ML050610713

LER 04-03-001 Oyster Creek, Unit 1, Regarding Actuation of Reactor Protection System Due to Spurious Hi-Hi Trip Signals on Intermediate Range Monitors Caused by Electromagnetic Interference

ML050610713
Person / Time
Site:	Oyster Creek
Issue date:	02/16/2005
From:	Swenson C AmerGen Energy Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2130-04-20222 LER 04-03-001
Download: ML050610713 (5)

Text

AmeTGen Energy Company, LLC www.exeloncorp.com AmerGen An Exelon Company SM Oyster Creek US Route 9 South, P.O. Box 388 Forked River, NJ 08731-0388 10 CFR 50.73 February 16, 2005 2130-04-20222 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 - 0001 Oyster Creek Generating Station Facility Operating License No. DPR-16 NRC Docket No. 50-219

Subject:

Licensee Event Report 2004-003-01: Supplement to Actuation of Reactor Protection System due to Spurious HI-HI Trip Signals on Intermediate Range Monitors Caused by Electromagnetic Interference

Reference:

Licensee Event Report 2004-003-00: Actuation of Reactor Protection System due to Spurious HI-HI Trip Signals on Intermediate Range Monitors Caused by Electromagnetic Interference, July 22, 2004 Enclosed is Supplemental Licensee Event Report 2004-003-01. This event did not affect the health and safety of the public or plant personnel.

If any further information or assistance is needed, please contact David Fawcett at 609-971-4284.

SincerW C. N. Swenson Vice President, Oyster Creek Generating Station CNS/DIF Attachment 1: Summary of AmerGen Energy Company, LLC Commitments

Enclosure:

Licensee Event Report 2004-003-01 cc: S. J. Collins, Administrator, USNRC Region I P. S. Tam, USNRC Senior Project Manager, Oyster Creek R. J. Summers, USNRC Senior Resident Inspector, Oyster Creek File No. 04106

ATTACHMENT t

SUMMARY

OF AMERGEN ENERGY CO. LLC COMMITMENTS The following table identifies commitments made in the document by AmerGen Energy Co. LLC (AmerGen). Any other actions discussed in this submittal represent intended or planned actions by AmerGen. They are described to the NRC for the NRC's information and are not regulatory commitments.

COMMITMENT COMMITTED DATE OR "OUTAGE" Maintenance Training Program will be revised to include an introduction to electrically induced noise. Specifically, 03/3012005 addressing the sensitivity of the NI System electronics to electrical noise induced problems and how to avoid them in the future.

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BYOMB: NO. 3150-0104

• EXPIRES: 06rCt207 (6-2004) Estimated burden per response to comply with this mandatory collection request:

50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to Industry. Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001

• or by internet e-mail to LICENSEE EVENT REPORT (LER) infocollectsenrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202 (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to knpose Information collection does (See reverse for required number of not display a currently valid OMB control number, the NRC may not conduct or digits/characters for each block) sponsor, and a person Is not required to respond to, the information collection.

1. FACILITY NAME 2. DOCKET NUMBER 3. PAGE Oyster Creek, Unit 1 05000 219 1 OF 3

4. TITLE Actuation of Reactor Protection System due to Spurious Hi-Hi Trip Signals on Intermediate Range Monitors Caused by Electromagnetic Interference

5. EVENT DATE 6. LER NUMBER 7. REPORT DATE 6. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO MONTH DAY YEAR 05000 05 27 2004 2004 - 003 - 01 02 16 200 5 FACILITY NAME DOCKET NUMBER

9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TOTHE REQUIREMENTS OF 10 CFR 5: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)

N 20.2201 (d) 20.2203(a)(3)(ii) 50.73(a)(2)ii)XA) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)iii) 50.73(a)(2)(ix)(A)

10. POWER LEVEL 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) I/ 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71 (a)(4) 002 20.2203(a)(2)Ov) 50.46(a)(3)Cii) 50.73(a)(2)(v)(B) 73.71 (a)(5) 20.2203(a)(2)(v) 50.73(a)(2)i)(A) 50.73(a)(2)(vXC) OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D) Sper inAbstract below

__ _ _ __ _ _ _ I __ _I___I or in NRIC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (-uda Are Code)

David Fawcett, Licensing Engineer (609) 971-4284

13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT CAUSE SYSTEM COMPONENT MANUS REPORTABLE N CAUSE SYSTEM COMPONENT MANU - REPORTABLE FACTURER TO EPIX FACTURER TO EPIX

14. SUPPLEMENTAL REPORT EXPECTED 15. EXPECTED MONTH DAY YEAR SUBMISSION [___l

=lYES (IfyescompleteEXPECTEDSUBMISSIONVDATE) VI NO DATE ABSTRACT (Li to 1400 spaces. Le., 15 -spaced h amxknatety wrftn e)

On May 27, 2004, at 00:31 hours, with the Reactor Mode switch in the Startup position, a reactor scram from approximately 2 0/% power was caused by a spurious actuation of Nuclear Instrumentation (NI) Intermediate Range Monitor (IRM) (EIIS-IG) channels 13, 14, and 18. The spurious actuation was caused by electromagnetic interference (EMI). The reactor shut down as designed. I The safety significance of this event is considered minimal. The plant responded as designed for this type of event.

