ML20024G696

LER 91-007-00:on 910326,unknown Inadequacy in Jumper Connection Results in Scram During Surveillance in Cold Shutdown.Cause Unknown.Functional Test Completed & Surveillance Procedure revised.W/910422 Ltr

ML20024G696
Person / Time
Site:	Hatch
Issue date:	04/25/1991
From:	Beckham J, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-1580, LER-91-007-01, LER-91-7-1, NUDOCS 9104250220
Download: ML20024G696 (6)

Text

_ - - - _ _ _ _ _ _ _ _ _ _ _ - _ . . - _ _ _ - _ _ _ _ _ _ _ _

i Georgia fbwer Comphny. ~

,_ .3 L 40 Inv etness Center Parkway

' Cont Ofite Dox 1295 -

humingham. Alabama 35201 .;

. .' ! )

hiephone 205 677-7279

,]

<- J. T. Beckham, Jr. . Georgia '

Power 'i

Wce President-Naclear . Ps udNvo enrPre, syst.in-Hatch Project .

HL-1580 001449 April 22, 1991 U.S. Nuclear Regulatory Commission ATTN: Document-Control Desk ~

-t

. Washington, D.C. 20555 g PLl14T HATCH - UNIT 2 NRC DOCKET 50-366 OPERATING LICENSE NPF-5

-LICENSEE EVENT REPORT UNKNOWN INADEQUACY IN.JVMPER CONNECTION RESULTS IN SCRAM DURING SVRVEIllANCE IN COLD SHUTDOWN Gentlemen:-

In-raccordance with the requirements-of 10.CFR 50.'73(a)(2)(iv), Georgia

Power . Company- is submitting the enclosed Licensee Event Report (LER) concerning the unanticipated actuation of an Engineered Safety Feature (ESF)l, This event occurred at Plant Hatch - Unit.2.

Sincerely, 7 _-

J. T. Beckham, Jr,

-SWR /ct

Enclosure:

LER 50-366/1991-007 f

.cc:-(See next page.)

9

$, E 19io4250220 s10425 PDR.

S ADOCK 05000366 PDR

- f[22 -

l} t

.a.. - , , . i :. . .. - . - . . . , . - . . ., . - . . . , . . . .

Georgia Power 1 U.S. Nuclear Regulatory Commission April 22, 1991 Page Two l

cc: Gjorai_a Power Comp _am  ;

Mr. H. L. Sumner, General Manager - Nuclear Plant l Mr. J. D, Heidt, Manager Engineering and Licensing - Hatch NORMS V.S. Nuclear Reaulatory Commission. Washinaton. D.C.

Mr. K. Jabbour, Licensing Project Manager - Hatch j V.S. Nuclear Reaulatory Commission. Reaica 11 '

Mr. S. D. Ebneter, Regional Administrator Mr. L. D. Wert, Senior Resident Inspector - Hatch 001449

g re ass . , u.s. nucin a aima, o u m .- - ur a n g u iO4 LICENSEE EVENT REPORT-(LER) ,

rACILITT mAME (1) DocEET WUMnER (2) . mr o i .

PIANT HATCH, UNIT 2 - 05000366  !

1 l0Fl 4 TITLE (4).

UWNOW INADEQUACY IN JUMFER CONNECTION RESULTS IN SCRAM SIGNAL DURIfC SURVEILLANCE IN COLD SHUTDOW I EVENT DATE (5) LER NUMBER (6) REPORT DATE (1) oTHER FACILITIES INYoLVED (8)

MogrrH DAT TEAR TEAR SEQ NUM REV MoirrH DAY TEAR FACl!JTT NAMES DOCEET NUMBER (s) 05000 0'3 26 91 91 0 0 7- 00 04 25 91 05000

, , , , Tuts REPORT s susMirrED PuRsuArr To Tut REoutREMEnTs or 10 crR tit) node (9) 4 20.402(b) 20.405(c) ^ 50.73(a)(2)(iv) 7L 11(b)

PowtR 20.40$(a)(1)(1) 50.36(c)(1) 50.13(a)(2)(v) 73.71(c) 20.405(a)(1)(ii) _

50.36(e)(2) _

50.73(a)(2)(v11) _

OTHER (specify in 20.405(a)(1)(iii) 50.73(a)(2)(1) 50.73(a)(2)(viii)(A) Abstract below)

