ML19310A312

Discusses Effect of Dc Power Supply Failure on ECCS Performance.Forwards Listing of ECCS Sys Available W/ Various Single Failures.Loss of Equipment Due to Water Spillage Has Been Satisfactorily Addressed

ML19310A312
Person / Time
Site:	Cooper
Issue date:	06/03/1980
From:	Pilant J NEBRASKA PUBLIC POWER DISTRICT
To:	Ippolito T Office of Nuclear Reactor Regulation
References
LQA8000294, NUDOCS 8006110075
Download: ML19310A312 (3)

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Lsa8000294 GENERAL OFFICE Nebraska Public Power District ' '" fcfcMSe7*U'SIE.*>" ""'

June 3, 1980 Director, Nuclear Reactor Regulatica Attention: Mr. Thomas A. Ippolito, Chief Operating Reactors Branch No. 2 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Effect of a DC Power Supply Failure on ECCS Performance Cooper Nuclear Station NRC Docket No. 50-298, DPR-46

Reference:

1) Letter from T. A. Ippolito to J. M. Pilant Dated April 25,1980, "same subject"

2) Letter from J. M. Pilant to D. L. Ziemann Dated October 1,1976, "RHR System-Addicional Information"

3) Letter from D. L. Ziemann to J. M. Pilant Dated November 10,1976, " Amendment 32 to Facility Operating License - Modifications to Improve the Performance of the LPCI System of the ECCS"

Dear Mr. Ippolito:

Reference 1 requested Nebraska Public Power Distri:t to confirm the conclusion of a General Electric Co. study regarding the minimum ECCS equipment availability with a DC power supply failure, and to submit a list of ECCS equipment that would be available at Cooper Nuclear Station (CNS) for a similar single failure with large and smau recirculation loop discharge and suction breaks. Loss of equipment due to water sp11-lage was also to be addressed.

A listing of the ECCS systems available with various single failures was submitted to the NRC as Attachment C to Reference 2 during the Licensing process for the LPCI modification at CNS. This listing con-sidered loss of DC power supply for both suction and discharge side breaks, and is included again as Enclosure 1 for information.

As to confirming the conclusion of the GE study, NPPD has verified tnat the study do.2s consider the worst-case ECCS system availability combin-ation as applied to CNS. Additionally, General Electric Co. has been S requested to specifically compare the ECCS single failure evaluation for f xeo.uos7g

Thomas A. Ippolito June 3, 1980 Page 2 CNS (Enclosure 1) against the GE study to ensure that the ECCS systems assumed available oy GE for a small suction break on a LPCI mod plant (2 CS + 2 LPCI one in each loop + ADS) is in fact more conservative than the ECCS systems available at Cocper Nuclear Station for a similar break with loss of 250V de battery power (2 CS + 2 LPCI in one loop + ADS) .

Loss of equipment due to water spillage has been satisfactorily addressed during the licensing process for the LPCI modification, and was summarized as follovs in the staff Safety Evaluation Report (Reference 3):

"Section 3.1.5.2 ' Break Effects' of Reference 3 states that a study of the drywell geometry is being performed to determine the effects of water jet impingement resulting from a postulated recirculation line break. For the suction line break, protection devices or barriers will be provided, if required, to prevent discharge valve operator damage. By letter dated October 20, 1976, NPPD reported the completion of the drywell geometry study. NPPD determined that for the suction line break, the physical location of the system equip-ment provides a barrier to prevent possible discharge valve operator damage; and, therefore, no protection devices or barriers are necessary.

Based on the results of the licensee's study, we conclude that water jet impingement from a postulated recirculation line break will not prevent the recirculation pump discharge valve operators from func-tioning as designed."

Should you have any questions or require additional information, please contact me.

Sincerely, i k

. Pilant Director of Licensing and Quality Assurance JDW/cmk Enclosure t

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s NED0-21335 ENCLOSURE 1 Attachm:nt "C" l

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5. ECCS SINGLE FAILURE' EVALUATION 1

=k gJ The ef fects of a range of single failure in the modified emergency core cooling (

system (ECCS) were evaluated by Burns and Roe, Architect-Engineers. A summary

~1. of the results is shown in Table 5-1. The results show that for both suction ,.

and discharge breaks, failure of the LPCI valve or the LPCI valve operator -

h 230 Vdc battery power supply is limiting. This is consistent with the break j y; spectrum analysis shown on Figure 4-11.

E g Table 5-1 ECC SYSTEMS AVAILABILITY IN MODIFIED SYSTEM WITH SINGLE FAILURE ,

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5. .

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'f% Suction Side Break Remaining ECC System (Pumps)

N i No Failure 2 core spray, 2 LPCI in each loop, HPCI, ADS 2 core spray, 2 LPCI in one loop, HPCI, ADS f) g LPCI Valve Failure

• 4 p.7 Loss of 250 Vdc Battery Power

• 2 core spray, 2 LPCI in one loop, HPCI, ADS [

Limiting Diesel Failure 1 core spray, 2 LPCI, one in each loop, HPCI, ADS (.'

k.

% Limiting MCC Failure 2 core spray, 2 LPCI, one in each loop, HPCI, ADS {

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._g Limiting Bus Failure 1 core spray, 2 LPCI, one in each loop, HPCI, ADS j i

2 core spray, 2 LPCI in each loop, ADS

.a HPCI Failure .

I' 1

-h Discharge Side Break l' W i d *,, No Failure 2 core spray, 2 LPCI in one loop, HPCI, ADS ,

I

'g: 5 LPCI Valve Failure

• 2 core spray, HPCI, ADS 1 Loss of 250 Vdc Battery Power

• 2 core spray, HPCI, ADS l' N Limiting Diesel Failure 1 core spray, 1 LPCI, HPCI, ADS ,

f Limiting MCC Failure

• 2 care spray, HPCI, ADS f!

if d Limiting Bus Fa3' re 1 core spray, 1 LPCI, HPCI, ADS

-M i g HPCI Failure 2 core spray, 2 LPCI in each loop, ADS I

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• Limiting failures ,l l :{-

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