ML18038A405

LER 88-024-00:on 880605,ESF Actuation Occurred Due to Resetting of Failed Radiation Monitor Microcomputer.Caused by Lack of Personnel Training.Defective Cards & Modules in RE14B Microcomputer & DRMS Panel replaced.W/880701 Ltr

ML18038A405
Person / Time
Site:	Nine Mile Point
Issue date:	07/01/1988
From:	Ronaldo Jenkins, Joseph Willis NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
LER-88-024, LER-88-24, NMP-35801, NUDOCS 8807110100
Download: ML18038A405 (10)

Text

T NIAGARA NNP-3580 I 0 MOHAWK NINE MILE POINTUNIT 2/P.O. BOX 63. LYCOMING, NY 13093/TELEPHONE (315) 343 2110 July I, 1988 United States Nuclear Regulatory Commission Document Control Desk Washington, OC 20555 RE: Docket No. 50-410 LER 88-24 Gentlemen:

In accordance with 10 CFR 50.73, we hereby submit the following Licensee Event Report:

LER 88-24 Is being submitted in accordance with 10 CFR 50.73 (a) (2) (iv), "Any event or condition that resulted in manual or automatic actuation of any Engineered Safety Feature (ESF), including the Reactor Protection System

'RPS)."

A 10FR50.72 (b)(2)(ii) report was made at 0208 hours0.00241 days <br />0.0578 hours <br />3.439153e-4 weeks <br />7.9144e-5 months <br /> on June 6, 1988.

This report was completed in the format designated in NUREG-1022, Supplement 2, dated September 1985.

Very truly yours,

+ Q. li'+C.MC

. L. Wi 1 s General Superintendent Nuclear Gener ation JLW/PB/mjd Attachments cc: Regional Administrator, Region 1 Sr. Resident Inspector, W. A. Cook

HRC Form 144 U.S. HUCLEAA REOULATOAY COMMISSION 19 821 APPROVEO OM& NO )I(04104 EXPIRES; Ill)i&4 LICENSEE EVENT REPORT HLER)

I'ACILITYHAMK (II DOCKET NVMSER Ill tA E Nine Mi le Point 0 5 0 0 0 410 > oF 04 Engineered Safety Feature Actuation due to Resetting a Failed Radiation Monitor Mic m EVENT OATK ISI LER NUM&ER 141 RCPORT OATE 171 OTHEA FACILITIES IHVOLVEO (>>

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~ $ 0.7 SN Ill I I(ill 50.71(4 Ill)(cl LICENSEE CONTACT SOR THIS LCR (12)

HAMS TELEPHONE NUM&CA AREA COOE Robert E. Jenkins, Assistant Supervisor. Technical Support 315 349-4220 COMPLETE ONC LINE SOll EACH COMPONENT SAILVRC OCSCRI ~ CO IN THIS RCtORT (Ill MAHUSAC ' MANUFAC. KPOATA&L CAVSK SYS'(EM COMtOHCNT 'TUAKR T() rrtAOS nr I'Pal 'O, o ~C. '>P

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CAVSE SYSTEM COMtOHENT TVREA TO HFROS X IL CPU K020 +~~jjg, X IL JX K020  %~gp~gg IL IMOD K020 SUPPLKMENTAI. REtORT EXPECTEO 1141 MONTH OAY YEAR EXPECTEO SU4MISSION CATE (151 YES IIIyee. comparce SXPKCTKO SUSAIISSIOII OA yfl HO ASSTAACT ILimic io 1400 epecee. I.e., eppeoe(me(cry iiireen single epece cyperrrircen iineel ll>>

While at 68% power on June 5, 1988 at 2224 hours0.0257 days <br />0.618 hours <br />0.00368 weeks <br />8.46232e-4 months <br />, the secondary containment isolated and the Standby Gas Treatment (GTS) and emergency Reactor Building Ventilation (HVR) systems auto-initiated on a spurious trip signal.

At 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br />, the Division 2 Above Refuel Floor Radiation Monitor (RE14B) lost comaunication with the Digital Radiation Monitoring System (DRMS) computer.

Radiation Protection (RP) personnel attempted to restore the microcomputer by pushing the reset switch. However, the microcomputer could not be restored due to a hardware failure. Resetting the microcomputer caused a spurious trip signal which led to the auto-initiations. The root cause is the lack of training of RP personnel in DRMS alarm response.

