ML17195A691
| ML17195A691 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/20/1984 |
| From: | Zwolinski J Office of Nuclear Reactor Regulation |
| To: | Farrar D COMMONWEALTH EDISON CO. |
| References | |
| TASK-2.K.3.18, TASK-TM LSO5-84-12-018, LSO5-84-12-18, NUDOCS 8412240097 | |
| Download: ML17195A691 (3) | |
Text
UNITED STATES
- NUCLEAR REGULATORY COMMISSION
. WASHINGTON, D. C. 20555 Docket Nos.
50~237/249
. LSOS-84-12-018 Mr. Dennis L.* Far~ar Director of NuclAar Licensing Common\\'1ea l th Edi son Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Farrar:
December 20, 1984
SUBJECT:
CLOSE OUT OF TM! ACTION PLAN ITEM II.K.3.18, "ADS LOGIC MODIFICATION" FOR ISOLATION CONDENSER BOILING WATER REACTORS Re:
Dresden Nuclear Power Station, Unit Nos. 2 and 3 In a letter from T. J. Dente to D. G. Eisenhut dated October 28, 1982, the BWR.Ownfrs Group proposed a response to TM! Action Plan Item II.K.3.18, 11Modif1cation of ADS Logic.
0 The staff approved two of the options proposed. -
The first option removes the high drywell pressure permissive from the logic and adds a manually operated inhibit switch.
The second option adds a timer which begins on low wate~ level, and when timed out, bypasses the high drywell pressure permissive. A manually operated inhibit switch is also included in the second option. All BWR licensees were requested to implement one of the approved options.
In a letter from C. V. Mangan (Niagara Mohawk Power Corpdratio~) 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 p*resent except for high drywell pressure.
Bypassing the high drywell*pressure permissive (as in both approved options) would, therefore, result in actuation of the ADS.
Vess~l 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 vRlve or a small break LOCA outside containment.
Since for AWPs with isolation condensers other events are adversely impacted, the proposed modifications provide no clear overall safety enhancement.
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Mr. Dennis L. Farrar December 20, 1984 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 Dresden Units 2 and 3.
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Mr. Dennis L. Farrar cc Robert G. Fitzgibbons Jr.
Isham, Lincoln & Beale Three First National Plaza Suite 5200 Chicago, Illinois 60602 Mr. Doug Scott Pla~t Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450 U. S. Nuclear Regulatory Commission Resident Inspectors Office Dresden Station Rura 1 Route #1 Morris, Illinois 60450 Cha. i rma n Board of Supervisors of Grunc!y.County Grundy-County Courthouse Morris, Illinois 60450 U. S. Environmental Protection Agency Federal Activities Branch Region V Offii::e ATTN: *Regional Radiation Representative 230 South Dearborn Street Chicago, Illinois 60604 J2mes G. Keppler, Regional Administrator Nuclear Regulatory Commission, Region III 799 Roosevelt Street Glen Ellyn, Illinois 60137 Gary N. Wright, Manager Nuclear Facility Safety -
Illinois DApart~ent of Nuclear Safety 1035 Outer Park Drive, 5th Floor Springfield, Illi.nois 62704 December 20, 1984