05000237/LER-2013-002, Movement of Control Rods with Control Rod Block Monitor Inoperable
| ML13283A013 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 09/27/2013 |
| From: | Marik S Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| SVPLTR 13-0038 LER 13-002-00 | |
| Download: ML13283A013 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| 2372013002R00 - NRC Website | |
text
ADresden Nuclear Power Station 6500 North Dresden Road Exe!.on Generation, Mor ri-, IL 60450 815 942 2920 telephone wwwý exelonicorp corn 10 CFR 50.73 SVPLTR # 13-0038 September 27, 2013 U. S. Nuclesr Regulatory Commission ATTN: Document Control Desk Wahington, DC 20556-0001 Dresden Nucler Power Station, Uni 2 Renewd Facility Operaft License No. DPR-19 NCDocket No. 50-237
Subject:
Lk-icene Event ReW 237/2013-002-00, Movement of Control Rods with Control Rod Bkxlk Monit Inoperable Enclosed is Licensee Event Repot 237/2013-002-00, Movmyent of Control Rods with Control Rod Block Monitor Inoperabte. This is a "lna repot which discribe an event which is being reported in acordncle with 10 CFR 50.73(a)(2XiXB), "Any operation or condition which was prohibited by the psns Technical fcetons."
There are no regulatiory -cm-mients contained in this submit.
Should you have any questions concemng this lterW pleme contact Mr. Glen Momrow at (815) 416-2800.
Respectfully, Shane M. Marik Site Vice President Dresden Nuclea Power Station Enclosure cc:
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is 01P6414c~rM vwmm mm On July 20,2013, at approumatu 1630 houms COYT, Operation personn were pemfortn Dreseen Operatin Surveilance (DOS) 0700W 7, Rod Slock MmA Funcbonil TWA, for Rod Block Manitor S. The prooedure inxltd pemonnel to lower ft Rod Bl*
Monitor (OM) 9kndii poer usn Me PVVA knob urd Vo asocild dowrecal.
indicAt *IlMt il*nts ~hi1h ndicaltes & downso lVp of the monior. However, whire towen toe potreiomeler, the lower stop was remched bef the downeafle Wd was received. The mall0nolon was dcused and It was concluded that the inabi to achleve the downscae was due to a mfunction in the stin ccuitry. Thereaore ROM 8 was cosidered operable, tmed to servime nd ioblemoin was plmd. Prior to.oub l
being cope
, thme contr rft wame witdwn. A s engeriming oevluon of M
dOM r*Ie that RBM shoukl havw been dedced inoperable due a faied card on July 20, 2013. The wthdawa of the conrol rods with the R8M inopermile, constued a oim pan wih Ltine Condft for Operation Ap*pcbty 3.0.4.
Stop 1.24 of procde DO8 0700-07 was not amxnotas as an AccepUnce Crtera.
This resulled in fie Si Ope*ratio personnel not rcom "a tM e ROM was inperable. Therefore cnto rode wae wimirawn we the R83Mwas notameeting a prabiltyrequiremente The fild cardwa replacedf. Plantproceduresare beingreisedl to ensure tha the teein of the downseale Umbdon is recognlad as acceptanc criftsa. Additlonally, the results of the
- - v investgatonm beingV preeete to appropr~iae pln personne.
The redundan Chanol, ROM 7, was operable during tis evmt ad was cpable of provicin the comrol rod block function if the monitor setings were eceeded.
This event is bmen repomr in accordance with 10 CFR 50.73(X)(2XIXS), -Any operation or conciion whh was protd by the pkms Technical o..
NRC FORM 366 U.NUCLUAR IerLAToRY cownmIS (10-010)&.ugwu 1swu em~r VONO.
COUT#4UATICINSMET Dresden Nuclear Power Station, Unit 2 06000237 I
2 OF 4
2013 002 00 NARRATIV PLANT AND SYSTEM IOENT1WCATION Dresden Nuclear Power Station (DNPS) Unit 2 is Gener" ecf Company Soiling Water Reactors with a licensed maximum power level of 2957 megawat thermw.
The Energy Industry Identillcation System codes used In the text ae identified as (XXI.
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Unit 02 Event Dai: 07-20-2013 Event Time: 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> CDT Reactor Mode: I Mode Name: Power Operation Power Level: 100 percent B.
d wt On July 20, 2013, at -lproxlmately 1630 hours0.0189 days <br />0.453 hours <br />0.0027 weeks <br />6.20215e-4 months <br /> COT, COprations personnel were performing Desden Operating Srveiln (DOS) 0700-07, Rod Block Monitor Functional Tet, for Rod Block Monitor 8. The proedr instructed personnel to lower Mte Rod Block Monitor (ROM) [IGI indicated power using the PWR knob until the assocated downecale indKcatg g illuminates which Indicates a downecale tip of the monx
. However while oWeing the po om*er, the lower stop was reached befre te downece trip we reived. The bwest power that was sacived was approximatelsen (7) pecon. The perlIormance of the surveillance was suspended. The tmalfunctio was disc ed aW it was concluded tha th inability to achieve t downecle was due to a malfunction in tfe tling circuitr.
Therefto ROM & was considerme operable, returned to service and troublasoIVg was planneod.
