ML20207Q258

Application for Amend to License DPR-35,consisting of Proposed Change 87-01,changing Tech Specs to Reduce Restrictive Criteria for Flow & Filter Train Differential Pressure for Control Room High Efficiency Air Filter Sys

ML20207Q258
Person / Time
Site:	Pilgrim
Issue date:	01/19/1987
From:	Howard J BOSTON EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
Shared Package
ML20207Q259	List: ML20207Q258 ML20207Q263
References
BECO-87-007, BECO-87-7, NUDOCS 8701270084
Download: ML20207Q258 (5)

Text

r' 10CFR50.90 enerow soisaw COMPANY l 500 SOVLaTON 5f atET l SceTON. MAesAOMUSEYTS 03199 J. COWARO MOWARD Z:"*.'""!....

January 19, 1987 BEco 87-007 Proposed Change 87-01

! U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 l License DPR-35 Docket 50-293

! Proposed Techniccl Specification Change to Section 4.7.8.2.a l

Dear Sir,

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Pursuant to 10CFR50.90. Boston Edison hereby proposes the attached l modification to Appendix A of Operating License No. OPR-35. This modification l revises the acceptance criteria for flow and filter train differential pressure for the Control Room High Efficiency Air Filter System (CRHEAF). The proposal is made to reduce overly restrictive criteria, the strict interpretation of which prevents the system from being considered operable.

The strict Interpretation is also in conflict with vendor design information.

Should you wish further information on this submittal, please contact us.

Very truly yours.

PHK/ns 0

Attachment l One Original and 37 Coples Commonwealth of Massachusetts) ,

County of Suffolk )

Then personally appeared before me, J. E. Howard, who, being duly sworn, did state that he is Vice President - Nuclear Engineering and Quality Assurance Department of Boston Edison Company and that he is duly authortred to execute l and file the submittal contained herein in the name and on behalf of Boston

! Edison Company and that the statements in said submittal are true to the best of his knowledge and belief.

My commission espires: 8ch ol jf$f DATE

, . k ' UOLIC N0 fARY (c

cc: See next page g12ggg go M! l Y PDR l

BOSTON EDISON COMPANY January 19, 1987 U.S. Nuclear Regulatory Commission Page 2 cc: U.S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Senior NRC Resident Inspector Pilgrim Nuclear Power Station Robert M. Hallisey, Olrector Radiation Control Program Mass. Dept. of Public Health 150 Tremont Street F-7 Boston, MA 02111

Proposed Change to Technical Specifications Proposed Change Reference is made to Pilgrim Station Operating License No. DPP-35, page 1588 Section 4.7.B.2.a. This currently states:

At least once every 18 months the pressure drops across each combined filter train shall be demonstrated to be less than 3 inches of water at 1000 cfm.

This will be changed to provide 6 inches of water pressure drop and a 10%

tolerance to the flow rate, and shall state, in part:

... less than 6 inches of water at 1000 cfm or the calculated equivalent."

Reason for Change The change is proposed to allow flexibility in surveilling the Control Room High Efficiency Air Filtration (CRHEAF) system. The existing 1000 cfm is too restrictive in that no tolerance is specified, therefore strict compilance requires a flow rate of exactly 1000 cfm. This is contrary to common operating practice in that it does not provide for small variations in the system, the atmosphere, or measuring at any particular surveillance.

The "3 inches of water" pressure drop is very restrictive when applied to the combined filter train, as currently required. A review of vendor design information indicates that 3 inches of differential pressure is the vendor recommended action point for changeout for irach HEPA filter. Each filter train consists of a profilter, two HEPA filters, a charcoal adsorber, and heaters, all of which contribute to differential pressure. When 3 inches is applied to the combined HEPA filters it is overly restrictive vis-a-vis the vendor recommended criteria, i.e., filters should be either tested separately to 3 inches or less, or the differential pressure raised to 6 inches or less for the combined filter train.

Safety _ Considerations The addition of a " calculated equivalent" to the CRHEAF acceptance criteria is in keeping with the standard engineering and operating practice of providing tolerance in measuring HVAC system flow performance, and allows the procedural use of a performance curve with flow rates bounded by TS 3.7.8.2.d.

The changing of the differential pressure criterlon to 6 inches of water is acceptable for the following reasons:

o The summation of vendor recommended action levels for all components in each filter train gives a total differential pressure of approximately 8 inches of watert o The maxtrium vendor allowed differential pressure across any gne HEPA unit is 8 inches of water; o The expected value for the summation of component differential pressures for a filter train with new filter media is approximately 3.75 inches of waterl

Therefore, a value of 6 inches of water across the combined filter train .

