B17244, Submits Results of Evaluation of Reg Guide 1.97 Design Criteria for Certain Type a & Type B Variables Used for CR Indication for Millstone,Unit 2.Commitment Made by Util, Encl

Submits Results of Evaluation of Reg Guide 1.97 Design Criteria for Certain Type a & Type B Variables Used for CR Indication for Millstone,Unit 2.Commitment Made by Util, Encl

ML20248B991
Person / Time
Site:	Millstone
Issue date:	05/19/1998
From:	Bowling M NORTHEAST NUCLEAR ENERGY CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-REGGD-01.097, RTR-REGGD-1.097 B17244, NUDOCS 9806020035
Download: ML20248B991 (8)

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Hope Ferry Rd. (Route 156), Waterford. Ur C6385 Nudear Energy wantone Noacar Po.er siation Northeast Nuclear Energy Company P.O. Ilon 128

. '. Waterford. CT 06385-0128 (860) 447-1791 Fax (860) 444-4277

'lhe Northeast Utilities System MAY I 91998 Docket No. 50-336 B17244 Re: RG 1.97 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Millstone Nuclear Power Station, Unit No. 2 Conformance to Regulatory Guide 1.97, Revision 2 Update on Control Room Indication Discrepancies The purpose of this letter is to inform the NRC of the results of our evaluation of Regulatory Guide (RG) 1.97 design criteria for certain Type A and Type B yariables used for control room indication for Millstone Unit No. 2. This issue was identi:ied as a RG 1.97 discrepancy in a letter dated April 9,1997.' An update on the conformance status of several variables that have been modified as a result of the evaluation is also included herein.

This correspondence provides update information only. No action by the NRC is requested.

BACKGROUND

. RG 1.97, Rev. 2, recommends that Category i variables meet the qualification and quality assurance requirements of safety-related Class 1E equipment. These requirements apply to the complete instrument channel from sensor to display.

' Northeast Nuclear Energy Company (NNECO) has completed a review of RG 1.97 commitments for Millstone Unit No. 2 which included a design basis review and verification of equipment installations. This review. identified minor installation .

discrepancies for certain Class 1E instrument loops credited for some Category 1

' M. L. Bowling to U. S. Nuclear Regulatory Commission, " Millstone Nuclear Power

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i Station, Unit No. 2 - Regulatory Guide 1.97 Deviations," dated April 9,1997, 1 .

Es J l l 9906020035 980519 r PDR ADOCK 05000336'A p PDR &

U.S. Nuciar R:gulatory Commission B17244/Page 2

- variables,' and further identified qualification deficiencies with certain displays. NNECO determined that, although the identified instrument loops are Class 1 E, the control room displays are non-Class 1E. Therefore, even though these displays were properly isolated, they did not meet the RG 1.97 design and qualification criteria for Category i variables.

DISCUSSION NNECO is implementing a plant design change to modify the discrepant instrument loops, and upgrade the non-Class 1E displays to fully comply with the Millstone Unit No. 2 license basis for RG 1.97 Category 1 design and qualification criteria. However, for seven of the parameters, NNECO is upgrading the displays for only two of four instrument channels previously credited. Therefore, the conformance status of those variables for which these seven parameters are credited has been changed.

Attachment (1) to this letter provides a list of those variables for which the credited channels are being reduced from four to two.

L For Category 1 variables, RG 1.97 does not specifically recommend a minimum number l of channels, but does provide the guidance that no single failure within the accident-monitoring. Instrumentation should prevent the operators from being presented the information necessary to determine the safety status of the plant and to bring the plant to safe shutdown following an accident. Furthermore, RG 1.97 notes that for a Category 1 variable, redundant or diverse channels should be electrically independent and physically separated in accordance with RG 1.75. To meet this standard, a ,

minimum of two channels is required. l 1

NNECO has previously indicated that it intended to provide no more than two channels for Category i variables in which information ambiguity is not a concern. NNECO's commitment to a specific number of channels was made in a letter dated April 9,1984,2 in which NNECO stated its general position on the design and qualification criteria presented in RG 1.97, Revision 2. In this letter, NNECO committed to providing "a third channel of instrumentation for Category 1 instruments ... only if a failure of one accident monitoring channel results in information ambiguity that could lead the operators to defeat or fail to accomplish a required safety function, and if one of the following measures cannot provide the information." These measures included (1) cross-checking with an independent channel that monitors a different variable bearing a known relationship to the variable being monitored, (2) providing the operator with the capability of perturbing the measured variable to determine which channel has failed by observing the response on each instrument, (3) the use of portable instrumentation for validation, or (4) the use of analytical redundancy. However, notwithstanding the stated NNECO position, where four channels of Class 1E instrumentation have been W. G. Counsil to J. R. Miller (USNRC), "Haddam Neck Plant, Millstone Nuclear Power Station, Unit Nos.1 and 2 - Supplement 1 to NUREG-0737, Revision 2 to Regulatory Guide 1.97," dated April 9,1984.

