05000285/LER-2006-007, Regarding Inadequate Seismic Design of Reactor Vessel Head Refueling Stand
| ML070170381 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 01/08/2007 |
| From: | Faulhaber H Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-06-0131 LER 06-007-00 | |
| Download: ML070170381 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ix)(A) 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)(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)(i)(B), Prohibited by Technical Specifications |
| 2852006007R00 - NRC Website | |
text
Omaha Public Powei Distri
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1946 - 2006 Fort Calhoun Station P.0. Box 550 Fort Calhoun, NE 68023 January 8, 2007 LIC-06-0131 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, DC 20555
Reference:
Docket No. 50-285
Subject:
LiCensee Event Report 2006-007 Revision 0 for the Fort Calhoun Station Please find attached Licensee Event Report 2006-007, Revision 0, dated January 8, 2007. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(ii)(B), 50.73(a)(2)(v)(B, C and D) and 50.73(a)(2)(ix)(A). If you should have any questions, please contact me.
Sincerely, H.. auaber Division Manager Nuclear Engineering HJF/epm Attachment i c:
B. S. Mallett, NRC Regional Administrator, Region IV Alan Wang, NRC Project Manager J. D. Hanna, NRC Senior Resident Inspector INPO Records Center
NRC FORM 366 U.S. NUCLEAR REGULATORY COMh APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007
- 6-2004)
Estimated burden per response to comply with this mandatory collection request: 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail LICENSEE EVENT REPORT (LER) to infocollects@nrc.gov, and to the Desk Officer, Office of Information and RegulatoryAffairs, NEOB-1 0202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the (See reverse for required number of information collection.
digits/characters for each block)
- 3. PAGE Fort Calhoun Station 05000285 1 OF 3
- 4. TITLE Inadequate Seismic Design of Reactor Vessel Head Refueling Stand
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR SEQUENTIAL REV FACILITY NAME DOCKET NUMBER YEAR NUMBER NO.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 11 08 2006 2006 - 007 -0 00 01 08 2007 05000
- 9. OPERATING
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
MODE
[] 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
El 20.2201(d)
[E 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A) 0l 50.73(a)(2)(viii)(A) 5 El 20.2203(a)(1)
El 20.2203(a)(4) 0 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
_ 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL Ej 20.2203(a)(2)(ii)
[I 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) 0l 50.36(c)(2)
[] 50.73(a)(2)(v)(A)
El 73.71(a)(4) 0l 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
Z 50.73(a)(2)(v)(B)
El 73.71(a)(5) 0 0
20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A) 0D 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
E-50.73(a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify in Abstract below or in (If more space is required, use additional copies of NRC Form 366A) (17)
CORRECTIVE ACTIONS
An attempt was made to qualify the existing floor. However, the piers that the RVH rests on have little shear resistance and the beams are under-designed when torsional and shear loads from a maximum hypothetical earthquake are considered. Engineering change (EC) 39709 installed a seismic guard that will prevent the RVH from falling into the area of concern. This protects the SDC suction header and two of the three SI headers. Therefore decay heat removal is still possible after a postulated earthquake. This modification was completed and accepted for operation on November 14, 2006.
If the RVH falls toward the bioshield wall or containment wall, it will be deflected with very little structural damage.
These massive walls are very close to the RVH. The RVH would have little time to pick up sufficient momentum to cause significant damage. A drop straight through the floor is bounded by a heavy load drop analysis (EA-FC-98-008) and does not result in any unacceptable conditions. The RVH falling into the refueling cavity (and hypothetically onto the fuel transfer machine) is bounded by a fuel-handling accident in containment (UFSAR Section 14.18). Thus the consequences of the RVH falling from its support location in the laydown area in any direction, except the undesired location, are acceptable.
Because the RVH is now prevented from falling in the undesired location and damaging equipment required for decay heat removal, the plant is in an analyzed condition before, during, and after fuel movement during refueling outages. The consequences have been analyzed and are acceptable from a design basis perspective. All the equipment previously mentioned has been analyzed and adequately protected.
SAFETY SIGNIFICANCE
With fuel in the vessel, an un-isolable break in the SDC suction line results in a condition of an open path from the RCS to the containment floor. The loss of all three safety injection headers upstream of their respective isolation valves would result in an unanalyzed plant condition where it would not be possible for SI water to reach the RCS. The result of one or both of these events is unanalyzed. The consequences of this event are being reviewed and is expected to be completed to allow a revision to this document by April 30, 2007.
SAFETY SYSTEM FUNCTIONAL FAILURE This event does 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.
NXRJ FORM 366A (1 -2001)