ML20012D957

Submits Supplemental Response to Util 890417 & 0803 Responses to Station Blackout rule,10CFR50.63.Util Reserves Right to Review Final Issue of NUMARC 87-00,App D Prior to Implementation

ML20012D957
Person / Time
Site:	Cooper
Issue date:	03/23/1990
From:	Trevors G NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TAC-68534, NUDOCS 9003290150
Download: ML20012D957 (4)

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GENERAL OFFICE ,

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--Nebraska Public Power District r_m.~.__..,-_ , , , i 1

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U.S.1 Nuclear Regulatory Commission '+

Il L -Attention: Document Control Desk j

Washington, DC 20555

Subject:

Supplemental Response to the Station Blackout (SBO) Rule,~10CFR50.63 Cooper Nuclear Station'(TAC No. 68534)

NRC Docket No. 50-298, DPR-46

References:

1) Letter from Byron Lee, Jr. (NUMARC) to NUMARC Board of i

~ Directors, dated January 4, 1990, ." Station Blackout (SBO)  ;

Implementation: Request for SBO Submittal to NRC"

2) Letter ' NLS8900153, L. G. Kuncl to USNRC, dated April 17, L' 1989,=" Response to Station Blackout Rule, 10CFR50.63" -[

3) . Letter NLS8900284, G. A. Trevors to USNRC, dated August - 3, 1989, " Updated Response to Station Blackout Rule, 10CFR50.63" i a '

L Gentlemen:

The Nuclear Management and Resources Council (NUMARC) requested in

Reference:

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p that ;each utility ' review their previous Station Blackout (SBO) responses in d

!: ' light of NRC concerns, and confirm th'at the guidance of>NUMARC 87-00 and its.  ;

l attachments was followed and-that deviations from the-accepted guidance have! ,

been identified.

Accordingly, the Nebraska Public Power District (District) has verified that the two! previous . responses fto . the~ Station Blackout Rule, 10CFR50.63, l (References 2 and.3) and the supporting documentation and calculations are

- consistent .with the NUMARC 87-00 guidance and the supplemental guidance provided by the attachments to tNUMARC 87-00. In addition, the applicability '

of the NUMARC 87-00 assumptions have also been documented in the District's gg Station Blackout Coping Assessment Report.

The only significant departure from the accepted NUMARC 87-00 methodology has

,$ in Reference 3. In Reference 3, the District

@6 .been. informed previously' the NRC that, identified based upon the utilization of plant specific weather

,;Mo@ data, Cooper Nuclear Station is a P1 weather plant. Therefore, the CNS

.$8- Emergency Diesel Generator (EDG) target reliability has been established at

• O .95. The CNS plant specific weather data information has been formalized into y an' approved calculation file for audit purposes, wO

@@ The District understands that the target reliability of .95 for the CNS EDG N must be maintained. At this time, the District expects to utilize NUMARC

-7 $g 87-00, Appendix . D, - as the guidance document for the CNS EDG maintenance and L$@g reliability-program. However, the District reserves the right to review the 0

' final issue of ' this document prior to implementation.

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NLS9000102 March 23,_1990  ;

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e k' The initial District SBO submittal (Reference 2) did not identify any_ required modifications to CNS to improve the capability 'of the station to cope _ with a station blackout for four hours. There are.still no modifications required; hc. wever, below please find an updated response to various sections - of _ the  :

Reference 2 submittal.

I A. Procedure Description The District identified initial required procedure revisions and stated e that these would be implemented by October 1, 1989. The' three procedures listed below were approved by the Station Operations Review - Committee (SORC) on October 1, 1989.

EP 5.1.2 Operation During Tornado. Watch Rev. 9 EP 5.2.5 loss of AC Power Rev. 19 EP 5.2.5.1 Loss of All AC Power - Station Blackout Rev. 6' Also, a new District Transmission Procedure, Instruction 7, was generated and approved on September 1, 1989, This instruction, titled " Cooper ~ '

Nuclear Station, Black Plant Procedure", is a power restoration procedure ,

for CNS. This document describes the interfaces with the remainder of NPPD (non-nuclear) Land adjacent power districts to restore power to CNS in the event'of a Station Blackout.

