Information Notice 1996-12, Control Rod Insertion Problems

Control Rod Insertion Problems

ML031060255
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	02/15/1996
Revision:	0
From:	Crutchfield D M Office of Nuclear Reactor Regulation
To:
References
IN-96-012, NUDOCS 9602090161
Download: ML031060255 (10)

February 15, 1996

NRC INFORMATION NOTICE 96-12: CONTROL ROD INSERTION PROBLEMS

Addressees

All holders of operating licenses or construction permits for nuclear powerreactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to recent events during which rod control clusterassemblies failed to insert fully. It is expected that recipients will reviewthe information for applicability to their facilities and consider actions, asappropriate, to avoid similar problems. However, suggestions contained inthis information notice are not NRC requirements; therefore, no specificaction or written response is required.

Description of Circumstances

South Texas ProjectOn December 18, 1995, with South Texas Unit 1 at 100 percent power, a pilotwire monitoring relay actuation caused a main transformer lock out whichresulted in a turbine trip and reactor trip. While verifying that controlrods had inserted fully after the trip, operators noted that the rod bottomlights of three control rod assemblies were not lit; the digital rod positionindication for each rod indicated six steps withdrawn. Boration of thereactor coolant system was occurring with the charging pump suction havingbeen transferred to the refueling water storage tank. One rod did drift intothe fully inserted rod bottom position within one hour, and the other two rodswere manually inserted later. During subsequent testing of all control rodsin the affected banks, the rod position indication for the same threelocations as well as a new location indicated six steps withdrawn. Ascompared to prior rod drop testing, no significant differences in rod droptimes were noted before reaching the upper dashpot area for any of the controlrods. Within an hour after the rod drop tests, two of the rods drifted to rodbottom position and the other two were manually inserted. All four controlrods were located in fuel assemblies that were in their third cycle withburnup greater then 42,880 megawatt days(MWD)/metric ton uranium(MTU).CPf\ j45T OcA7(ce-~ cW~4oI2- o9602090161 ;ts>\3Sq IN 96-12February 15, 1996 Wolf CreekOn January 30, 1996, after a manual scram from 80-percent power, five controlrod assemblies at Wolf Creek failed to insert fully. Two rods remained'at sixsteps withdrawn, two at 12 steps, and one at 18 steps. Three of the affectedrods drifted to fully inserted within 20 minutes, one within 60 minutes, andthe last one within 78 minutes. After the scram, the licensee initiatedemergency boration, as required, because all rods did not insert fully. Thefive rods were all in 17x17 VANTAGE 5H fuel with burnup greater than47,000 MWD/MTU.DiscussionAt both South Texas units, a 14-foot active fuel length core design is used.Several differences between the standard 12-foot active fuel design and the14-foot one are as follows: the 14-foot fuel design is approximately 76.2 cm[30 inches] longer than the standard fuel assembly design, it has 10 mid gridscompared to 8 and the dashpot region is 25.4 cm [10 inches] longer andcomprises a double dashpot. The control rod radial clearances above and inthe dashpot region of the 14-foot fuel assembly are similar to those of thestandard design. The South Texas core contains three different 17x17 fueltypes--Standard XL, Standard XLR, and VANTAGE 5H--all of which are designedand fabricated by Westinghouse. This was the first operating cycle withVANTAGE 5H fuel. The core also contains 57 silver-indium-cadmium rods. Thefour affected rods were found in twice-burned Standard XLR fuel assemblies.During subsequent testing, the rod drop traces revealed no significant changein dashpot entry time; however, the affected rods did not show recoil on therod drop trace. Recoil is a dampening affect that is normally seen in thetraces due to control rod assembly spider hub spring contact against the fuelassembly. When similar rods in Unit 2 were tested, the results revealed noadverse indications. One rod did show the "no recoil" effect but insertedfully into the core.At Wolf Creek, subsequent cold, full flow testing of all of the control rodassemblies indicated that eight control rods, including the five control rodsthat did not fully insert following the January 30, 1996, reactor trip, didnot fully insert when tripped. One control rod, H2, paused at 96 steps,stopped