ML19354E561

LER 89-025-00:on 891223,sample Lines for Stack Radiation Monitor Froze,Resulting in Samples Not Indicative of Ongoing Releases.Caused by Lack of Insulation on Lines Exiting Stack.Sample Lines insulated.W/900119 Ltr

ML19354E561
Person / Time
Site:	Brunswick
Issue date:	01/19/1990
From:	Harness J, Harris T CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BSEP-90-0066, BSEP-90-66, LER-89-025, LER-89-25, NUDOCS 9001310368
Download: ML19354E561 (5)

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l Brunswick Nucicar Project P. O. Box 10429 Southport, NC 28461-0429 January 19, 1990 FILE: B09-135100 10CFR50.73 SERIAL: BSEP/90-0066 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk l Washington, DC 20555

BRUNSWICK STEAM ELECTRIC PLANT UNIT 1 l DOCKET NO. 50-325 LICENSE NO. DPR-71

LICENSEE EVENT REPORT 1-89 025 i

Gentlemen:

In accordance with Title 10 to the Code of Federal Regulations, the enclosed Licensee Event Report is submitted. This report fulfills the requirement for a written report within thirty (30) days of a reportable occurrence and is in accordance with the format set forth in NUREG-1022, September 1983.

Very truly yours,

d. 4t44N J. L. llarness, General Manager-Brunswick Nuclear Project Til/mcg Enclosure cc: Mr. S. D. Ebneter Mr. E. G. Tourigny l BSEP NRC Resident Office l

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~suse>Cs u m, n om a.c., . . .w.. w, o,*,,,,, ,,ve a.<. rvnewu,w no, On I?/23/89, during extreme cold conditions, the sample lines for the stack radiation monitor froze, result ing in samples which were not indicative of ongoing releases.

During normal operating conditions, the stack radiation monitor collects the samples that are required to ensure that the dose limits set forth in Technical Specification 3.11.2.1 are not exceeded. LCOs were initiated against Technical Specifications 3.3.2, 3.3.5.3 and 3.3.5.9 for inoperable instrumentation.

The stack sample lines froze due to the lack of insulation on a 3' section of the lines as they exited the stack. These lines were not insulated during original plant modification installation. No reason for the lack of insulation on these lines could be determined.

Surveillance requirements listed in Table 4.11.2-1 could not be implemented i during this event, nor were representative samples obtained in the ACTION requirements of Technical Specifications 3.3.5.9 and 3.3.5.3; however, the increased sampling and monitoring of other plant parameters ensured that the limiting conditions for operation in Technical Specification 3.11.2.1 did not exist. The safety significance of this event is therefore r.onsidered minimal.

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Event i Surveillance requirements of Technical Specification 4.11.2.1, Table 4.11.2-1 i could not be implemented, in that continuous sampling performed fren 12/23/89 i at 0045 until 12/25/89 at 0405 was not representative of ongoing releases. {P Initial Conditions  !

On 12/23/89. Unit I was operating at 100*. reactor power and Unit 2 was in day 97 of a scheduled 160 day refuel / maintenance outage. Operating Instruction ['

(01)-43, Freeze Protection and Cold Weather Bill, was in effect due to extreme cold conditions. As required by 01-43, Preventative Maintenance (PM)-HT001, Preventative Maintenance on Plant Freeze Protection and Heat Tracing System ,

(EIIS/FD), had been performed. Instrument lines 719 and 720 heat tracing for stack radiation monitoring (EIIS/WF/ MON) had been checked as operable as part of that instruction.

Event Description ,

on 12/23/n9, at 0030, the plant Environmental and Chemistry (E&C) group received notification from the Control Room that the control board annunciator indicating ,

"down-inop" for the stack radiation monitor had been received. Upon investi-gation, an E&C technician discovered the loss of sample flow to the stack -

radiation monitor. The technician was unable to establish sample flow with either the mid/high range pump or the low range pump (EIIS/WF/ MON /P). Auxiliary sampling equipment was placed'in service with proper flow rate of approximately 1,66 scfm. Limiting Conditions for Operation (LCOs) were initiated as a result of the equipment inoperability. ,

A review of stack gas sample number 89-3917, taken at 0642 on 12/23/89 from i the auxiliery sampler, showed abnormally low gas activity. It was also r identified that the auxiliary sample pump showed signs of strain, The ESC technician notified an ESC Foreman and the Unit 1 Shift Foreman'of the '

potential that the stack sample line flow was restricted. Instrumentation and '

Control technicians were asked to investigate the operability of the heat trace on the sample lines. A 3-foot section of the sample lines at the point where the lines exit the stack (approximately 129' elevation) was found uninsulated.

