05000245/LER-1996-054, :on 961030,high Range Stack Gas Monitor Failed & Declared Inoperable.Due to Intermittent Nature of Failure. Cause of Event Will Be Provided in Supplemental Rept.Cause of Intermittent Failures Will Be Determined

:on 961030,high Range Stack Gas Monitor Failed & Declared Inoperable.Due to Intermittent Nature of Failure. Cause of Event Will Be Provided in Supplemental Rept.Cause of Intermittent Failures Will Be Determined

ML20134J785
Person / Time
Site:	Millstone
Issue date:	11/13/1996
From:	Hinnenkamp P, Robert Walpole NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
B16005, LER-96-054, LER-96-54, NUDOCS 9611180062
Download: ML20134J785 (4)

LER-1996-054, on 961030,high Range Stack Gas Monitor Failed & Declared Inoperable.Due to Intermittent Nature of Failure. Cause of Event Will Be Provided in Supplemental Rept.Cause of Intermittent Failures Will Be Determined

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
2451996054R00 - NRC Website

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Waterford, CT 06385-0128 (203) 447-1791 November 13,1996 Docket No. 50-245 B16005 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 l

This letter forwards Licensee Event Report (LER) 96-054-00, documenting an event that occurred at Millstone Nuclear Power Station, Unit No.1 on October 30,1996. This LER is submitted as a Special Report, pursuant to the Millstone Unit No.1 Technical Specifications.

The following are Northeast Nuclear Energy Company's commitments made within this letter.

' All other statements made within this letter are for information only.

B16005-1 The cause of the intermittent failures will be determined and it is expected that the l

High Range Stack Noble Gas Monitor will be returned to service prior to i

November 30,1996.

B16005-2 Supplemental report will be submitted prior to December 15,- 1996, with cause of the intermittent problems.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY j

f-L P. D. Hinnenkamp V

Director, Unit Operations 9611100062 96 1 3 l

PDR ADOCK 05000245 1

j.

S PDR i

Attachment: LER 96-054-00 i

Y cc:

H. J. Miller, Region 1 Administrator T. A. Eastick, Senior Resident Inspector, Millstone Unit No. I J. W. Andersen, NRC Project Manager, Millstone Unit No. I osa422., nov. i.,s l

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FACluTY NAME nl DOCKET NUMBER (2)

PAGE (3)

Millstone Nuclear Power Station Unit 1 05000245 1 of 3 TITLE 14)

High Range Stack Noble Gas Monitor inoperable EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR FACluTY NAME DOCKET NUMBER NUMBER 10 30 96 96 054 00 11 13 96 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR B: (Check one or more) (11)

MODE (9)

N 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(11 20.2203(a)(3)(i) 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 000 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)

X OTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v) specify in Abstract below I

A 20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

SpTcYaNeElo7t 66A LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER linclude Area Codel Robert W. Walpole, MP1 Nuclear Licensing Manager (860)440-2191 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFACTURER REPORTABLE TO NPRDs TO NPRDS l

l SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR j

SUBMISSION f

YES NO 12 15 96 l

(if yes, complete EXPECTED SUBMISSION DATE).

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

On October 30,1996 at 0525 hours0.00608 days <br />0.146 hours <br />8.680556e-4 weeks <br />1.997625e-4 months <br />, with the plant shutdown and the reactor in the COLD SHUTDOWN condition, the High Range Stack Noble Gas Monitor failed and was declared inoperable. Due to the intermittent nature of the failure, subsequent troubleshooting could not determine a definitive cause of the problem; therefore, the monitor remains inoperable with the alternate pre-planned method established in accordance with Technical Specification 3.8.D.7 to monitor stack effluent releases. An extensive troubleshooting effort has been initiated with resources from Millstone Unit Nos.1 and 3, as well as the services of the vendor to determine the cause of the intermittent failures and return the High Range Stack Noble Gas Monitor to service.

