Information Notice 1998-14, Undocumented Changes to Non-Power Reactor Safety System Wiring

Undocumented Changes to Non-Power Reactor Safety System Wiring

ML031050184
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:	04/20/1998
From:	Roe J W Office of Nuclear Reactor Regulation
To:
References
IN-98-014, NUDOCS 9804150188
Download: ML031050184 (10)

UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555-0001April 20, 1998NRC INFORMATION NOTICE 98-14: UNDOCUMENTED CHANGES TO NON-POWERREACTOR SAFETY SYSTEM WIRING

Addressees

All holders of operating licenses or construction permits for test and research reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to informaddressees of undocumented modifications that have occurred in the scram system wiring oftwo research reactors. In the first case, the modification in conjunction with a switch failureresulted in the reactor being operated for a short time without any technical specification (TS)required scrams. In the second case, because of a modification, a switch failure could haveresulted in a TS required scram being disabled. It is expected that recipients will review theinformation for applicability to their facilities and consider action, as appropriate, to avoid similarproblems. However, suggestions contained in this information notice are not NRCrequirements; therefore, no specific action or written response is required.

Description of Circumstances

Oregon State UniverstyOn the morning of February 17, 1998, the TRIGA non-power reactor at Oregon State University(OSU) had completed a routine 14-minute run at 15 watts of power to perform core excessreactivity measurements. An attempt was made to manually scram the reactor at the end of therun using the scram button. When the manual scram button did not work, the operators nextstep was to turn off power to the scram circuit using the reactor's three-position key switch.This switch-1s OFF, OPERATE, and RESET positions with a spring return between theRESET and OPERATE positions. As the operator touched the switch, the switch moved from aposition between OPERATE and RESET to the OPERATE position. The operator then tried themanual scram button again and this time it worked.The licensee determined that a buildup of dirt prevented the three-position switch from returningto the OPERATE position. When the switch is in the RESET position, the scram bus isdisabled. This switch dates to 1967 when the original console was installed. The switchoperated properly during preoperational testing before startup.Upon further investigation, the licensee discovered that the wiring of the scram circuit wasdifferent from the wiring shown in the Instrument Maintenance Manual provided by the reactorvndr. Fgure I shows part of the circuitry as designed. If the key switch is in the OPERATE D04151-'i ureg 1D s4 ows~g- lt;)X

K>IN 98-14April 20, 1998 position, ac power is supplied from terminal block one, terminal number four (TBI -4) throughTBI-9, to TB2-3, the A3 and Al contacts of the three-position switch, and then the consolepower switch. This allows transformer four (T4) to power the rod magnets. When the key isturned to RESET, this circuit is opened and the magnet current is cut off. This prevents rodwithdrawal if the rods are down, or causes the rods to drop if they are up. This design featureprevents a single failure of the three-position switch from disabling the scram circuits. In theRESET position, power is supplied to the scram reset relays (K19, K20, and K24), which resetthe scram relays (only one scram relay, K12, is shown). If the key switch sticks in the RESETposition, the scram relay will continued to be energized by the reset relay even if a scram signaloccurs. This is not a problem because the power would already be cut off to the magnets.Figure 2 shows the wiring as found in the OSU console. The wiring that was between TB1-9and TB2-3 in the "as designed" circuit was between TBI-9 and TBIO-10 in the OSU console.As a result, there is power to the magnets when the switch is in the RESET or OPERATEposition.The licensee concluded that the location of the jumper was probably modified during initialinstallation of the reactor console in 1967. This modification was probably done to providepower to the *B deck3 on the three-position switch to power REACTOR ON lights.The licensee took a number of corrective actions. The three-position switch was removed,cleaned, relubricated, and reinstalled in the console. The reactor console wiring was restoredto its as-designed condition. The wiring in the scram circuitry and in other non-scram-relatedcircuits was checked physically and electronically to demonstrate that the wiring in the consoleis as designed. The reactor startup procedure was rewritten to test that the magnet power iscut off when the three-position switch is placed in the RESET position. The reactor consolewas subject to routine startup checks and the semiannual console check procedure. Thereactor vendor was contacted to obtain checkout procedures to confirm that all suggestedsurveillances are done before reactor operation.Texas A&M UniversiyOSU quickly placed information about the failure to scram on the Organization of Test,Researth and Training Reactors (TRTR) list server. As a result, the staff at the Texas A&MUniversity N&clear Science Center checked the logic diagrams for its TRIGA research reactorand determined that its reactor could not fail to scram. The Texas A&M console differs from theone at OSU in that there is no master reset equivalence to the three-position switch. Three ofthe scrams have push-button spring-returned switches that clear the locked-in alarm on theconsole and allow the scram relay coil to be reenergized if the signal is clear.The licensee also tested the circuit and determined that each of the three scrams associatedwith these switches could be defeated by holding its switch down in the RESET position (thissimulated a switch failure). In this case, the failure of a single switch could prevent an individualscram signal but would have not disabled all scrams. The licensee then checked the wiringdiagrams for the console and discovered that the wiring of the console matched the wiringdiagrams. The RESET switches were wired in parallel with the normally closed scram contacts.This wiring maintained power to the magnets through one parallel path if the switch was

