05000397/LER-2015-005, Regarding Reactor Pressure Vessel Level Indication Switch Failures
| ML15233A409 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 08/20/2015 |
| From: | Hettel W Energy Northwest |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GO2-15-122 LER 15-005-00 | |
| Download: ML15233A409 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 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)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 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 |
| 3972015005R00 - NRC Website | |
text
w. Grover Hettel Columbia Generating Station N0RIHVVEST Ph. 5O9.377.8311F 509.377 41 50 wghettelenergy-northwest.com 10 CFR 50.73 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001
Subject:
COLUMBIA GENERATING STATION, DOCKET NO. 50-397 LICENSEE EVENT REPORT NO. 2015-005-00
Dear Sir or Madam:
Transmitted herewith is Licensee Event Report No. 201 5-005-00 for Columbia Generating Station. This report is submitted pursuant to I 0 CFR 50.73(a)(2)(i)(B) and I 0 CFR 50.73(a)(2)(v)(A).
There are no commitments being made to the NRC by this letter.
If you have any questions or require additional information, please contact Mr. JR. Trautvetter, Regulatory Compliance Supervisor, at (509) 377-4337.
Executed on Aw 2o, Respectfully, W. G. HetteTh Vice President, Operations
Enclosure:
Licensee Event Report 2015-005-00 cc: NRC Region IV Administrator NRC NRR Project Manager NRC Senior Resident lnspector/988C CD Sonoda BPNI 399 WA Horin Winston & Strawn GO2-15-122 August 20, 2015
26158 R6 NRC Form 366 (01-2014)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (01-2014)
LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block).
APPROVED BY OMB: NO. 3150-0104 EXPIRES 01/31//2017 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.Resource@nrc.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 impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Columbia Generating Station
- 2. DOCKET NUMBER 05000 397
- 3. PAGE 1
OF 3
- 4. TITLE Reactor Pressure Vessel Level Indication Switch Failures
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 06 25 2015 2015 005 00 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 2 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 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) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 1.7 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 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)(v)(C)
OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in
Plant Conditions
At the time of the event the reactor was starting up from a refueling outage and was transitioning from Mode 4 to Mode 2 with pressure increasing from approximately 140 psig to 945 psig. Reactor Pressure Vessel (RPV) level band started at +50 inches to +80 inches and in Mode 4 and decreased incrementally when entering Mode 2 and continued to decrease to approximately +36 inches. There were no structures, systems, or components that were inoperable at the start of the event which contributed to the event.
Event Description
On June 25, 2015, at 0952, Columbia Generating Station (Columbia) entered Mode 2 for plant startup. At approximately 2200, during performance of the Shift Operator Rounds, it was identified that Columbias Reactor Protection System (RPS) [JE] A trip logic was unable to generate a full scram on Reactor Pressure Vessel (RPV) [RPV] low level (level 3) (+13 inches) because level 3 indicating switches [LIS], Main Steam [SB] Level Indicating Switches 24A and 24C (MS-LIS-24A and 24C), were mechanically bound high off scale. The equipment was declared inoperable at 2200 and at 2246 in accordance with Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.1.1 Required Action, a half scram was generated on RPS trip system A to restore full scram capability.
These instruments are narrow range level indicating switches. The instruments only provide a local indication and do not directly indicate in the main control room. The switches provide an RPV Level 8 (+54 inches) signal for Reactor Core Isolation Cooling System (RCIC) pump logic, and a Level 3 (+13 inches) signal to the Reactor Protection System (RPS) logic and Nuclear Steam Supply Shutoff Group 5 and Group 6 isolation logic, Residual Heat Removal (RHR) [BO] Miscellaneous valves, and RHR Shutdown Cooling valves respectively.
The startup procedure requires that the operability of these indicating switches is verified prior to entering Mode 2, however as the indication is off-scale high during outage conditions due to flood up of the RPV for shutdown cooling, the verification is limited to verifying that the indication is off-scale high. In this event, while entering Mode 2 the level band was set at +50 inches to +80 inches and level was above the off-scale high value of +60 inches. It was during subsequent Shift Operator Rounds, after level had been decreased, that the switches were found to be degraded.
Cause
The failed indicators are two ITT Controls - Barton Instrument indicators, Model 288A. The direct cause of the event was that the switches were mechanically bound with the indicator off-scale high against the rubber stop.
The root cause of the event is that the procedure for calibrating the level indicating switches is not in alignment with the vendor manual with respect to setting the mechanical stops. Contributing causes were that there was no established preventative maintenance to ensure the stops were set correctly and there was no verification that the level switch indication was on scale prior to entering Mode 2.
The coincident failure of MS-LIS-24A and -24C resulted in a loss of the safety function for RPS trip on low RPV level (+13 inches), TS 3.3.1.1 Function 4. These level switches provide input to the RPS A1 and A2 channels; their coincident failure would have prevented the RPS A system from initiating a half scram due to low RPV water level, which would have prevented an automatic scram from occurring. This function is required in Modes 1 and 2.
Additionally, failure of MS-LIS-24C resulted in a loss of the safety function for Primary Containment isolation, TS 3.3.6.1.Function 2a.
This level switch provides an input to the inboard isolation valve logic which requires two out of two to isolate. With one inboard channel failed, the Primary Containment isolation would not have occurred on low RPV level. This function is required in Modes 1, 2, and 3.
It was also determined that the indicating switches should have been declared inoperable when the instruments were initially over ranged during the refueling outage beginning May 10, 2015 until they were unstuck and calibrated per plant procedures on June 26, 2015. TS 3.3.6.1 Primary Containment Isolation Instrumentation LCO completion times were exceeded during the refueling outage.
Required action to isolate the Residual Heat Removal Shutdown Cooling System was not completed as required by TS. This function is required in Modes 3, 4, and 5.
26158A R3