ML20010E098
| ML20010E098 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/26/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TASK-07-06, TASK-7-6, TASK-RR LSO5-81-08-046, LSO5-81-8-46, NUDOCS 8109030075 | |
| Download: ML20010E098 (4) | |
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August 26,19El Docket :10. 50-245 LS05 08-046 jjdp ifG.;,,s.
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II. G. Counsil, Vice President f-PI fluclear Engineering and Operations y SCr 0 31981
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Post Office Box 270 Hartford, Cannecticut 06101 D
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Dear !!r. Counsil:
SUBJECT:
SEP TOPIC VII-G, FREQUENCY DECAY SAFETY EVfsLUATIO'l FOR !!ILLSTO.'lE 1 The enclosed staff safety evaluation is based on a contractor docunent that has bec i made available to you previously. This evaluation is the staff's )osition regarding design of your facility in the subject area.
With egard to the referenced topic, the staff has concluded that your fa flity neets current ~icensing criteria.
Sincerely, Dennis li. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
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Docket No. 50-245 l
Mr. W. G. Counsil 1
cc William H. Cuddy, Esquire Connecticut Energy Agency i
Day, Derry & Howard ATTN: Assistant Director j
Counselors at Law Research and Policy One Constitution Plaza Development i
Hartford, Connecticut 06103 Department of Planning and Energy Policy Natural Resources Defense Council 20 Grand Street 91715th Street, N. W.
Hartford, Connecticut 06106 Washington, D. C.
20005 Northeast Nuclear Energy Company ATTN: Superintendent Millstone Plant P. O. Box 128 j
Waterford, Connecticut 06385 l
Mr. Richard T. Laudenat Manager, Generation Facilities Licensing t
Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Resident Inspector c/o U. S. NRC P. O. Box Drawer KK Niantic, Connecticut 06357 Waterford Public Library Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Town of Waterford Hall of Records 200 Boston Post Road Waterford, Connecticut 06385 John F. Opeka j
Systems Superintendent i
Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 U. S. Environmental Protection Agency Region I Office ATTN: EIS C0ORDINATOR JFK Federal Building Boston, Massachusetts 02203 i
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SYSTDtATIC EVALUATION PROGRAM
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._0PIC VII-6 1
j MILLSTONE 1
l TOPIC VII-6 FREQUENCY DECAY j
I.
Introduction Issue 9 of NOREG-0138 states that the staff should require that a post-i ulated rapid decay of the frequency of the offsite power system be included in the accident analysis and that the results be demonstrated i
to be acceptable. Alternatively, the reactor coolant pump (RCP) circuit breakers should be designed to protection system criteria and tripped to i
separate the pump motors from the offsite power system because rapid decay of the fraquency of offsite Tower system has the potential for 1
j slowing down or braking the RCP thereby reducing the coolant flow rates to levels not considered in previous analyses.
~
II.
Review: Criteria i
The review criteria for reactor trip systems are presented in Table 7-1 of the Standard Review Plan.
III.
Related Safety Tooics and Interfaces Set Points (Topic VII-1.A) and Degraded Grid (Topic VIII-1.A) are relat-ed review areas that are outside the scope of this Topic.
Although Topic VIII-1.A is not dependent on the present topic for comp-letion, the conclusions with regard to frequency decay should be compat-able.
1 IV. Review Guidelines Issue 9 of NUREG-0138, " Staff Discussion of r 'tecn 'achnical' Issues Listed in Attachment to November 3,1976 Memorandum from Director, NRR to NRR Staff," provides suitable guidance for this review.
4 V.
Evaluation 1
Oak Ridge National Laboratory (ORNL), under a technical assistance program, l
reviewed the frequency decay rate phenomena and its effects on RCP's. The results of the review are presented in Section 4 of NUREG CR 1464, " Review of Nuclear Power Plant Offsite Power Source Reliability and Related Recom-mended Changes to the NRC Rules and Regulations." In summary, the report shows that the conditions required for dynamic braking of reactor coolant pumps are a sustained and rapid decrease in frequency while maintaining bus voltage. These conditions are only reali:ed in a highly capacitive system using large amounts of buried transmission cables (such as Long Island).
The Northeast Nuclear Energy systen does not use large amounts of buried transmission cable.
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" VI.
Conclusion The conditions necessary for an unacceptable frequency decay rate are not present in the Millstone of fsite electrical distribution systen.
Accordingly, the staf f considers this issue not applicable to Millstone.
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