IN 9S*14April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches shouldhave been wired in series. The licensee cannot determine when the console was wired thisway, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawnin 1976, which differs from the wiring diagram and the as-wired console, appears to have beenbased on system knowledge of how it should be configured rather than on the actualconfiguration.To correct this situation, the licensee changed the wiring to put the RESET switch in series withthe protective action contacts, physically verified console wiring for scram circuits, identifiedvarious failure modes, and tested the console for proper operation.DiscussionThe circumstances described above demonstrate the importance of controlling modifications,ensuring that all of the consequences of a modification are carefully considered, and ensuringthat design features in the scram circuitry perform as designed. Careful reviews ofmodifications through the safety review process can be an effective method to help to ensurethat unintended deleterious effects from modifications do not occur. The identification of safetysystem design features could lead to surveillances or tests that could prevent the occurrence ofsimilar problems. The staff noted that many licensees contacted the NRC to discuss the resultsof testing performed on consoles because of the information placed on the TRTR listed serverby OSU.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact the technical contact listed below.Jack Roe, Acting DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact: Alexander Adams, Jr., NRR301-415-1127.E-mail: axa@nrc.govAttachments:1. Figure 1, *Reactor Operate Circuit, As-Designed"2. Figure 2, Reactor Operate Circuit -As Found"3. List of Recently Issued NRC Information Notices-L vD C EmDOCUMENT NAME: G:WVERN\OSUSCRAM.INF Tech Editor concurred on 3126/98To receive a copy of this document, indicate in the box C=Copy wlo attachmentlenclosure E=Copy with attachmentfenclosure N = NIcopyOFFICE PDND (A)D:PDND C:PECB (A)D:DRPIV\S ANAME AAdams* MMendonca* JStolz* JRoe*[DATE 03/30198 03/30/98 04/06/98 04/13/98 5'OFFICIAL RECORD COPY

P6-3 5 P22-1 0 TB10Switched AC (H)T P2 f6 2 T T1Bi B36P22-l1 T9104 T450 Operate Permissive Jumper 1 3A .34P3-21 TB2 14TB` P3-202CBB1l A4 >3P5-4AC (N) *OFF0J5) *OPERATE (*RESETPart of Console Key SwitchTBl 0dAC (N)External ScramAC (N)-. (Kl12K19 K20 K24Kl2 l H tK1 6-7 'Switched AC (H)Fiaure I. Reactor OnprAt0 Circiuit. Aq-dpeinnadr..I-- -..--. -V-- --- -..-- .-, --- --- .U.-

Si9P6-35 P22-10 TB10 TB10Si "KSwitched AC (H)82 AC (N) TB1POWER OR P6-36 P22-11 TB10 E3T4P5-1A2 .341 P3(2 T82 P3-0Cal 8LP5-4AC (N) f*OF*OPERATE* RESETPart of Console Key Switch (TB1 0SIAC (N)Exterral ScramNOAC (N)0- -- 9X6-7l_______ Switched AC (H) f5BFtcFigr 0. Reco prt 0cft- A Fud

