ML17349A458

LER 92-010-00:on 921002,containment Ventiliation Isolation & Control Room Ventilation Isolation Occurred Due to Spurious Signal.New R11/R12 Skid Being Installed for Unit 3 & Will Be Tested for sensitivity.W/921030 Ltr

ML17349A458
Person / Time
Site:	Turkey Point
Issue date:	11/02/1992
From:	Knorr J, Plunkett T FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-92-295, LER-92-010-01, LER-92-10-1, NUDOCS 9211040013
Download: ML17349A458 (6)

Text

acczcm~rzD Das~maurrar DsrvrOr', m~nox SvSram REGULARLY INFORMATION DISTRIBUTIO YSTEM (RIDS)

ACCESSION NBR:9211040013 DOC.DATE: 92/ll/02 NOTARIZED: NO DOCKET FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light C 05000250 AUTH. NAME AUTHOR AFFILIATION KNORR,J.E. Florida Power S Light Co.

PLUNKETT,T.F. Florida Power !; Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 92-010-00:on 921002,containment ventiliation isolation

& control room ventilation isolation occurred due to spurious signal. New Rll/R12 skid being installed for Unit 3 a will be tested for sensitivity.W/921030 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR ) ENCL I SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:NRR RAGHAVANiL 05000250 /

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-2 LA 1 1 PD2-2 PD 1 1 AULUCKgR 1 1 INTERNAL: ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 NRR/DST/SRXB 8E 1,

1 1

1 NR&fB~SPLB8Dl REG FILE 02 1

1 1

1 RES/DSIR/EIB 1 1 R FILE 01 1 1 EXTERNAL: EG&G BRYCEiJ.H 2 2 L ST LOBBY NARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A I 1 NSIC POOREgW. 1 1 NUDOCS FULL TXT 1 1 NOTES: 1 1 NOTE TO ALL RIDS RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK.

ROOM P 1-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 30 ENCL 30

P.O. Box 029100, Miami, FL, 33102-9100 L-92-295 10 CFR 50.73 U~ S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 92-010-00 Containment Ventilation Isolation and Control Room Ventilation Isolation Due to a S urious Si nal The attached Licensee Event Report 250-92-010-00 is being provided in accordance with 10 CFR 50.73 (a) (2) (iv) .

If there are any questions please contact us.

Very truly yours, T. F. Plunkett Vice President Turkey Point Nuclear TFP/JEK/jk enclosure cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC Ross C. Butcher, Senior Resident Inspector, USNRC, Turkey Point Plant P~ii0/0613 5'2ii02 PDR ADOCK 05000250 S PDR an FPL Group company I

LICENSEE EVENT REPORT (LER)

DOCKET NQYSER (2) PACE (5)

FACILITY NAlC (I)

TURKEY POINT UNIT 3 05000250 OF 3 TITLE (() Containment Ventilation Isolation and Control Room Ventilation Isolation Due to a Spurious Signal RP'I DATE (I) OTHER FACILITIES INV, (S)

EVENT DATE (5) LER NUMBER (6)

SEQ I DOCKET P IS)

MON YR NAME 10 02 92 92 010 00 02 92 OPERATINC NODE (2) 10 CFR 50.73 a 2 i iv LICENSEE CONTACT FOR THIS LER (12)

James E. Knorr, Regulation and Compliance Specialist TELEPHONE MUHSER 305-246-6757 CONPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIEED IN THIS REPORT (15)

SYSTEM MANUFACTURER NPRDS CAUSE MPRDS SUPPLEMENTAL REPORT EXPECTED ll(l EXPECTED SUSHI SS ION MONTH DAY YEAR DATE (15)

(II Fee. ecnplete EXPECTED SUSHISSIOM CATE)

On October 2, 1992, at 1345 EDT, while Unit 3 was in Mode 6, a spurious actuation signal caused a containment ventilation isolation and control room ventilation isolation. Only two sources of an engineered safety features actuation signal could result in only containment ventilation isolation and control room ventilation isolation. Manual actuation and a containment gaseous and particulate radiation monitor (R11/R12) skid high radiation signal are the two signal sources. There was no reason to suspect a manual actuation. There is also no evidence of a high radiation signal or that both trains of the actuation signal failed simultaneously. Inspection of the common internal wiring in the cabinets did not reveal any loose or intermittent connections.

