DCL-18-112, Technical Specification 5.6.8 PAM Instrumentation Report
| ML18354A925 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/20/2018 |
| From: | Gerfen P Pacific Gas & Electric Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PG&E Letter DCL-18-112 | |
| Download: ML18354A925 (2) | |
Text
Pacific Gas and Electric Campany*
December 20, 2018 PG&E Letter DCL-18-112 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Paule Gerten Station Director Technical Specification 5.6.8 PAM Instrumentation Report
Dear Commissioners and Staff:
Diablo Canyon Power Plant Mail code 104/5/502 P.O. Box 56 Avila Beach, CA 93424 805.545.4596 Internal: 691.4596 Fax: 805.545.4234 Pacific Gas and Electric Company (PG&E) is submitting the enclosed report in accordance with Technical Specifications (TS) 3.3.3, "Post Accident Monitoring (PAM) Instrumentation", and TS 5.6.8, "PAM Report", for an inoperable Unit 2 Neutron Flux Wide Range (Gamma-Metrics) Nl-52 channel.
PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter. If you have any questions or require additional information, please contact Mr. Hossein Hamzehee at (805) 545-4720.
Si12L;
- Paula Gerten i-rntt/4231 /SAPN 51004541 Enclosure cc:
Diablo Distribution cc/enc:
Kriss M. Kennedy, NRC Region IV Administrator Christopher W. Newport, NRC Senior Resident Inspector Balwant K. Singal, NRR Senior Project Manager A member of the STARS Alliance Callaway
- Diablo Canyon
- Palo Verde
- Wolf Creek
Diablo Canyon Power Plant, Unit 2 Enclosure PG&E Letter DCL-18-112 Post Accident Monitoring (PAM) Instrumentation lnoperability Report DCPP Unit 2 Neutron Flux (Wide Range Nuclear Instrumentation System (NIS))
Channel Nl-52 lnoperability Condition/ Requirement:
Diablo Canyon Power Plant (DCPP) Technical Specification (TS) 3.3.3, "Post Accident Monitoring (PAM) Instrumentation," Table 3.3.3-1, Function 1, defines the instrumentation requirements for the Neutron Flux Wide Range Nuclear Instrumentation System (NIS). On November 15, 2018, the DCPP Unit 2 Neutron Flux Wide Range (Gamma-Metrics) Nl-52 channel was declared inoperable when excessive signal noise caused the channel to not meet the surveillance test procedure acceptance criteria.
When Limiting Condition for Operations (LCO) 3.3.3, Condition A cannot be met, Condition B requires, per TS 5.6.8, a PAM Report be submitted within the following 14 days.
The following information is submitted as required by TS 5.6.8, "PAM Report":
- 1. The preplanned alternate method of monitoring:
One PAM ch,annel provides neutron flux indication and is environmentally qualified.
Wide Range NIS channel Nl-51 Backup indications to the Nl-51 and Nl-52 instrument loops are provided by 2 source range (Nl-31, Nl-32), 2 intermediate range (Nl-35, Nl-36) and 4 power range instrument loops (Nl-41 through Nl-44).
- 2. The cause of the inoperability:
Troubleshooting determined the noise is being generated from field cables, connectors, or the detector. The components are in containment and cannot be properly tested or repaired with the unit at power. The noise is impacting the signals from both detector chambers in the Nl-52 detector assembly.
- 3. The plans and schedule for restoring the instrumentation channels of the function to operable status:
The plans for restoring the instrumentation channel to an operable status will require a plant shutdown. The repair is being scheduled for September 2019 during the next planned Unit 2 refueling outage.
1