ML17265A469

LER 98-003-01:on 980904,actuations of CR Emergency Air Treatment Systems (Creats) Occurred.Caused by Radon build-up During Temp Inversion.Creats Actuation Signal Was Reset & Normal Ventilation Was Restored to CR

ML17265A469
Person / Time
Site:	Ginna
Issue date:	11/25/1998
From:	St Martin J ROCHESTER GAS & ELECTRIC CORP.
To:
Shared Package
ML17265A468	List: ML17265A467 ML17265A469
References
LER-98-003, LER-98-3, NUDOCS 9812070106
Download: ML17265A469 (17)

Text

NRC FORM 366 U. UCLEAR REGULATORY COMMISSION APPRO BY OMB NO. 31RMRBC 06/30/2001

!5-1999) Estimated burden per response to comply with this mandato Information collection request: 50 hrs. Reported lesson learned are incorporated into the licensing process and f LICENSEE EVENT REPORT (LER) back to industry. Forward comments regarding burde estimate to the Rocords Management Branch (T4) F33), US Nuclear Regulatory Commlsgon, Washlfon, Dc 2055 (See reverse for required number of 0001 ~ and to the Papenvork Reduction Pro ect (31504104) digits/characters for each block) (Ãioo of Management and Budget, Washington, DC 20503.

an information collection does not display a currently vali OMB control number, the NRC may not conduct or sponsor, FACILITYNAME 11) DOCKET NUMBER (2) PAGE I3)

R. E. Ginna Power Plant 05000244 I OF 9 TITLE (I)

Radon Build-up During Temperature Inversion Results in Actuations of Control Room Emergency AirTreatment Systems F, Ãlfh BFR RFPORTDA F. OTHF.RF CI IT Fe)INVO .D PACILBYNAME SEOVENDAL REvISION MONDI DAY YEAR NIIMBER NDMBER MONI DAY 05000 PACILIIYNAME 09 04 1998 1998 003 01 11 25 1998 05000 OPERATINC THIS FPO TISSlJBMITTRD P'U RS )ANT O I F F UIRF IF SO 10 htoDE (9) 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(

POWER 20.2203 a I 20.2203 a 3 i 50.73 a 2 ii S0.73 a 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 50.73 a 2 iv OTHER 20.2203(a)(2)(iii) 50.36(c)(l) 50.73(a)(2)(v) specify ia eaieae deicer << ia Nac 20.2203(a)(2)(iv) 50.36(c)(2) Fsns aeea 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME 1ELEPHONE NUMBER (hetude Area Code)

John St.Martin - Technical Assistant (716)771-3641 COMPLETE ONE LINE FOR EACH COhIPONENT FAILURE DESCRIBED IN THIS REPORT (13) cAusE S YSTEhf COMPONENT MANVPACIURER REPORTABLE TO EPIX SYSIEM COMPONENT 0

SUPPI,FMRNTAI RFPORT RXPI?CTFD 14 EXPECTED YES X NO SUBMISSION gf yes, complete EXPECTED SUBMISSION DATE). DATE (15)

ABSTRACT (Limitto 1400 spaces, i.e., approximately 1S sinaiospaced typcNTitten lines) (16)

On September 4, 1998, at approximately 0740 EDST, the plant was in Mode 1 at approximately 100% steady state reactor power. Control Room Radiation Monitors reached their alarm setpoints, and actuated the Control Room Emergency Air Treatment System to isolate the Control Room atmosphere to and from outside a3.r. The same event occurred on September 15, 1998 at approximately 0051 EDST, and September 18, 1998 at 0452 EDST, and, October 27, 1998 at 0706 EST.

On these dates, an atmospheric temperature inversion was present, and an unusually high concentration of Radon built up that was trapped due to the inversion. Control Room Radiation Monitors alarmed due to the presence of this unusually high concentration of naturally occurring radioactive Radon and Radon decay action was taken to determine the source of radiation. In these events,"air products'mmediate samples were taken which determined that the source of radiation was naturally occurring Radon and Radon decay products. These air samples confirmed that fission product activ3.ty was not the cause.

No immediate 'corrective actions were required. A Root Cause Analysis was conducted. The results of the Root Cause Analysis are outlined in Section III.C. Corrective action to prevent recurrence is outlined in Section V.B.

