ML20217C245
| ML20217C245 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/15/1997 |
| From: | Andersen J NRC (Affiliation Not Assigned) |
| To: | Carns N, Loftus P NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TAC-M97508, NUDOCS 9710010290 | |
| Download: ML20217C245 (5) | |
Text
- - _ ___ __ _ _ - _,
Mr.:Neil S. Carns Y
Senior Vice President-September 15, 1997 and Chief Nuclear Officer Northeast Nuclear Energy Company c/o Ms. Patricia A. Loftus Director - Regulatory Affairs P.O. Box 128 Waterford, CT 06385
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING THE MILLSTONE UNIT 3 EMEP.GENCY DIESEL GENERATOR EXHAUST. STACK (TAC NO. M97508)
Dear Mr. Carns:
By letter dated July 24, 1997, the staff provided you an update of the NRC's Millstone Restart Assessment Plan (Plan). to the Plan contained the Significant Items List (SIL) for Millstone Unit 3.
SIL #75 for 3
Millstone Unit.3 addressed two inspector follow-up items; one concerning the emergency diesel generator exhaust stack. The NRC staff has reviewed the closure package for this item and in order to support further NRC_ evaluation, you are requested to provide the NRC with ai.swers to the enclosed questions.
Please respond to this request for additional inforination expeditiously in order for the staff to complete ;ts review in a timely manner.
Sincerely, original signed-by:
James W.-Andersen, Project Manager Special Projects Office - Licensing Office of. Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
As stated cc w/ encl: See next page
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%,.....,o September 15, 1997 Mr. Neil S. Carns Senior Vice President and Chief Nuclear Officer Northeast Nuclear Energy Company c/o Ms. Patricia A. Loftus Director - Regulatory Affairs P.O. Box 128 Waterford, CT 06385
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING THE MILLSTONE UNIT 3 EMERGENCY DIESEL GENERATOR EXHAUST STACK (TAC NO. M97508)
Dear Mr. Carns:
1 By letter dated July 24, 1997, the staff provided you an update of the
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NRC's Millstone Restart Assessment Plan (Pirn). to the Plan contained the Significant Items List (SIL) for Millstone Unit 3.
SIL #75 for Millstone Unit 3 addressed two inspector follow-up items; one concerning the emergency diesel generator exhaust stack.
The NRC staff has reviewed the closure package for this item and in order to support further NRC evaluation, you are requested to provi9 the NRC with answers to the enclosed questions.
Please respond to this request for additional information expeditiously in order for ;he staff to complete its review in a timely manner.
Sincerely, am'es W. Andersen, Project Manager Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-423
Enclosure:
As stated cc w/ enc 1:
See next page
Northeast Nuclear Energy Cempany Millstone Nuclear Power Station 6
Unit 3 cc:
Lillian M. Cuoco, Esquire Mr. William D. Meinert Senior Nuclear Counsel Nuclear Engineer Northeast Utilities Service Company Massachusetts Municipal Wholesale P. O. Box 270 Electric Company Hartfo % CT 06141-0270 P. O. Box 426 Ludlow, MA 01056 Mr. Kevin T. A. McCarthy, Director Monitoring and Radiation Division Joseph R. Egan, Esquire Department of Environmental Drotection Egan & Associates, P.C.
79 Elm Street 2300 N Street, NW Hartford, CT 06106-5127 Washington, D.C. 20037 Regional Administrator, Region I Mr. F. C. Rothen U.S. Nuclear Regulatory Commission Vice President - Nuclear Work Services 475 Allendale Road Northeast Nuclear Energy Company -
King of Prussia, PA 19406 P. O. Box 128 Waterford, CT 06385 First Selectmen Town of Waterford Ernest C. Hadley, Esquire Hall of Records 1040 B Main Streat l
200 Boston Post Road P. O. Box 549 l
Waterford, CT 06385 West Wareham, MA 02576 i
Mr. Wayne D. Lanning Mr. John Backingham
. Deputy Director of Inspctions Department of Public Utility Control Special Projects Office Electric Unit 475 Allendale Road 10 Liberty Square King of Prussia, PA 19406-1415 New Reitain, CT 06051 Michael H. Brothers Mr. James S. Robinson Vice President - Millstone Unit 3 Manager, Nuclear Investments and Northeast Nuclear Energy Company Administration P. O. Box 128 New England Power Company Waterford, CT 06385 25 Research Drive Westborough, MA 01582 lir. M. R. Scully, Executive Director Connecticut Municipal Electric _
Mr. D. M. Coebel Energy Cooperative Vice President - Nuclear Oversight 30 Stott Avenue Northeast Nuclear Energy Company Norwich, CT 06360 P. O. Box 128 Waterford, CT 06385 Mr. David Amerine Recovery Officer - Nuclear Engineering and Support Northeast Nuclear Energy Company P. O. Box 128 Waterford, Connecticut 06385
Northeast Nuclear. Energy Company Millstone Nuclear Power Station cc:
Deborah Katz, President Mr. B. D. Kenyon Citizens Awareness Network President and Chief Executive Officer P. O. Box 83 Northeast Nuclear Energy Company Shelburne Falls, MA 03170 P. O. Box 128 Waterford, CT 06385 Senior Resident Inspector I
Millstone Nuclear Power Station Mr. Daniel L. Curry l
c/o U.S. Nuclear Regulatory Project Director l
Commission Parsons Power Group Inc.