.IAttachment 3IN 98-14April20, 1998 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to98-13 Post-Refueling Outage Reactor 4120/98 All holders of operating licensesPressure Vessel Leak TestingBefore Core Criticalityfor nuclear power reactors exceptthose that have permanentlyceased operations and havecertified that fuel has beenpermanently removed from thereactor vessel98-129&-1 1Licensees' ResponsibilitiesRegarding Reporting and Follow-upRequirements for Nuclear-PoweredPacemakersCracking of Reactor VesselInternal Baffle Former Boltsin Foreign Plants4/3/983/25/98All U.S. Nuclear RegulatoryCommission nuclear pacemakerlicenseesAll holders of operating licensingfor pressurized-water reactors(PWRs) except those who haveceased operation and havecertified that fuel has beenpermanently removed from thereactor vessel.95-52, Supp. 1 Fire Endurance Test Resultsfor Electrical Raceway FireBarrier Systems ConstructedFrom 3M Company Interam-ire Barrier Materials3/17/98All holders of operatinglicenses for nuclear powerreactors except those whohave permanently ceasedoperation and have certified thatfuel has been permanentlyremoved from the reactor vessel.98-1098-09Probable MisadministrationsOccurring During IntravascularBrachytherapy With TheNovoste Beta-Cath SystemCollapse Of An Isocam IIDual-Headed NuclearMedicine Gamma Camera3/9/983/5/98All Medical LicenseesAll Medical LicenseesOL = Operating LicenseCP = Construction Permit

• KIN ?-14April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches shouldhave been wired in series. The licensee cannot determine when the console was wired thisway, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawnin 1976, which differs from the wiring diagram and the as-wired console, appears to have beenbased on system knowledge of how it should be configured rather than on the actualconfiguration.To correct this situation, the licensee changed the wiring to put the RESET switch in series withthe protective action contacts, physically verified console wiring for scram circuits, identifiedvarious failure modes, and tested the console for proper operation.DiscussionThe circumstances described above demonstrate the importance of controlling modifications,ensuring that all of the consequences of a modification are carefully considered, and ensuringthat design features in the scram circuitry perform as designed. Careful reviews ofmodifications through the safety review process can be an effective method to help to ensurethat unintended deleterious effects from modifications do not occur. The identification of safetysystem design features could lead to surveillances or tests that could prevent the occurrence ofsimilar problems. The staff noted that many licensees contacted the NRC to discuss the resultsof testing performed on consoles because of the information placed on the TRTR listed serverby OSU.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact the technical contact listed below.orig /sfd by D. B. MatthewsFORJack Roe, Acting DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact: Alexander Adams, Jr., NRR301-415-1127E-mail: axa~nrc.govAttachments:1. Figure 1, OReactor Operate Circuit, As-Designed'2. Figure 2, uReactor Operate Circuit -As Found"3. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:WVERN\OSUSCRAM.INF Tech Editor concurred on 3/26198To receive a copy of this document indicate In the box C=Copy wlo attachmentenclosure E=Copy with attachmentlenclosure N = No copyOFFICE PDND (A)D:PDND I C:PECB Il (A)D:DRPM Il NAME AAdams* MMendonca* JStolz* JRoe*lDATE _ 03/30/98 03/30/98 04106198 j 04/13/98OFFICIAL RECORD COPY

-- INbe14April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches shouldhave been wired in series. The licensee cannot determine when the console was wired thisway, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawnin 1976, which differs from the wiring diagram and the as-wired console, appears to have beenbased on system knowledge of how it should be configured rather than on the actualconfiguration.To correct this situation, the licensee changed the wiring to put the RESET switch in series withthe protective action contacts, physically verified console wiring for scram circuits,.identifiedvarious failure modes, and tested the console for proper operation.DiscussionThe circumstances described above demonstrate the importance of controlling modifications,ensuring that all of the consequences of a modification are carefully considered, and ensuringthat design features in the scram circuitry perform as designed. Careful reviews ofmodifications through the safety review process can be an effective method to help to ensurethat unintended deleterious effects from modifications do not occur. The identification of safetysystem design features could lead to surveillances or tests that could prevent the occurrence ofsimilar problems. The staff noted that many licensees contacted the NRC to discuss the resultsof testing performed on consoles because of the information placed on the TRTR listed serverbyOSU.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact the technical contact listed below.Jack Roe, Acting DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact: Alexander Adams, Jr., NRR301-415-1127E-mail: axa@nrc.govAttachments:1. Figure 1, uReactor Operate Circuit, As-Designed"2. Figure 2, "Reactor Operate Circuit -As Found"3. List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:WVERNOSUSCRAM.INF Tech Editor concurred on 3/26198To receive a copy of this document, indicate in the box C=Copy wlo attachmentlenclosure E=Copy with attachmentenclosure N = NlcopyI OFFICE PDND I (A)D:PDND l C:PECB I (A)D:DRPNAME AAdams* MMendonca* JStoz* JRoe*l DATE 03/30/98 03/30/98 04/06/98 04/13/98OFFICIAL RECORD COPY