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U.S. Nucl;cr Rrgulatory Commission B17244/Page 3

. available to satisfy a Category i variable, all four have been conservatively credited in demonstrating conformance to the RG 1.97 guidance.

In reducing the number of credited channels to two, NNECO has determined in each case that a third channel of instrumentation is not necessary. The two channels of each parameter that are not being upgraded to Class 1E display provide validation capability using non-Class 1E indicators.

As part of the implementation of the plant design change to upgrade the displays, the control board labeling will be modified to distinguish the RG 1.97 channels from the non-RG 1.97 channels. Furthermore, operators will be trained on this change to ensure that they are cognizant of those channels that are qualified for post-accident use.

SUMMARY

NNECO has completed the evaluation of RG 1.97 design criteria for certain Type A and Type B variables used for control room indication for Millstone Unit No. 2. As a result of this evaluation, several instrument loops are being modified to satisfy the RG 1.97 design and qualification criteria for Category i variables, in conjunction with these modifications, the number of channels credited for some variables has been reduced.

COMMITMENTS Attachment 2 identifies those actions committed to by NNECO in this letter.

Should you have any questions on the inforrnation provided herein, please contact Mr.

R. G. Joshi at (860) 440-2080.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY l

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h Martin L. Bowling, Jr. J l

Recovery Officer - Technical Services l

Attachments (2) cc: - See Page 4 i l

U.S. Nucicar Regulatory Commission B17244/Page 4 cc: W. D. Travers, Ph.D, Director, Special Projects Office H. J. Miller, Region l Administrator D. P. Beaulieu, Senior Resident inspector, Millstone Unit No. 2 D. G. Mcdonald, Jr., NRC Senior Project Manager, Millstone Unit No. 2 P. F. McKee, Deputy Director of Licensing, Special Projects Office W. D. Lanning, Deputy Director of Inspections, Special Projects Office

Docket No. 50-336 B17244 Atta::hment 1 1

Millstone Nuclear Power Station, Unit No. 2 Conformance to Regulatory Guide 1.97, Revision 2 Update on Control Room Indication Discrepancies J l

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May 1998 L____--_____-________ _ _ _ _

U.S. Nuclear Regul: tory Commission l B17244/ Attachment 1/Page 1 l

Millstone Unit No. 2 RG 1.97 Category 1 Variables Reduced to Two Channels Variable NNECO Credited Monitored Plant Designation (s) Loops Parameter RCS (Pressurizer) Pressure A-1, B-07A, B-11 A,- P-102A & Pressurizer Pressure, C-04A, C-09A P-102B High Range Steam Generator Pressure A-4 P-1013A & Steam Generator No.1 l P-1013B Pressure Steam Generator Pressure A-4 P-1023A & Steam Generator No.2 P-10238 Pres ure l

l Steam Generator Level A-5, D-16 L-1113A & Steam Generator No.1 i L-1113B Level, Narrow Range l

Steam Generator Level A-5, D-16 L-1123A & Steam Generator No.2 L-1123B Level, Narrow Range Refueling Water Storage A-8, D-08 L-3001 & Refueling Water Tank Level L-3002 Storage Tank Level Containment Pressure B-13 P-8113 & Containment Pressure P-8114 l

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. Docket No. 50-336 B17244 Attachment 2 Millstone Nuclear Power Station, Unit No. 2 Conformance to Regulatory Guide 1.97, Revision 2 Update on Control Room Indication Discrepancies List of Regulatory Commitments 1

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l May 1998 l

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U.S. Nucl:ar Regul tory Commission B17244/ Attachment 2/Page 1 List of Regulatory Commitments i

The following table identifies those actions committed to by NNECO in this document.

Any other actions discussed in the submittal represent intended or planned actions by NNECO. They are described to the NRC for the NRC's information and are not regulatory commitments. The Manager - Regulatory Compliance, Millstone Unit No. 2, should be notified of any questions regarding this document or any associated regulatory commitments.

REGULATORY COMMITMENT COMMITTED DATE OR OUTAGE B17244.01 - Implement Class 1E Prior to entering Mode 4 from the current modifications to discrepant RG 1.97 outage.

Category 1 instrument loops, j

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