NRC Generic Letter 1980-66
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| ML031350407 | |
| Person / Time | |
|---|---|
| Issue date: | 07/18/1980 |
| From: | Sayfrit K V NRC Region 4 |
| To: | |
| References | |
| BL-80-017, Suppl 1 GL-80-066, NUDOCS 8009180115 | |
| Download: ML031350407 (5) | |
_bcc to DAC:ADM:-4TRAL FILESr REate UNITED STATES PDR:HQNUCLEAR REGULATORY COMMISSION LPDR61 REGION IV 70200TIC61 RYANPLAZAORIVE,SUITE 1000ICARLINGTON, TEXAS 76012 NSICJuly 18, 1980Docket No. 50-298Nebraska Public Power DistrictATTN: J. M. Pilant, DirectorLicensing & Quality AssurancePost Office Box 499Columbus, Nebraska 68601Gentlemen:Enclosed is IE Supplement No. 1 to Bulletin No. 80-17 which requires actionby you with regard to your power reactor facility with an operating license.In order to assist the NRC in evaluating the value/impact of each Bulletinon licensees, it would be helpful if you would provide an estimate of themanpower expended in conduct of the review and preparation of the report(s)required by the Bulletin. Please estimate separately the manpower associatedwith corrective actions necessary following identification of problems throughthe Bulletin.Should you have any questions regarding this Bulletin or the actions requiredby you, please contact this office.
Sincerely,Karl V. SeyfritDirector N
Enclosures:
1. IE Supplement No.. 1 to Bulletin No.80-172. List of Recently Issued IE Bulletinscc: L. C. Lessor, SuperintendentCooper Nuclear StationPost Office Box 98Brownville, Nebraska 683218009 18 0//5Ue ISSINS No.: 6820Accession No.:UNITED STATES 8006190027NUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555IE Bulletin No. 80-17Supplement No. 1Date: July 18, 1980 FAILURE OF 76 OF 185 CONTROL RODS TO FULLY INSERT DURING A SCRAM AT A BWR
Description of Circumstances
- Please refer to IE Bulletin 80-a7, issued July 3, 1980, for complete detailsof the initiating event.Although we are essentially confident that the event was caused by water in theScram Discharge Volume (SDV) system, we do not yet have a complete explanationas to why the water was present. The best estimate is that some type of blockageexisted in the vent and/or drainage system for the SDV, precluding adequatedrainage. To ensure that the SDV is empty, Browns Ferry (BF-3) has installedinstrumentation to continuously monitor the water level in the scram dischargevolume. Such instrumentation is being considered by other plants.Since issuance of IE Bulletin 80-17, additional information has been identified.Specifically:a) At Browns Ferry a discrepancy was found between the "as-built" scramdischarge system and the "as-designed" system. An unused one-inch(1") instrument line was found uncapped on the.four-inch (4") drpinheader on the west side (the side whose rods scrammed) scram dischargevolume vent system of Unit No. 3. It is believed that this lineimproved the venting, and therefore the drain time for that system.b) It has been determined that the vent systems on some scram dischargevolumes interconnect with vent headers that are also common with andare connected to other systems. The interconnected "vent" systemsmay contain water drained or being drained from those other systems.This water could potentially affect performance of the SDV. Also,both the vent and drain systems for the scram discharge system maycontain long lengths of relatively small bore piping. Designs specifya very gradual slope, such that small errors in the "as-installed"piping could result in degraded performance (for example, due toloop seals).c) Concerns have been expressed within the NRC Staff regarding potentialdelays that may occur before start of injection of boron into the BWRsystem from the Standby Liquid Control System (SLCS) when this manualoperator action is required. The potential delays could be caused by IE Bulletin No. 80-17Supplement No. 1Date: July 18, 1980 unavailability of the SLCS key which is required to initiate this system,and/or administrative delays which require supervisory approval beforethe SLCS can be manually initiated by the control room licensed operator.In view of the above items, the following actions in addition to those specifiedin IE Bulletin 80-17 are to be taken by BWR licensees.A. Actions to be Taken by BWR Licensees Upon Receipt and to be ReportedWithin 20 Days of the Date of This Letter:1) Provide to the NRC Regional Office an analysis of the adequacy ofthe "as-built" SDV system and associated vent and drain systems,including any identified design deficiencies. Include copies ofverified "as-built" isometric drawings of the SDV and detaileddescriptions of the remainder of the system, verified to be correct,as part of this analysis.2) Revise and implement Operating Procedures as necessary to provideclear guidance to the licensed operator