ML17303A706

LER 87-015-01:on 870816,control Room Essential Filtration Actuation Initiated on ESFAS Channels a & B.Caused by Voltage Spike on RU-30.Monitor Reset,Train B Returned to Svc & Procedural Change initiated.W/871124 Ltr

ML17303A706
Person / Time
Site:	Palo Verde
Issue date:	11/24/1987
From:	Bradish T, Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
192-00285-JGH-T, 192-285-JGH-T, LER-87-015, LER-87-15, NUDOCS 8711300177
Download: ML17303A706 (7)

Text

REGULA. Y INFORNAT ION D ISTR I BUT I SYBTEN (R I DB )

ACCESSION NBR: 8711300177 DOC. DATE: 87/if/24 NOTARIZED: NO }

DOCKET r

FACIL: STN-50-529 Palo Verde Nuclear Stationi Unit 2i Arizona Pub AUTHOR AFFILIATION li 05000529 AUTH. NANE BRADISHi T. R. Ar izona Nuclear Power ProJect (Former lg Arizona Public Serv HAYNES'. G. Arizona Nuclear Power Pro Ject (formerly Arizona Public Serv REC IP. MANE REC IP IENT AFFILIATION

SUBJECT:

LER 87-015-Of: on 870816'ontrol room essential Filtration actuation initiated on ESFAS Channels A h B. Caused bg voltage spike on RU-30. Noni tor resets Train B returned to svc 5 procedural change initiated. W/871124 1tr.

DISTRIBUTION CODE: IE22D COPIEB RECEIVED: LTR TITLE: 50. 73 Licensee Event Report (LER) i

+ ENCL ~ SIZE:

Incident Rpti etc.

NOTES: Standardized plant. 05000529 RECIPIENT COPIES RECIPIENT COP IEB ID'ODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 PD5 PD 1 1 LICITRAiE 1 1 DAVIS' 1 1 INTERNAL: ACRB NICHELSON 1 1 ACRS NOELLER 2 2 AEOD/DOA 1 1 AEOD/DBP/NAS 1 AEOD/DSP/ROAB 2 2 AEOD/DSP/TPAB 1 1 ARN/DCTS/DAB 1 1 DEDRO 1 1 NRR/DEBT/ADS .,1 0 'NRR/DEBT/CEB NRR/DEST/ELB NRR/DEST/ICBB 1 NRR/DEST/MEB 1 NRR/DEST/NTB 1 NRR/DEBT/PSB . 1 1 NRR/DEST/RBB 1 1 NRR/DEST/SGB 1 1 NRR/DLPG/HFB 1 NRR/DLPG/GAB 1 f NRR/DOEA/EAB 1 NRR/DREP/RAB 1 f NRR/DREP/RPB 2 2 NRR/DRIB/SIB 1 ~

NRR/PNAS/ILRB 1 EQ F L- 02 1 1 RES DEPY GI 1 ES TELFO Ds J 1 1 RES/DE/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EGGG GROHi M 5 5 H ST LOBBY WARD 1 LPDR 1 1 NRC PDR 1 NSIC HARRIS' 1 1 NSIC M*YBtG 1 NOTES: 1 1 TOTAL NUNBER OF COPIES REQUIRED: LTTR 47 ENCL 46

0 NAC Form 355 V.S. NUCLEAR REOULATOR Y COMMISSION (9 53 I APPROVED OMB NO. 31500104 LICENSEE EVENT REPORT {LER) EXPIRES: SISIISS FACILITY NAME (II DOCKET NUMBER (2) PA 3>

Pal o Verde Uni t 2 o 5 o o o 52 91OF03 Actuation ause y purious arm rip igna on Radiation Monitor (RU-30)

EVENT DATE (SI LER NUMBER (5) REPORT DATE 17) O'THER FACILITIES INVOLVED (5)

MONTH OAY YEAR YEAR c)Xr 550UENTIAL REV>C>ON DAY YEAR FACILITY NAMES DOCKET NUMBER(s)

NUMBER %IS NUMBER MONTH N/A 0 5 0 0 0 0 8 1 6 8 7 8 7 0 1 5 0 1 24 87 N/A 0 5 0 0 0 OPERATING THIS REPORT IS SUBMITTED PURSUANT T 0 THE REOVIREMENTS OF 10 cFR (It ICnrctr onr or more ol tnr lollowlnol (ill MODE (Sl 20.402(ol 20.405(c) 50.73(c)(2)l(v) 73.71(b)

