ML20206H386

Forwards Response to NRC Request for Addl Info Re Normal Operation of Control Room make-up Air Subsystem & Summary of Addl Confirmatory Dose Calculations Performed to Account for Minor Sys Alignment Changes & Operational Considerations

ML20206H386
Person / Time
Site:	Seabrook
Issue date:	04/09/1987
From:	George Thomas PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NYN-87051, NUDOCS 8704150342
Download: ML20206H386 (8)

Text

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George S. Thomas UI Vice President-Nuclear Production Pub 5C Service of New Hampshire New Hampshire Yankee Division NYN-87051 April 9, 1987 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:

Document Control Desk

References:

(a) Facility Operating License NPF-56, Construction Permit CPPR-136, Docket Nos. 50-443 and 50-444 (b) PSNH Letter (NYN-87013), dated February 9,1987,

" Request for Additional Information", G. S.

Thomas to the NRC

Subject:

Request for Additional Information Gentlemen:

Reference (b) provided additional information describing the Seabrook Station Control Room liabitability System and a summary of confirmatory dose analyses. The information provided therein emphasized post-LOCA operation of the Control Room Make-Up Air Subsystem.

In subsequent discussions, NRC Bethesda and Region I Staf f requested additional information pertaining to normal operation of this subsystem.

Pursuant to these discussions, attached please find the additional information addressing specific activities regarding normal operation of the Control Room Make-Up Air Subsystem. Also attached is a summary of additional confirmatory dose calculations performed to account for minoc system alignment changes and operational considerations. This additional information supports the conclusions of our previous system review; i.e.,

no problems exist that would affect the present design, maintenance, or operation of the Control Room liabitability System with respect to. low power operation.

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P.O. Box 300. Seabrook, NH 03874. Telephone (603) 474 9574

United States Nuclear Regulatory Commission April 9, 1987 Attention: Document Control Desk Page 2 We trust this information is acceptable and request that satisf actory resolution of this item be provided in the next supplement to Seabrook's SER.

Very truly yours, George S. Thomas At tachments cc: Atomic Safety and Licensing Board Service List Mr. Victor Nerses, Acting Director PWR Project Directorate No. 5 Division of PWR Licensing - A United States Nuclear Regulatory Commission Washington, DC 20555 Regional Administrator U. S. Nuclear Regulatory Commission - Region I 631 Park Avenue King of Prussia, PA 19406 Mr. A. C. Cerne NRC Senior Resident Inspector Seabrook Station Seabrook, NH -03874 l

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Dicn2 Currcn, E quiro P: tor S. M3thiw3, Mayor

.Harmon & W21ss City Ms11 2001 S Street, NW Newburyport, MA 01950 Suite 430 Washington, DC 20009 Judith H. Mizner Silvergate, Certner, Baker, Sherwin E. Turk, Esquire Fine, Good & Mizner Office of the Executive Legal Director 88 Broad Street U.S. Nuclear Regulatory Commission Boston, MA 02110 Tenth Floor Washington, DC 20555 Calvin A. Canney City Manager Robert A. Backus, Esquire City Hall 116 Lowell Street 126 Daniel Street P.O. Box 516 Portsmouth, NH 03801 Manchester, NH 03105 Stephen E. Merrill, Esquire Philip Ahrens, Esquire Attorney General Assistant Attorney General George Dana Bisbee, Esquire Office of The Attorney General Assistant Attorney General State House Station #6 Of fice of the Attorney General Augusta, ME 04333 25 Capitol Street Concord, NH 03301-6397 Mrs. Sandra Cavutis, Chairman Board of Selectmen Mr. J. P. Nadeau RFD 1 Box 1154 Selectmen's Office Kensington, NH 03827 10 Central Road Rye, NH 03870 Carol S. Sneider, Esquire Assistant Attorney General Mr. Angie Machiros, Chairman I

Office of the Attorney General Board of Selectmen One Ashburton Place, 19th Floor Town of Newbury Boston, MA 02108 Newbury, MA 01950 4

Senator Gordon J. Humphrey Mr. William S. Lord United States Senate Board of Selectmen Washington, DC 20510 Town Hall - Friend Street Attention: Tom Burack Amesbury, MA 01913 Richard A. Hampe, Esquire Senator Cordon J. Humphrey Hampe and McNicholas 1 Eagle Square, suite 507 35 Pleasant Street Concord, NH 03301 Concord, NH 03301 Attention: Herb Boynton Thomas F. Powers, III H. Joseph Flynn, Esquire Town Manager Office of General Counsel Town of Exeter Federal Emergency Management Agency 10 Front Street 500 C Street, SW Exeter, NH 03833 Washington, DC 20472 Brentwood Board of Selectmen Paul McEachern, Esquire RFD Dalton Road Matthew T. Brock Esquire g

Brentwood, NH 03833 Shatnes & McEachern 25 Maplewood Avenue Cary W. Holmes, Esquire P.O. Box 360 Holmes & Ells Portsmouth, NH 03801 47 Winnacunnet Road Hampton, NH 03842 Robert Carrigg Town Office Mr. Edward A. Thomas Atlantic Avenue FEMA, Region I North Hampton, NH 03862 442 John W. McCormack Post 3

l Office and Courthouse Boston, MA 02109

Administrative Judge Helen Hoyt, Chairperson Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, DC 20555 Administrative Judge Sheldon J. Wolfe, Chairman Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, DC 20555 Dr. Emmeth A. Luebke Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, DC 20555 Dr. Jerry Harbour Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, DC 20555 Administrative Judge Costave A. Linenberger, Jr.

Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, DC 20555 4

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ATTACRMENT 1 TO NYN-87051 CONTROL ROOM RABITABILITY SYSTEM DESCRIPTION

REFERENCES:

1.

PSNH Letter (NYN-87013) dated February 9,1987, G. S. Thomas to the NRC 2.

Seabrook Station FSAR (a) Section 6.4 (b) Section 9.4 (c) Figure 9.4-1 2

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Figure 1 - Simplified Flow Diagram (attached)

INTRODUCTION:

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Reference I provided a detailed description of the Seabrook Station j

' Control Room Habitability (CBA) System. The description emphasized operation of the Control Room Make-Up Air Subsystem following a design basis LOCA to maintain the radiological exposure of operators below acceptable limits for the 30-day accident mitigation period. The submittal also included a definition of single train operation of this subsystem with regard to Technical Specification 3/4.7.6, Control Room Ventilation.

This additional information was provided for clarification of the descrip-tion of the Control Room Make-Up Air Subsystem in References 2(a) and 2(b).

Additional information has recently been requested by the NRC concerning normal operation of the Control Room Make-Up Air Subsystem. The infor-mation generally pertains to details of system operation for specific plant scenarios not addressed in Reference 1.

DISCUSSION:

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The Control Room Make-Up Air Subsystem and interf acing portions of the CBA System are diagrammed in Reference 2(c). Reference 3 is provided for j

use with this discussion.

j During normal plant operation, the Control Room Make-Up Air Subsystem is aligned to deliver 1200 cfm of outside air from one of the two remotely located intakes to the Control Room complex. For this mode, one supply f an (CBA-FN-27A or 27B) is operating and either 1-CBA-V9 or 2-CBA-V9 is closed. The make-up air discharges into CBA-F-38 and flows through a roll-type roughing filter. The air ~then bypasses the remainder of the filtration system as CBA-FN-16A and 16B are not operating. The Control Room exhaust fan (CBA-FN-15) is operating and its discharge control damper (CBA-DP-28) modulates to maintain the Control Room complex at a pressure of slightly greater than (+) 1/8" W.G. with respect to adjacent areas.

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ATTACHMENT 1 TO NYN-87051 (Continued)

CONTROL ROOM HABITABILITY SYSTEM DESCRIPTION With either 1-CBA-V9 or 2-CBA-V9 normally closed, resetting the Control Room isolation switches (1 per train) at the main control board will defeat the isolation function of the radiation monitors for the intake associated with the closed valve. The definition of single train operation detailed in Reference 1 requires this isolation function to be intact for a single train to be considered operable.

In the event a high radiation / isolation signal is generated f rom the isolated intake and must be reset to reestablish Control Room make-up air, the closed intake valve will be cycled to restore the radiation monitors' isolation function when it is determined that the intake is not contaminated.

Until recently, the purge valve corresponding to the isolated remote intake (CBA-V2 for west intake, CBA-V4 for east intake) was aligned in the open position. However, due to operational concerns with aligning the system for continuous purging, both purge valves are now normally closed. Purging will only be performed in response to detec-tion of high radiation in a remote intake. Without continuous purging, leakage through a closed intake isolation valve (conservatively speci-fled as 50 cfm) may be radiologically contaminated at certain times following an accident. A revised post-LOCA Control Room dose analysis which includes this leakage as a radiological contributor is summarized in Attachment 2.

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ATTACHMENT 2 TO NYN-87051 CONFIRMATORY DOSE CALCULATIONS The Control Room radiological habitability evaluation based on the as-built Control Room design and a 5% power core fission product inventory has been confirmed. The results are a 0-30 day thyroid dose to the Control Room operators of approximately 5.0 REM and a whole body dose of ( 0.1 REM. These values are well within the acceptance criteria of 30 REM thyroid and 5 REM whole body dose for the assumed 30-day duration of the DBA-LOCA.

The parameters used in the analysis were as follows:

o Control room infiltration rate during half-hour periods of depressurization = 70 SCFM (based on measured exleakage of 131 SCFM @ 0.19 in. H 0).

2 o

Fresh air remote intake flow rate when aligned for 23 hr/ day

= 1150 CFM.

o Contaminated air remote intake flow rate when aligned for 23 hr/ day = 50 CFM (assumed isolation valve leakage).

o La = 0.15% per day.

o Emergency exhaust filter bypass leakage = 60%.

o Annulus area evacuation time = 8 min.

Control Room X/Qs per RBH for time stepped 0-30 days 95 o

percentile values.

o Inversion X/Q used for 2nd 1/2 hour of release and wind shif ts every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

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