05000285/LER-2014-001, Regarding Reactor Shutdown Due to Sluice Gate Failure
| ML14069A348 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/07/2014 |
| From: | Cortopassi L Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-14-0028 LER 14-001-00 | |
| Download: ML14069A348 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(8) 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2852014001R00 - NRC Website | |
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ilppo Omaha Public Power District 444 South 16th Street Mall Omaha, NE 68102-2247 March 7, 2014 LI C-14-0028 u.s. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Fort Calhoun Station, Unit No.1 Renewed Facility Operating License No. DPR-40 NRC Docket No. 50-285
Reference:
none 10 CFR 50.73
Subject:
Licensee Event Report 2014-001, Revision 0, for the Fort Calhoun Station Please find attached Licensee Event Report 2014-001, Revision o. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(A), 50.73(a)(2)(i)(8) and10 CFR 50.72(a)(2)(v)(8).
No commitments are being made in this letter.
If you should have any questions, please contact Terrence W. Simpkin, Manager, Site Regulatory Assurance, at (402) 533-6263.
Respectfully, Lo IS P. Cortopassi Site Vice President and CNO LPC/epm Attachment c:
J. M. Sebrosky, NRC Sr. Project Manager M. l. Dapas, NRC Regional Administrator, Region IV J. C. Kirkland, NRC Sr. Resident Inspector Employment with Equal Opportunity
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 31S0-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the
- 13. PAGE Fort Calhoun Station 05000285 1 OF 5
- 4. TITLE Reactor Shutdown due to Sluice Gate Failure
- 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 FACILITY NAME DOCKET NUMBER 01 08 2014 2014 - 001 - 00 3
7 2014 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii) 1 D
20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2203(a)(1)
D 20.2203(a)(4)
D 5O.73(a)(2)(ii)(B)
D 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)
D 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL D
20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4) 100 D
20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
~ 50.73(a)(2)(v)(B)
D 73.71(a)(5)
D 20.2203(a)(2)(v)
~ 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(C)
D OTHER D 20.2203(a)(2)(vi)
~ 50.73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
Specify in Abstract below or in Technical Specification (TS), Limiting Condition for Operation (LCO) 2.4(1 )a, Containment Cooling, defines the minimum requirements for raw water pump operability for reactor criticality (except for low-temperature physics tests). The reactor may be made critical with one inoperable raw water pump; however, LCO action statements shall apply.
TS 2.4(1) also states:
b. During power operation one of the components listed in (1 )a.i. or ii. may be inoperable. If the inoperable component is not restored to operability within seven days, the reactor shall be placed in hot shutdown condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If the inoperable component is not restored to operability within an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor shall be placed in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
c. For cases involving Raw Water pump inoperability, if the river water temperature is below 60 degrees Fahrenheit, one Raw Water pump may be inoperable indefinitely without applying any LCO action statement. When the river water temperature is greater than 60 degrees Fahrenheit, an inoperable Raw Water pump shall be restored to operability within 7 days or the reactor shall be placed in a hot shutdown condition within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. If the inoperable Raw Water pump is not restored to operability within an additional 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor shall be placed in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
In the event a Limiting Condition for Operation and/or associated action requirements cannot be satisfied because of circumstances in excess of those addressed in the specification, the unit shall be placed in at least HOT SHUTDOWN within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, in at least subcritical and < 300°F within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and in at least COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, unless corrective measures are completed that permit operation under the permissible action requirements for the specified time interval as measured from initial discovery or until the reactor is placed in an Operating Mode in which the specification is not applicable. Exceptions to these requirements shall be stated in the individual specifications.
EVENT DESCRI PTION At approximately 2230 Central Standard Time (CST), on January 8,2014, CW-14C, TRAVELING SCREEN SLUICE GATE, motor operator shaft was found damaged (bent) by Operations personnel.
