ML20153D232

Safety Evaluation Accepting Licenseee Proposed Mod to Control Room Habitability Sys

ML20153D232
Person / Time
Site:	Seabrook
Issue date:	08/24/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20153D222	List: ML20153D220 ML20153D232
References
NUDOCS 8809020113
Download: ML20153D232 (4)

Text

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Enclosure 1 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION INPUT TO SUPPLEMENT NO. 8 0F THE SAFETY EVALUATION REPORT SEABROOK STATION, UNIT 1 PLANT SYSTEMS BRANCH DOCKET NO. 50-443 S.4 Control Room Habitability In Section 6.4 of the Seabrook SSER 7, the staff found that the inherent single-failure problem of the control room habiubility system restricted operation to no greater than 5% of rated power; and Stated that, before proceeding above ,

G% of rated power, the licensee shall demonstrate to the satisfaction of the NRC staff that the control building air system prcvides protection in accordance with the provisions of SRP Sections 6.4, 6.5.1, and 9.4.1 and GDC-19.

In SSER 7. the staff stated that inspectors observed that the Control Building HVAC (CBA) System was susceptible to the single failure of 4160-Y ac bus E5 or E6 in the absence of operator action; and that other problems were noted in system operation and logic that may have negated the design basis presented in the licensee's safety evaluation report. If a vital electric bus fails, the dix 0er located on the discharge of the operable makeup air fan must be opened mhoually with a handwheel override operator to allow the control room to be pressurized. In this situation the control room cannot be isolated since the radiation monitors cannot function as designed. This realignment process also necessitates that the makeup air purge line valve, correspondirg to the contami-nated intake, be manually opened. This allows the contaminated intake to be purged with air from the clean intake when the makeup air fan restarts.

In their letter NYN-87024, dated March 2, 1987, the licensee committed to provide the details of modifications to the CBA System for NRC review prior to implemen-tation. In their letter NYN-88007, dated January 22, 1988, the licensee provided a description of the proposed modifications to the CBA System and a reanalysis of the post-LOCA radiological doses to the control room personnel in the proposed modification. Additional information was provided by the licensee in their ,

letter NYN-88084, dated June 17, 1988.

) New bypass piping and para'ilel back-draft dampers have been added, in the modification, around the normal makeup air supply fans and associated discharge dampers to guarantee a flow path during emergency modes of operation. Each outside air intake valve remains in a throttled open position for both the normal and emergency modes of operation. In the event of a failure of either  ;

bus E5 or E6, the operating supply fan that is being powered from the failed  ;

bus will shut down and the opposite train damper will close resulting in a temporary loss of control room positive pressure. Manual actuation, from the i

control room, of the filter train powered from the unaffected bus will re-esta-

'l bitsh positive pressure using the bypass piping. The unaffected filter train would also automatically start on a high radiation or "S" signal. Therefore. -

control room pressurization will not be compromised in the case of a vital bus i

OC P l

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T 2-failure combined with a design basis accident. The new design eliminates the need for a purging operation sinct both intakes remain in a throttled open position; hence, the purge lines will be capped off and their associated purge valves removed. The nominal makeup air flow rate during emergency conditions is 600 cfm. Adjustments will be made during preoperational system balancing to ensure that the excess makeup air flow will not cause unacceptably high control room complex pressures and satisfy all associated design requirements.

The staff has reviewed the information provided in the above submittals and, based on its review, has concluded that the ,nroposed modification, when imple-mented as described in the licensee's submittals, would satisfactorily eliminate the single-failure problem described in SSER 7. In addition, the staff has concluded, based on its independent analysis of potential control room operator doses, that the doses are within the GDC-19 acceptance criteria and, therefore, that, when the proposed modification is implemented as described in the licensee's submittals the control room habitability system will provide protection in accordance with the provisions of SRP Sections 6.4, 6.5.1, and 9.4.1 and GDC-19 and, therefore, is acceptable. There are no open items, therefore, regarding the SSER7 Section 6.4 findings except confirmation that the modification is, in effect, implemented as described in the licensee's submittal.

As a separate action, the licensee has stated in the June 17, 1988, submittal, that as a result of a recent offsite fire, the licensee is reevaluating nearby industrial toxic chemical sources and transportation routes relative to the potential negative effects on control room habitability; and that they commited to provide the final results of the updated offsite chemical hazards reevaluation to the staff as soon as they become available.

