ML18352A329

Cancelling of Event Report No. 76-020: After Further Review, Concluded No Longer Reportable, Effects of Seiches Were Appropriately Considered in Design & Construction

ML18352A329
Person / Time
Site:	Palisades
Issue date:	06/28/1976
From:	Sewell R Consumers Power Co
To:	James Keppler Office of Nuclear Reactor Regulation
References
LER 1976-020-00
Download: ML18352A329 (3)

Text

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consumers Power company General Offices: 212 West Michigan Avenue, .Jackson, Michigan 49201

• Area Code 517 788-0550 Jrme 28, 1976 Mr James G. Keppler US Nuclear Regulatory Commissi 799 Roosevelt Road Mail Soction Dockel Clark Glen Ellyn, IL 60137 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 that 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 primary 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 a.nd. construction of the Palisades Plant. Thus,~.:we are no longer considering this item reportable and. are, therefore, cancelling it. Some of the reason*s f'or this conclusion are sum-marized in the attached. lett.er.

Ralph B. Sewell (Signed)

. Ralph B. Sewell Nuclear Licensing Administrator

T.o Palisades Pla ~ew Committee

' ' /112./)

RBSewell, P-21-317 /':::'f/~

FROM DATE June 25, 1976 SUBJECT REVIEW OF EFF:i;;CTS OF A SEICHE INTERNAL

.CORRESPONDENCE BLHarshe, Covert cc DABixel, P-21-319 HWKeiser, P-21-109 I have reviewed. the following documentation with respect to how seiches were considered in evnluation of the Plant Design:

1) The references listed in DABixel's letter of ~my 27, 1976, to JGLewis/PRC.

2) Event Report PAL-76-020.

3) HHKeiser letter of June 21, 1976, to ?RC.

I hnve concluded that the potential loss of four Primary Coolant PUmps due to flooding caused by a seiche is not an unreviewed safety question. In the follm'ling paragraphs I will attempt to o*ntline the basis for my conclusion

• First, the Loss of Coolant Flow Incident described in Section 14.7 is an !lntici-

pated transient. An anticipated transie::-it is sonething that is expected to occur several tir:1es or r:iore during plant life. ?or anticipated transients a m.inir::urn trar1sient D~rn ratio limit of 1. 30 has generally been estcrblished by the HRC as the acceptance criteria. This limit i9 established to insure that damage to the fuel will not occur for these moderate probability events. I note *specificall~r that a sfr:ultaneous loss of four coolant pumps was not*

considered in this tran'sient analysis because it was judged to be of very low probability. Section 14.7.4 of the FSAR states in part: ":!!'or the case of a single stuck rotor there will be some rods for which the transien*t; mrn ratio droJ:ls below 1.30.however the very low probability of this incident allows acceptance of this.condition."* That statement also applies p'.1ilosophicnlly to the very low probability case of a s:i.:r.ml taneous loss of all four primi:..ry coolant pumps.

FSAR Ap:pendix 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 nodern lake level. Six (6) of these 7 .3 feet are described as. an allowance* for seiche, thus, I would conclude that the J?ossibility of a seiche was properly considered in the design of the Plant against f'looding to the 590 foot level. I note that the bottom of the four primary coolant pwnp breakers are mou.~ted at the 590 foot level *

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2.

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A rev.i.ew of question 2 .4 of Amendments 15 and 18 to the FSAR reveals the following key words. They are:

"Maximum increase" "especially severe seiche" *

"shutdown safely" "with or without s:pecial 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 equipment reg_uired to obtain and maintain a safe shutdo~*m condition would be functional. The answer given was 594 feet 8 inches and states that equipment required to obtain and maintain a safe shutdown*condition would not be flooded until water level exceeded thi.s value. This question did not intend to imply that the four primary coolant pu.mps could not trip sequentially *. The probability.is conveyed as extremely low as compared to anticipated transients.

The six foot allowance for a seiche 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"g!?.n City, Indiana and 0 at the same time at Holland, J:ld.chigan.

Further, J~IT(eiser's calculations show the maximum level .at Palisades to be much less than 6 ~eet

• Therefore, I have concluded that the FSAR has appropriately considered and evaluated the effects _of seiches on the Palisades Plant and the design and construction of the Palisades Plant was in accordance with the requirements of the FSAR. Thus, my conclusion is that this item is not an unreviewed safety qu:-;!stion and is not reportable in accordance with Section 6. 9.2 a-8 of the Technical Specifications. Further, I believe that this event report should be closed out. With PRC concurrence, I will inform the NRC that we no longer consider this event reportable and are therefore canceling it *