ML20114F978

Provides Responses to Addl Info Requests Identified by NRC During 920827 Visit to Plant to Provide Addl Info Re Maint & Testing of Standby Nitrogen Injection Sys & Sys Use in Emergency Procedures for Resolution of GL 84-09

ML20114F978
Person / Time
Site:	Cooper
Issue date:	10/05/1992
From:	Horn G NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-84-09, GL-84-9, NSD921059, NUDOCS 9210140013
Download: ML20114F978 (3)

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NSD921059 October 5, 1992 U.S. Nualear Regulatocy Commission Attention: Document Control Desk Washiagton, DC 20555 l i

Subject:

Standby Nitrogen Injection System Cooper Nuclear Station

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NFC Docket No. 50-298, DPR 46

Reference:

Letter from G. A. Trevors (NPPD) to USNRC dated July 13, 1990,

" Standby Nitrop n Inj ection System" Gentlemen:

Information concerning the Standby Nitrogen Injection (SBNI) system installed at Cooper Nuclear Station (CNS) was submitted in the reSrer.ce to support resolution of 10CFR50.44 and Generic Letter 84-Of n the CNS docket. A NRC staff visit to CNS on August 27, 1992 was held to provide additional information concerning the maintenance and testing of SBNI and its use in the CNS emergency procedures.

During the course of this visit additional information requests concerning ehis subject wete identified that the District would respond to 9 sub:.equent correspondence before the NRC wouli. issue a Safety Evaluation on dBNT.

This letter provides the District's responses to all of the additional

!nformation requests identified by the NRC staff during the August 27, 1992 meeting. The requested information and our responses are provided in the e*tachment.

If there are any questions on the information contained in this correspondence, plea a c l'l .

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.gR Horn Nur ear Power Group Manager

/dls Attachment ec: Regional Administrator USNRC Region IV Arlington, Texas NRC Senior Resident Inspector Cooper Nuclear Station o f. . . ) G 9210140013 921005 Q0l PDR ADOCK 05000298 I$/ )

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c 4-NRG Information Requests on the Standby. Nitrogen Injection (SSNI)

Cooper Nuclear Station __ '

NRC Docket No. 50-298, DPR-46

1. Request: Reanalyze the heat loss from the N2 vaporization pit following -  ;

the loss of heaters for a . more bounding ambient out.ide ,

temperature.

Responu A new engineering calculation assuming an ambient temperature of -5*F has been completed to determine the amount of time the liquid nitrogen would be vaporized using the heat stored in the liquid water in the pit. It is-conservative)y estimated that nitrogen gas ' flow rates required for SBNI-operation would be-availab1n for et least twenty hours following loss of vaporization-pit hee.t s r= This provides time to implement corrective actions such as _ restornie, .. ylt heaters or provide other means for nitrogen vaporization or injection. (

2. Request: V r- y that the SDNI system will be repaired if discrepancies are our.d with it.

Response

Discrepancies found on the SBNI system will be repaired and corrected. .If the- discrepancy is found during an outage when the plant J* in a <old .

shutdown condition when the SBNI function is not needed, ' rep.Ars will be made to SBNI prior to startup from the outage.

3. Request: Evaluate if the oxygen contained in the standing, air wi. ein the SBNI piping does not appreciably a ffec t the primary containment oxygen concentration when SBNI is initiated.

Besnonse The. volume of the SBNI piping in question is.less than ten standard cubic feet cout. ting both divisions of SBNI . fince oxygen comprises 20 percent of' air's total volume, then-less 'han two standard cubic feet of oxygen would be injected into the prin.nry containment 15 both divisions of SBNI were initiated. This is an insignificant amount _ compared to the total primary containment air volume of 238,850 standard cubic feet, Initiation-of 'SBN1 will not appreciably affect primary containment oxygen concentration.

4 Request: Provide details of SBNI manuu valve preventive maintcaance -

activities.

Response

i All valves within the SBNI system are visually inspected and manipulated to ensure functior, and operability once per operating cycle (currently every 18 months)-per CNS Surveillance Procedure 6.3.1.6. The majority of ,

the manual valves Jr. the SBNI flow path a r i 1" stainless steel ball valves with self ' lubricating PTFE (Teflon) seals and therefore do not require

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NSD921059 Page 2 of 2 l, , .

additional lubrication. The SBNI division isolation valves (SBN1 V 4 and SBNI-V 8) are Y type globe valves that are inspected, manipulated, and have their stems lubricated during the performance of the above surveillance procedure.

$. Request: Verity the availability of replacement nitrogen with offsite suppliers.

F>sitonu Three heparate region:1 nitrogen suppliera are located in Omaha, Lincoln, and Kansas City. All three suppliers, at any time of the year, can nrevida a su f fic ie nt. amount of nitrogen to CNS withi n 74 hours8.564815e-4 days <br />0.0206 hours <br />1.223545e-4 weeks <br />2.8157e-5 months <br /> notice, this re- onse period provides for timely raplacement of the on-site two day supt..y of nitrogen for SBNI prior to its depl tica.. =

6. Request: Discuss arrangements with the ven 't r f ar the repir of liquid nitrogen storage tank and vapor pit component.s.

ILtEPhna Under terms of the Product Supply Agreement, the vendor (Linde) is responsible for the maintenance of these unita. Past experience confirms that the vendor to responsive to District requests for maintenance and repair outside of the regularly scheduled yearl, vendor visits, s

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