Ioeediate corrective actions by NMPC operators were to monitor control room panel indications. Operators observed that the remaining Division 2 monitors had also lost coomunication with DRMS. Consequently, all Division 2 monitors were declared inoperable and the associated Technical Specification action statements were entered. The failed components were identified and replaced and Division 2 monitors were returned to service on June 7, 1988. The RE14B was restored on June 9, 1988. Additiona'l corrective actions include training and Lessons Learned documents for applicable departments.

NRC Penll 2SSA U.S. NUCLEAR REQULATORY COMMISSION N43 I l LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPAOVEO OMS NO, 2150&IOS EXPIRES! S/SI/ISI PACILITY NAME III OOCKEE NVMSER I'2) LER NVMSEA ISI PACE ISI YEAR SEQUENTIAL I.'lP ll5V l5 lO N NUM 5ll 5?8 NUM 5 II 410 88 024 00 02 oF 04 Nine Mile Point Unit 2 o s o o o lSKT /d GAWP /RPPP N /PSvSSSL lNP NANO'//V/IC/ANNI 00SA'5/ II2I.

I. DESCRIPTION OF EVENT Whi'Ie at 68% power on June 6, 1988 at 2224 hours0.0257 days <br />0.618 hours <br />0.00368 weeks <br />8.46232e-4 months <br />, the secondary containment isolated and the Standby Gas Treatment (GTS) and emergency Reactor Building Ventilation (HVR) systems auto-initiated on a spurious trip signal. Prior to the event, the GTS Train B was operating to control drywell pressure.

At 2129 hours0.0246 days <br />0.591 hours <br />0.00352 weeks <br />8.100845e-4 months <br />, the Digital Radiation Monitoring System (DRHS) computer indicated that the Above Refuel Floor Radiation Monitor, 2HVR*RE14B, lost coomunication with the DRHS. Some time after 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br />, Niagara Mohawk Radiation Protection (RP) personnel noted the loss of communication alarm while performing their routine check of the DRHS hourly alarm report. While RP personnel were discussing what actions should be taken in response to the alarm, control room operators notified RP personnel that the alarm had also been observed in the control room and requested that the condition be investigated. Subsequently, a technician was dispatched to the RE14B microcomputer to investigate and correct the problem. The technician attempted to restore the microcomputer by pushing-the reset switch but the reset process appeared to be unsuccessful. RP personnel continued investigating.

At 2224 hours0.0257 days <br />0.618 hours <br />0.00368 weeks <br />8.46232e-4 months <br />, the secondary containment isolated and GTS Train A and emergency HVR auto-initiated. Niagara Mohawk control room operators received indication in the control room of the unexpected actuations but did not observe any indication of the initiating condition. A problem with RE14B and the DRHS computer was suspected, however, since they had observed the RE14B DRHS alarms come in.

Imediate corrective actions were to observe the visual alarms at the DRHS control and indication panel, 2CEC*PNL880, and to contact RP, Instrument and Controls ( I&C) and computer personnel to investigate and correct the problem.

Operators observed that all Division 2 safety-related monitors had lost coomunication with the DRHS computer. Consequently, all Division 2 monitors, including RE14B, were declared inoperable and the associated Technical Specification action statements were entered.

I Subsequently,. the affected ORMS computer loop and Division 2 monitors, with the exception of RE14B, were returned to service on June 7, 1988. The RE14B was returned to ser'vice on June 9, 1988. At that time, GTS and emergency HVR were secured, and normal HVR was returned to service.

II. CAUSE OF EVENT The cause of the loss of communication with RE14B was a failure of a Central Processina Unit (CPU) card in the RE14B microcomputer. Multiple coincidental hardware failures in the Division 2 safety-related DRMS computer loop were the cause of the loss of communication with the remaining Division 2 monitors.

The causes for the CPU component failure and the multiple coincidental hardware failures are unknown.

