ML19317F537
| ML19317F537 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/31/1974 |
| From: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Roe L TOLEDO EDISON CO. |
| References | |
| NUDOCS 8001150851 | |
| Download: ML19317F537 (5) | |
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OCT 3 1 M4 Docket No. 50-346 The Toledo Edison Company ATTN: Mr. Lowell E. Roe Vice President, Power Edison Plaza 300 Madison Avenue Toledo, Ohio 43652 Gentleren:
As a result of our continuing review of the Final Safety Analysis Report (FSAR) for Davis-Besse Nuclear Power Station, Unit 1, we find that we need additional infomation regarding accident analysis. The requests for additional information are enclosed and are based upon the FSAR infomation and your responses to our first-round requests. Your response to these requests is needed by February 23, 1975 in orcer that we can maintain our review schedule.
Sincerely.
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A. Schwencer, Chief Light Water Reactors Branch 2-3 Directorate of Licensing
Enclosure:
As stated ces:
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.c Toledo Edison Cenpany ccs: Donald H. Hauser, Csouire The Cleveland Electric Illu:ninatina Ccmpany P. O. Box 5000, Room 610 Cleveland, Ohio 44101 Gerald Charnoff, Esquire Shaw, Pittman, Potts,Trowrridge and "adden 910 17th Street, N. W.
Washington, D. C.
20006 Leslie Henry, Esquire Fuller, Seney, Henry & Hodge 800 Owens-Illinois Building 405 ifadison Avenue Toledo, Ohio 43604 OISTRIBUTION:
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ACCIDENT ANALYSIS Request No.
6.2.2.4 Your response to Request 6.2.24 does not address the ability of the emergency ventilation system to pull down the annulus to negative pressure nor does it provide tha details and sensitivity of the pressure tests to be conducted on the annulus volume as was requested. Provide this information.
15.4.4 We have reviewed Section 15.4.8 (revisions 1 and 3) and the response to Request 15.4.4 with respect to chlorine protection against the provisions in the attachment.
It appears that adequate protection for control room occupants against chlorine has been provided with the exception of the requirement for a bottled air supply for breathing apparatus.
In this regard indicate how you will meet the bottled air provision as described in the attachment hereto.
15.4.7 Section 15.4.6.6 (Revision 1) states that the analysis of the effects of a turbine room steam-line rupture on control room habitability is in progress. The analysis or its results are not apparent in the FSAR revisions to date. Indicate when the analysis will be completed.
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PROVISIONS FOR ADEOUATE PROTECTION ACA!NTT l
A CHLORINE RELEASE j
i Adequate protection of the control room against an on-site chlorine release vill be achieved if provisions are included in the plant design to isolate the control room auto =atically.
to limit the potential build-up of chlorine within the control room, and if equipment and procedures are provided to assure ic=ediate use of breathing apparatus by the control room operators.
Similar precautions vould help mitigate consequences of most postulated toxic gas releases.
To acco=plish the autoestic isolation quick-response chlorini. detectors should be located in the fresh air inlets to the control roe.
These detectors should be able to detect and signal a step increase in chlorine concentration within a time period not to exceed 3 seconds.
The detectors should be capable of signaling a step increase from zero to 15 ppa of chlorine by volu=e or.sreater.
Detectors should be provided at the control room fresh air inlet for all plants that have storage facilitics that might accidently release a total of 500 pounds of chlorine. Additional detcetors should be provided at chlorine storage locations that are less than 100 =eters fron the control room or that cay release core than 3 tons of chlorine as a result of any postulated accident. These detcetors should be placed, and the detcetor trip point adjusted, se as to assure detectica of a leak or a container rupture.
Deccctor trip signals should initiate auto =stic isulation of the control roca and provide an audible alara to the operators. The ccans used to initiate auto =atic isolation should meet single active failure and seis=ic criteria.
Control roon isolation should be accomplished within about seven seconds after detector trip. Adequate isolation requires all openings to the control room to have low leakage characteristics.
This would include doors, ds=pers, and penetrations.
Total in-filtration into the isolated control roc = should be less than 100 cfm assuming a 1/8" water gasc pressure differential across all openings and the maximun operating differential across the isolation ds=pers upstream of recirculating f.,ns.
This leakage limit should be reduced to 25 cfm if chlorine storage is within 100 meters of the control room or if more than 3 tons of chlorine can be released as a result of any postulated accident.* Normal fresh air make-up should be limited to no more than 1 to 1 1/2 air changes per hour. An administrative procedure should provide all doors leading to the control room be kept closed when not in use.
- These leakage rates are based on a control roon volume of 100,000 cubic feet and thus should be adjusted as directly proportional 1
to actual ccatrol room voluce.
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Control room isolation should be followed i==ediately by the start-up and operation of the e=ergency recirculating charcoal filter or equivalent equipment designed to re=ove or otherwise limit the accu =ulation of conta=ination within the control room.
Under certain =eteorological conditions control room isolation may not be sufficient by itself to limit chlorine concentrations to levels below those which cause physical disco = fort or disability.
Therefore, the use of self-contained breathing apparatus should be considered when developing a chlorine release e=ergency plan.
Since calculations indicate that rapid increases in chlorine concentrations are possible, e=ergency plan provisions and rehearsal of these provisions for i==ediate donning of breathing apparatus on detection of chlorine release are necessary.
Storage prcvisions for breathing apparatus and procedures for use 'should be such that operators can begin using the apparatus within two minutes after an alarm.
benning of breathing apparatus shculd be =andatory prior to the determination of the cause of an alarm.
A toxic environ =ent =sy be present for -several days or ' longer if a chlorine leak cannot be fixed or the leaking container rc=oved.
In any event, adequate bottled air capacity (at'lcast six hours) should be readily available on-site to assure that sufficient ti=c is available to locate and transport bottled air from off-site locations.
This off-site supply should be capable of delivering several hundred hours of bottled air to the me=bers of the c=ergency crew.
Isolation and air supply equipment relied on should acco==cdate a single failure of an active component and still perform the required function.
(In the case of self-contained breathing apparatus this may be acco=plished by r.upplying one extra unit for every three units required.)
Protection requirc=ents for plants located nearby other facilitics that store significant quantitics of ch'orine or plants located nearby oajor chlorine transportation ro. ;cs will be determined on a case-by-case basis.
Similarly plar.ts having storage facilitics that might accidentally release a total of 500 pounds of chlorine or less util be revicued on a case-by-case basis to deter-mine need for protection, against accicental release.
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