ML17265A702

LER 99-010-00:on 990615,ventilation Isolation of Auxiliary Bldg Occurred When Auxiliary Bldg Gas Radiation Monitor R-14 Reached High Alarm Setpoint.Cr Operators Rest Auxiliary Bldg Ventilation Isolation Signal.With 990715 Ltr

ML17265A702
Person / Time
Site:	Ginna
Issue date:	07/15/1999
From:	Mecredy R, St Martin J ROCHESTER GAS & ELECTRIC CORP.
To:	Vissing G NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-99-010, LER-99-10, NUDOCS 9907220014
Download: ML17265A702 (8)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9907220014 DOC.DATE: 99/07/15 NOTARIZED: NO DOCKET FACIL:50-244 Robert Emmet Ginna Nuclear Plant, Unit 1, Rochester G 05000244 AUTH. NAME AUTHOR AFFILIATION ST MARTIN,J.T. Rochester Gas 6 Electric Corp.

MECREDY,R.C. Rochester Gas &. Electric Corp.

RECZP.NAME "

RECIPIENT AFFILIATION VISSING,G.S.

SUBJECT:

LER 99-010-00:on 990615,ventilation isolation of auxiliary bldg occurred when'uxiliary bldg gas radiation monitor R-14 reached high alarm setpoint.CR operators rest auxiliary bldg ventilation isolation signal. With 990715 ltr.

DISTRIBUTION CODE: IE22T  !

COPIES RECEIVED:LTR ENCL ( SIZE:

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

NOTES:License Exp date in accordance with 10CFR2,2.109(9/19/72). 05000244 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL LPD1-1 PD 1 1 VISSING,G. 1 1 INTERNAL .~~E CEÃVER 1 1 NRR/DIPM/IOLB 1 1 NRR/DRIP/REXB 1 1 NRR/DSSA/SPLB 1 1 RES/DET/ERAB 1 1 RES/DRAA/OERAB 1 1 RGN1 FILE 01 1 1 EXTERNAL: L ST LOBBY WARD 1 1 LMITCO MARSHALL 1 1 NOAC POORE,W. 1 1 NOAC QUEENER,DS 1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 15 ENCL 15

0 AND It.

ROCHESTER GAS AND ElECTRIC CORPORATIOhl ~ 89 EAST AVEhlUE, ROCHESTER, N.Y. Id6d9.0001 AREA CODE 716 5'-2700 ROBERT C. MECREDY Vice Pretident Nvcteor Operotiont Zuly 15 1999 U. S. Nuclear Regulatory Commission Document Control Desk Attn: Guy S. Vissing Project Directorate I-1 Washington, D.C. 20555

Subject:

LER 1999-010, Radiation Monitor Alarm, Due to Higher than Normal Radioactive Gas Concentration, Results in Auxiliary Building Ventilation Isolation R.E. Ginna Nuclear, Power Plant Docket No. 50-244

Dear Mr. Vissing:

The attached Licensee Event Report LER 1999-010 is submitted in accordance with 10 CFR 50.73, Licensee Event Report System, item (a) (2) (iv), which requires a report of, "Any event or condition that resulted in manual or automatic actuation of any engineered safety feature (ESF)".

Very truly yours, gp Robert C. Mecred xc: Mr. Guy S. Vissing (Mail Stop 8C2)

Project Directorate I-1 Division of Reactor Projects -

Office of Nuclear Reactor Regulation I/II U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Regional Administrator, Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 U.ST NRC Ginna Senior Resident Inspector ctt90722 0014 9907%5 05000244 PDR AD g PDR 8

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6 IBBS)

@SPIKY PunPeyn peiI response IL coirtpPywiILs nIIYIIo Information collection request: 50 hrs. Reported lasso'ns learned are incgrporated into the licensing process and ted back to LlCENSEE EVENT REPORT (LER) industry. Forward comments regarding burden estimate to the Records Management Branch (T< F33), U.S. Nuclear Regulatory Commission. Washington, DC 205554001 and to (See reverse for required number of the Paperwork Reducbon Project (31504104), Office of

~

digits/characters for each block) Management and Budget, Washington, DC 20503. If an Information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a FACILITY NAME (1) DOCKET NUMBER I2) PAGE I3)

R. E. Ginna Nuclear Power Plant 05000244 1 OF 5 TITLE te)

Radiation Monitor Alarm, Due to Higher than Normal Radioactive Gas Concentration, Results in Auxiliary Building Ventilation Isolation EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

SEOUENTIAL REVISION FACIUTY NAME OOCKETNUMBER MONTH OAY YEAR MONTH DAY NUMBER NUMBER 05000 FACIUTY NAME DOCKET NUMBER 06 15 1999 1999 010 00 07 15 1999 05000 OPERATING THIS REPORT IS SUBMITTED P URSUANT TO THE REQUIREMENTS OF 10 CFR E: (Check. one or more) (11)

