NRC Generic Letter 1980-43

NRC Generic Letter 1980-043: Transmittal of IE Bulletin 1980-013: Cracking in Core Spray Spargers

ML031350399
Person / Time
Issue date:	05/12/1980
From:	Engelken R H NRC Region 4
To:
References
BL-80-013 GL-80-043, NUDOCS 8007140587
Download: ML031350399 (5)

!- v l ,/_ I.1° UNITED STATES' <tNUCLEAR REGULATORY COMMISSIONREGION VffJJJi~/ t1990 N. CALIFORNIA BOULEVARDSUITE 202, WALNUT CREEK PLAZA* *WALNUT CREEK, CALIFORNIA 94596May 12, 1980Docket No. 50-397Washington Public Power Supply SystemP. 0. Box 9683000 George Washington WayRichland, Washington 99352Attention: Mr. N. 0. StrandManaging DirectorGentlemen:The enclosed IE Bulletin No. 80-13 is forwarded to you for information. Nowritten response is required. If you desire additional information regardingthis matter, please contact this office.

Sincerely,R. E. EngelkenDirector

Enclosures:

1. IE Bulletin No.80-132. List of Recently IssuedIE Bulletinscc w/enclosures:M. E. Witherspoon, WPPSSW. C. Bibb, WPPSSJ. P. Thomas, WPPSSW. J. Talbott, WPPSSG. C. Sorensen, WPPSS8007140 s77 SSINS No.: 6820Accession No.:UNITED STATES 8002280661NUCLEAR REGULATORY COMMISSIONOFFICE OF INSPECTION AND ENFORCEMENTWASHINGTON, D.C. 20555May 12, 1980IE Bulletin No. 80-13CRACKING IN CORE SPRAY SPARGERS

