ML20054B571

Forwards Response to NRC 810305 Request for Addl Info Re Incore Neutron Flux Measurement Instrumentation Using Moveable & Fixed Detectors.Sys Tested to Assure Reliability & Proposed License Amend W/Supporting Analysis Will Be Sent

ML20054B571
Person / Time
Site:	Seabrook
Issue date:	04/13/1982
From:	Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE
To:	Miraglia F Office of Nuclear Reactor Regulation
References
SBN-256, NUDOCS 8204160606
Download: ML20054B571 (3)

Text

SEABROM STATION PUBLIC SERVICE Engineedng Office:

< Companyof New Hemph 1671 Worcester Road Framinchom, Massachusetts 01701 (617) - 872 - 8100 April 13, 1982 SBN-256 9 YYQk,D T. F. B 7.1.2 /

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- '". -9 United States Nuclear Regulatory Commission C; &, jf ; O /S [

Washington, D. C. 20555 - 4:a CE $ d g e$ g Mr. Frank J. Miraglia, Chief s

Attention:

Licensing Branch #3  % m Y

N Division of Licensing

References:

(a) Construction Permits CPPR-135 and CPPR-136, Docket No s . 50-443 and 50-444 (b) USNRC Let ter, dated March 5,1981, " Request for Additional In f o rma t io n , " F. J. Miraglia to W. C. Tallman Su bj ec t : Response to RAI 491.1; Core Performance Branch Dear Sir-We have attached a response to the subject RAI which you forwarded in Re f e rence (b) .

Ve ry t ruly yours, YANKEE ATOMIC ELECTRIC COMPANY

{ . Af heffJohnDeVincentis Project Manager Attachment e i 9204160606 820413 PDR ADOCK 05000443 A PDR

, i OVESTION 491.1 It is noted that your incore neutron flux measurement instrumentation is dif feren t from previous Westinghouse design in tha t i t incorporates, in adaition to a moveable detector, a set of fixed detectors. So that we can understand the significance of this change, please provide informa-tion on the following:

1. Describe the geometrical details of the incore part of the system and indicate differences from previous Westinghouse designs.

2. If details related to the moveable detectors, their environment t output or operation are different from previous design, what infor-mation has been developed to assure accuracy and reliability of operatio n?

3. Are any differences from previous Westinghouse reactor operation contemplated for the use of or requirements (including Technical Specifications) for the moveable system?

. 4. What uses and/or requirements are contemplated for the fixed detec-tor system? Will it be associated in a nyway with safety analyses, e.g. , via LCO monitoring, or calibration of or substitution for other instrumentation, e.g., substitution for required moveable '

detector readings? If so, full details relating to use, related calculations, accuracy and reliability are required.

l RESPONSE TO OUESTICN 491.1 Al though Seabrook incore neutron flux instrumentation incorporates a set of platinum sel f-powered fixed detectors in addition to a moveable detector, it is functionally similar to the previous Westinghouse design. The seabrook moveable detector performs the same function that moveable detectors perform on plants with the previous Westinghouse

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1. The Seabrook moveable detector is functionally identical to the  !

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, coveable detectors previously used, and is similarly constructed.

however, the Seabrook moveable detector is smaller in diameter than those useo previously and, therefore, outputs a smaller current.

Al though the absolute current output is smaller, the electronics have been adjusted to accept this smaller current and the overall system has a perfonnance which should be conparable to that of the previous Westinghouse design.

2. As was stated above, the output of the Seabrook moveable detector is smaller than that of the detectors used previously but the overall system performance should be comparable to that of the previous Westing-house design.

The cddition of the fixed detectors to the environment of the move-able detector is not detrimental to the performance of the moveable detector because the.effect of the platinum self-powered fixed detectors on the output of the moveable detector should be essentially negligible.

There is an ongoing test program to assure reliability of the system.

3. No diff erences from previous Westinghouse reactor operation are contemplated for the use of, or requirements for, the moveable s ys te m .

4. Seabrook Station will be initially operated as a standard Wes tinghouse reactor. During this period, data will be accumulated on the perforcunce (including accuracy and reliability) of the fixed detector sys tem. Ul tima tely , the fixed detector system will be used to monitor LCO requirements on linear heat generation rate. This will allow some relaxation of the target band in Constant Axial Offset Control.

Sa fety analysis methodology to support wide-band CAOC operation is currently being developed. This will be used to verify that LCO's for normal opera tion can be met and to verify reactor protection provided by the setpoints of the

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high flux trip, the Overpower AT trip, and the Overtempera ture AT trip.

Prior to wide-band CAOC operation, a proposed license amendment with j supporting analysis will be submitted.

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