MODE (9) 20.2201 (b) 20.2203(a) (2) (v) 50.73(a) (2) (i)(B) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3) (i) 50.73(a)(2)(ii) 50.73(a) (2) (x)

LEVEL (10) 100 20.2203(a)(2)(i) 20.2203(a) (3)(ii) 50.73(a)(2) (iii) 73.71 20.2203(a) (2)(ii) 20.2203(a)(4) X SO.73(a)(2)(iv) OTHER 20.2203(a) (2)(iii) 50.36(c)(1) 50.73(a)(2)(v) Specify in Abstract below 20.2203(a)(2) (iv) 50.36(c) (2) 50.73(a)(2)(vu) or in NRC Form 366A LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER Undude Ares Code)

John T. St. Martin - Technical Assistant (716) 771-3641 REPORTABLE REPORTABIE CAUSE SYSTEM COMPONENT MANUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO EPIX TO EPIX SUPPLEMENTAL REPORT EXPECTED (14) MONTH OAY YEAR EXPECTED YES NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). X. DATE (IE)

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On June 15, 1999, at approximately 0356 EDST, the plant was in Mode 1 at approximately 100% steady state reactor power. Reactor coolant activity was higher than normal due to a suspected leaking fuel assembly. During activities associated with draining a CVCS holdup tank containing radioactive fluid, radioactive gas was released from the tank and radioactive gas concentration increased within the auxiliary building, where the tank is located. A ventilation isolation of the auxiliary building occurred when auxiliary building gas radiation monitor R-14 reached its high alarm setpoint.

Immediate operator action was to perform the applicable actions of alarm response procedures.

Corrective action to prevent recurrence is outlined in Section V.B.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 19 1999)

LICENSEE EVENT REPORT (LER).

TEXT CONTINUATION FACILITY NAME I1) DOCKET I2) LER NUMBER I6) PAGE I3)

SEBUENTIAE REVlSION NUMBER NUMBER R.E. Ginna Nuclear Power Plant 05000244 1999 010 00 2 OF 5 TEXT (lf more spece is required, use eddidonel copies of NRC Form 366Al I17)

PRE-EVENT PLANT CONDITIONS:

On June 15, 1999, the plant was in Mode 1 at approximately 100%'steady state reactor power. Activity of the reactor coolant system (RCS) was higher than normal (by a factor of approximately six) due to a suspected leaking fuel assembly. RCS fluid is routinely diverted to one of three CVCS holdup tanks in the auxiliary building. Planned draining of the "A" CVCS holdup tank to the auxiliary building sump had just been completed. Radioactive gas was released from the tank to the auxiliary building atmosphere during the final stages of draindown. Due to the increased RCS activity and consequent increased activity in the CVCS holdup tanks, airborne radioactive gas coricentration increased within the auxiliary building to levels higher than normal for this evolution. Control Room operators noted increases in radiation monitors R-13 (auxiliary building particulate) and R-14 (auxiliary building gas).

DESCRIPTION OF EVENT:

A. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

June 15, 1999, 0356 EDST: Event date and time.

June 15, 1999, 0356 EDST: Discovery date and time.

o June 15, 1999, 0357 EDST: Control Room operators verify all auxiliary building ventilation isolation functions have occurred.

B. EVENT:

When R-13 and R-14 increased above 100 counts per minute, the Control Room operators directed an auxiliary operator (AO) to close the drain valves from the "A" CVCS holdup tank in the auxiliary building. He closed these valves but the already released airborne radioactive gas continued to increase the readings on radiation monitors R-13 and R-14. At approximately 0356 EDST, the Control Room operators received annunciator alarm L-1 (AUX BLDG VENT SYSTEM CONTROL PANEL), indicating that an auxiliary building ventilation isolation had occurred. The Control Room operators verified that radiation monitor R-14 had reached its high alarm setpoint, causing the ventilation isolation.

The Control Room operators immediately referred to Alarm Response procedure AR-L-1 and procedure AR-RMS-14, and verified that auxiliary building ventilation isolation had occurred. They performed the applicable actions of the alarm response procedures.

After consulting with the Radiation Protection group, it was determined that the high alarm setpoints for R-13 and R-14 were set with excessive conservatism (approximately 1% of the release limits as defined by the Offsite Dose Calculation Manual), with leaking fuel causing elevated RCS activity. After the activity decreased in the auxiliary building, the ventilation isolation signal was reset.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6 IBBSI LICENSEE EVENT REPORT (LER),

TEXT CONTINUATION FACILITY NAME (1) DOCKET (2) LER NUMBER (6) PAGE (3)

SEOUENTME REVISION YEAR NUMBER NUMBER R.E. Ginna Nuclear Power Plant 05000244 1999 010 00 3 OF 5 TEXT llfmore spaceis, required, use additional copies of NRC Form 366Al (17)

C. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:

None D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None E. METHOD OF DISCOVERY:

This event was anticipated due to the observed increase in airborne radioactivity in the auxiliary building during the draining evolution. The actuation of auxiliary building ventilation isolation was immediately apparent due to Main Control Board annunciator alarm and other indications of the auxiliary building ventilation system on the Main Control Board.

