ML20005B812

Forwards Safety Evaluation of SEP Topic VII-6 Re Frequency Decay.Facility Meets Current Licensing Criteria

ML20005B812
Person / Time
Site:	Yankee Rowe
Issue date:	08/28/1981
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Kay J YANKEE ATOMIC ELECTRIC CO.
References
TASK-07-06, TASK-7-6, TASK-RR LSO5-81-08-072, LSO5-81-8-72, NUDOCS 8109020296
Download: ML20005B812 (4)

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August 28, 1981 pd-1 Docket No. 50-29 LS05 08-072 N

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SEp 0.11937, 3 Mr. James A. Kay 7 g Q %*8 S6nior Ehgineer - Licensing 3';~

Yankee Atomic Electric Company 1617 Worcester Road s

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SUBJECT:

SEP TOPIC VII-6, FREQUENCY DERAY SAFETY EVALUATION FOR YANKEE R0WE The enclosed staff safety evaluation is based on a contractor r'scument that has been made available to you previously. This evaluation is the staff's position regarding design of your facility in the subject area. With regard to the referenced topic, the staff has concluded your facility meets current licensing criteria.

Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing

Enclosures:

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Mr. James A. Kay YANKEE R0WE Docket No. 50-29 cc Mr. Jam 2s E. Tribble, President Yankee Atomic Electric Company 25 Research Drive Westborough, Massachusetts 01581 Greenfield Community College 1 College Drive Greenfield, Massachusetts 01301 Chairman Board of Selectmen Teun of Rowe Rcwe, Massachusetts 01367 Energy Facilities Siting Council 14th Floor One Ashburton Place Boston, Massachusetts 02108 U. S. Environnental Protection Agency Region I Office ATTN: EIS COORDINATOR JFK Federal Building Boston, Massachusetts 02203 Resident Inspector Yankee Rowe Nuclear Power Station c/o U.S. NRC Post Office Box 28 Monroe Bridge, Massachusetts 01350 l

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SYSTEMATIC EVALUATION PROGRAM TOPIC VII-6 YANKEE R0WE TOPIC VII-6 FREQUENCY DECAY I.

Introduction Issue 9 of NUREG-0138 states that the staff should require that a post-ulated rapid decay of the frequency of the offsite power system be included in the accident analysis and that the results be demonstrated to be acceptable. Alternatively, the reactor coolant pump (RCP) circuit breakers should be designed to protection system criteria and tripped to separate.the pump motors from the offsite power system because rapid decay of the frequency of offsite power system has the potential for slowing down or braking the RCP thereby reducing the coolant flow rates to levels not considered in previous analysss.

I II.

Review Criteria

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The review criteria for reactor trip systems are prciented in Table 7-1 j

of the Standarc 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 tnat are outside the scope of this Topic.

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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.

IV.

Review Guidelines Issue 9 of NUREG-0138, " Staff Discussion of Fifteen Technical' Issues Listed in Attachment to November 3,1976 Memorandum from Director, NRR to NRR Staff," provides suitable guidance for this review.

V.

Evaluation Oak Ridge National Laboratory (ORNL), under a technical assistance program, reviewed the frequency decay rate phenomena and its effects on RCP's. The results of the review are pre ented 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 sumnary, 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 realized a a hig ly capacitive system using large amounts of buried transmissic., cables such as Long Island). The Yankee Atomic Electric system does not use arge amounts of buried transmission cable.

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- VI. Conclusion The conditions necessary.for an unacceptable frequency decay rate are l

not present in the Yankee Rowe offsite electrical distribution system.

Accordingly, the staff considers this issue not to be applicable to l

Yankee Rowe.

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