05000400/LER-2016-004, Regarding Reactor Trip and Safety Injection During Turbine Control Testing at Low Power
| ML16342B682 | |
| Person / Time | |
|---|---|
| Site: | Harris  (NPF-063) |
| Issue date: | 12/07/2016 |
| From: | Hamilton T Duke Energy Progress |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| HNP-16-108 LER 16-004-00 | |
| Download: ML16342B682 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) |
| 4002016004R00 - NRC Website | |
text
Tanya M. Hamilton Vice President Harris Nuclear Plant 5413 Shearon Harris Road New Hill, NC 27562-9300 919.362.2502 10 CFR 50.73 Serial: HNP-16-108 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Shearon Harris Nuclear Power Plant, Unit 1 Docket No. 50-400/Renewed License No. NPF-63 Subject: Licensee Event Report 2016-004-00 Ladies and Gentlemen:
Duke Energy Progress, LLC, submits the enclosed Licensee Event Report 2016-004-00 in accordance with 10 CFR 50.73 for Shearon Harris Nuclear Power Plant, Unit 1. This report details a reactor trip with safety injection that occurred on October 8, 2016, prior to a refueling outage. The site was performing turbine testing with the unit at approximately 8 percent power when the event occurred. The unit was shut down successfully, with all Engineered Safety Features and Reactor Protection Systems functioning as designed. Further evaluation is underway.
This document contains no regulatory commitments. Please refer any questions regarding this submittal to Jeff Robertson, Manager - Regulatory Affairs, at (919) 362-3137.
Sincerely, Tanya M. Hamilton Enclosure: Licensee Event Report 2016-004-00 cc:
Mr. C. D. Jones, NRC Sr. Resident Inspector, HNP Ms. M. Barillas, NRC Project Manager, HNP NRC Regional Administrator, Region II
LICENSEE EVENT REPORT (LER)
NRC FORM 366 (06-2016)
U.S. NUCLEAR REGULATORY COMMISSION 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 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.
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (See Page 2 for required number of digits/characters for each block) 1 OF
- 3. PAGE 05000
- 4. TITLE
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR SEQUENTIAL NUMBER REV NO.
FACILITY NAME 05000 DOCKET NUMBER FACILITY NAME 05000 DOCKET NUMBER
- 9. OPERATING MODE
- 10. POWER LEVEL
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
- 12. LICENSEE CONTACT FOR THIS LER LICENSEE CONTACT TELEPHONE NUMBER (Include Area Code) CAUSE SYSTEM COMPONENT MANU-FACTURER REPORTABLE TO EPIX
CAUSE
SYSTEM COMPONENT MANU-FACTURER REPORTABLE TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO
- 15. EXPECTED SUBMISSION DATE YEAR DAY MONTH ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
NRC FORM 366 (06-2016)
YEAR YEAR DAY MONTH 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(vii) 20.2203(a)(2)(ii) 20.2203(a)(2)(i) 20.2203(a)(1) 20.2201(d) 20.2203(a)(2)(iii) 20.2203(a)(2)(iv) 20.2203(a)(2)(v) 20.2203(a)(2)(vi) 20.2203(a)(3)(ii) 20.2203(a)(4) 50.36(c)(1)(i)(A) 50.36(c)(1)(ii)(A) 50.36(c)(2) 50.46(a)(3)(ii) 50.73(a)(2)(i)(A) 50.73(a)(2)(i)(B) 50.73(a)(2)(ii)(A) 50.73(a)(2)(ii)(B) 50.73(a)(2)(iii) 50.73(a)(2)(iv)(A) 50.73(a)(2)(v)(A) 50.73(a)(2)(v)(B) 50.73(a)(2)(v)(C) 50.73(a)(2)(v)(D) 50.73(a)(2)(viii)(A) 50.73(a)(2)(viii)(B) 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5)
OTHER Specify in Abstract below or in Note: Energy Industry Identification System (EIIS) codes are identified in the text within brackets [ ].