F. OPERATOR ACTION:

The Control Room operators discussed the higher than normal activity in the "A" CVCS holdup tank prior to starting the draindown evolution. They responded to the increase in counts on R-13 and R-14 by directing that the drain valves be closed. The Control Room operators responded to the event by performing the applicable actions of alarm response procedures, and other actions as deemed necessary. The Control Room operators notified higher supervision and the NRC resident inspector. The Shift Supervisor subsequently notified the NRC per 10 CFR 50.72 (b) (2) (ii), non-emergency four hour notification, at approximately 0745 EDST on June 15, 1999.

G. SAFETY SYSTEM RESPONSES'one III. CAUSE OF EVENT:

A. IMMEDIATE CAUSE'he immediate cause of the auxiliary building ventilation isolation was R-14 reaching its high alarm setpoint due to increased radioactive gas concentration in the auxiliary building atmosphere.

B. INTERMEDIATE CAUSE:

The intermediate cause of the increased radioactive gas concentration was the draining evolution of the "A CVCS holdup tank, as a result of higher than normal RCS activity (due to a suspected leaking fuel assembly) and consequent higher than normal activity in the CVCS holdup tanks.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION IB IBBB)

LICENSEE EVENT REPORT (LER).

TEXT CONTINUATION FACILITY NAME I1) DOCKET I2) LER NUMBER I6) PAGE I3)

SEBUENTIAL REYISIBN YEAR NUMBER NUMBER R.E. Ginna Nuclear Power Plant 05000244 1999 - 010 00 4 OF 5 TEXT llfmore spaceis required, use additional copies of NRC Form 366A/ l17)

C. ROOT CAUSE:

The underlying cause of the alarm on R-14 was an excessively conservative high alarm setpoint with suspected leaking fuel, and the original planning package for the draining evolution did not account for the higher than normal activity in the CVCS holdup tank.

IV. ANALYSIS OF EVENT:

This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a) (2) (iv),

which requires a report of, "Any event or condition that resulted in manual or automatic actuation of any engineered safety feature (ESF)" The auxiliary building ventilation isolation due to R-14 alarm was an

~

automatic actuation of a system referred to in 10 CFR 50.73 (a) (2) (iv) (B) (v).

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

There were no operational or safety consequences or implications attributed to the auxiliary building ventilation isolation because:

o The auxiliary building ventilation system design basis is established by the consequences of the limiting Design Basis Accident (DBA), which is a fuel handling accident. The Ginna Station Updated Final Safety Analysis Report (UFSAR) addresses this accident. The radiological consequences of the fuel handling accident occurring in the auxiliary building are significantly less than the limits of 10 CFR 100.

o The postulated failure of a gas decay tank (GDT) is evaluated in the Ginna Station UFSAR.

Even with the worst expected conditions, the offsite doses following release of this gaseous activity would be very low. The activity in the GDT analysis was assumed to be greater than the maximum amount that could accumulate from operation with cladding defects in 1% of the fuel elements. Ginna Station is currently operating with cladding defects that are significantly below this level. The amount of activity assumed in the analysis is 100,000 Ci equivalent Xenon-133. The actual amount of activity in the gas decay tanks on June 15, 1999 was significantly below this level.

o The auxiliary building ventilation system operated as designed to isolate when R-14 reached its high alarm setpoint. The auxiliary building ventilation isolation was in the conservative direction.

Based on the above, it can be concluded that the plant operated as designed, that there were no unreviewed safety questions, and that the public's health and safety was assured at all times.

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (B IBBS)

LICENSEE EVENT REPORT (LER).

TEXT CONTINUATION FACILITY NAME I 1) DQGKET I2) LER NUMBER (6) PAGE I3)

~R SEQUENTML NUMBER REYISION NUMBER R.E. Ginna Nuclear Power Plant 05000244 1999 -- p1p .. pp 5 OF 5 TEXT llfmore spaceis required, use additional copies of iVRC Form 366AJ I17)

V. CORRECTIVE ACTION:

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:

The Control Room operators reset the auxiliary building ventilation isolation signal and restored the system to pre-event status.

ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

New R-13 and R-14 alarm setpoints are being evaluated as appropriate for current plant conditions. Plant setpoint procedure P-9 (Radiation Monitoring System) will be revised to reflect these setpoints.

Ginna Station will develop a comprehensive response plan to address operation with suspected leaking fuel assemblies. This plan is intended to include provisions for reviewing the effects on normal plant operations from elevated RCS activity, the effect on gaseous releases to the environment, the effect on potential doses to workers, and instrumentation responses (including setpoint adjustments if warranted).

VI. ADDITIONALINFORMATION:

A. FAILED COMPONENTS'one B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: LER 97-04 was a similar event (containment ventilation isolation).

C. SPECIAL COMMENTS:

/

None