ML20202F357
| ML20202F357 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 02/12/1998 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-98-0040, BYRON-98-40, GL-96-01, GL-96-1, NUDOCS 9802190184 | |
| Download: ML20202F357 (3) | |
Text
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unmmonw rahh lihven Company
- b)ron Generating station
,4 450 North German Chun h Road n3ron,i:.oinin9 n Tel Hi V23 6-5161 February 12,1998 1.TR: llYRON 98-0040 FILE 2.01.0207 U. S. Nuclear Regulatory Commission NITN: Document Control Desk Washington, D.C 20555
Subject:
Response to NRC Generic Letter 96-01 Byron Station lI its 1 and 2 n
Docket Nos.50-454 and 50 45ji Braidwood Station Units 1 and 2 Docket Nos 50-456 and 50-457
References:
1.
NRC Generic Letter 96-01, ' Testing of Safe +y-Related Logic Circuits,"
datedJanuary 10,1996 2.
J, C. Brons letter to the Nuclear Regulatory Commission (NRC).
" Commonwealth Edison Company (Comed) Response to NRC Generic Letter (GL) 96-01," dated April 19,1996 3.
Gene Stanley letter to the Nuclear Regulatory Commission (NRC),
"Braidwood Station Units 1 and 2 Response to NRC Generic Letter 96-01:
Testing of Safety-Related Logic Circuits," dated August 13,1997 The purpose of this letter is to inform the Staff that the original expected completion date of actions requested by GL 96-01 is being revised due to the expanded work scope.
In Reference 1, the NRC transmitted Generic Letter (GL) 96-01. This GL requested licensees to review certain systems again* their Technical Specification surveillances to ensure all portions of the logic circuitry are adequately covered to fulfill the Technical Specification requirements.
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For any inadequately tested portions of the logic circuit, the licensee must either revise i
surveillances as necessary, or request relief through an amendment to Technical Specifications.
These actions were requested to be accomplished prior to startup from the first refueling outage commencing one year after the issuance of GL 96-01.
In Reference 2, Comed transmitted the 60 day response to the GL, agreeing that the Byron and Braidwood Nuclear Generating Stations would implement the actions as described in GL 96-01.
Reference 2 also stated that Byron and Braidwood Stations would confirm completion of the actions requested within 30 days following their completion. The first Byron refueling outage f-corresponding to the GL beg:m November 7,1997 and is currently scheduled to end February Q Qf 25,1998.
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' Page 2 U.S. Nuclear Regulatory Commission While this commitment was in progress, an event occurred during the course of the Byron and Braidwood reviews that indicated an expansion of the original review scope was appropriate.
Operating Experience Report OE8435, "SSPS P.11 Not Surveilled Quarterly," was issued in June IW7, which identified inadequate testing ofinterlock circuitry for the P 11 Permissive at another Pressurized Water Reactor (PWR) station. Upon review of this OE, Byron and Braidwood Station personnel found that this condition existed at both stations, and issued LERs Subsequently, it was determined that an expanded rev'ew of logic circuitry would be required to fully complete the GL 96-01 request.
The expansion scope amounted to approximately a 50% increase over the initial review scope. An approximate tval of 4000 contacts were reviewed in the initial Byron Unit 1 and Unit 0 expanded scope cos. tac + review, with a similar number expected for Braidwood Unit 1 and Unit O.
The original plus expanded scope initial contact review completion schedule is as follows:
Byron Unit 1 and Unit 0 review was completed onJanuary 16,1998 Byron Unit 2 review is expected to be completed by February 16,1998 Braidwood Unit 1 and Unit 0 review is expected to be completed by February 23,1998 Braidwood Unit 2 review is expected to be completed by March 2,1998 The purpose of the initial contact review is to identify potentially untested contacts. Following receipt of the initial contact review, site personnel will perform a detailed, systematic site
- evaluation to make a-final determination as to whether the contacts are tested in any site surveillance and to determine appropriate followup actions. The review will be conducted in an expeditious manner, placing high priority on the most safety significant contacts. The specific followup actions will be addressed promptly in accordance with the requirements of Technical Specifications (if applicable). Of the approximately 4000 contacts reviewed for Byron Units 1 and 0,250 potentially untested contacts have been identified. It should be noted that this does not represent 250 untested interlock paths since there is frequently more than one contact per path and each contact may be counted in multiple train logic. The Byron Unit 2 initial review is not expected to add significantly to the 250 potential contact issues identified for Byron Unit I cnd 0, and similar results are expected for the review of Braidwood Units 0,1, and 2.
- Byron and Braidwood concur with the staff notes and discussion as described in GL 96-01 below:
"... in cases when suneillana testing ofthe logic circuits has not been awplete, it is likeh that onh my smallportions ofthe circuits han been omittedfrom the test. Further, the NRC stafis not awan ofinstanas ofspeafwalh identified suneillana inadequa.ies that nsulted in the unavailabilip of the safey system when called on during an ennt. "
In the past, Comed has identified previously untested contacts and submitted LERs for any rontacts that were untested in violation of Technical Specifications. All of these contacts have performed successfully when tested. For the above reasons, Comed has a high degree of confidence that any existing untested contacts would perform their required safety function if called upon to actuate. It can also be noted that, in some cases, potentially untested contacts are located on relays and switches tbat are regularly tested ar.d have performed as required. Since the contacts undergo the same operating conditions, this reinforces the belief that the untested contacts would perform if required. Several other justifications exist that add to the assurance that the safety systems will perform their required function and are listed as follows:
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' Page 3 U.S. Nuclear Regulatory Commission inherent redundancy in the design of the systems, high success rate during surveillance testing of the safety systems, high safety system availability, successful testing of the 3750 (~94% of the Unit 1 and 0) contacts that were identified in the initi,1 review, and only 250 (-6% of the Unit 1 and 0) out of an approximate 4000 contacts have potentially not been tested.
Therefore, based on the above, Byron and Braidwood have established that reasonable assurance exists to aliow for an extension of the review schedule that is commensurate with the safety signitiance of the issue.
Byron and Braidwood will be coordinating the detailed site reviews due to commonality of equipment and similarity in site surveillances. In Reference 3, Braidwood Station submitted a commitment change for GL 96-01 actions to extend the completion date to March 15, 1998.
Similarly, the Byron detailed site evaluation will not be completed prior to startup from the current Unit 1 outage as originally committed in Reference 2. Byron and Braidwood Stations i
expect to complete all actions associated with GL 96-01 for both Units 1 and 2 by December 15, 1998. An,: issues discovered during the site evaluations will be addressed in accordance with the GL l
If you need any additional information concerning this document, please contact Marcia Lesniak, Nuclear Licensing Administrator, at (630)663-6484.
Sincerely,.
K. L Graesser Site Vice President Byron Nuclear Generating Station KLG/LZ/rp cc:
Regional Admiitistrator-RIII Byron Project Manager - NRR Braidwood Project Manager-NRR Byron Senior Resident inspector Braidwood Senior Resident Inspector Office of Nuclear Safety-IDNS 1