'F812070106 'i)81i24 PDR ADQCK 05000244 8 PDR

I 1

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-1999)

LICENSEE EVENT. REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER 'UMBER R. E. Ginna Nuclear Power Plant 50-244 1998 oas 01 2 OF 9 TEXT flfmore speceis required, use edditionel copies of NRC Form 366Ai I17)

I. PRE-EVENT PLANT CONDITIONS:

On September 4, 1998, at approximately 0740 EDST, the plant was in Mode 1 at approximately 1009 steady state reactor power. Unrelated to plant activities, an atmospheric temperature inversion was present. A temperature inversion limits the dispersion of matter from the ground into the upper atmosphere.

II. DESCRIPTION OF EVENT:

A. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:

0 September 4, 1998, 0740 EDST: First event date and time.

September 4, 1998, 0740 EDST: Discovery date and time.

0 September 1 5 r 1 998 r 005 1 EDST Second event date and time.

0 September 15, 1998, 0051 EDST: Discovery date and time.

0 September 18, 1998, 0452 EDST: Third event date and time.

0 September 18, 1998, 0452 EDST: Discovery date and time.

0 September 18, 1998, 1631 EDST: Invalid actuation of Control Room Emergency Air Treatment System.

0 October 20, 1998, 0403 EDST:,Invalid actuation of Control Room Emergency Air Treatment System.

October 27, 1998, 0706 EST: Fourth event date and time.

0 October 27, 1998, 1050 EST: Fourth event discovery date and, time.

B. EVENT The Control Room Radiation Monitors monitor outside air in the vicinity of the Control Room. A high radiation signal on one of these monitors will initiate the Control Room Emergency Air Treatment System (CREATS) filtration train and isolate each air supply path to and from the Control Room.

NRC FORM 366A I6-1998)

OI NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-199BI LlCENSEE EVENT REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 - - 3 OF 9 1998 oo3 01 TEXT /Ifmore spaceis required, use additional copies of NRC Form 366A/ I17I On September 4, 1998, the plant was in Mode 1 at approximately 1004 steady state reactor power. Due to the temperature inversion, there was an unusually high concentration of naturally occurring radioactive Radon and Radon decay products in the lower atmosphere. At approximately 0740 EDST, Control Room Radiation Monitors reached their alarm setpoints. The CREATS actuated and isolated the Control Room atmosphere to and from outside air upon reaching these setpoints.

Samples were taken to determine the isotopic content of the air in the Control Room. These samples determined that there was an unusually high concentration of Radon and Radon decay products from the outside air, and indicated that fission product activity was not the cause of the increase in radioactivity.

On September 15, 1998, at approximately 0051 EDST, Control Room Radiation Monitors reached their alarm setpoints and the CREATS isolated the Control Room atmosphere to and from outside air.

Again, a temperature inversion was present, and samples determined that there was an unusually high concentration of Radon and Radon decay products from the outside air.

On September 18, 1998, at approximately 0452 EDST, Control Room Radiation Monitors reached their alarm setpoints and the CREATS isolated the Control Room atmosphere to and from outside air.

For a third time, a temperature inversion was present, and samples determined that there was an unusually high concentration of Radon and Radon decay products from the outside air.

On October 27', 1998, at approximately 0706 EST, Control Room Radiation Monitors reached their alarm setpoints. Prior to this time, the CREATS had been manually isolated for troubleshooting of the Control Room Radiation Monitors. Therefore, when the radiation alarms occurred, no CREATS actuation or Control Room alarm occurred. Later that morning (at approximately 1050 EST),

Instrument and Control (I&C) technicians observed the radiation monitor alarm on a local panel outside the Control Room, and notified Control Room operators of the alarm. Another temperature inversion was determined to be present.

NRC FORM 366A I6-1998)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6.1 99 BI LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 oos 01 4 OF 9 TEXT flfmore spaceis required, use additional copies of NRC Form 366A/ 1171 In addition to these valid events, there were two (2) invalid CREATS actuations that occurred in the recent past. On September 18, 1998, at approximately 1631 EDST, an invalid CREATS actuation occurred. Control Room operators checked the Control Room Radiation Monitors locally, and discovered that there was no alarm condition. There was no temperature inversion present, and there had been no significant increase in radioactivity as monitored by the Control Ro'om Radiation Monitors. It was determined that this event (September 18 at 1631 EDST) was an invalid actuation.