at 90 steps, and slowly inserted to 30 steps over the next 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.The control rod was then manually inserted. The 7 other affected rods stoppedat various heights in the dashpot region, 5 of which fully inserted within22 minutes. One of the other two drifted to the bottom within one and a halfhours while the remaining rod needed to be manually inserted. The remaining45 rods fully inserted when dropped, although a number of the rods did notexhibit the expected number of recoils. Of the total 53 control rodassemblies, H2 (thie only rod slowing outside the dashpot region) is a hafniumcontrol rod, while the remaining are silver-indium-cadmium control rodassemblies. The licensee retested all rods that stuck, as well as those rodsthat failed to recoil more than twice, and the results were similar to theprevious testin IIN 96-12February 15, 1996 Westinghouse, Westinghouse Owners Group, and the respective licensees arepursuing the root cause identification of these events. Possible root causesare as follows: debris (foreign matter), control rod or drive linedegradation, corrosion products, thimble tube bow, fuel assembly bow and/ortwist, reduction in thimble tube diameter, adverse alignment of guide tubecards, and/or design tolerances.Some foreign reactors have also experienced slow and/or stuck control rodassemblies.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.a orDivision of Reactor P gram ManagementOffice of Nuclear Reactor RegulationTechnical contacts: Margaret Chatterton, NRR(301) 415-2889Internet: msc1@nrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information Notices K>AttachmentIN 96-12February 15, 1996 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to96-1196-1096-0996-08Ingress of DemineralizerResins Increases PotentialStress Corrosion Crackingof Control Rod DriveMechanism PenetrationsPotential Blockage byDebris of Safety SystemPiping Which is Not UsedDuring Normal Operationor Tested During Surveil-lancesDamage in Foreign SteamGenerator InternalsThermally Induced Pres-sure Locking of a HighPressure Coolant Injec-tion Gate ValveSlow Five Percent ScramInsertion Times CausedBy Viton Diaphragms inScram Solenoid PilotValvesDesign and TestingDeficiencies of TornadoDampers at Nuclear PowerPlantsPartial Bypass of ShutdownCooling Flow from theReactor VesselIncident Reporting Require-ments for RadiographyLicensees02/14/9602/13/9602/12/9602/05/9601/26/9601/25/9601/18/9601/10/96All holders of OLs or CPsfor pressurized waternuclear power reactorsAll holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor pressurized waterreactorsAll holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor boiling water reactorsAll holders of OLs or CPsfor nuclear power reactorsAll holders of OLs or CPsfor boiling water reactorsAll radiography licenseesand manufacturers of radio-graphy equipment96-0796-0696-0596-04OL = Operating LicenseCP = Construction Permit IN 96-12February 15, 996Westinghouse, Westinghouse Owners Group, and the respective licensees arepursuing the root cause identification of these events. Possible root causesare as follows: debris (foreign matter), control rod or drive linedegradation, corrosion products, thimble tube bow, fuel assembly bow and/ortwist, reduction in thimble tube diameter, adverse alignment of guide tubecards, and/or design tolerances.Some foreign reactors have also experienced slow and/or stuck control rodassemblies.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.original signed byDennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Margaret Chatterton, NRR(301) 415-2889Internet: mscl@nrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.govReviewed and concurred on by tech editor 02/01/96CONCURRENCESDOCUMENT NAME: 96-12.INTo receive a copy of this document, Indicate in the box: 'C' = Copy without enclosures 'E'*SEE PREVIOUSIOFFICE ITECH CONTS I IC:SPLB l I c:NAME MChatterton* RJones* AChaffeeSKoenick* LDATE 02/07/96 02/08/96 02/08/9602/06/96I,~- I-T,'T~AI nrd~r l dflflvUrrtIMaL KLtUKU 6ur l IN 96-xxFebruary xx, 996hafnium control rod, while the remaining are silver-indium-cadmium RCCAs. Thelicensee retested all rods that stuck, as well as those rods that failed torecoil more than twice, and the results were similar to the previous testing.Some foreign reactors have also experienced slow and/or stuck RCCAs.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Margaret Chatterton, NRR(301) 415-2889Internet: mscl~nrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information Noticeskkil pv0. 4,.X- , ka-n.-.. IBIr&T IVAI u.d!