IN' XX .K ApexL 1998 (this simulated a switch failure). In this case, the failure of a single switch could preve anindividual scram signal but would have not disabled all scrams. The licensee then ecked thewiring diagrams for the console and discovered that the wiring of the console moed thewiring diagrams. The RESET switches were wired in parallel with the normall y-losed scramcontacts. This wiring maintained power to the magnets through one paralle ath if the switchwas depressed, even if a scram contact opened in the other parallel pathThe switches shouldhave been wired in series. The licensee cannot determine when the sole was wired thisway, but notes that the console underwent a major upgrade in 1968. e logic diagram, drawnin 1976, which differs from the wiring diagram and the as-wired co sole, appears to have beenbased on system knowledge of how i should be configured rat r than on the actualconfiguration.To correct this situation, the licensee changed the wiring put the RESET switch in series withthe protective action contacts, physically verified conso wiring for scram circuits, identifiedvarious failure modes, and tested the console for probr operation.DiscussionThe circumstances described above demon ate the importance of controlling modifications,ensuring that all of the consequences of a odification are carefully considered, and ensuringthat design features in the scram circuit perform as designed. Careful reviews ofmodifications through the safety revie process can be an effective method to help to ensurethat unintended deleterious effects f m modifications do not occur. The Identification of safetysystem design features could lead o surveillances or tests that could prevent the occurrence ofsimilar problems. The staff note that many licensees contacted the NRC to discuss the resultsof testing performed on consols because of the information placed on the TRTR listed serverby OSU.This information notice r uires no specific action or written response. If you have anyquestions about the inf ation in this notice, please contact the technical contact listed below.Jack Roe, Acting DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical c ctac: Alexander Adams, Jr., NRR301-415-1127E-mail: axaenrc.govAttac ent: List of Recently Issued NRC Information NoticesDT e MENT NAME: G:WVERN\OSUSCRAM.INFTo receive a copy f this document. indicate In the box C=Copy w/o attachmeE=Copy with coOFFICE PDND I _ (A)D:PDND l C:PE'CB (A)D:DR hl1 INAME AAdams* MMendonca* iQStolz JRoe JkDATE 03/30198 03/30/98 g 4 /j3198OFFICIAL RECORD COPY a-) .

IN'- XX_ ApiV..x, 1998 switch failure). The licensee then checked the wiring diagrams for the console and discoveredthat the wiring of the console matched the wiring diagrams. In this case, the failure of a singleswitch could prevent an individual scram signal but would have not disabled all scrams. TheRESET switches were wired in parallel with the normally closed scram contacts. This wiringmaintained power to the magnets through one parallel path if the switch was depressed, even ifa scram contact opened in the other parallel path. The switches should have been wired inseries. The licensee cannot determine when the console was wired this way, but notes that theconsole underwent a major upgrade in 1968. The logic diagram, drawn in 1976, which differsfrom the wiring diagram and the as-wired console, appears to have been based on systemknowledge of how it should be configured rather than on the actual configuration.To correct this situation, the licensee changed the wiring to put the RESET switch in series withthe protective action contacts, physically verified console wiring for scram circuits, identifiedvarious failure modes, and tested the console for proper operation.DiscussionThe circumstances described above demonstrate the Importance of controlling modifications,ensuring that all of the consequences of a modification are carefully considered, and ensuringthat design features in the scram circuitry perform as designed. Careful reviews ofmodifications through the safety review process can be an effective method to help to ensurethat unintended deleterious effects from modifications do not occur. The identification of safetysystem design features could lead to surveillances or tests that could prevent the occurrence ofsimilar problems.This information notice requires no specific action or written response. If you have anyquestions about the information in this notice, please contact the technical contact listed below.Jack Roe, Acting DirectorDivision of Reactor Program ManagementOffice of Nuclear Reactor RegulationTechnical contact: Alexander Adams, Jr., NRR301-415-1127E-mail: axa@nrc.govAttachment: List of Recently Issued NRC Information NoticesDOCUMENT NAME: G:WVERN\OSUSCRAM.INFTo receive a copy of this document, indicate in the box C=Copy wlo attachment/endosure E=Copy with attachment/enclosure N = No copyOFFICE PDND I l (A)D:PDND l l C:PECB (A)D:DRPM IlNAME AAdams OA l MMendonca L4/) T JStolz JRoeDATE 1 031/)/98 l 0313)198 1 03/ /98 7 03/ /98OFFICIAL RECORD COPY