POWER 20.405( ~ ) (I) II) 50,35 (cl (I I 50.73( ~ )(2)(v) 73.71(cl LEYEL 1 0 0 20.405 (4) (I I (5) 50.35(c) (2) 50.13(el(2) (vBI OTHER ISpeclly In Abrtrrct below end ln Tert. HIIC Form 20.405( ~ I(1 l(>III 50.13(c) (2) II) 50.73(r) (2)HI)II(A) 3FSAI 20A05( ~ l(ll(ivl 50.1 34) 12)(II) 50.73(cl(2)iv(5)(S) 20.405( ~ l(1 l(v) 50.7 34)(2) I III) 50.73(r ) (2) (4 I LICENSEE CONTACT FOR THIS LER (12I NAME TELEPHONE NUMBER AREA CODE Thomas R. Bradish, Compliance Lead 6 02 39 3-3 531 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRI ~ EO IN THIS REPORT (13)

CAUSE SYSTEM COMPONENT MANUFAC. MANUFAC EPORTABLE TURER TO CAUSE SYSTEM COMPONENT NPRDS,g+~@g(Q@$ TVRER TO NPRDS PcccNA>E ~5%~%4 SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED SUBMISSION IIIyrt, comPlrtr DATE (I BI YES EXPECTED SVSMISSIOH OATEI NO ABSTRACT ILlmlt tO l400 tprcee, I e., rpprorlmrtrly llltren tlnolr tprtr tyorwrlttrn liner) (15)

This is a supplement to LER 2-87-015-00 submitted on September 3, 1987.

On August 16, 1987 at 0609, Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) at 100 percent power when a Control Room Essential Filtration Actuation (CREFAS) was initiated on Channels A and B of the Engineered Safety Features Actuation System (ESFAS).

The actuation was in response to a spurious alarm/trip signal on the "BA Control Room Ventilation Intake Noble Gas Monitor (RU-30), and occurred coincident with an attempt to reset a local alarm on the subject monitor with a portable indication and control unit (PIC). An investigation was conducted to determine the cause of the event, and to determine if improper utilization of the PIC was a contributing factor; The results of the investigation are provided in this supplement.

As immediate corrective action, the actuated equipment was returned to a normal operations configuration, and the Train HBA CREFAS was placed in bypass pending further evaluation.

Other events involving CREFAS actuations have been reported, however, these events did not involve the sequence of activities noted above and ar e not considered similar events.

8711300177 871124 3l'i L I PDR ADOCK 05000529 NRC eorm 345 S PDR

NRC Foim 344A 19413) U.S. NUCLEAR REOULATORY COMMISSION LICENSEE EVENT REPORT ILER) TEXT CONTINUATION APPROVEO OMS NO. 3150MI04 EXPIRES: 8/31/88 FACILITY NAME 111 OOCKET NUMSER 131 LER NUSISER t81 ~ AOE 131 YEAR IZP SSOVSNZIAL NVM 4 II @% VISION

'mi NVMSSA Palo Verde Unit 2 o s o o o 5 2 9 8 7 015 01 02 oF 0 3 TEXT litIINYP u>>cs iI IFSvired, v>> hlhaonaSHhC Fsvm 3RLL'sl Iltl This is a supplement to LER 2-87-015-00 submitted on September 3, 1987.

On August 16, 1987 at 0609 MST, Palo Verde Unit 2 was in Mode 1 (POWER OPERATION) at 100 percent power when a Control Room Essential Filtration Actuation (CREFAS) was initiated on Train "B" of the Engineered Safety Features Actuation System (ESFAS)(JE). The Train UB" CREFAS cross-tripped the Train "AU CREFAS, per design, and all associated equipment [e.g., the essential chillers (EC)(KH), essential cooling water system (EW)(BI),

essential spray ponds (SP)(BS) and control room essential filtration system (AHU)] operated satisfactor ily. The CREFAS was initiated by the "B" Control Room Ventilation Intake Noble Gas Monitor (RU-30)( IL)(RI). The actuations were identified by the control room operators (utility-licensed) as a result of main control board (HCBD) annunciations (ANN).

Following the ESF actuations, the control room operators (utility-licensed) verified that there were no actual radiation level increases by comparing the RU-30 results to the RAU Control Room Ventilation Intake Noble Gas Monitor (RU-29)( IL)(RI), and by determining that, coincident with the event, a radiation protection ( RP) technician (utility-non-licensed) had reset the local alarm on RU-30 by utilizing a por table indication and control unit (PIC)(HIC) with the monitor placed in LOCAL mode.

Based on the above information, the shift supervisor (utility-licensed) determined the alarm/trip to be spurious. At 0622 HST the control room operator (utility-licensed) reset the CREFAS "A" and "B" alarms and placed the Train "B" CREFAS in bypass, pending further investigation. The control room operators (utility-licensed) then reset the Train "AU and RB" CREFAS actuated equipment, securing the event at 0712 HST. The total duration of the event was approximately 63 minutes.