• T'. IUI CT rD CCIVLAWWMLtNI C ; b; %a\n tall InOFFICE PECB/DRPM SPLB/DSSA ADM:PUB I lODSSA I RIV/DRSNAME SKoenlck* MChatterton* nTECH ED* EWelss* JPellet*DATE 2/06/96 2/07/96 2/01/96 l2/07/96 _ 2/08/96_ _ _ _ _ .___ _ I ---- --Annis I unrrTrFor.-stRIzinVS IISC*PFRIDOPs IICtVLb!UUV0 II U/UKPMI Mwerr1sv 1 cw%, .PFIWr / luzn I ,, ,., -" _ ._,. __.,,,,,,,,NAME RJones* I EGoodwin* AChaffee DCrutchfieldDATE 2/08/96 12/07/96 2/7/96 2/ /96See previous concurrenceOFFICIAL RECORD COPY IN 96-xxFebruary xx, 996hafnium control rod, while the remaining are silver-indium-cadmium RCCAs. Thelicensee retested all rods that stuck, as well as those rods that failed torecoil more than twice, and the results were similar to the previous testing.Some foreign reactors have also experienced slow and/or stuck RCCAs.This Information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Margaret Chatterton, NRR(301) 415-2889Internet: mscl@nrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\IN\IN ST CR.SSKOFFICE PECB/DRPM I SPLB /DSSA ADM:PUB I SC:SPLBDSSA 1 RIVDRSNAME SKoenick* MChatterton* TECH ED* EWeiss*DATE 2/06/96 2/07/96 2/01/96 2/07/96 l 2/08/96OFFICE IBC:SPLB/DSSA I ISC:PECB/DOPS-1C/PECB:DOPS I DRPM I -NAME RJones* EGoodw/ n ( AChaffee DCrutchfeldDATE 2/08/96 E 12/72 /96 Afe 2/ /96 d2/ /96 l* See previous concurrenceUFFI.IAL KtLUKU WrY'

IN 96-xxFebruary xx, 1996 rods did not exhibit the expected number of recoils. The licensee retestedall rods that stuck, as well as those rods that failed to recoil more thantwice, and the results were similar to the previous testing.Some foreign reactors have also experienced of slow and/or stuck RCCAs.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Margaret Chatterton, NRR(301) 415-2889Internet: mscltnrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.gov

Attachment:

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• CI R. iniv IISr.PFrRInnPs IC/PEvk DOPS II U/UKrMI 11WI I _%,L__. W * -P LuW uv"n I .-.. ---,- -I I -_ ._ - , -_ --NAME RJones I EGoodwin I AChaffee IDCrutchfeld lDATE 2/ /96 12/ /96 2/ /96--^*A IrJ^n 4^nOFF1161AL KLLUKU url IN 96-xxFebruary xx, 1996 Some foreign reactors have also experienced of slow and/or stuck RCCAs.This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation project manager.Dennis M. Crutchfield, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Margaret Chatterton, NRR(301) 415-2889Internet: msclnrc.govStephen Koenick, NRR(301) 415-2841Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information NoticesDOCUMENT NAME:G:\IN\IN ST CR.SSKOFFICE PECB/DRPM I SPLB/DSSA I ADM:PUB I SC:SPLB/DSSA I lRIV/DRS I jNAME SKoenick* MChatterton* TECH ED* EWeiss*DATE 2/06/96 2/07/1/92/ 96 2/07/96 2/ /96..I .OFFICEBC:SPLB/DSSA.1 c. ISC:PECB/DOPS IIC/PECB:DOPS II D/DRPMI 1I_--- _ __*................................................ .....NAME I oneL Lz'^J/ 4d EGoodwin I AChaffee JDCrutchfieldDATE 2/ T/96 I 2/ /96 12/ /96 Z/ /96See previous concurrenceOFFICIAL RECORD COPY Dennis M. Crutchfi'YXd, DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contacts:Stephen Koenick, NRR(301) 415-2841/_ Internet: ssk2@nrc.gov

Attachment:

List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:\IN\IN-DAMPOFFICE SPLB/DSSA I SCSPLB/DSSA I ADM:PUB I BC:SPLB/DSSA I RIV/DRS INAME MChatterton EWeiss TECH ED kp6 RJonesDATE 2/ /96 2/ /96 2///96 2/ /96 2/ /96T - -- _- ar - - I- -. .. IOFFICEELUB/URPMI4suncpEu~DPS IG/LfPEBWOPSID/UKI'MINAME SKoenick EGoodwin AChaffee DCrutchfieldDATE j2/ /96 2/ /96 2/ /96 2/ /96------- ------ -----WtI1LAPL KtLUKU LUFi