A. Background Event Date: October 8, 2016 Initial Mode: 1 Initial Reactor Power: ~8 percent Event Time: 0150 EDT Final Mode: 3 Final Reactor Power: 0 percent This event is reportable per 10 CFR 50.73(a)(2)(iv)(A) as an event or condition that results in valid actuation of any of the systems listed in paragraph (a)(2)(iv)(B) of [10 CFR 50.73] due to actuation of the reactor protection system [JC],
general containment isolation signal [JE], emergency core cooling systems [BQ], auxiliary feedwater systems [BA], and emergency diesel generators [EK]. All actuated safety systems functioned as designed.
B. Event Description
On October 8, 2016, at 0150, the Shearon Harris Nuclear Power Plant (Harris) was reducing power to enter a planned refueling outage (RFO-20). The plant was at approximately 8 percent power in MODE 1 when the unit experienced an unplanned reactor trip with a safety injection (SI) and main steam line isolation (MSLI). The SI was terminated in 6 minutes with pressurizer level at 80 percent. Pressurizer safety valves did not actuate.
The licensee was performing testing on the turbine mechanical overspeed trip system. The digital-electrohydraulic (DEH) control system [TG] was in throttle valve (TV) [FCV] control. Operators initiated the swap from TV control to governor valve (GV) [FCV] control per the test procedure. The GVs unexpectedly opened to about 15 percent with the TVs still at full open. This valve alignment caused excessive steam flow through the main turbine [TRB], drawing down the steam generator (SG) [SG] pressure. This resulted in the actuation of SI and MSLI signals on Low Steam Line Pressure (rate compensated), as steam line pressure rapidly dropped from 1050 psig to 1000 psig. The SI and MSLI signal initiated a reactor trip, turbine trip, feedwater isolation signal, and closed the main steam isolation valves.
This event was caused by a combination of degraded equipment within the DEH control system, which failed to align the TVs and GVs to properly control turbine speed. Two of the five high-pressure hydraulic accumulators [ACC] were out-of-service at the time of the event. In addition, an oil pressure switch [PS] was found to be improperly functioning. The combination of high hydraulic fluid demand due to the TV to GV control swap and the degraded equipment caused the GVs to not properly position to control turbine speed.
The high-pressure DEH accumulators are Parker Hydraulics series A7L hydraulic accumulators. One accumulator had been found with low pressure in August 2015 and was scheduled for repair. A second accumulator was found to have low pressure during troubleshooting following the event. The pressure switch is a United Electric Controls series 400 switch, and was identified deficient after the event.
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- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
C. Causal Factors
- The test procedure did not contain a validation that at least four out of five of the high-pressure DEH accumulators be in service prior to performing turbine testing.
- The hydraulic oil pressure switch was not functioning properly, causing the turbine to improperly position the control valves.
D. Corrective Actions
Completed Actions:
- All five accumulators have been restored to service and the hydraulic oil pressure switch was replaced with a switch verified to be functioning properly.
- The Turbine Mechanical Overspeed Trip testing procedure has been revised to add verifications for ensuring at least four accumulators are in service prior to testing.
- The Power Operation (Mode 2 to Mode 1) procedure was revised to include additional verifications for ensuring at least four accumulators are in service prior to turbine start-up. (Accumulators are required for turbine start-up, but are not necessary during normal operation. The turbine will still be able to trip in the event of a loss of all accumulators. No actions required for ensuring normal turbine operation.)
Planned Actions:
- A new calibration procedure will be implemented for the deficient oil pressure switch to ensure better quality control over verifying switch function.
E. Safety Analysis
At the time of the event, Harris was at approximately 8 percent power and descending. The safety injection was terminated six minutes after initiation, with pressurizer level at 80 percent. All Engineered Safety Features [B] and Reactor Protection Systems [J] functioned as designed. No loss of reactor coolant system (RCS) inventory or excessive RCS cooldown occurred. Pressurizer safety valves did not actuate. Thus, this event is low risk significant per Probabilistic Risk Assessment analysis. This event represents a minimal challenge to the health and safety of the public, with no actual dose consequence.
F. Additional Information
No similar events have occurred over the past three years.
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