05000388/LER-2011-002-01, Regarding Condition Prohibited by Technical Specification Due to Unknown RCIC Inoperablitliy
| ML12132A226 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 05/11/2012 |
| From: | Helsel J Susquehanna |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| PLA-6822 LER 11-002-01 | |
| Download: ML12132A226 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(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 |
| 3882011002R01 - NRC Website | |
text
Jeffrey M. Helsel Nuclear Plant Manager U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop OP1-17 Washington, DC 20555 PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3510 Fax 570.542.1504 jmhelsel@pplweb.com SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-388/2011-002-01 LICENSE NO. NPF-22 PLA-6822 Docket No so:.J88 Attached is supplemental Licensee Event Report (LER) 50-388/2011-002-01. The event involved an unknown inoperability of Unit 2 RCIC and was reported under 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specification. At the time that the original LER was submitted, the vendor failure analysis was not yet complete and the root cause analysis was still in progress. This supplement provides information obtained as a result of the failure analysis and the completed root cause evaluation.
There were no actual consequences to the health and safety of the public as a result of this event.
Attachment: LER 50-388/2011-002-01 Copy:
NRC Region I Mr. P. W. Finney, NRC Sr. Resident Inspector Mr. R. R. Janati, DEP/BRP Ms. C. J. Sanders, NRC Project Manager
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES:10/31/2013 (10-2010)
, the NRC digits/characters for each block) may not conduct or sponsor, and a person is not required to respond to, the information collection.
\\3. PAGE Susquehanna Steam Electric Station Unit 2 05000388 1 OF4
- 4. TITLE Condition Prohibited by Technical Specification Due to Unknown RCIC lnoperability
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR 05000 05 II FACILITY NAME DOCKET NUMBER 06 27 2011 2011
- - 002
- - 01 2012 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMilTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 2 D 20.2201 (b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii)
D 20.2201 (d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A)
- 10. POWER LEVEL D 20.2203(a)(1)
D 20.2203(a)(4)
D 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
D 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
Less than 2%
D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A) 0 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(c)(2) 0 50.73(a)(2)(v)(A)
D 73.71(a)(4) 0 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER 0 20.2203(a)(2)(vi)
[8] 50.73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
Specify in Abstract below or in
Analysis of Event
2011
- - 002
- - 01
- 3. PAGE 30F4 Following the overspeed trip, the EGM and RGSC output data was reviewed. The review identified that the outputs became abnormal following test potentiometer and switch jumper installation associated with the RCIC Turbine Overs peed Testing on May 1 0, 2011. The values decreased during testing when the flow controller was placed in MANUAL and returned to the abnormal values when the flow controller was returned to AUTO following testing. The output remained abnormal until the flow controller was placed in MANUAL prior to the starting the RCIC turbine to perform the 24 month RCIC Flow Verification Test on June 27, 2011. Following the testing, the outputs returned to the abnormal values and remained abnormal following the overspeed trip on June 29, 2011. RCIC was restored to OPERABLE status on July 2, 2011.
Failure Analysis The failed component was a Woodward Model9903-091 RGSC. The RGSC circuit board did not show any indications of heat damage. The failed RGSC was sent to Woodward for analysis. The Woodward report concluded that the most probable cause of the failure was a voltage spike/overvoltage on the supply input which caused the Op-Amp to fail.
CAUSE OF THE EVENT
The causes of the event were determined to be as follows:
Procedure content was less than adequate-Test Procedures did not test all aspects of the system that were relied upon for operability, specifically the RGSC and EG-M, because SSES had not adopted a procedure process that fully utilizes industry best practices for procedure development, review and validation, including use of industry Operating Experience.
The System Monitoring and Health Reporting Program failed to maintain equipment reliability - Management involvement in the Station Health and Equipment Reliability Programs has not resulted in elimination of challenges associated with unanticipated equipment failures, which ultimately resulted in failure of the RCIC RGSC.
The direct cause/apparent cause of the component failure was determined to be as follows:
A voltage induced spike/over voltage on the supply input that caused the RGSC U1 Op-Amp to fail as a result of failure to incorporate vendor recommendations to remove power prior to test equipment installation and removal into test procedures.
ANALYSIS/SAFETY SIGNIFICANCE
Actual Consequences:
The failure rendered the RCIC system unavailable for 109.15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> from the time reactor pressure exceeded 150 psig until the system became available following RGSC replacement and quarterly flow surveillance retest. During this time, the RCIC turbine could have been manually started in accordance with procedures.
Potential Consequences:
Even though the RCIC System is not an Emergency Core Cooling System and no credit is taken in the safety analyses for RCIC system operation, RCIC would have been unable to perform its terminal mission (Risk Significant Function) in automatic to inject 600 gpm on a low reactor water level. Review of equipment out of service during the time when RCIC was unavailable revealed approximately two hours when both RCIC and HPCI were out of service. Incremental Core Damage Probability (ICDP) and Incremental Large Early Release Probability (ILERP) were evaluated for the cumulative timeframe, and both were below the NRC guidance threshold defined in Appendix K of Inspection Manual Chapter 0609.
CORRECTIVE ACTIONS
The following are the key corrective actions associated with this issue:
- 1.
The RGSC was replaced.
U.S. NUCLEAR REGULATORY COMMISSION
- 6. LER NUMBER I
SEQUENTIAL NUMBER
- - 002 I
REVISION NUMBER
- - 01
- 3. PAGE 40F4
- 2.
High priority computer alarms for the HPCI and RCIC EGM and RGSC points were created.
- 3.
A systematic review is being performed to validate that current testing is adequate to ensure compliance with TS requirements.
- 4.
Applicable Unit 1 RCIC test procedures have been revised and applicable Unit 2 RCIC test procedures will be revised to correct identified deficiencies.
- 5.
The station health reporting procedure was revised to require engineering supervisors to review health reports and challenge engineers on the content and rigor applied to ensure that all vital information is included to maintain the health and reliability of the system, program, or component.
- 6.
Applicable Unit 1 RCIC and HPCI test procedures have been revised and applicable Unit 2 RCIC and HPCI test procedures will be revised to ensure that power to the EGM is turned off prior to installation/removal of the test potentiometer to the EGM and to record EGM and RGSC output values prior to installation and after removal of test equipment.
- 7.
Applicable RCIC and HPCI calibration procedures will be revised to ensure that power to the EGM is turned off prior to installation/removal of permanent wiring to the EGM and RGSC.
PREVIOUS SIMILAR EVENTS
A root cause of this LER was procedure content less than adequate. The following recent LERs identified similar
causes
LER 387/2011-002, "Unit 1 Manual Scram Due to Unisolable Extraction Steam System Leak" identified deficient work instructions as one of the causes.
LER 388/2011-003, "Unit 2 Scram due to Main Turbine Trip during ICS Surveillance Testing" identified conflicting and unclear procedure requirements and less than adequate reinforcement of management expectations for work package content as one of the causes.