05000461/LER-2006-002, Re Main Turbine Bypass System Safety Function Lost Due to Circuit Card Failure
| ML062860547 | |
| Person / Time | |
|---|---|
| Site: | Clinton  (NPF-062) |
| Issue date: | 10/13/2006 |
| From: | Bryan Hanson AmerGen Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-603788 LER 06-002-00 | |
| Download: ML062860547 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 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 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4612006002R00 - NRC Website | |
text
U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D. C. 20555-0001 Subject :
Licensee Event Report 2006-002-00 Enclosed is Licensee Event Report (LER) No. 2006-002-00: Main Turbine Bypass System Safety Function Lost Due to Circuit Card Failure. This report is being submitted in accordance with the requirements of 10 CFR 50.73. The cause evaluation for this event is not complete; a supplemental report will be submitted to include the cause of the circuit card failure, corrective action, safety analysis and previous similar event information. The supplemental report is expected to be submitted by November 16, 2006.
Should you have any questions concerning this report, please contact Mr. Ronald Frantz, Sr.
Regulatory Specialist, at (217)-937-2813.
Respectfully, Bryan Hanson Site Vice President Clinton Power Station RSF/blf Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Enclosures :
Licensee Event Report 2006-002-00 Summary of Commitments cc :
Regional Administrator - NRC Region III NRC Senior Resident Inspector-Clinton Power Station Office of Nuclear Facility Safety - I EMA Division of Nuclear Safety 10 CFR 50.73 SRRS 5A.108 U-603788 October 13, 2006
NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPER NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (s-zoo4)
, the NRC may digits/characters far each block) not conduct or sponsor, and a person is not required to respond to, the information nnIlantinn 1. FACILITY NAME
- 2. DOCKET NUMBER
- 3. PAGE Clinton Power Station 05000 461 1
OF 3
- 4. TITLE Main Turbine Bypass System Safety Function Lost Due to Circuit Card Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR None 05000 FACILITY NAME DOCKET NUMBER 08 17 2006 2006 - 002 - 00 10 13 2006 None 05000
- 9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§ : (Check all that apply)
E] 20.2201 (b) 171 20.2203(a)(3)(i) 1771 50.73(a)(2)(i)(C) 171 50.73(a)(2)(vii) 1 El 20.2201 (d)
[I 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A) f_1 20.2203(a)(1)
F1 20.2203(a)(4) 171 50.73(a)(2)(ii)(B) 171 50.73(a)(2)(viii)(B) 0 20.2203(a)(2)(i) 171 50.36(c)(1)(i)(A) 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 171 20.2203(a)(2)(ii) 171 50.36(c)(1)(f)(A) 1771 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) 171 20.2203(a)(2)(iii) 50.36(c)(2) 171 50.73(a)(2)(v)(A)
/~ 73.71 (a) (4) 096 20.2203(a)(2)(iv) 1 50.46(a)(3)(ii)
(] 50.73(a)(2)(v)(B)
- 73.71 (a) (5) 171 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C) 0 OTHER 20.2203(a)(2)(vi) 171 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Fnrm 366A 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)
T. R. Husted, System Manager 1(217) 937-3834 13. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT FACTURER RE TO EP XLE REPORTABLE EPIXLE 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
E1 NO DATE 1 1 16 2006 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On August 17, 2006, with the station operating in Mode 1 at 96 percent power, operators received a Main Condenser low vacuum alarm. Operators verified condenser vacuum was normal.
Initial troubleshooting identified a false low condenser vacuum signal was present, inhibiting the Main Turbine bypass valves from being able to perform their safety function if called upon. Since no other system performs the Main Turbine Bypass System safety function, the safety function was not available. The actions of Technical Specifications (TS) 3.7.6, Main Turbine Bypass System, were entered for the inoperable Main Turbine Bypass System, requiring the system to be restored to operable status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. A lead was lifted to remove the low vacuum inhibit logic input which restored the Main Turbine Bypass valve function before the TS 2-hour action completion time expired. The cause of this event was failure of the Main Condenser Pressure Trip Unit (electronic circuit card). The circuit card has been removed from the system and is undergoing failure analysis.
A redundant circuit card is providing the necessary function to inhibit the steam bypass function upon a loss of condenser vacuum. The cause of the circuit card failure, corrective action, safety analysis and previous similar event information will be provided in a supplement to this report.
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
Issue Report 520922 was initiated to perform a cause evaluation of this event and to identify
corrective action
No automatic or manually initiated safety system responses were necessary to place the plant in a safe and stable condition. No other inoperable equipment or components directly affected this event.
CAUSE OF EVENT
The cause of this event is the failure of the Main Condenser Pressure Trip Unit (electronic circuit card). The circuit card is undergoing failure analysis by the card manufacturer to identify the cause for the failure of the card.
The cause for the failure of the circuit card will be provided in a supplement to this report.
SAFETY ANALYSIS
This event is reportable under the provisions of 10 CFR 50.73 (a)(2)(v)(D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. Events that are reportable under 10 CFR 50.73 (a)(2)(v)(D) are considered to be safety system functional failures.
The safety analysis for this event will be provided in a supplement to this report.
CORRECTIVE ACTION
Immediate corrective action for this event was lifting a wire to restore the Main Turbine Bypass System function to an operable condition.
Corrective action for the circuit card failure will be determined following completion of the failure analysis and will be provided in a supplement to this report.
PREVIOUS OCCURRENCES
Previous occurrence information for this event will be provided in a supplement to this report.
COMPONENT FAILURE DATA
Manufacturer : Moore Industries Nomenclature : Main Condenser Pressure Trip Unit (electronic circuit card)
Manufacturer Model Number : DCA/4-20MA/DX1 X4/45VDC/-AD-D PST
SUMMARY OF COMMITMENTS Clinton Power Station L4603788 The following table identifies commitments made in this document.
(Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)
COMMITMENT TYPE
COMMITMENT
ONE-TIME ACTION Programmatic (Yes/No)
(Yes/No)
This document has no regulatory
commitments