NG-96-0728, Responds to GL 96-01, Testing of Safety-Related Logic Circuits

Responds to GL 96-01, Testing of Safety-Related Logic Circuits

ML20107G530
Person / Time
Site:	Duane Arnold
Issue date:	04/17/1996
From:	Franz J IES UTILITIES INC., (FORMERLY IOWA ELECTRIC LIGHT
To:	Russell W NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-01, GL-96-1, NG-96-0728, NG-96-728, NUDOCS 9604230265
Download: ML20107G530 (4)

Text

IES Utilettes Inc.

e 200 First Stmet S E.

PO. Box 351 Cedar Rapids, IA 5240fr0351 Teleohone 319 398 8162 Fau at9 390 6192 UTILITIES Vge Pres >dont. Nuclear April 17,1996 NG-96-0728 Mr. William T. Russell, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station Pl-37 Washington, DC 20555-0001

Subject:

Duane Arnold Energy Center Docket No: 50-331 Op. License No: DPR-49 Response to NRC Generic Letter 96-01 References; l) NRC Generic Letter (GL) 96-01," Testing of Safety-Related Logic Circuits," January 10,1996.

2) R. McGaughy (IELP) to A. Davis (NRC)," Augmented Logic Circuit Testing," NG-87-2287, June 11,1987.

3) J. Franz (IES) to W. Russel!(NRC)," Response to Request for Additional Information Regarding Removal of Certain Motor-Operated Valvesfrom the 9AEC Generic Letter 89-10 Program,"

NG-95-0815, March 10,1995.

File:

A-10lb, C-61

Dear Mr. Russell:

In Reference 1, the Staff requested that we provide our plans and schedule for performing a review of our testing practices of safety-related logic circuits to ensure that these practices adequately demonstrate that these circuits will perform their intended safety function, in accordance with our Technical Specifications (TS). This letter provides that requested information.

The Duane Arnold Energy Center (DAEC) has previously performed a comprehensive evaluation and enhancement of our logic testing practices to ensure safety-related circuitry components and contacts are demonstrated operable per design intent.

Reference 2 describes these efforts.

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NG-96 0728 April 17,1996

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We have confidence that these previous efforts remain valid based on our administrative i

controls, such as biennial reviews of TS-required surveillance testing procedures, i

- corrective action and audit programs, industry operating experience review program, as j

well as our recent completion of the design basis reconstitution effort ofinstrument setpoint calculations for TS instrumentation and implementation of an Instrument Setpoint Control program. Therefore, a complete re-review of our logic testing practices is not warranted. However, based upon recent industry experiences with deficiencies in 4

testing practices after circuit modifications have been made, as described in GL 96-01 and Information Notices referenced therein, we believe that a selective review of modifications made to logic circuits since our previous review is prudent. We plan to perform such a review as permitted by the Note on page 5 of the GL. This review will consist of:

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1) identification of those design changes made since the review described in Reference 2 that had the potential to affect the safety function of TS-required logic *

2) an engineering evaluation of the post-modification tests performed on those logic j

circuits to ensure that those design changes actually performed per the design -

intent

3) an evaluation to ensure that the current routine testing procedures adequately test the safety-related function of those modified logic circuits,'to the extent practicable and prudent to safe plant operation.

4 It is important to note that because of the DAEC's design vintage, it is not always possible or practicable to test every part of a safety-related logic circuit without compromising plant safety and reliability. There are situations where the risk of an inadvertent equipment actuation and subsequent plant transient from testing some part of 3

a logic circuit is not prudent or safe (for example, to intentionally challenge portions of logic that seal-in a signal or provide equipment interlocks or inhibits with the equipment operating.) It is the DAEC's philosophy and practice to test logic circuits only where the benefit of the test outweighs the risk of performing it. We therefore test only under the proper plant conditions or only test those parts of the logic that are practically and safely testable, while still ensuring that the TS requirements are satisfied.

' Note: It is our understanding, based upon the Staff's clarifications at the Nuclear Energy Institute's workshop, that those parts oflogic circuits, such as annunciators / alarms, computer points, interlocks and bypasses that do not perform a safety function or are r

incapable ofinhibiting a safety function, per the plant's design basis, need not be covered 4

- by the GL-required review.

Mr. William T. Russell NG-96-0728 April 17,1996 Page 3 Lastly, as stated in Reference 3, while it is part of the DAEC plant design for certain components in safety-related systems to automatically re-align to their accident mitigation positions upon receipt of an actual demand signal, this feature is not relied upon in our accident analysis. Consequently, it is not necessary for us to confirm that this design feature is tested as part of the surveillance testing program per this Generic Letter.

The DAEC is in the process of converting to the Improved Standard Technical Specifications (NUREG-1433) which will both modify some existing TS-required logic tests and add new ones Therefore, we propose to perform the GL 96-01 review as part of '

the impleme:itation program for our new TS. Because some new tests may be safely conducted only during a plant outage, our schedule for completing this ieview will be startup froin Refueling Outage (RFO) 15, currently scheduled for Spring 1998. This schedule is consistent with that proposed in the GL.

This letter contains the following new NRC commitments:

1. Perform the review of testing practices of safety-related Technical Specification loy: circuits as described in this letter. This review will be completed prior to stan ap from RFO 15.

2. Inform NRC of the completion of the GL 96-01 review within 30 days of completion.

Please contact this office if you have any questions regarding this matter, 1

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Mr. William T. Russell NG-96-0728 April 17,1996 Page 4 This letter is true and accurate to the best of my knowledge and belief.

IES UTILITIES INC.

Ily 811< /t/h J.hn F'. Frand ice President, Nuclear State ofIowa (County) of Linn Si 'ned and sworn o before rne on this / 7 day of O.2_)

,1996,by i\\ k AA &

DEBRA J. SCHWENKER

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