide additional protection for only a small number of events such as a stuck open relief valve or a small break LOCA outside containment.
Since for BWRs with isolation condensers other events are adversely
- impacted, the proposed modifications provide no clear overall safety enhancement'.
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Mr. B.
G. Hooten The staff concludes, therefore, that for plants with isolation condensers, no modifications to the ADS logic are required and that implementation of emergency procedures is sufficient for satisfying Action Plan Item II.K.3.18.
This letter thus closes out TMI Action Item II.K.3.18 for Nine Mile Point Unit l.
Sincerely, Original signed by/
Domenic B. Vassallo, Chief Operating Reactors Branch ¹2 Division of Licensing cc:
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Mr. B. G. Hooten Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station, Unit No.
1 CC:
Troy B. Conner, Jr., Esquire.
Conner 5 Wetterhahn Suite 1050 1747 Pennsylvania
- Avenue, N.
W.
Washington, D.
C.
20006 Frank R. Church, Supervisor Town of Scriba R.
D. ¹2
- Oswego, New York 13126 Niagara Mohawk Power Corporation ATTN:
Mr. Thomas Perkins Plant Superintendent Nine Mile Point Nuclear Station Post Office Box 32
- Lycoming, New York 13093 Resident Inspector U. S. Nuclear Regulatory Commission Post Office Box 126
- Lycoming, New York 13093 John W. Keib, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 Thomas A. Murley Regional Administrator Region I Office U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pennsylvania 19406 Mr. Jay Dunkleberger Division of Policy Analysis and Planning New York State Energy Office Agency Building 2 Empire State Plaza
- Albany, New. York 12223
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