Work in progress in the area of the R11/R12 skid, included grinding and welding appears to have caused a spurious actuation signal.

A new R11/R12 skid is being installed for Unit 3 and will be tested for sensitivity to welding in the area. If welding sensitivity is noted during testing, other corrective actions will be evaluated appropriate.

and implemented if

LXCENSEE ENT REPORT (LER) TEXTQNTTNURTXON FACILZTy NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 3 05000250 92-010-00 02 oF 03 I. DESCRIPTION OF THE EVENT On October 2, 1992, at 1345 EDT, while Unit 3 was in Mode 6, a containment ventilation isolation and control room ventilation isolation occurred. A spurious actuation signal appears to have caused the engineered safety features actuation signal.

Only two sources of an engineered safety features actuation signal exist which would result in only containment ventilation isolation and control room ventilation isolation; the manual push buttons on the control room control board, and a high level signal on the gaseous and particulate radiation monitors (R11/R12) for the containment atmosphere.

II. CAUSE OF THE EVENT As stated above there are only two sources of an actuation signal which could activate these engineered safety features. There was no reason to suspect a manual actuation. There is also no evidence that both trains of the actuation signal failed simultaneously. Inspection of the common internal wiring in the cabinets did not reveal any loose or intermittent connections.

Work was progressing in the area including grinding and welding. R11/R12 is a pulse counter which by its nature is sensitive to electrical noise. Electric welding generates noise not only from the arc but also from inductance of the welding leads which carry irregular current during the welding process.

Therefore the most probable root cause of the engineered safety feature actuation is welding in the immediate vicinity of the R11/R12 detectors.

III. ANALYSIS OF THE EVENT The containment ventilation isolation actuation signal is designed to isolate containment atmosphere from the outside environment by closure of those penetrations of the containment building which communicate between the inside and outside of the containment building. The control room ventilation isolation signal is designed to isolate the control room from the outside atmosphere to protect the control room personnel from the effects of a radiological release which could occur in the highly unlikely event of a containment building barrier failure. This high radiation ventilation isolation signal is generated when there is an indication of high radioactivity in the containment atmosphere. Since the signal in this case was spurious and no actual high radiation condition existed, no compromise to the health and safety of plant personnel or the general public occurred due to the isolation of the containment ventilation or the control room ventilation systems.

1 LICENSEE ENT REPORT (LER) TEXTONTINUATION

~

~~~ FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 3 05000250 92-010-00 03 OF 03 IV. CORRECTIVE ACTIONS

1. A new R11/R12 skid is being installed for Unit 3 and will be tested for sensitivity to welder operation by evaluating the effect of welder activity, in the immediate area of the skid, on control room indication or spurious signal generation.

2. If welding will be sensitivity is noted during testing, other corrective actions if evaluated and implemented appropriate. This testing will be completed prior to November 30, 1992, and appropriate corrective actions will be completed prior to December 30, 1992.

3. A sign will be installed in the area of the R11/R12 skid prior to November 30, 1992, to warn of potential spurious signals generated by welding in the area

4. The welding permit procedure, O-ADM-046, Control of Welding Special Processes, will be revised prior to December 30, 1992, to include a warning about the potential for spurious signal generation during welding processes near electronic equipment.

5. Radio frequency interference was evaluated by testing the new R11/R12 skid with portable radios keyed nearby and was found to not produce any spurious high radiation signal generation.

V. ADDITIONAL INFORMATION None.