On October 20, 1998, at approximately 0403 EDST, another invalid CREATS actuation occurred. Control Room operators determined that one of the Control Room Radiation Monitor channels had spiked above the alarm setpoint. There was no temperature inversion present, and there had been no significant increase in radioactivity as monitored by the Control Room Radiation Monitors. It was determined that this event (October 20 at 0403 EDST) was an invalid actuation.

C~ I NOPERABLE STRUCTURES r COMPONENTS r OR SYSTEMS THAT CONTRI BUTED TO THE EVENT:

None D. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None E. METHOD OF DISCOVERY:

The events of September 4, 15, and 18 were immediately apparent due to the actuation of CREATS to isolate the Control Room atmosphere to and from outside air. The event. of October 27 was not apparent to Control Room operators, since there was no CREATS actuation and no alarm in the Control Room. This event was discovered by I&C technicians.

NRC FORM 366A I6-1998)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (6.1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION

'SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 oo3 01 5 OF 9 TEXT /lfmore spaceis required, use additional copies of NRC &rm 366Al I17l F. OPERATOR ACTION:

During the events of September 4, 15, and 18, the Control Room operators acknowledged Main Control Board annunciators associated with the radiation monitor alarms and actuation of the CREATS, entered Alarm Response Procedure AR-E-11 (Control Room HVAC Isola'tion), and notified higher supervision and the NRC. They confirmed that Control Room Radiation Monitor R-37 (which measures particulate radiation) was locked in to the alarm condition. Independent air samples were requested, and when the results of these air samples confirmed the presence of radioactivity (Radon and Radon decay'products), the Control Room operators determined that, valid actuations of the CREATS had occurred. For the event which occurred on October 27, no operator response or action was warranted.

The Shift Supervisor subsequently notified the NRC per,10 CFR 50.72 (b) (2) (ii), non-emergency four hour notification, at approximately 1115 EDST on September 4, 1998.

On September 15, 1998, the NRC was notified at approximately 0442 EDST. On September 18, 1998, the NRC was notified at approximately 0915 EDST. This last notification was slightly beyond the four hour timeframe due to delays in confirming the presence of Radon and Radon decay products.

On October 27, 1998, the NRC was notified at approximately 1439 EST.

G. SAFETY SYSTEM RESPONSES: I For the events of September 4, 15, and 18, the CREATS actuated to isolate the Control Room atmosphere to and from outside air when the radiation monitors reached their alarm setpoints. For the event on October 27, the CREATS was already actuated as a prerequisite for troubleshooting the system, so no response occurred.

III. CAUSE OF EVENT:

A. IMMEDIATE CAUSE:

The immediate cause of the actuation of the CREATS was Control Room Radiation Monitors reaching their alarm setpoints, resulting in isolation of the Control Room atmosphere to and from outside air. (On October 27, no actuation occurred.)

NRC FORM 366A I6-1998)

NRC FORM 366A U.S. NUCLEAR REGUlATORY COMMISSION (6-1996)

LICENSEE EVENT REPORT ILERI TEXT CONTINUATiON.

SEOUENTIaL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 oo3 O1 6 OF 9 TEXT Iifmore speceis required, use edditionel copies of NRC Form 366AI I17)

B. INTERMEDIATE CAUSE:

The intermediate cause of the radiation monitors reaching their alarm setpoints was increased radioactivity of the outside air, due to an unusually high concentration of Radon and Radon decay products.

C. ROOT CAUSE:

There were valid and invalid CREATS actuations during the recent past.

For the valid actuations, the underlying cause of the unusually high concentration of Radon and Radon decay products was an atmospheric temperature inversion; which trapped the naturally occurring Radon in the lower atmosphere, limiting the dispersion of matter from the ground into the upper atmosphere. Samples taken confirmed that the CREATS actuation was due to the temperature inversion, and not due to fission product activity.

Also, the alarm setpoints for R-36 and R-37 have been evaluated to be unnecessarily conservative, which resulted in CREATS actuations.

