ML20141G408

Submits Actions That Fulfill Commitments Made in Response to NRC Bulletin 96-003, Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Bwrs

ML20141G408
Person / Time
Site:	Cooper
Issue date:	05/16/1997
From:	Horn G NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
IEB-96-003, IEB-96-3, NLS970107, NUDOCS 9705220352
Download: ML20141G408 (4)

Text

,

P.O. BOX BOCrWNV AB 68321 4 Nebraska Public Power District "=EFE""

l _ w._ .n ~ - --

NLS970107 May 16,1997 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:

Subject:

Completion of NRC Bulletin 96-03 Commitments Cooper Nuclear Station, NRC Docket 50-298, DPR-46

Reference:

1. NRC Bulletin 96-03 dated May 6,1996," Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Boiling-Water Reactors"

2. Letter to USNRC from G. R. Horn dated October 10,1996, " Response to l NRC Bulletin 96-03, Cooper Nuclear Station, NRC Docket 50-298, DPR-46" In response to NRC Bulletin 96-03 (Reference 1), the Nebraska Public Power District (District) committed, by letter dated October 10,1996 (Reference 2), to modify the Emergency Core Cooling System (ECCS) suction strainers at the Cooper Nuclear Station (CNS) during Refueling Outage 17. This commitment was contingent upon fmalissuance of the Utility Resolution Guidance (URG) document. Although the URG has yet to be fmalized, actions to implement the ECCS suction strainer modification have been completed. Specifically, the District has installed large capacity passive strainers that utilize a stacked disk configuration. The new design, based on proposed URG assumptions with added conservatisms, increases the strainer surface area thus I

ensuring that the resulting debris loading will not result in the available net positive suction head \

(NPSH) pressure falling below that required for ECCS pump operation during a postulated loss of coolant accident (LOCA). While conservative assumptions were utilized in development, the /

District will evaluate the new design against the URG, once finalized, and resolve outstanding $

issues as required.

In addition to the aforementioned modification, the District took positive actions during Refueling Outage 17 to desludge the torus and to reduce the loading of calcium silicate insulation in the drywell, however, mineral wool, in lieu of reflective metal insulation, was used in some instances to reduce this loading.

220081 9705220352 970516 Illllllllill.lllllll!li,l'l,Gl,lI['Il.ll PDR ADOCK 05000298-

. PDR h Y k k $?hh. h Y h b W b b N b W E NY

==

= = =xx = = ==n=we a -__

. o i

NLS970107 May 16,1997 Page 2 of 3 These actions fulfill commitments made by the District in response to NRC Bulletin 96-03.

Should you have any questions concerning this matter, please contact me.

Sincer ly, 4

0.

lw

.I orn S ice President Of Energy Supply _

/crm cc: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1 Senior Resident Inspector USNRC.

NPG Distribution I

i l

i

2. q i

NLS970'107- )

~ May 16,1997 '

Page 3 of 3  ;

i STATE OF NEBRASKA ) l

)

NEMAIIA COUNTY ) i G. R. Iforn, being first duly sworn, deposes and says that he is an authorized representative of the i Nebraska Public Power District, a public corporation and political subdivision of the State of  ;

Nebraska; that he is duly authorized to submit this correspondence on behalf of Nebraska Public >

> Power District; and that the statements contained herein are true to the best of his knowledge and  !

belief.  ;

m n G. R.'liorn  ;

Subscribed in my presence and sworn to before me this / h day of HThy 1997.

( ,

~

] s L P N4h8A* l

{ NOTARY PUBLIC h t

1 1

'l ,

ATTACHMZNT 3 LIST OF NRC COMMITMENTS l i

i Correspondence No: NLS970107 The following table identifies those actions committed to by the District in this  ;

document. Any other actions discussed in the submittal r;present intended or i planned actions by the District. They are described to the NRC for the NAC's l information and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITTED DATE COMMITMENT OR OUTAGE ,

The District will evaluate the new ECCS suction strainer " "**

design against the URG, once finalized, and resolve outstanding issues as required.

i l

i j

l i

l PROCEDURE NUMBER 0.42 l REVISION NUMBER 4 l PAGE 8 OF 9 l j l

I