At 2330 CST a large block of ice buildup was observed on top of the sluice gate caused by a pinhole leak in the backwash piping located directly above the CW-14C gate. At 0250 CST, January 9,2014, Operations unsuccessfully attempted manual closing of CW -14C. At 0315 CST the station entered TS 2.0.1 (1) due to all RW pumps being declared inoperable. At 0518 CST the station commenced a reactor shutdown. At 0542 CST the NRC Headquarter Operations Office (HOO) was notified of the inoperability of the RW pumps (10 CFR 50.72(b)(3)(v)(B) and TS required shutdown 10 CFR 50.72(b)(2)(i) (Event Notification49703 and 49704). At 0900 CST the station completed the reactor shutdown. This event is being reported per 10 CFR 50.73(a)(2)(i)(A), 50.73(a)(2)(i)(B) and10 CFR 50.72(a)(2)(v)(8). The issue was entered into the corrective action system as condition report (CR) 2014-00329.
CW -14C was manually lowered and then verified closed by divers. The flooding strategy for the Intake Structure was met at 0350 CST on January 10, 2014. Raw water Pumps AC-10A, AC-108, AC-10C and AC-1 00 were declared operable and TS 2.0.1 (1) was exited.
CONCLUSION
- 2. DOCKET YEAR 05000285 2014
- 6. LER NUMBER
- 3. PAGE 4
OF I SEQUENTIAL I REV NUMBER NO.
001 o
Engineering Analysis (EA)12-018 upgraded the sluice gates to limited-critical quality element (L-CQE). The CW-14 sluice gates had not been previously credited as safe shutdown equipment.
Even though the CW-14 sluice gates became credited as safe shutdown equipment, FCS did not treat the sluice gates any different than before the reclassification. Consequently, the valves' motor operators (MOVs) were never entered into the MOV program, additional analyses and preventative maintenance (PM) items were not implemented.
CW-14C torque switch as found setting was different than the last time the switch was adjusted. In April, 2013, the torque switch for CW-14C was set to increment 2.5. The as found value after the event initiating this report was 3.75. Additionally, the torque switch was found preloaded in the open direction - meaning that it would take more torque applied to the valve before the valve would trip on torque in the shut direction. The torque switch was preloaded 2 increments bringing the total value of the torque setting to 5.75, placing the MOV in a condition where it would cause significant damage to the MOV had the stem not bent.
Additionally, the spring pack - the part of the MOV which translates motor torque to the torque limiter switch was unable to complete its function due to the amount of grease that had seeped into the spring plate section. The grease would not allow the spring pack to compress thereby not translating motor torque to the torque limiter switch. The combined effect as described above in addition to the extreme cold temperatures on the intake structure veranda was that the MOV would not have tripped on over-torque before failure of the MOV.
The Root Cause was determined to be that CW-14C MOV torque setting was at a value that allowed the stem to be bent.
CORRECTIVE ACTIONS
Immediate Corrective Actions:
CW-14C was lowered and then verified closed by divers. The flooding strategy for the Intake Structure was met at 0350 CST on January 10, 2014. Raw water Pumps AC-10A, AC-10B, AC-10C and AC-10D were declared operable and TS 2.0.1(1) was exited.
The covers were opened for CW-14 A, CW-14B, and CW-14F to see if the condition existed with other sluice gates with known bent stem problems (CW-14A1B) and no know history of bent stems (CW-14F). None of the other MOVs inspected had significant preloading.
Long Term Corrective Actions All CW-14 and CW-15 MOVs will be added to the MOV program having similar treatment to a GL 89-10 MOVs.
SAFETY SIGNIFICANCE
FCS has evaluated potential flooding scenarios and under the conditions that existed at the time of the event flooding would not have affected the ability of the station to mitigate a flood as a flooding event could not have occurred without several days' notice. The actions needed to allow the station to mitigate a flood were completed in about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as indicated above.
SAFETY SYSTEM FUNCTIONAL FAILURE This does not represent a safety system functional failure in accordance with NEI 99-02, Revision 7.
The actions needed to allow the station to mitigate a flood were completed in about 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> as indicated above.
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