In addition, each of the Station Blackout Response guidelines in NUMARC 87-00 were assessed in detail and recomended procedure updates have been identified where appropriate. As per the commitment. listed in Reference 2, these procedural changes will be completed six months- after -the District's recolpt' of' the Station Blackout SER. Most, if not all, of'the additional procedure changes uffect EP 5.2.5.1, " Loss of All.- AC Power, Station Blackout."

'B. Condensate Inventory The condensate inventory calculation was _ revised according to the supplemental guidance, and a 25 gpm leakage rate for each of the recirculation pumps was factored into the four hour blackout period. With this calculation revision, 64,668 gallons of water are required for decay heat removal for the required P1 coping duration. The minimum permissible condensate storage _ tank level identified in the USAR provides 100,000 gallons of water which exceeds the required quantity for coping with .a  ;

four hour station blackout event.

C. Class IE Batteries Capacity The CNS battery capacity calculations were performed pursuant to NUMARC 87-00, Section 7.2.2. These calculations were performed consistent with IEEE 485 and utilized a 70"F electrolyte temperature correction factor.

The results document that the CNS 125V and 250V batteries have sufficient capacity to meet the station blackout loads for four hours without any

" required" load stripping. Additionally, AC breaker control loads, after the four hour SBO event were included as a part of the battery capacity calculation.

, Y ' NLS9000102 p,

LMarch 23, 1990

,rgge 3; D. Effects of Loss of Ventilation Subsequent to the District submittal to the NRC in response to the Station Blackout Rule (Reference 2),' more detailed room- heatup ' calculations were.

performed utilizing a computer code for performing transient heat transfer calculations. The DC Switchgear Room calculation utilized the standard NUMARC methodology from the 87-00 document. The results of these calculations are presented below and show the steady state air temperature after four hours, j

Area Temperature y

RCIC Room- 121"F -!

DC Switchgear Rooms 127"F -l Control Room 100"F j The control room heatup calculation validates the statement made in Reference 2 that the control room is not a dominant area of concern. As-stated previously, reasonable assurance of the operability of station L blackout response equipment in the above listed dominant areas of concern -

(RCIC Room, DC Switchgear Rooms) has been assessed using Appendix F, Revision 1, dated October 1, 1988 to NUMARC' 87-00 and/or Appendix F  ;

Topical- report dated October 1988. No modifications or associated d procedures are required to provide reasonable assurance of equipment j

-operability in the dominant areas of concern. j

'l E. Containment Isolation j i

As discussed in ' Reference 2, the plant list of containment isolation' /

valves has been reviewed to determined those valves which must be capable of being closed or that must be operated (cycled) under ' station blackout conditions, with indication, independent of the preferred and blacked-out  !

Class 1E AC power supplies. No plant modifications and/or associated l procedure ' changes' were determined' to be required to ensure that j appropriate containment integrity can be provided under SBO conditions.

For this review, the District utilized the five exclusion categories as identified in NUMARC 87-00 document. These categories are: ,

1. Valves normally locked closed during operation;  ;

2. Valves that fail closed on loss of AC power or air;

3. Check valves;

4. Valves in non-radioactive closed-loop systems not expected to be breached in a station blackout (with the exception of lines that communicate directly with the containment atmosphere);

5. All valves less then 3-inch nominal diameter.

For evaluation purposes, the District also utilized the following three additional categories:

6. At least one valve is DC-powered; i

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7. At least'one valve is normally closed, AC-powered, failing as-is;

8. Valve (s) are,normally,open, AC-powered, failing as-is, and failure.

l position is acceptable, if-not desirable.

Should ; , you . . have ; any questions or require additional - information, . please contact this office.

Sincerely,--

G. . Trevors Division Manager

-Nuclear Support

/$w cc: U.S.' Nuclear Regulatory Commission Region IV Arlingtor., TX

-NRC Resident Inspector Office Cooper Nuclear, Station-NUMARC

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