Technical Specification limits were maintained. There was no radioactive release. All safety systems were fully operable. Off-site power was available. Operator performance was satisfactory.

A Root Cause Analysis has been completed identifying the root cause of the EMI induced spiking of the IRM channels.

IRM-13 & 14 were found to have loose cable connections at the drawer and nicks in the outer surface of the cable.

This has been traced as the entry point of the noise intrusion and the reason the channels spiked. A coated surface on the circuit preamplifier box, on IRM-1 8, caused a poor connection to a common ground point and provided another entry point for noise intrusion.

Connections were tightened, damaged cabling was repaired, and one IRM pre-amplifier was replaced.

NRC FORM 366 (6-2004)

1.I NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME 2.DOCKET 6. LER NUMBER 3. PAGE Oyster Creek, Unit 1 05000219 YEAR SEQUENTIAL NUMBER REVISION NUMBER 2004 - 003 - 01 2 OF 3

17. NARRATIVE (ifnore space Is required, use additional copies of NRC Form 366A)

Description of Event On May 27, 2004, at 00:31 hours, with the Reactor Mode switch in the Startup position, Nuclear Instrumentation (NI)

Intermediate Range Monitor (IRM) (EIIS-IG) channels 13,14 (Reactor Protection System (RPS) (EIIS-JC) Channel 1), and IRM channel 18 (RPS Channel 2) simultaneously spiked, indicating Hi-H/INOP, which caused a full reactor scram. The reactor was at approximately 2% power in the process of being shut down for a planned maintenance outage. The Source Range Monitoring (SRM) detectors were being driven into the core in accordance with the shutdown procedure.

The reactor scram shut down the reactor as designed. All control rods fully inserted. Level control was in automatic and there was only a slight variation in level during the transient. Pressure control was stable. Operator actions were in accordance with plant procedures.

Analysis of Event The safety significance of this event is considered minimal. The plant responded as designed. Technical Specification limits were maintained. There was no radioactive release, nor any effect on the health and safety of the public. Operator performance was satisfactory.

Cause of Event Actuation of the Reactor Protection System was caused by Hi-Hi/INOP signals from IRM channels in both Reactor Protection Systems. The Hi-Hi/INOP signals on the IRM channels were caused by an EMI (electro-magnetic interference) induced spike. The EMI spiking on the IRM instrumentation was apparently caused by loose connectors, cable damage, and/or high resistance in IRM ground path.

The Root Cause forthis specific event has been traced to spiking on IRM-13, 14 & 18. IRM-13 & 14 were found to have loose cable connections at the drawer and nicks in the outer surface of the cable. This has been traced as the entry point of the noise intrusion and the reason the channels spiked. A coated surface on the circuit preamplifier box, of IRM-1 8, caused a poor connection to a common ground point and provided an entry point for noise intrusion.

Corrective Actions:

Interim:

1. The SRM and IRM signal cable connectors were inspected and tightened as necessary.

2. The damaged cable sections were removed or repaired.

3. One IRM pre-amplifier (IRM-1 8), with a high resistance to ground connection, was replaced.

Long Term to prevent recurrence:

1. Maintenance Training Program will be revised to include an introduction to electrically induced noise.

Specifically, addressing the sensitivity of the NI System electronics to electrical noise induced problems and how to avoid them in the future.

2. Implement a preventative maintenance (PM) task that provides a method of testing the NI System for noise related issues, using vendor provided equipment or similar test instruments, just prior to a controlled shut down or startup. (Completed)

NRC FORM 366A (1-2001)

I NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGE Oyster Creek, Unit 1 0500021 9 YEAR YER SEQUENTIAL EUMENRA N REVISION RUMERII 2004 -003 - 01 3 OF 3

17. NARRATIVE (If more space is required, use additional copies of NRC Foann 366A)

Additional Information A. Failed Components:

None B. Previous similar events:

LER 92-007-00, Reactor Scram Caused by Electrical Noise from a Failed IRM Bypass Switch During Plant Startup There have been additional cases of IRM spiking problems, but they did not result in a reactor scram while the reactor was critical. An IRM spiking trend has been identified through the Corrective Action Program and a root cause evaluation has been completed.

C. Identification of components referred to in this Licensee Event Report:

Components IEEE 805 System ID IEEE 803A Function Neutron Monitors IG RI NRC FORM 366A (1-2001)