~

20.405(a)(1){lv) 50.73(a)(2)(ii) 50.7)(a)(2)(v111)(B) 20.405(a)(1)(v) 50.73(a)(2)(lill l 50.13(a)(2)(a)

L3CEnsEE cofrrACT Poa TuIs LEn (12i M TELEPHONE NUMBER PJtEA CODE STEVEN B. TIPPS, MANAGER NUCLFAR SAFETY AND COMPLIANCE, HATCH 912 367-7851 COMPLETE oss LinE roR EAcn rAILuRE described in Tuts REPORT (13) cAusE sisTEP coMPonEsrr QF,AC- y,8,73, cAust sTsTEp coMPonEwT QrAC-suPPLEMElfrAL REPORT EEPECTED (14) MOIrrH DAT TEAR EXPECTED sunMission

] TEstif yes,~: complete EXPECTED susMIssion DATE) ] No - DATE (15)

AasTRAct (16)

On-3/26/91, at approximately 1155 CST, Unit 2 was in Cold Shutdown with reactor coolant torperature at approximately 100 degrees Fahrenheit, reactor pressure at

' atmospheric, and all control rods fully inserted. . At_that time, licensed plant y

-operators observed indications that a full scram' signal had been received.

In accordance with-Technical' Specifications requirements _priot-to entering _

Refuel. mode, surveillance procedure 345V-C51-00142S vas being performed:to test the_ Neutron Monitorir.g System (NMS, EIIS Code 1G) noncoincident scram logic. lThis required the placement of electrical-jumpers in the Reactor Protection ~ System (RPS, EIIS Code JE)= logic to ensure a full scram was not-generated while-testing NHS trip functions. In this event, it appears that at least o_ne jumper. failed to maintain contact resulting in- a full scram signal

~

when NHS-signals vere induced.per the surveillance procedure.

The cause of this event could-not.be conclusively determined. However, it appears to be an isolated event resulting from an unknown inadequacy in a jumper connection.

Corrective actions for this event. Include completing the functional test which verified operability of the NHS noncoincident scram logic and revising the surveillance' procedure to reduce the probability of recurrence.

t

- rtus Jean. Arr mu are m nz-em U s. surxmst amts-u cmemowii l

.d i

L(M) q FActLITY mans (1) Docast mmata (2) Lam summa (s) rAos (3) 4 rsAn sto mw arv j PLANT HA1DI, LNIT 2 -- 05000366 91 007- 00 2 0F 4 TsFT

PLANT AND SYSTEM IDENTIFICATION General Electric - Boiling' Vater Reactor EnergyLIndustry Identification System codes are identified in the text as (EIIS l Code-XX).

DESCRIPTION OF THE EVENT I

On-3/26/91,=at approximately 1155 CJT, licensed plant operators were performing

.a functional test of the Startup Range Neutron Monitors (SRMs) in accordance l vith procedure 34SV-C51-001-2S, "SRM: FUNCTIONAL TEST." This procedure is '

routinely performed to verify'the operability of the SRMs and to test the_ ,

. Neutron _Honitoring System (NMS, EIIS Code IG) noncoincident scram logic, in

-accordance vith1 Technical Specifications requirements, prior to the plant fentering the Refuel mode.- The noncoincident; scram-logic is required when in the

-Refuel mode during core alterations and shutdown margin demonstrations and is made effective via removal of the ' shorting links' from the Reactor Protection-System (RPS,' EIIS Code'JE). logic, Vith the RPS shorting links removed, a trip of any single _NMS instrument,-specifically.any one of the SRMs, Intermediate Range Monitors-(IRMs),,and Average Power Range Monitors (APRMs), vill initiate a -

L. full _ scram ./Lactuating both channels of RPS. logic.

LThe procedure requires-one of the RPS shorting links to be removed so that noncoincident NHS scram logic can be tested.' Then electrical _ jumpers are-

-installed in the RPS logic so thatEtest signals. emanating from the NHS vill affect only one-channel of RPS logic (half scram) at a time.- This allows foru all the noncoincident NHS scram logic to be tested without' generation of a full scram; signal. NHS test signals are then: generated by opening various links in-the logic;to simulate the.various NHS instrument trips. Annunciators and lights are Used to" verify that the RPS channel actuates as expected.

On 3/26/91,111 censed Operations personnel installed. the jumpers on the correct relay terminals as required by the procedure. However, when a link vas opened -

to simulate:an_NHS trip, both channels of RPS actuated, resulting in a full scram: signal rather than a' half scram as expected.