P. O. Box 513 2675 Morgantown Road Niantic, CT 06357 Reading, Pennsylvania 19607 Hr. Allan Johanson, Assistant Director Mr. Don Schopfer Office of Policy and Management Verification Team Manager Policy Development and Planning Division Sargent & Lundy 450 Capitol Avenue - MS# 52ERN
-55 E. Monroe Street P. O. Box 341441 Chicago, Illinois 60603 Hartford, CT 06134-1441 Citizens Regulatory Commission ATTN: Ms. Susan Perry Luxton 180 Great Neck Road Waterford -Connecticut 06385 The Honorable Terry Concannon Co-Chair Nuclear Er.ergy Advisory Council Room 4035 Legislative Office Building Capitol Avenue Hartford, Connecticut 06106 Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council 128 Terry's Plain Road Simsbury, Connecticut 06070 Little Harbor Consultants, Inc.
Millstone - ITPOP Project Office P. O. Box 0630 Niantic, Connecticut 06357-0630
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REQUEST FOR ADDIT 10NAL INFORMATION e
,00NCERNING EMERGENCY DIESEL GENERATOR EXHAUST STACKS MILLSTONE NUCLEAR POWER STATION. UNIT 3 TAC NO. M97508 1.
Based on a probabilistic risk assessment (PRA)-described in the final summary report, " Tornado Missile Risk Analysis of Millstone Unit 3 Emergency Generator Enclosure Openings," dated March 1985, Northeast
~ Nuclear. Energy Company (NNECO). concluded that the probability of significant damage to an emergency diesel generator,(EDG) exhaust piping from tornado generated missiles is less than 1 x 101 per year.
Accordingly, a change was implemented in the last amendment (dated March 1996) to the Final Safety Analysis Report (FSAR) to delete the licensing-commitment, which required NNECO to open the EDG exhaust piping access hatches during'a tornado alert. The staff finds that the above cited PRA was only performed to demonstrate the risk of tornado generated missiles, which could enter any of the openings in the exhaust olenums
-to cause damage to the EDG exhaust system.- It does not address.the-probability of the ED6 exhaust stacks located outside.the building being hit by tornado generated missiles.- Therefore, provide a PRA to demonstrate the risk of tornado generated missiles, which could cause damage to any portion of the EDG exhaust stacks. This PRA should consider all potential modes of tornado missile damage to the exhaust stacks, not just the probability that missiles will enter one of the openings of the exhaust--plenum.
-2.
Your r_isk-_ assessment for-protection.against tornado generated missiles only addresses the acceptance criteria for a single vulnerability, i.e.,
the EDG exhaust system.
In-order to rely on probabilistic arguments that tornado missile protection'is not required, the risk assessment must also.show that the overall risk from.. tornado generated missiles has not been-increased (by not providing protection for the EDG exhaust system) beyond the acceptance-criteria discussed in the guidance of Standard Review Plan (SRP) Section 2.2.3, which deals with identification of design basis. events using probabilistic methods.
Therefore,- the-analysis should also consider all other structures,.
- systems, or components-(SSCs) not protected from tornado generated
' missiles that are required to prevent-a release of radioactivity in excess of'10 CFR Part 100 that are not protected from turnado generated
- missiles. This guidance states that an expected-rate of occurrence of potential exposur approximately 10',es in excess of the 10 CFR Part 100 guidelines of per year is acceptable if, when combined with reaswable qualitative arguments, the risk can be expected to be lower.
This request for additional information need not be addressed if all other safety-related SSCs (other than the EDG' exhaust system) are adequately-protected-(by existing barriers / structures) from the effects of tornado generated missiles.
Enclosure
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