05000255/LER-1976-020, Advises That LER 76-020 Cancelled.Potential Loss of Four Primary Coolant Pumps Due to Flooding Caused by Seiche Not Unreviewed Safety Issue

Advises That LER 76-020 Cancelled.Potential Loss of Four Primary Coolant Pumps Due to Flooding Caused by Seiche Not Unreviewed Safety Issue

ML20085E510
Person / Time
Site:	Palisades
Issue date:	06/28/1976
From:	Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 8308150168
Download: ML20085E510 (3)

LER-2076-020, Advises That LER 76-020 Cancelled.Potential Loss of Four Primary Coolant Pumps Due to Flooding Caused by Seiche Not Unreviewed Safety Issue

Event date:
Report date:
2552076020R00 - NRC Website

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S P ' CORSum8FS i Power Aw .- Company 0 General Offices: 212 West Michigan Avenue.. Jackson. Mecnegan 49201. Area Code 517 788 0550 June 28, 1976

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t- 62 Mr James G. Keppler 9 W' OA' US Nuclear Regulatory Commission h.*/ he%N [..e 799 Roosevelt Road Glen Ellyn, IL 60137 'Q ,

DOCKET 50-255, LICENSE DPR-20 PALISADES PLANT On June 15, 1976, Mr G. Hein of the Palisades Plant staff reported to Mr K.

Baker of your office that we were evaluating a question t' hat had arisen and considered that it might be reportable under Technical Specification Section 6.9.2.a-8. The question involved the postulated loss of four pri=ary coolant pumps due to flooding caused by a postulated seiche. This was classified as Event Report No 76-020.

After further review, we have concluded that the effects of seiches were appropriately considered in the design and construction of the Palisades Plant. Thus,-ve are no longer considering this item reportable and are, therefore, cancelling it. Scme of the reasons for this conclusion are sum-marized in the attached letter.

Ralph B. Sevell (Si6ned)

Ralph B. Sevell Nuclear Licensing Administrator 8308150168 760628 PDR ADOCK 05000255 S PDR 6536 COPY ENT RW. _-

O O V . .V To Palicades Flo Review Committee FaoM RBSewell, F-21-317/5 /- ggggg DAtt June 25, 1976 hhbN[

Cemitny SueJccT REVIDi 0F EFFECTS OF A SEICIIS INicRNAL ConatsrowccNec BLHarshe, Covert cc DABixel, F-21-319 IMKeiser, ?-21-109 I have reviewed the follouing documentation with respect to how seiches were considered in evcluation of the Plant Design:

1) The references listed in DABixel's letter of Fay 27, 1976, toJGLewis/PRC.

2) Event Report FAL-76-020.

3) Iraciser letter of June 21, 1976, to PRC.

I have concluded that the potential loss of four Primary Ccolant Penps due to ficoding caused by a sciche is not an unreviewed safety question. In the following paragraphs I will attempt to cutline the basis for my conclusion.

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( First, the Loss of Coolant Flow Incident described in Section Ih.7 is an entici-pated transient. An anticipated transient is sonething that is expected to occur several tires or more during plant life. For anticipated transients a ,

mini =un transient D:!3 ratio linit of 130 has generally been established by the 130 as the acceptance criteria. This limit is established to insure that damage to the fuel will not occur for these moderate probability events. I note specifically that a situltaneous loss of four coolant pumps was not considered in this transient analysis because it was judged to be of very low probability. Section 14.7.4 of the FSAR states in part: "For the case of a single stuck rotor there will be some rods for which the transient DI!B ratio

' drops below 130 however the very low protability of this incident allows acceptance of this condition."' That stt. tenent also applies philosophically to the very low probability case of a simultaneous loss of all four prier.ry coolant pumps.

FSAR Appendix A.2(g) describes the Plant design with respect to flooding as protected up to elevation 590 feet. This provides a margin of 7.3 feet above the highest reported redern lake level. Six (6) of these 7 3 feet are described as an allowance for seiche, thus, I would conclude that the possibility of a seiche was properly considered in the denii;n of the Plant agsinst flooding to the 550 foot level. I note that the bottoa of the four primary coolant puq) breakcrs are mounted at the 590 foot level.

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,. 9 .o A review of question 2.!+ of Amendments 15 and 18 to the FSAR reveals the folletting key words. They are:

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,i "Mav4 == increase" "especially severe seiche"*

I / " shutdown safely" i

"with or without special procedures

' and provisions executed at the time of flooding." .

The context of this question is an inextremis situation. It is intended to convey a very low probability event and asks what the maximum flooding level

- is that equipr..ent required to obtain and maintain a safe shutdoun condition j vould be functional. The answer given was 591+ feet 8 inches and states that equipment required to obtain and maintain a safe shutdown condition would not be flooded until water level exceeded this value. This question did not intend to imply that the four primary coolant pumps could not trip sequentially. .The probability,is conveyed as extremely low as compared to anticipated transients.

The six foot allowance for a sciche appears conservative. Section 2.2.2(a) shows the greatest level change due to a seiche over an 105 year period to be 6 feet at Michi'gan City, Indiana and 0 at the same time at Holland, Michistan.

Further,IrdKeiser's calculations show the maximum level at Palisades to be 6

much less than 6 fect.

Therefore, I have concluded that the FSAR has appropriately considered and evaluated the effects ,of seiches on the Palisades Plant and the desi5n and construction of the Palisades Plant was in accordance with the requirements of the FSAR. Thus, my conclucion is that this item is not an unreviewed safety question and is not reportable in accordance with Section 6 9 2 a-8 of the Technical Specifications. Further, I believe that this event report l

should be closed out. With FRC concurrence, I will infom the ERC that we 4

no longer consider this event reportable and are therefore canceling it.

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