Subsequent investigation revealed that, prior to the event, the Control Room notified the Radiation Protection office that the local alarm (ALH) on radiation monitor RU-30 was on. The RP technician (utility non-licensed) verified that RU-30 was not registering an alarm condition on the Display and Control Unit (DC) (AIC) located in the RP office, and that the specified setpoints (e.gs3 2.0 X E-5 micro Curie [Ci]/cubic centimeter [cc]) were in the monitor. The RP technician then notified the Control Room that the RU-30 local alarm would be reset with a PIC. The reset is accomplished by connecting the PIC to the monitor, switching the PIC from REMOTE and LOCAL mode, and depressing the "ALARM ACK" button. These actions were completed, however, following the alarm reset the PIC may have been disconnected from the radiation monitor while in the LOCAL mode. Procedural controls required the PIC to be switched to the REhIOTE mode prior to being disconnected from the monitor. This action was believed to have caused a voltage spike on the radiation monitor, which in turn generated a spurious alarm/trip signal, however, the actual setting of the LOCAL/REMOTE switch at the time the PIC was disconnected could not be verified.

vsIC I OIIM 344A 19 83 i

NRC Form 344A U.S. NUCLEAR REOULATORY COMM/44)ON IS 83)

LICENSEE EVENT REPORT ILERI TEXT CONTINUATION APPROVED OMS NO 3)50-8)44 EXPIRES: 8/31/48 FACILITY NAME (1) DOCKET NUMSER 12)

LER NUMSER 14) ~ AOE IS) 4EOVENT/AL SrtP IIEVI4ION NVM 4/I rrvM44A Palo Verde Unit 2 o s o o o 52 98 7 0 1 5 0 1, 0 3 QF 0 3 TEXT ///mare taoce/I /o)r)worL vto ~f//ICform ~'tl ))7)

The assessment of the event as a spurious alarm/trip was substantiated when, following the event, the RP technician found the alarm/trip setpoint for RU-30 to be at the default value (2.2 X E-6 micro Ci/cc) in lieu of the specified value noted above. The remote indication and control unit (RIC)(AIC) normally downloads the specified setpoints to the radiation monitor, however, the default setpoints will be downloaded if the specified values are lost'due to a voltage spike or electronic circuit noise.

As corrective action the monitor was reset, returning the setpoints to the specified values, and the Train "BU CREFAS returned to service.

An investigation was subsequently conducted to determine the cause of the event, which included an evaluation to determine if proper utilization of the PIC was a contributory factor. Several attempts were made to recreate the event by disconnecting the PIC from the monitor while in LOCAL mode. In each case, both the monitor and the associated RIC continued to operate without generating a spurious alarm/trip, or resetting to the default setpoints.

Based on these results, the spurious alarm/trip is attributed to a voltage spike on RU-30. While the voltage spike is believed to have occurred while connecting or disconnecting the PIC from'the subject monitor, no personnel or procedural errors were identified as contributing factors.

Other events involving spurious alarm/trips on radiation monitors have been r eported, including LERs 1-85-011, 1-85-031 and 1-86-013. However, these events did not involve the sequence of activities noted above and are not considered similar events. Corrective actions to prevent recurrence for these previous events include the installation of an isolated grounding system (FC) to reduce electronic circuit noise in radiation monitors. This installation (in process for Unit 2) should also serve minimize recurrence of this type of event.

As additional corrective action, a procedural change has been initiated to place selected radiation monitors in bypass (plant conditions permitting) whenever the affected monitor is to be operated with a PIC. These changes will apply to radiation monitors which provide actuation signals to Engineered Safety Features Actuations System (ESFAS)(JE).

Based on the actions described above, which included verification that no abnormal radiation levels existed pursuant to the event, these was no effect on the health and safety of the public and no safety impact on the unit. No systems or components inoperable prior to the event were identified contributing factors.

'r/IC IOaM 341io IQ 431

Arizona Nuclear Power Project P.O, BOX 52034 ~ PHOENIX. ARIZONAS5072-2034 192-00285-JGH/TRB/KCP November 24, 1987 NRC Document Control Desk Nuclear Regulatory Commission

-Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 2 Docket No. STN 50-529 Licensee Event Report 2-87-015-00 Fi le: 87-020-404 Attached please find Supplement No. 1 to Licensee Event Report (LER No.

2-86-015-00 prepared and submitted pursuant to the requirements of 10CFR 50.73(d). We are herewith forwarding a copy of this report to the Regional Administrator of the Region Y Office.

If you have any questions, please contact T. R. Bradish, Compliance Lead at (602) 393-3531.

Very truly yours,

.c //~.

J. G. Haynes Vice President Nuclear Production JGH/TRB/KCP/kj Attachment CC: 0. N. DeHichele (all w/a)

E. E. Van Brunt, Jr.

J. B. f1artin J. R. Ball R. C. Sorensen E. A. Licitra A. C. Gehr INPO Records Center gigf r