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, Mr. Robert J. Harrison Public Service Company of New Hampshire Seabrook Nuclear Power Station CC:

Thomas Dignan Esq. E. Tupper Kinder Esq.

John A. Ritscher, Esq. G. Dana Bisbee, Esq.

Ropes and Gray Assistant Attorney General 225 Franklin Street Office of Attorney General Boston, Massachusetts 02110 208 State Hosue Annex Concord, New Hampshire 03301 Mr. Bruce 3. Beckley, Project Manager Public Service Company of New Hampshire Resident Inspector Post Office Box 330 US Nuclear Regulatory Commission Manchester, New Hampshire 03105 Post Office Box 1149 Seabrook, New Hampshire 03874 Dr. Mauray Tye, President Sun Valley Association Mr. A. M. Ebner, Project Manager 209 Summer Street United Engineers & Constructors Haverhill, Massachusetts 08139 Post Office Box 8223 Philadelphia, Pennsylvania 19101 Robert Backus Esq.

Backus, Meyer and Solomon Steven Oleskey, Esq.

116 Lowell Street Office of the Attorney General Manchester, New Hampshire 03106 One Ashburton Place P.O. Box 330 Diane Curran Esq. Boston, Massachusetts 02108 Hermon and Weiss 2001 S Street, NW Carol S. Sneider, Esq.

Suite 430 Office of the Assistant Attorney General Washington, D.C. 20009 Ore Ashburton Place P.O. 30x 330 Philip Ahren, Esq. Boston, Massachusetts 02108 Assistant Attorney General State House Station f6 D. Pierre G. Cameron, Jr., Esq.

Augusta, Maine 04333 General Counsel Public Service Company of New Hampshire Mr. Warren Hall Post Office Box 330 Public Service Company of Manchester, New Hampshire .03105 New Hampshire Post Office Box 330 Regional Administrator, Region !

Seabrook, New Hampshire 03874 U.S. Nuclear Regulatory Commission 475 Allendale Road Ms. Jane Doughty King of Prussia, Pennsylvania 19406 Seacost Anti-Pollution League 5 Market Street Portsmouth, New Hampshire 03801 M. Brock, Esq.

Shaines & McEachern 25 Maplewood Ave.

Portsmouth, N.H. 03801 Mr. Diana P. Randall 70 Collins Street Seabrook, New Hampshire 03874

Public Service Company of Seabrook Nuclear Power Station New Hampshire cc:

Mr. Calvin A. Canney, City Manager Mr. Alfred V. Sargent, City Hall Chairman 126 Daniel Street Board of Selectmen Portsmouth, New Hampshire 03801 Town of Salisbury, MA 01950 soard of Selectmen Senator Gordon J. Humphrey RFD Dalton Road ATTN: Tom Burack Brentwood, New Hampshire 03833 531 Hart Senate Office Building U.S. Senate Ms. Roberta C. Pevear Washington, D.C. 20510 Town of Hampton Falls, New Hamoshire Drinkwater Road Mr. Owen B. Durgin. Chairman Hampton Falls, New Hampshire 03844 Durham Board of Selectmen Town of Durham Mr. Guy Chichester, Chaiman Durham, New Hampshire 03824 Rye Nuclear Intervention Comittee Jane Spector c/c Rye Town Hall Federal Energy Regulatory East Kingston, New Hampshire 03827 Comission 825 North Capital Street, NE Chairman, Board of Selectmen Room 8105 RFD 2 Washington, D. C. 20426 South Hampton, New Hampshire 03827 Mr. R. Sweeney R. Scott Hill - Whilton Three Metro Center Lagoulis, Clark. Hill-Whilton Suite 610

& McGuire Bethesda, Maryland 20814 79 State Street Newburyport, Ma. 01950 Mr. Richard Strome. Director Ms. R. Cashman, Chairman New Hampshire Office of Emergency Board of Selectmen Management Town of Amesbury State Office Park South Town Hall 107 Pleasant Street Amesbury, Massachusetts 01913 Concord, New Hampshire 03301 Adjudicatory File (2)

Honorable Peter J. Matthews Atomic Safety and Licensing Board Mayor, City of Newburyport Panel Docket City Hall U.S. Nuclear Regulatory Comission Newburyport, Massachusetts 01950 Washington 0.C. 20555 Mr. Donald E. Chick, Town Ma..oger Congressman Nicholas Mavroules Town of Exeter 70 Washington Street 10 Front Street Salem. Massachusetts 01970 Exettr, New Hampshire 03823 r

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