I components is conservative because it will prompt action before any single HEPA would reach its maximum, and before the vendor recommended level for the combined filter train is reached. ,

This proposed change has been reviewed by and approved by the Operations Review Committee and reviewed by the Nuclear Safety Review and Audit Committee.

Supportina Information and No Significant Hazards Conditions Analyses The proposed change provides a tolerance to the test success criteria for CRHEAF by allowing the use of a procedural curve relating differential

pressure to 1000 cfm as bounded by TS 3.7.8.2.d. The change also raises the differential pressure criteria to 6 inches from 3 Inches of water.

. The Code of Federal Regulations, 10CFR50.91 requires that at the time a licensee requests an amendment, it must provide to the Commission its analysts i using the standards in 10CFR50.92, about the issue of no significant hazards i consideration. Therefore, in accordance with 10CFR50.91 and 10CFR50.92 the following analysis has been performed.

1 i 1. Operating Pilgrim Station in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of

an accident previously evaluated.

The CRHEAF creates a positive pressure in the Control Room, using air from a which it has filtered out radiolodines and particulates. Currently, TS i

. 4.7.B.2.a requires that at least once every 18 months a pressure drop of l less than 3 inches of water be demonstrated across the filters at a flow "

rate of 1000 cfm. TS 3.7.B.2.d requires that CRHEAF fans operate within 1000 cfm +10%. The system is designed to provide a positive Control Room

! pressure If the fans can provide a flow rate of 900 to 1100 cfm and the l

filters are not plugged. Vendor information indicates that filter l J

degradation from plugging is indicated by a differential pressure of 3 ,

a inches or greater of water across each HEPA filter. Therefore, when  ;

measured across two HEPA filter elements, and the rest of the CRHEAF l components which create differential pressure, a differential of less than 6 inches of water demonstrates that HEPA plugging has not reached j

action levels. Hence, if the fans can generate 900 to 1100 cfm to satisfy 3.7.8.2.d and has a pressure drop across the filter trains less than 6 i'

inches at 1000 cfm or the calculated equivalent, sufficient flow exists to t provide a positive pressure in the Control Room. Therefore, the purpose  !

i of the CRHEAF as a mitigator of the results of an accident will not be

impaired by this proposed change. Hence, allowing the differential pressure of 6 inches of water 1000 cfm to be established at flow rates between 900 and 1100 cfm in conformance with a calculated procedural  ;

l acceptance curve wil' not involve a significant increase in the 6 l

probability or conssquances of an accident previously analyzed. l I 2. Operating Pilgrim Station in accordance with the roposed amendinent will j not create the possibility of a new or different ind of accident from any i accident previously evaluated. j 1 i e

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O e The purpose of CRHEAF 15 to mitigate the consequences of certain accidents by filtering out radiolodines and particulates from air which is then used I to maintain a positive pressure in the Control Room. The amendment allows r a tolerance by allowing a calculated value, based on 6 inches of water at  !

1000 cfm, to be used for demonstrating that the filter train elements are not plugged. The flow range for the calculated value is 900 - 1100 cfm, determined by existing TS 3.7.B.2.d.

The change to 6 inches of water from 3 is in compilance with vendor >

Information. The change of these criteria therefore is consistent with  ;

the design and fan capabilities of the system, and does not degrade the system's ability to perform its designed function of providing positive  !

pressure in the Control Room with filtered alr; therefore, operating l Pilgrim in accordance with the proposed change will not create the i possibility of a new or different kind of accident from any accident previously evaluated.

3. Operating Pilgrim Station in accordance with the proposed amendment will I not involve a significant reduction in the margin of safety.

The proposed change does not reduce the CRHEAF's ability to perform its designed function of creating a positive pressure in the Control Room with filtered air. Hence, accident analysis which take credit for CRHEAF as a mitigator are not affected and the safety margin remains the same.

Therefore, the operation of Pilgrim in accordance with the proposed amendment to TS 4.7.B.2.a will not involve a significant reduction in the margin of safety. 7 Schedule of Change f This change will become effective immediately following approval by the f CommtssIon.  ;

i Fee Determination Pursuant to 10CFR170.12(c) an application fee of $150.00 1s appropriate. The fee will be provided under a separate cover letter in the near future.

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