Description of Circumstances

Instances of cracking in core spray spargers have occurred at two BWR facilities.This trend indicates a need for more intensive inspection of these componentsduring subsequent refueling outages.Oyster Creek Nuclear Generating StationJersey Central Power and Light Company notified the NRC on October 18, 1978,that a crack had been found in Core Spray Sparger System II during remotevisual inservice inspection at their Oyster Creek Nuclear Generating Station.The crack was located at 208 azimuth and extended at least 180 circumferen-tially around the sparger. An evaluation of the event by the licensee postu-lated that deformation of the sparger had occurred during fabrication andinstallation which led to cracking by Intergranular Stress Corrosion Cracking(IGSCC) during service in the BWR environment. A temporary repair was effectedby installing a clamp assembly over the crack. The licensee's analysisindicated that the crack had relieved the stresses present and thereforeprecluded further cracking. The NRC safety evaluation permitted operationuntil the next refueling outage and required inspection of the sparger at thattime.The NRC was informed by the Jersey Central Power and Light Company onJanuary 16, 1980 that further cracking was discovered in the core sprayspargers during an inservice inspection conducted in conjunction with therefueling outage. A total of twenty-eight cracks 0.001 to 0.002 inches inwidth and of varying lengths were identified in both core spray spargers. Thelicensee stated that they believed the majority of additional cracks werepresent earlier and not discovered during the 1978 inspection due to inspectionequipment limitations. Near term repair consisted of the application of nineadditional clamp assemblies in areas of the spargers where cracks were visuallyobserved on the accessible portion of the sparger and UT indications werepresent in the inaccessible portion of the sparger and in the junction boxregion. The licensee analyzed the flow characteristics of the spargers anddetermined that adequate flow distribution would be maintained if thru wallcracking .005 inches wide and 180 in length were present. The licenseestated that the installation of the clamps would assure the sparger wouldmaintain its physical integrity and remain in plac IE Bulltin No. 80-13 May 12, 1980 The repair measures proposed were determined by the NRC to be adequate untilthe following refueling outage. The NRC evaluation stated that actions shouldbe taken to develop and install an improved replacement system at the followingrefueling outage.Pilgrim Nuclear Power StationOn January 31, 1980 the Boston Edison Company (BECo) informed the NRC thatfive indications in the upper core spray sparger and two indications on thelower core spray sparger at the Pilgrim Nuclear Power Station were identifiedduring remote visual inservice inspections. The indications were confirmed ascracks after hydrolasing and brush cleaning. The licensees evaluation indicatedthat the sparger will retain structural integrity throughout the next cycle,although core spray flow distribution may be affected due to through-wallcracks. However, core spray flow delivery to the shroud interior would not beexpected to decrease. A loose parts analysis was presented which addressed(1) corrosion, (2) flow blockage, and (3) control rod interference.To support power operation in Cycle 5 with the core spray sparger in itspresent condition, BECo has reanalyzed ECCS taking credit only for core sprayreflood, taking no credit for core spray heat transfer. The submission byBECo is currently under review by the staff. The analysis is expected tocover a full spectrum of core spray failures. It is expected that the limitingcondition will be the failure of recirculation suction line. A MAPLHGR limitred't.tion will likely be imposed during Cycle 5 to compensate for the assump-tion of no core spray heat transfer.Based on results from other sparger inspections and previous pipe crackingexperience, cold work and sensitization during fabrication and installationstresses are considered to be the major factors in causing the observed cracksat the Pilgrim Station. The cracks are hypothesized to be initiated andpropagated by intergranular stress corrosion (IGSCC).A meeting was held with representatives from GE in Bethesda, Maryland onMarch 13, 1980 to discuss core spray sparger cracking at BWRs. At the meetingGE provided the following information:1. In February 1979, GE issued to BWR licensees Service Information Letter(SIL) No. 289 that recommended inspection of the core spray spargers forvisual indications of cracking. To date, 19 of 21 plants inspected haveno observed cracking. Cracks have been found at 2 facilities (Pilgrimand Oyster Creek).2. The key contributors to IGSCC vary from plant-to-plant, although stressesfrom cold work and sensitization during fabrication and installation areconsidered prime factors leading to IGSCC at Pilgrim and Oyster Creek.Because the cause of cracking is not yet confirmed by metallurgicalanalysis, GE is developing tooling to extract sparger samples to verifythe postulated cracking mechanis IE Bulletin No. 80-13 May 12, 1980 . GE is evaluating methods of improving the sparger inspection techniques,and is considering a modification to the SIL, if warranted.The staff agreed that improved inspection techniques should be developed andmetallurgical examinations should be performed to determine the mode of failure.The staff asked GE to keep them informed of progress in these areas.Actions to be Taken by Licensees:For all boiling water power reactor facilities with an operating license:1. At the next scheduled and each following refueling outage until furthernotice, perform a visual inspection of the Core Spray Spargers and thesegment of piping between the inlet nozzle and the vessel shroud. Remoteunderwater TV examinations are acceptable if adequate resolution can bedemonstrated. The viewing in situ of 0.001 in. diameter fine wires isconsidered as an acceptable means of demonstrating suitable resolution ofthe TV examinations. Such techniques as the use of oblique lighting, andthe ability to light from each side independently are considered useful inenhancing the image of cracks to facilitate detection.2. In the event cracks are identified during examination of the core spraysparger system, the location and extent of the indications shall berecorded and reported to the NRC. Supplementary examinations usingvolumetric methods may be performed to aid in characterizing the extentof cracking in nonvisible locations. An evaluation shall be submittedto NRR for review and approval prior to return to operation..3. Any cracking identified in the core spray cooling system shall be reportedto the Director of the appropriate NRC Regional Office within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> ofidentification.4. A written report of the results of the examinations including anycorrective measures taken shall be submitted within 30 days of the comple-tion of the examination to the Director of the NRC Regional Office with acopy to the NRC Office of Inspection and Enforcement, Division of ReactorOperations Inspection, Washington, D. C. 20555.Approved by GAO, B180225 (R0072); clearance expires 7-31-80. Approval wasgiven under a blanket clearance specifically for identified generic problem , It~ eIE Bulletin No. 80-13May 12, 1980EnclosureRECENTLY ISSUEDIE BULLETINSBulletinNo.80-12SubjectDecay Heat Removal SystemOperabilityDate Issued5/9/80Issued ToEach PWR with an OL80-1180-1080-0980-0880-0780-0680-0579-O1B80-0480-03Masonry Wall DesignContamination ofNonradioactive System andResulting Potential forUnmonitored, UncontrolledRelease to EnvironmentHydramotor ActuatorDeficienciesExamination of ContainmentLiner Penetration WeldsBWR Jet Pump AssemblyFailureEngineered Safety Feature(ESF) Reset ControlsVacuum Condition ResultingIn Damage To Chemical VolumeControl System (CVCS) HoldupTanksEnvironmental Qualificationof Class IE EquipmentAnalysis of a PWR MainSteam Line Break WithContinued FeedwaterAdditionLoss of Charcoal FromStandard Type II, 2 Inch,Tray Adsorber Cells5/8/805/6/804/17/804/7/804/4/803/13/803/10/802/29/802/8/802/6/80All power reactorfacilities with anOL, except TrojanAll power reactorfacilities with anOL or CPAll power reactoroperating facilities andholders of power reactorconstruction permitsAll power reactors witha CP and/or OL no laterthan April 7, 1980All GE BWR-3 andBWR-4 facilities withan OLAll power reactorfacilities with an OLAll PWR power reactorfacilities holdingOLs and to those witha CPAll power reactorfacilities with an OLAll PWR reactor facilitiesholding OLs and to thosenearing licensingAll holders of PowerReactor OLs and CPs