05000255/LER-2015-001, Regarding Automatic Reactor Trip Results from a Turbine Trip Initiated from the Digital Electro-Hydraulic Control System
| ML15314A667 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 11/10/2015 |
| From: | Vitale A Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PNP 2015-085 LER 15-001-00 | |
| Download: ML15314A667 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2552015001R00 - NRC Website | |
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~Entergy PNP 2015-085 November 10, 2015 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Entergy Nuclear Operations, Inc.
Palisades Nuclear Plant 27780 Blue Star Memorial Highway Covert, MI 49043 Tel 269 764 2000 Anthony J. Vitale Site Vice President
SUBJECT:
Automatic Reactor Trip Results from a Turbine Trip Initiated from the Digital Electro-Hydraulic Control System Palisades Nuclear Plant Docket 50-255 License No. DPR-20
Dear Sir or Madam:
Licensee Event Report (LER) 2015-001-00 is enclosed. This LER describes an event that is reportable in accordance with 10 CFR 50.73(a)(2)(iv)(A) due to the automatic actuation of the reactor protection system and the auxiliary feedwater system.
This letter contains no new commitments and no revisions to existing commitments.
Sincerely,
/
ajv/tad Attachment: LER 2015-001-00, Automatic Reactor Trip Results from a Turbine Trip Initiated from the Digital Electro-Hydraulic Control System CC Administrator, Region III, USNRC Project Manager, Palisades, USNRC Resident Inspector, Palisades, USNRC
ATTACHMENT LER 2015-001-00 AUTOMATIC REACTOR TRIP RESULTS FROM A TURBINE TRIP INITIATED FROM THE DIGITAL ELECTRO-HYDRAULIC CONTROL SYSTEM 2 Pages Follow
NRC FORM 366 u.s. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3160*0104 EXPIRES: 01/31/2017 02-2014)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME
~_ DOCKET NUMBER i*
PAGE PALISADES NUCLEAR PLANT 05000255 10F2
- 4. TITLE Automatic Reactor Trip Results from a Turbine Trip Initiated from the Digital Electro-Hydraulic Control System
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL REV MONTI-FACILITY NAME pOCKET NUMBER MONTH DAY YEAR NO.
DAY YEAR
~5000 NUMBER FACILITY NAME pOCKET NUMBER 09 16 2015 2015
- - 001
- - 00 11 10 2015
~5000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) o 20.2201(b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) 1 o 20.2201(d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1)(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(c)(1)(ii)(A) 181 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71 (a)(5) 085 o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) o 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(O)
Specify in Abstract below or in
EVENT DESCRIPTION
APPROVED BY OMB: NO. 3150*0104 EXPIRES: 01/31/2017
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 6. LERNUMBER
- 3. PAGE YEAR I SEQUENTIAL I REVISION NUMBER NUMBER 20F2 2015
- - 001
- - 00 On September 16, 2015, the plant was operating at approximately 85% power perfonning a coastdown in preparation for refueling outage 1 R24. At approximately 0117 hours0.00135 days <br />0.0325 hours <br />1.934524e-4 weeks <br />4.45185e-5 months <br />, an anomaly within the digital electro-hydraulic (DEH) turbine control system [JJ] initiated a turbine [TRS] trip. As designed, the turbine trip actuated the reactor protection system [JC] to automatically trip the reactor [RCT] due to a loss of load. The auxiliary feedwater system [SA] started automatically, as designed, to recover steam generator [SG] levels.
No safety-related structures, components, or systems were inoperable at the start of the event that contributed to the event.
The Palisades DEH control system is based on the Westinghouse Distributed Processing Family (WDPF) MOD III that was installed in 1992.
CAUSE OF THE EVENT
The direct cause of the event is the turbine tripped due to actuation of the "DEH controller loss of power" turbine trip logic.
The cause for the turbine trip logic actuation was two-fold. Initially, there was a failure of a power supply [JX] module on a circuit board in the DEH turbine control system. Subsequent to the power failure on the circuit board, a second failure, either a loss of power to the overspeed protection control (OPC) distributed processing units (OPUs) or a loss of communications between the primary and backup OPC OPUs, occurred resulting in an actuation of the "DEH controller loss of power" turbine trip logic.
The root cause of the event is that the design of the DEH system contains unnecessary trip logic associated with turbine overspeed monitoring.
CORRECTIVE ACTIONS
The failed circuit board was replaced. A modification was implemented that removed the DEH system's trip logic for OPC loss of power and loss of communications.
ASSESSMENT OF SAFETY CONSEQUENCES
There were no actual consequences to general safety of the public, nuclear safety, industrial safety, or radiological safety for this event. The automatic reactor trip occurred as designed as a result of the turbine trip. The potential consequences of this event are considered to be of very low safety significance.
PREVIOUS SIMILAR EVENTS
None