05000400/LER-2006-001, Re Multiple Turbine EHC Low Fluid Pressure Switches Inoperable Due to a Common Cause
| ML060530368 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 02/15/2006 |
| From: | Mccartney E Progress Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| HNP-06-030 LER 06-001-00 | |
| Download: ML060530368 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability |
| 4002006001R00 - NRC Website | |
text
Progress Energy Serial: HNP-06-030 IFEB 1 5 2006 1 0CFR50.73 U.S. Nuclear Regulatory Commission ATTN: NRC Document Control Desk Washington, DC 20555 SHEARON HARRIS NUCLEAR POWER PLANT UNIT 1 DOCKET NO. 50-400/LICENSE NO. NPF-63 LICENSEE EVENT REPORT 2006-001-00 Ladies and Gentlemen:
The enclosed Licensee Event Report 2006-001-00 is submitted in accordance with IO CFR 50.73. This report describes a condition prohibited by Technical Specifications (TS) in that Turbine Generator Electro-Hydraulic Control Low Fluid Pressure switches in both trains were not operable due to a common cause.
This document contains no new Regulatory Commitment.
Please refer any questions regarding this submittal to Mr. Dave Corlett, Supervisor -
Licensing/Regulatory Programs, at (9'19) 362-3137.
Sincerely, etceH+
Eric McCartney Plant General Manager Harris Nuclear Plant EAIM/khv Enclosure c:
Mr. R. A. Musser (HNP Senior NRC Resident)
Mr. C. P. Patel (NRC-NRR Project Manager)
Dr. W. D. Travers (NRC Regional Administrator, Region II)
Progress Energy Carolinas, Inc.
Harris Nuclear Plant P. ).Box 165 New Hill, NC 27562
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06@30/2007 (6-2004)
, the NRC maynot conduct digits/characters for each block) or sponsor, and a person is not required to respond to, the information
- 3. PAGE Harris Nuclear Plant - Unit 1 05000400 1 OF 3
- 4. TITLE Multiple Turbine EHC Low Fluid Pressure Switches Inoperable due to a Common Cause
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE N.
OTHER FACILITIES INVOLVED SEUNILRVFACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR S
EQUENTIAL REOV MONTH DY YEAR N/A 05000 FACILITY NAME DOCKET NUMBER 12 19 2005 2006 -
001 -
00 2
1 5 2006 N/A 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check al that apply) o 20.2201(b) 0 20.2203(a)(3)Xi) 0 50.73(a)(2XiXC) 0 50.73(a)(2Xvii) 1 0 20.2201(d) 0 20.2203(aX3XiI) 0 50.73(aX2XiiXA)
D 50.73(aX2)(viiiXA)
O 20.2203(a)(1)
J 20.2203(a)(4) 0 50.73(aX2X#iXB) 0 50.73(aX2)(viii)(B) 0E 20.2203(a)(2)(i) 0 50.36&cX1Xi)(A) 0 50.73(aX2Xiii) 0 50.73(a)(2Xix)(A)
- 10. POWER LEVEL 0 20.2203(a)(2Xii) 0 50.36&cXIXiiXA) 0 50.73(a)(2)(NvXA) 0 50.73(a)(2Xx) 0 20.2203(a)(2Xiii) 0 50.36i'cX2) 0 50.73(a)(2Xv)(A) 0 73.71 (a)(4) 0 20.2203(a)(2Xiv) 0 50.46aX)(3Xii) 0 50.73(aX2Xv)(B) 0 73.71 (a)(5) 100 0
20.2203(aX2Xv) 0 50.73a)aX2Xi)(A) 0 50.73(a)(2)(vXC) 0 OTHER 0
20.2203(aX2Xvi) 0 50.73KaX2)(iXB) 0 50.73(aX2Xv)(D)
Specify in Abstract below or in (If more space is required, use additional copies of A (If more space is required, use additional copies of NRC Forn 366A)
II. CAUSE OF EVENT
The Root Cause of this event was that the original instrument uncertainty calculation did not allow sufficient margin between the trip setpoint and allowable value due to a change in specifications subsequent to the time of the calculation development. The vender changed the repeatability specification for the current model from 1.5% to 3.0% which was not reflected in the uncertainty calculation and/or margin allowed for these pressure switches.
Ill. SAFETY SIGNIFICANCE Though the Turbine Generator (EHC) Low Fluid Pressure Switches were not operable by TS, they retained their function of providing indication of turbine trip to the SSPS. On a turbine trip, EHC fluid pressure will drop rapidly from approximately 2000 psig to 0 psig. Despite the fact that the TS limits were exceeded, the switches would have still functioned to initiate an anticipatory reactor trip on a turbine trip, although at a pressure lower than the TS limit of greater than or equal to 950 psig. This function is redundantly accomplished by the sensing of turbine throttle valve shut limit switches.
In addition to maintaining their functionality, the direct reactor trip on turbine trip function of the turbine stop emergency trip fluid pressure switches is not credited in the accident analysis in FSAR Chapter 15.
This condition is reportable as a condition prohibited by Technical Specifications pursuant to 10 CFR 50.73(a)(2)(i)(B) and as common-cause inopere bility of independent trains pursuant to 10 CFR 50.73 (a)(2)(vii). The condition prohibited by TS was rectified by the calibration of the pressure switches by the initial surveillance testing on December 19, 2005. The common-cause of the inoperability was rectified by the implementation of EC 63114 which raised tlhe setpoints to allow adequate margin based on a revised uncertainty calculation on January 9, 2006.
IV. CORRECTIVE ACTIONS
The con-ective action to prevent recurrence was to develop and implement Engineering Change (EC) 63114.
EC 63114 accounts for the vendor's increased repeatability specification from 1.5% to 3.0% and provides increased margin to the TS Limit of greater than or equal to 950 psig. This corrective action was completed on January 9, 2006.
Additional corrective actions are to revise the vendor manual to reflect the latest information on the repeatability specification and to revise the maintenance calibration procedure to incorporate lessons learned from bench testing which result in a setpoint that is less subject to a 'shift' in results due to the characteristics of this switch.
V. PREVIOUS SIMILAR EVENTS
No previous HNP events or conditions are known within the last five years where multiple Turbine Generator (EHC) Low Fluid Pressure Switches became inoperable due to inadequate margin in the setpoint calculation.