Due to the extreme cold, it was determined that condensation had accumulated and frozen in the 1/2" and 1/4" lines, restricting flow. Efforts were immediately begun to attempt to thaw the lines.

While the effort was continuing to thaw the sample lines, samples were being pulled at the outlet to the A0G (Augmented Off-Gas) System (EIIS/WF) to determine if the stack samples were representative of the release inputs. At 1011 on 12/23, a resample of the Unit 1 A0G outlet showed activity levels which were not indicated by the stack auxiliary pump samples. The E&C technician informed the Unit 1 Shift Foreman and the Environmental and Chemistry (ESC) i supervisor of the problem, f-t so.C P o.m 3BEA 48 1 s,. __

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0l 0 0l 3 Ol 4 Text u e === , esen.w anc s manw e At 1335 on 12/23, the Unit 1 Shift Foreman requested increased sampling of potential release pathways (A0G building, Radwaste Building, Unit 2 Drywell)-

and the operable unit A0G effluent stream. in addition to normal unit parameter monitoring performed by the Control Operators.

An effort was made to connect the auxiliary sampler to the stack sample discharge line, which connects to the stack. The effort to sample via this pathway did not result in representative scmples. At 1551 on 12/23, improvement was noticed on flow to the cuxiliary sampler and sample activity.

A 1729 sansple showed no activity, and auxiliary sampler flow problems were noted to be recurring.

At 0405 on 12/25, while sampling the stack gas, the ESC technician noted that.

the auxiliary line flow was at 3.5 scfm. At 0600 on 12/25 the normal sample pathway for the stack was reestablished. LCOs which had been established for the event were cancelled on 12/25 at 0802. .

The LCOs were initiated against Technical Specifications 3.3.2, 3.3.5.3 and 3.3.5.9 for inoperable instrumentation at the stack. Under normal operating conditions, the Stack Radiation Monitor collects the samples that are required to ensure that the dose limits set forth in Technical Specification 3.11.2.1 are not exceeded. Surveillance requirements listed in Table 4.11.2-1 during this event could not be implemented, nor were representative samples obtained i in the ACTION requirements of Technical Specifications 3.3.5.9 and 3.3.5.3; however, the increased sampling and monitoring of other plant parameters ensured that the limiting conditions for operation in Technical Specification 3.11.2.1 did not exist (see Event Assessment).

Event Investigation

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l As a result of the previously described events, it has been determined that l the stack sample lines froze due to the lack of insulation on the 3' section of lines as they exist the stack. Investigation concludes that the lines were not insulated during the original installation under Plant Modification

(80-036. Drawings indicate that the lines should have been heat traced and insulated from the stack monitoring building to the point where the lines exit the stack. The cause of the failure to properly insulate the lines could not be determined. This is believed, however, to be an isolated event.

Corrective Actions Taken 1

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The uninsulated section of the sample lines have been insulated. In addition, the Environmental and Chemistry (ESC) group performed an evaluation of the incident to determine if any limits specified in site Technical Specifications, 10CFR20 or 10CFR50 had been exceeded.

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rsxt u a=, a== e w. ease.w me a ma wim Event Assessment Based on a comparison of the inputs to the release during the event and the pre and post event samples of releases, dose summations were performed in accordance with the Off-Site Dose Calculation Manual (ODCM). The results show compliance was maintained with 10CFR20 limits in that instantaneous release  :

rate was calculated at 0.4604 mrem / year, or 0.03*. of Technical S;:ecification limits. 10CFR50 compliance was computed to be 0.275*. of the annual limit for  !

the most restrictive organ.  !

The safety significance of the event is considered to be minimal. The inputs to the stack were being monitored to ensure that elevated reles.se levels were not occurring. Routine monitoring of plant parameters and parametor annunciation /isolations would have given sufficient indication of increases in release rates had they occurred; therefore, this event is not considered significant, nor would it have been more cignificant under reasonable and credible alternative conditions.

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