RRC Sees 3SSA U.S. NUCLEAR REOULATORY COMMISSION llML3I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION APPROVEO OMS NO 3150&/OS EXPIRES: d/31/%

PAClLITY NAME ill OOCRET NUMSER 12) LER NUMEER ldl PACE (31 PX'0 SEOVSNTIAL IIS V IS lO N

X."" NVM SR HVM EII TE21T //PIPIT ~Nine~Nile Point d ace Unit 2 ASAbne/ HRC /SIIII 3RL1 z/1121.

o 5 o o o 410 88 024 00 03 oF 04 The immediate cause of the event was resetting the RE148 microcomputer. By design, resetting it will momentarily close the relay contacts which cause a secondary containment isolation and auto-initiation of GTS and emergency HVR.

RP personnel on shift were inexperienced with the DRNS and were not aware of this design feature. Therefore; the root cause of the event is a lack of training on the reset function of the microcomputer and the proper response to 1oss of communication alarms.

III. ANALYSIS OF EVENT There were no adverse safety consequences due to this event. The failure of a safety-related radiation monitor is controlled by Technical Specifications.

Therefore, any process effluents monitored by the radiation monitors that became inoperable were monitored by other means prescribed in the Technical Specifications. In the case of RE14B, the auto-initiation of Engineered Safety Features, such as GTS, preclude the uncontrolled release of radioactivity during any operational or emergency condition. GTS and emergency HVR systems are designed to operate so as to limit radioactive releases during an accident.

There were no radioactive releases during this event. Division 1 monitors remained operable throughout the event, thus providing a redundant means of monitoring important process effluents in the event of an unexpected release.

The Division 2 monitors were out of service for approximately two days. The RE14B monitor was inoperable for approximately four days.

IV. CORRECTIVE ACTIONS Inmediate corrective actions were to observe the visual alarms at the DRNS control and indication panel, 2CECE PHL880, and to contact RP, 18C and computer personnel to investigate and correct the problem. Operators observed that all Division 2 monitors had lost communication with the DRNS computer.

Consequently,'l'1'ivi'sion 2 monitors, including RE14B, were declared inoperable and the associated Technical Specification action statements were entered.

Further corrective,actions'ere to troubleshoot and replace defective cards and modules in both-the RE14B microcomputer and the DRNS panel. The spare components installed were tested and the associated monitors were returned to service.

NRC Sons 544A V.E. NUCLEAR REOULATORY COMMI5510N 14421 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION APPRQI/EO OME NO, 2150&l04 EXPIRES; 4/$ 1/EE PACILITY NAME III OOCXET NUMEER 121 LE/I NUMEEA 141 I'AOE 121 YEAR /pi<>~ 5EQVENTIAL AEVOIO/I

~ II/M Eh rb.;. //UM45A TACT /4 444/4 ~Nine~Mile Point JI Unit 2 Wr 4/h/POna/ H/IC A/RI ~'4/ IITI s 0 0 0 410 88 024 00 04 oF 04 Additional corrective actions are:

A Lessons Learned document will be issued to Operations, Computer, I&C and RP personnel to describe the reset function of the radiation monitor microcomputer and to provide the proper response to loss of colmunication alarms.

2. As requested by the RP Unit Supervisor, a Training Modification Request (TMR No. H88-24) has been issued to the RP Training Department to provide continued training to RP personnel on the proper response to DRMS alarms.

3. A Problem Report has been issued to Engineering to evaluate the possibility of modifying the reset function to prevent closing relay contacts.

4, The root causes for the component failures are unknown. However, the failed components have been returned to the vendor and the vendor will be requested to perform a failure analysis. If additional corrective actions are warranted as a result of the analysis, a supplement will be issued to describe any additional actions taken.

V. ADD ITIONAL INFORMATION A. Identification of Components Referred to in this LER IEEE 803 IEEE 805 Component EIIS Funct System ID Standby Gas Treatment System (GTS) N/A BH Reactor Building Ventilation (HVR) N/A VA Emergency Recirculation System (HVR) N/A VA Reactor Building N/A NG Radiation Monitor HON IL Digital Radiation Honitor'ing System (DRMS) N/A IL

/

B. Previous Similar Events - None C. Failed Components-SRMS Interface NIM Module, Part No. 450957-001 SRMS Isolation NIM Module, Part No. 450958-001 Power Supply, Part No. 45094-002 CPU Board, Part No. 451126-002 System Board, Part No. 450440-100 The RE148 microcomputer is manufactured by Kaman Instrumentation Corp.,

Model KEM-P

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