ML19199A559
| ML19199A559 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/11/1976 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Deyoung R Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905040103 | |
| Download: ML19199A559 (4) | |
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A Docket No.: 50-320 R. C. DeYoung, Assistant Director for Light Water Reactors, DPM REVISIGN 2 TO THE DRAFT SAFETY EVALUATION REPORT FOR THREE MILE ISLNtD NUCLEAR STATION, UNIT 2 Plant Name: Three Mile Island Nuclear Station, Unit 2 Docket No.: 50-320-Milestone No.: 24-04 Licensing Stage: OL NSSS Supplier: Eabcock & Wilcox Architect Engineer: Burns & Roe Containment Type: Dry Responsible Branch & Project Manager: LWR-2; H. Silver Raquested Completica Cate: N/A Review Status: Awaiting Infon:":ation Enclosed is Revision 2 to the draft Safetf dYaluation Report for the Three Mile Island Nuclear Station, Unit 2 (TMI 2). This report has been prepared by the Contain:mnt Systec:s Branch after having reviewed the applicable portions of the FSAR including Acendments 1 through 40. The applicant must submit previously requested infon::ation before we can conclude on tt'e adequacy of the containment functional design, the containment heat removal system and the acceptability of the pmposed use of the containment purge system during non::al operation.
The Containment Systems Branch has reviewed the minicum contain: cent pressure analysis for the ECCS evaluation.of Three Mile Island Unit 2.
The applicant references Topical Report BAW-10103, "ECCS Evaluation of 3Ts 177-FA Lowered LOOP NSSS" for the ECCS evaluation. The containment pressure calculation was done using the B&W ECCS evaluation model which has been appmved on a generic basis under Appendix K to 10 CFR Part 50. We required that certain plant-dependent infon::ation be submitted for our review, and justification for the containment volurm, passive heat sinks and operation of the containment heat removal systems was submitted by letter February 25, 1976. We have concluded that the minimum containment pressure calculated for Three Mile Island, Unit 2 is acceptable.
The outstanding items are briefly described as follows:
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Containment Subcompartments Analysis The applicant has not provided the resultant loading on the reactor cavity structures and compared it to design capf flity. We will report our finding after receiving the applicant's response to Question 042.17.
2.
Main Stea t Line Break Accident Analysis The applicant has not identified all sources of mass and energy which could contribute to the miease to the containment. In addition, the applicant has not adequately discussed the secondary system isolation signal (s) and total elapsed time including instrumentation dalay time for automatically teminating mass and energy addition to the affected steam generator. We will report our finding after reviewing the applicant's response to 042.18.
3.
Containment Purging During Nomal Plant Operation The applicant has indicated that containment purging during normal operation will be necessary. It is our position that containment parge systems which do not emeet our design guidelines for an on-line purge system, as stated in Branch Technical Position CSB 6-4, should be limited to about 90 hor s per year (about i percent of the time) during nortral plant operation.
4.
Heat Removal Systeas The NSSS vendor has reanalyzed the containment spray systei. perfomance.
Tne analysis indicates that the sodium hydroxide tank (SHT), sodium thio-sulfate tank (STT), and barated water storage tank (BWST) would not draw down together as previously precicted. This would result in the emptying of the SHT and STT up to twenty-two minutes before the BWST level set-point is reached. We will require the applicant to evaluate the effect of uneven drawdown.on system performance, including the potential for pump cavitation.
All of the above matters have been discussed with the applicant. We will com-plete our review of the remaining outstanding items after receipt of the requested information.
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Robert L. Tedesco, Assistant Director for Plant Sys+2ms Division of Systems Safety
Enclosure:
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REVIdiONS 7 THE DRAFT SAFETY EVALUATIL4 R~ ~1RT (CONTAIEENT SYSTEMS)
THREE MILE ISLAND STATICN, UNIT 2 DOCKET N0.: 50-320 1.
Delete item 1 of Revision 1 to the draft Safety Evaluation Report, dated May 17, 1976, and replace it with the folicwing:
"With regard to the containment purge system, the applicant proposes to intermittently purge the containment during normal plant operation.
However, since the system supply and vent lines are larger than that recomr. ended in Branch Technical Position, CSB 6-4, ' Containment Purging During Normal Plant Operations,' we will require the applicant to limit purge system operation to less than 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year (about 1 percent of the time) and will include this limitation on the use of the contain-ment purge system in the plant Technical Specifications.
2.
Delete the last paragraph of Section 6.2.6 in the draft Safety Evaluation Report and replace it with the following:
The applicant provided a comparison of the actual containment parameters for Three Mile Island, Unit 2 with those assumed by B&W in BAW-10103. The minimum containment pressure analysis presented in Topical Report BAW-10103 was demonstrated to be conservative for Three Mile Island, Unit 2.
We therefore conclude tnat the minimum containment pressure was calculated in accordance with *ppendix X to 10 CFR 50, and is acceptable.
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