Although all:the control rods vere already fully inserted, actuation of the.

l control rod drive accumulators due to the full ~ scram signal was indicated by the

romentary overtravel of the control rods and corresponding illumination of drift lights. 'The scram was reset.by approximately 1157 CST.

CAUSE OF THE EVENT The cause of this event could not be conclusively determined. Electrical jumpers-designed to prevent an NHS' signal from actuating both channels of RPS logic veresinstalled'between the correct connection points but apparently-failed to maintain good-electricalicontact. Therefore, when an NHS trip signal was induced in accordance with the procedure, the trip signal was sensed in two channels of RPS logic rather than_one, resulting in a full scram signal.

y y-=vi-E 7g-rrr "r & a -%e c. e e.-,e -- m wwim--w __i-. _--a- - - - - - - - - - - - - - - - - - -

, uma Ph e Jusuk U.5. IEum =====e-u hasumatus - ._me. W 15) JimcIM

, urwrg (LER)

FACILITT NAME (!) luoCF.tf mfmpta (3) 1.ER mmsth (t) Pact (3)

~ " ~ ~ '

I i

!  : .Am sto mm arv PLANT llA101, tNIT 2 05000366 91 ,007 00 3 0F 4 TSET The investigation into the cause of the event yielded the following information:

1 Immediately after the event, at least one licensed operator insp',eted the l jumper installation and determined the jumpers vere connected rsross the correct poiras.

2. The suspect jumpers vere electrically tested by Instrumenta. ton and Control technicians and vere found to be in good condition with no electrical discontinuities or loose connections. i

3. The applicable portion of procedure 345V-C51-001-25 vas subjected tv a  :

detailed review. It was determined to be correct in that there vere no anomalies in step order, technical detail or equipment identification which could have contributed to the event.

-4.- The-panel.in which the jumpers vere located was inspected and was found to be.in good condition with respect to physical condition, lighting, accessibility and labeling.

5. The Nuclear Plant Reliability Data Systen (NPRDS) was queried for information concerning failed electrical jumpers. No events similar to this event vere identified.

6. A review of industry experience vas performed. No events similar to this event vere identified.

Therefore, it was concluded that this vas-apparently an iso'ated event resulting from an unknown inadequacy in a jumper connection.

REPORTABILITY ANALYSIS AND SAFETY ASSESSHENT TMs event-is reportable per 10 CFR 50.73(a)(2)(iv) because an Engineered Safety Teature, specifically the Reactor Protection System, experienced an unplanned, automatic actuation.

The Reactor Protection System automatically initiates a reactor scram to ensure the radioactive materials barriers, such as fuel cladding and pressure system boundary, are maintained, and to mitigate the consequences of transients and accidents. The NHS-inputs into the RPS are designed to monitor neutron flux levels and to initiate a rod withdrawal block or=an RPS actuation if neutron flux exceeds preset levels. In the event described in this report,-the RPS actuated per design given the NHS signals which vere induced in the system during a required surveillance.

Based on the above analysis, it is concluded that this event had no adverse impact on nuclear safety.

1

IK h. EM

~

U.b. B11 Ahi l#A &E AtRN (tMitf6bh AIUtM2s (Mt Ni 31'A 0104

+ni .

gy 9

$.S$ (LER) LER WifMDER (%) fAGE (3)

FArtt.itt RAME (t) toCEET NtittHER (2)

TLAk St.Q NUM KEV 007 00 UP 4 PLA!G llATCll, LNIT 2 05000366 91 4 ftXT CORRECTIVE ACTIONS Corrective actions for this event include:

1. Completing the SRM functional test. This action is completed.

2. Revising procedure 345V-C51-001-25 to require fever jumpers to be installed, it is believed this vill reduce the probability that the event could recur.

This action vill be ampleted prior to returning the unit to operation, currently scheduled for 5/24/91.

3. Revieving the feasibility of ut.;ng a different kind of jumper for this procedure, such as a " banana plug" jumper. This reviev vill be completed prior to returning the unit to operation, currently scheduled for 5/24/91.

ADDITIONAL INFORMATION

1. Other Systems Affected: No other systems vere affected by this event.

2. Previous similar Events: No events were identified in which a jumper installed in the correct location apparently failed to maintain electrical continuity resulting in the actuation of an Engineered Safety Feature (ESF).

3. Failed Components Identification: No failed components contributed to this event.

_. -.... - ,