in the control room regardingwhen he should initiate the SLCS without obtaining prior supervisoryapproval. Provide a description of the implemented proceduralrequirements.3) Assure that procedures exist and are implemented for specifyingremedial action to be taken if water is found in the SDV systemat times when it should be free of water. Provide a descriptionof the implemented procedural requirements.4) Revise and implement administrative procedures as necessary to ensurethat the SLCS key shall be readily available to the licensed operatorin the control room. Provide a description of the implemented pro-cedural requirements.5) Continue daily monitoring of water levels in all scram dischargevolumes until continuous monitoring system(s) (discussed in B.1below) is (are) installed and operational (this requirementsupersedes the requirements of Item 5 of IE Bulletin 80-17 whichrequired daily surveillance for only 6 days).B. Actions to be Taken by BWR Licensees and Completed by September 1, 1980:1) Install a system to continuously monitor water levels in all scramdischarge volumes. Continuous recording and alarm features must beincluded in the design. Consideration should be given to use ofdiverse level sensors in this (these) system(s). The design installedshould represent the design with the highest level of reliabilitycompatible with completion of installation by September 1, 1980.Provide a written description of the system design to the NRC RegionalOffic IE Bulletin No. 80-17Supplement No. 1Date: July 18, 1980 If installation by September 1, 1980 is not possible, by August 15,1980, submit to the NRC Regional Office:1) Documentation in detail why the installation cannot becompleted by 9/1/80.2) A commitment to a firm schedule for installation.3). A commitment to equipment changes and/or surveillancerequirements in addition to those now in effect thatwill provide adequate assurance of SDV operability inthe interim until installation is completed.2) Perform a study of potential designs for improving the venting systemfor the scram discharge volumes and submit a description to NRC bySeptember 1, 1980. Improvements such as providing a redundant,independent vent for each significant volume in the system or locallyinstalling vacuum breakers close to each such volume should be con-sidered (some plants already include a design which vents locally toatmosphere). Include an estimate of the time that would be requiredto accomplish these modifications in your report to be submittedto the NRC Regional Office. We have been told that meetings havealready been scheduled by GE to discuss their proposals in this areawith licensees.Additional requirements are under consideration and will be the subject offurther communication from NRC.Licensees of all operating BWRs shall submit the information requested withinthe specified allowable times. This information is requested under the provis-ions of 10 CYR 50.54 (f). Accordingly, you are requested to provide withinthe time periods specified'above, written statements of the above informationsigned under oath or affirmation. Reports shall be submitted to the Directorof the appropriate NRC Regional Office and a copy forwarded to the Director,Division of Reactor Operations Inspection, NRC. Office of Inspection andEnforcement, Washington DC 20555.Approved by GAO, B180225 (R0071); clearance expires 7-31-80. Approval wasgiven under a blanket clearance specifically for identified generic problem IE Bulletin No. 80-17July 18, 1980RECENTLY ISSUED IE BULLETINSBulletinNo.Subj ectDate IssuedIssued To80-10Contamination ofNonradioactive System andResulting Potential forUnmonitored, UncontrolledRelease of Radioactivity to5/6/80EnvironmentAll power reactorfacilities with anOperating License (OL)or Construction Permit(CP)80-1180-1280-1380-1480-1580-1680-17Masonry Wall DesignDecay Heat Removal SystemOperabilityCracking In Core SpraySpangersDegradation of ScramDischarge VolumeCapabilityPossible Loss of EmergencyNotification System (ENS)with Loss of Offsite PowerPotential Misapplicationof Rosemount Inc., Models1151 and 1152 PressureTransmitters with Either"A" or "D" Output CodesFailure Of 76 of 185Control Rods To FullyInsert During A ScramAt A BWR5/8/805/9/805/12/806/12/806/18/806/27/807/3/80All power reactorfacilities with anOperating License (OL),except Trojanand holders of aConstruction Permit (CP)Each PWR with anOperating License (OL)or Construction PermitAll BWRs with anOperating License (OL)or Construction Permit(CP)(CP)All BWRs with anOperating License (OL)or Constructiou Permit (CP)All nuclear facilitiesholding Operating Licenses(OLs)All Power ReactorFacilities with anOperating License (OL)or a Construction Permit(CP)All BWR power reactorfacilities holdingOperating Licenses (OLs)or Construction Permit (CP)Enclosure