Due to the invalid CREATS actuations, troubleshooting and root cause analysis were performed. As a result, additional factors were identified that contributed to the invalid CREATS actuations. The Control Room Radiation Monitor is actually three (3) separate channels that analyze a common sample of outside air being supplied to the CREATS. Channel R-36 monitors noble gas.

Channel R-37 monitors particulate. Channel R-38 monitors iodine.

IGC personnel identified that the detector for R-37 was grounded.

They also discovered a damaged detector cable for R-37, and found damaged insulation on the power supply cable to the Control Room Radiation Monitor.

IV. ANALYSIS OF EVENT:

These events are 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) including the Reactor Protection System (RPS)". CREATS is listed in NUREG-1022 as an example system of what the NRC staff considers to be a system "provided .to.mitigate the consequences of a significant event."

NRC FORM 366A IS-1998)

I

\

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (8-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 -,, oos 01 7 OF 9 TEXT /If more space is required, use additional copies of NRC Farm 366Ai I17)

An assessment was performed'onsidering 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 CREATS actuation because:

o The CREATS provides a protected environment from which operators can control the plant following an uncontrolled release of radioactivity. There was no uncontrolled release of radioactivity which occurred on September 4, September 15, September 18, and October 27.

0 The CREATS actuation was in response to increased radioactivity in the vicinity of the Control Room. However, the increased radioactivity was due to naturally occurring Radon and Radon decay products. The increase in radiation detected was not due to any plant activity. Specifically, it was not due to an increase in fission product activity nor an uncontrolled release of radioactivity.

0 CREATS functioned as per design, to isolate the Control Room in response to levels of radioactivity that resulted in reaching the alarm setpoints on the Control Room Radiation Monitors.

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.

V. CORRECTIVE ACTION:

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

At the conclusion of the three temperature inversions in September, and after the Control Room Radiation Monitors decreased below their alarm setpoints, the CREATS actuation signal was reset, and normal ventilation was restored to the Control Room. For the event of October 27, no CREATS actuation occurred,'and no actions were warranted.

NRC FORM 366A I6-1998)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-1998)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 oo3 01 8 OF 9 TEXT llfmore space is required, use additional copies of iVRC Rearm '366Al I17)

B~ ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE; 0 The root cause of the valid actuations was the unusually high concentration of Radon and Radon decay products during an atmospheric temperature inversion, which trapped the naturally occurring Radon in the lower atmosphere, limiting the dispersion of matter from the ground into the This is a natural phenomenon. upper'tmosphere.

0 The setpoint for R-37 will be adjusted to eliminate unnecessary conservatism in the setpoint for actuation of the CREATS.

0 The setpoint for R-36 has been evaluated to determine there is unnecessary conservatism in the setpoint. The R-36 if setpoint will remain unchanged.

0 Contributing factors to the invalid CREATS actuations, which were due to spiking on these radiation monitors, have been addressed by the following actions:

1. The grounded R-37 detector and the damaged R-37 detector cable have been replaced.

2. The damaged insulation on the power supply cable has been replaced.

VI. ADDITIONAL INFORMATION:

A. FAILED COMPONENTS:

The failed components included the R-37 particulate detector (failed due to being grounded) and the detector cable (failed due to cold-working). These components were manufactured by or supplied by Nuclear Research Corporation. The detector is Model No. MD-34DT.

B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: No documentation of similar LER events with the same root cause at Ginna Station could be identified.

NRC FORM 366A I6-1998I

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION I6-1999)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION SEQUENTIAL REVISION NUMBER NUMBER R. E. Ginna Nuclear Power Plant 50-244 1998 003 01 9 OF 9 TEXT (Ifmore speceis required, use additional copies ol'VRC Form 366Al I17)

, C. SPECIAL COMMENTS:

Until 1998, Ginna Station did not consider the CREATS to be an ESF. In 1998, new NRC guidance was promulgated in NUREG-1022, Revision 1. NRC specifically listed the Heating, Ventilating and Air Conditioning System for Control Room as an example of an ESF system. Therefore, Ginna Station reporting procedures were revised in 1998 to be in accordance with this NRC guidance.

Individuals recall that, prior to 1998, there were some CREATS actuations at Ginna Station. However, these actuations were not reportable at =-those times. Since these earlier actuations were not reportable, no documents exist to confirm any of these earlier occurrences.

NRC FORM 366A I6-1998)