ML19329C010
| ML19329C010 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/01/1976 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19329C012 | List: |
| References | |
| NUDOCS 8002120754 | |
| Download: ML19329C010 (4) | |
Text
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!b OCT1 1978 Occket No. 50-346 MEMORAMDUM FOR:
D. Vassallo, Assistant Director for Light Hater Reactors, Ort!
FRCM:
R. Tedesco, Assistant Of rector for Plant Systems, DSS
SUBJECT:
REVISION TO THE DRAFT SAFETY EVALUATION REPORT - DAVIS-BESSE NUCLEAR POWER STATION, UNIT 1 Plant Nane: Davis-Besse Muclear Pwer Station, Unit 1 Docket Number:
50-346 Licensing Stage: CL NSSS Supplier: Babcock & '.-lilcox Containment Type: Dry Dual 4rchitect Engineer:
Bechtel Responsible Branch and Project Manager: L'iR Branch 4; L. Engle Review Status:
Incomplete Requested Ccapletion Date:
N/S Applicant's Resporse Date:
M/S Enclosed are revisions to the draft Safety Evaluation Report for the Davis-Besse & clear Pwer Station, Unit 1.
This report has been pre 9ared by the Contairrent Systms Branch after having reyf wed the anplicable cortions of the FSAR as amended (through Acendment 36).
In addition, we have prepared coments on the Technical Specificaticns concerning contairr: ant leak testing which are included in an enclosed request for additional infcmation.
The following items describe the status of the draf t Safety Evaluation Rerort (issued February 12, 1975 and revised Acril 30. 1976) and the Tachnical Specifications:
1.
Subconcartment Analysis The subcompartment analysis is still identified as an open its in the draft Safety Evaluation Report, as revised. For the reactor cavity and steam generator cosnpartments, we are calculatina differential i
pressures that exceed design values.
It should be noted that our confirmatory analysis of the reactor cavity is based on the use of
'nodified inertia (L/A) terms from a sinilar MU plan +
Contact.
D. Pickett, CSB l' li 432-7711 orrica e ownseasso p nave >
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D. Vassallo 007 1 1976 Upon examination of plan and elevation drawings of the reactor cavity, we detemined that certain vent areas were calculated incorrectly by the aoplicant. He have discussed this natter with the applicant and the applicant has agreed to submit a revised reactor cavity analysis using the correct vent area data, and has agreed to crovide the inertia tem data which we have previously requested from then. tie feel certain, however, that peak calculated differential pressures for the reactor cavity will exceed design conditions unless the basis for assuming a 14.14-ft2 longitudinal split in the hot leg is re-examined.
He have discussed this with the applicant, and the aoolicant plans to submit additional infomation regarding postulated pipe break configuratiens and sizes for the reactor cavity analysis.
The applicant has indicated his intentiens to adoot a sinilar approach for the stean generator compartment analysis, if necessary.
2.
S_hield Guilding Decressurization Time Amend.ent 35 presented a revised ther al analysis of the shield building following a LOCA which increased the shield building depressurization time frrn 65 seconds to 12.33 minutes. f!efore we can conclude on the acceotability of the revised shield building analysis, additional information will be recuired. The attached cuestions have been discussed with the applicant. We have also notified AAG of the increased depressurization time.
3.
Centaiment Furge Sys ten
'Je have revic.ied the applicant's plans for eneration of the containment
- urge systen during normal plant operation.
In the attached request for additional inforr.ation, we are requesting the anolicant to provide the analyses identified in Branch Technical Pesition CSB 6-4, "Containnent Purging During Nor al Plant Operations," to justify oneratinq the purge system during nomal clant operation.
4 Containment Leak Testing (Technical Specifications)
(a) Systen Ventinq and Draining
'!e w fil recuire that the systems to be vented and drained during the containment integrated leak rate (Type A) test be identified in the plant Technical Specifications. This is included in tha attached request for additional infor ation.
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OCT 1 B76
- 0. Vassallo (b) Fuel Transfer Tube Revision 1 to the draft Safety Evaluation Report states that the applicant intends to demonstrate zero leakage through the fuel transfer tube and thereby eliminate it as a potential bypass leak rath. Since the test method employed during the preoperational leak testing has been shcwn to be quite sensitive, the aoplicant can no longer cocnit to denonstrating zero leakage but pronoses to demonstrate negligible leakage. Rather than attempt to define what constitutes negligible leakace, we will renuire that the fuel transfer tube leak rate be included in the total for all potential bypass leak paths.
(c) personnel Air Loch The draft Technical Specifications allow a maxinum rate for an airlock of 0.05 La at Pa. (33 psig). Since the air lock is identified as a potential bypass leak cath, its individual leakage limit is in conflict with the raxinun allevable bvnass leak rate of 0.015 La. 'de have asked the applicant to propose a leak rate limit for the airlock that will not conflict with the maxinun allowable bypass leak rate.
Also the draft Technical Specifications state that periodic door seal leak testing must demonstrate no detectable seal leakoge at peak calculated accident pressure Pa. The applicant h:s inferred us in a telecon that the door seals cannot be leak tested at Da without the use of strongbacks. Furthemore, the applicant stated that they have detected sore leakage when pressurizing between the seals at a reduced pressure. The applicant, therefere, orc 00ses to specify a leak rate for a reduced pressure which, when extrapolated to Pa. would not exceed a maximum allcwable leak rate. We have asked the applicant to propose a test method for the air lock door seals including an acceptancs criterion.
Original signed by Robert L. Tedesco Robert L. Tedesco, Assistant Director for Plant Systers Division of Systems Safety
Enclosures:
As Stated cc: See Page 4 b
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