Prior to troublehootain eing cpleted, Iwee cont rods (CR) [M were wik*w. CR0 FS was moved from position 20 to position 22 on July 23,2013. On July 27,2013, CRDs 18 and M8 were moved from position 00 to position 0S.
Subsequent to the movement of the control rods, engineerng perlbrmed an etensive evaluation of the ROM S symptoms tat we observed duri the performance DO 0700-07. On July 29,2013, bsed on engineein' evaluation. it was eognized t the sympbrosobserved during the testing of ROM 8 on July 20,2013, had been mi*lsdianosd and the ROM mhuld hamve been declared inoperable folwin the inability to coroet the procedural tepe.
Plant Itchnical spe cifiations LCO 3.3.2.1, "Control Rod Stock I mentio," require that an inoperabl ROM channel be restored to the operbl status w 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. ;f the channel is not restored to the opeb status within Vil timerame, then one ROM channel must be placed in the tripped condition within one hour which would provent control rod widrvw.
Since it was unrecognized that ROM 8 was inoperable, these actions were not complet.
The selection of a non-peripheral control rod wit reactor thermal power greater than or eqal* to 30 pe rcet power during a time that the ROM Is inoperfl constitutes an entry into a Technical Specification speciW conditi that is prohilbtad by LCO Applicability 3.0.4.
This event is being reported in accordance with 10 CFR 50.73()X2XiX(S), "Any operation or condition which was prohibite by the psnfts Technical Specifications."
NRC FORM N0A (1o.201o)
NRC FORM 346A UA NUCLIAR WULATORY O005510N (10-20M0 UJICW@
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3 OF 4
2013 002 00 NARRATIE C.
cause of Engineering persornel commenced a review of the symptom hat had been observed by Operation personnel during the peforkmence of DOS 0700.07. Following an extensive review of the RBM circuft, Engineering determined Otha ROM 8 Downscale Rod Block Functon was not capable of performing It intended function In f postulated condit
- in.
Troublsooting and repair, as directed by Work Order 01659122-01, revealed th the symptoms observed during the July 20 tlsting were he results of a failure of quad trip card 2 (Z28), drut C or 3, such that contact K7 on averaging card Z30 was always energized. With conlc K7 energized, the contact would be in the cosed posmilon. Wtwe the RM cir i normal end*p*erations s peoming DOS 0700.07, averaging card Z30 contacts KI through KS we open. As a result of remaining energized the contact for K7 was cdoed on July 20,2013. This aftcted, the PWR TEST sign that Operations personnel adut while performing DOS 0700-07, Step 1.24.
The evaluation completed by Engineerin personnel revealed 9ta tre were multiple symptom within the circuitry that would indicate thea the ROM was not operating properly. Althxuh the indications existed, the signifIcance of thmes anomralies was outside the knowledge base of the licensed opemrto.
Even though procedure 0OS 0700-07 Stop 1.24 tested the downscale function, it was not annotated as acceptance critler.
Therefore this led the licsed operator to nmke a knowledge-based perorkmmnc mode decision.
An additional contributor to thi event was the faet tha the symtooms observed duW4n the July 20 renfrcdbyinnofomtin
~tha hdbeenprevmiosprvidedto theoperaftng sabymanenance personnel. The lack of a more r "go review to ensure channel opermbit fblln te anomakls symptoms llowed the RUM to go u tcte.
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The purpoes of the RUM is to Mlt control rod withdrawal If locafled neutron flux emoeeds a prdetermine setpoint during onl rod manplAtom. Even thugh not cremdite in tf Control Rod VWthrawal Err analysis, the ROM is designed to block control rod withdrawal to preclude a Minimum Critical Power Ratio Sfty Limit violation. The RBM supplies a trip signal to the Reacto Manual Control System [JOI to apprOpritey ini~ contr" rod wWthdrwal during power operation above the 30 perce RATED THERMAL POVER selpoint when a i
pheral control rod is seleced.
The thre control rods that OWa withdrawn between July 20, 2013 and July 29, 2013, F-G, 0-8 and M-8 were inltrior rods. ROM S would have used al 8 Local Power Range Monior (LPRM) sgnals, and none of the 8 LPRM signals were downscle. Vh them condtions, K7 being continuously energized would have no adverse effacts. Additnl
, RUM 7 wa operable during fths event and was capable of providing the control rod block ftnction if the monitor settings were exceeded.
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Plant personnel replaced th failed card.
NRC FORM 30A (10-010
NRC FORM MA (10-2010)
LI~ISEE YRIS POR (LR).&
WJoUL4%f R WORMY COMES&ONI I
NARRMTI A Training Request is bein g eWnead to eauae ft noe for Personnel ta a
wit" issues identified in the casual evasuk*on.
Plant Operations procedure DOS 0700-07 and MaIntnamnce procedure DIS 0700-06 we being revised to ensure thM the 19W"ln of fth downsae" functon is recognized ase aceptanceo criteri.
Additionaly, #10 rsult of the even IgOn a eMig prse"d to aWprpat Plant Operatons and Maintoeonce personnel.
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P-vime LER 50-2492011-001 Control Rod Block InostrumeNat Fa1ilur G.
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o wb General Electri QUA TRI CARD 13661322G00 RC FORM 3S8A (10.2010)