05000285/LER-2005-002, Inoperability of Pressurizer Power Operated Relief Block Valve Due to Human Error
| ML052850321 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/03/2005 |
| From: | Bannister D Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-05-0111 LER 05-002-00 | |
| Download: ML052850321 (8) | |
| 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)(8) 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 |
| 2852005002R00 - NRC Website | |
text
Omaha Pubhc Pow rD fftn 444 South 16th Street Mall Omaha NE 68102-2247 October 3, 2005 LIC-05-0111 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, DC 20555
Reference:
Subject:
Docket No. 50-285 Licensee Event Report 2005-001 Revision 0 for the Fort Calhoun Station Please find attached Licensee Event Report 2005-002, Revision 0, dated October 3, 2005. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B). If you should have any questions, please contact me.
Sincerely, D. J. Bannister Manager - Fort Calhoun Station DJB/EPM/epm Attachment
.c INPO Records Center 0-e lse-,:;, zl-)
Employment with Equal Opportunity 4171
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digits/characters for each block)
- 3. PAGE Fort Calhoun Station 05000285 1 OF 6
- 4. TITLE Inoperability of Pressurizer Power Operated Relief Block Valve Due to Human Error
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MNHDYYA YER SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 08 02 2005 2005 002 -
00 10 03 2005 05000
- 9. OPERATING
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
MODE o 20.2201 (b)
El 20.2203(a)(3)(i) 1-50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) o 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 1 0l 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(8)
Eo 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A) 1-50.73(a)(2)(iii)
E 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii) al 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 E 20.2203(a)(2)(v) 1-50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
El OTHER 0 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
As detailed in the chronology, it was found that the molded case circuit breaker providing power to the motor for HCV-151 had an incorrect instantaneous overcurrent setting that led to the intermittent tripping problem described. The period of vulnerability for the HCV-151 circuit breaker tripping has been determined to be from October 4, 2003, when the circuit breaker was set incorrectly to March 9, 2005, when the problem was discovered. Although it is reasonable to consider HCV-151 inoperable for the entire period, it is likely that the circuit breaker would have operated successfully had there been an actual demand situation. This is because the likelihood of tripping is largely dependent on the actual voltage available to operate the valve.
The power supplied to the HCV-1i 1 motor operated valve is from 480 volt motor control center MCC-4A1 via MCC-4A1 -
C05 cubicle. This cubicle houses a full voltage reversing starter unit that contains a molded case circuit breaker and two contactors (one contactor is provided to open and one to close the valve). When the plant is operating in Mode I, the voltage at MCC-4A1 is lower due to plant bus loading than during lightly loaded periods such as during refueling outages.
A known characteristic of motors such as the one for the HCV-15 1 operator is that the locked rotor amps delivered to the motor increase with increasing voltage levels. Normal voltage levels experienced during Mode I are less likely to result in the HCV-151 circuit breaker tripping during motor start than higher voltages which are seen during refueling outages. It is likely that HCV-151 would have operated during most accident conditions. Therefore, this event had no impact on the health and safety of the public.
SAFETY SYSTEM FUNCTIONAL FAILURE This event did not result in a safety system functional failure in accordance with NEI-99-02.
PREVIOUS SIMILAR EVENTS
There have not been any other instances of a similar nature that have occurred at the Fort Calhoun Station.
NRC FORM JbbA (I1-20U1