This event is reportable pursuant to Millstone Unit No.1 Technical Specification 3.8.D.7, which requires the submission of a Special Report to NRC, within 14 days of the event, when the High Range Stack Noble Gas Monitor cannot be made operable within seven days.

NRC FORM 366 (4-95)

4',

fiRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 2 of 3 96 054 00 TEXT lif more space is required, use additional copies of NRC Form 366A) (17) 1.

Descriotion of Event On October 30,1996 at 0525 hours0.00608 days <br />0.146 hours <br />8.680556e-4 weeks <br />1.997625e-4 months <br />, with the plant shutdown and the reactor in the COLD SHUTDOWN condition, the High Range Stack Noble Gas Monitor failed and was declared inoperable. Troubleshooting revealed that several circuit boards were suspect and replaced, which allowed the monitor to operate. Since it was not known whether the suspect boards failed on their own or due to another problem that still existed within the monitor, the monitor was left as inoperable. Additionally, recent intermittent problems with the monitor resulted in the conclusion that continued troubleshooting, which consisted of component replacement and subsequent monitoring for intermittent problems, was necessary to obtain reasonable assurance that the monitor would function properly when returned to service. Subsequently, the monitor failed again due to an unknown cause.

At this point, it was determined that since a definitive problem could not be found, the monitor would not be returned to service in a timely manner. Due to the history of intermittent problems that have surfaced with this instrurnent over the past several months and the failure of troubleshooting efforts to identify the root cause, it was deemed necessary to develop a plan to conduct extensive troubleshooting and system walkdowns to validate proper grounding, noise protection, and compliance with recommended installation instructions. Alternate pre-planned actions have been initiated and will remain in effect in accordance with Technical Specification 3.8.D.7.

II.

Cause of Event

The cause of the event will be provided in a supplemental report.

Ill. Analvsis of Event Per the Millstone Unit no.1 Updated Final Safety Analysis Report (UFSAR), the process and effluent monitoring system provides a means for compliance with 10CFR20,10CFR50 Appendix A GDC 60,63, and 64, and Regulatory Guides 1.21,1.97,4.15, and 8.8. The High Range Stack Noble Gas Monitor measures the gross gamma activity of noble gases exiting the Millstone Unit No.1 Main Stack to provide information to the operator for assessing plant conditions and classification of events, during and following an accident.

This event is reportable pursuant to Millstone Unit No.1 Technical Specification 3.8.D.7, which requires the submission of a Special Report to NRC, within 14 days of the event, when the High Range Stack Noble Gas Monitor cannot be made operable within seven days.

The High Range Stack Noble Gas Monitor is required to be operable at all times. The bases of the Technical Specifications delineates that, since the Millstone Unit No.1 stack represents the final release point for potential accident level releases from all three Millstone units, the applicability has been defined as at all times rather than relating it solely to Millstone Unit No. 1 operating modes. There are no safety consequences since the Millstone Unit No.1 Main Stack Noble Gas Activity Monitor remains operable as the initial alternate, pre-planned method to monitor effluent releases, in the event of an accident involving a release through the Main Stack, additional monitoring methods are available as described in Emergency Plan Operating Procedures.

. ~ _. -..

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ERC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION 4

(4 95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 1 05000245 NUMBER NUMBER 3 of 3 96 054 00 1

3 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)

J

IV. Corrective Action

The cause of the intermittent failures will be determined and it is expected that the High Range Stack Noble i

Gas Monitor will be returned to service prior to November 30,1996.

Supplemental report will be submitted prior to December 15,1996, with cause of the intermittent problems.

j V.

Additional InformatiDD

Similar Events

LER 96-044-01, dated: 7/29/96, "High Range Stack Noble Gas Monitor Inoperable Due to inadequate Calibration" LER 95-015-00, dated 8/21/95, " Stack High Range Noble Gas Radiation Monitor inoperable" Manufacturer Data None.