05000285/LER-2015-003, Regarding Containment Spray Inoperable Due to Original Design Error
| ML15166A545 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 06/15/2015 |
| From: | Cortopassi L Omaha Public Power District |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LIC-15-0062 LER 15-003-00 | |
| Download: ML15166A545 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 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)(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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2852015003R00 - NRC Website | |
text
Biiiili Omaha Public Power District 444 South 16111 Street Mall Omaha, NE 68102-2247 Ll C-15-0062 June 15, 2015 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 10 CFR 50.73
Subject:
Licensee Event Report 2015-003, Revision 0, for the Fort Calhoun Station Please find attached Licensee Event Report 2015-003, Revision 0. This report is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) and 50.73(a)(2)(v)(B). There are no new commitments being made in this letter.
If you should have any questions, please contact Terrence W. Simpkin, Manager, Site Regulatory Assurance, at ( 402) 533-6263.
ouis P. Cortopassi Site Vice President and CNO LPC/epm Attachment c:
M. L. Dapas, NRC Regional Administrator, Region IV C. F. Lyon, NRC Senior Project Manager S.M. Schneider, NRC Senior Resident Inspector
NRC FORM 366 (02-2014)
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (02-2014)
LICENSEE EVENT REPORT (LER)
(See Page 2 for required number of digits/characters for each block)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (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 information collection.
- 1. FACILITY NAME Fort Calhoun Station
- 2. DOCKET NUMBER 05000285
- 3. PAGE 1 OF 4 Containment Spray Inoperable due to Original Design Error
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 04 16 2015 2015 003 - 00 06 15 2015 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 5 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 0 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC FORM 366 (02-2014)
BACKGROUND Fort Calhoun Station (FCS) is a two-loop reactor coolant system of Combustion Engineering design.
EVENT DESCRIPTION
During design basis reconstitution of the Containment Spray (CS) system, it was discovered that the CS piping inside containment and the containment liner have higher stresses during a postulated Main Steam Line Break (MSLB) or Loss of Coolant Accident (LOCA) than previously analyzed. The preliminary analysis concluded that both CS piping trains inside containment and the containment liner failed to meet the operability requirements of American Society of Mechanical Engineers (ASME)
Section III Appendix F without implementing compensatory measures.
Evaluation of the condition identified three underlying issues:
- 1. Original plant design did not postulate that the empty CS pipe inside containment could heatup to approximately 290 degrees Fahrenheit following a postulated MSLB or LOCA. Documented in condition report (CR) 2015-04578.
- 2. Thermally stressed CS piping would transpose high loads onto the Containment liner because the CS pipe supports are directly attached to the liner. Documented in CR 2015-04578.
- 3. Poor configuration control during original construction resulted in 1 missing U-bolt in spray ring piping (due to spray nozzle interference), 2 supports had missing kickers and support gaps which were not properly indicated on plant drawings. Documented in CR 2015-06013.
The plant was in a cold shutdown condition for a refueling outage when the issue was discovered on April 16, 2015.
The extent of condition (EOC) was evaluated and is limited to the CS ring header piping downstream of Containment penetrations M-86 and M-89 in containment. The extent of condition does not extend to other safety injection (SI) piping because the CS system is open ended and voided when in standby and would therefore experience a temperature increase immediately prior to being filled with relatively cool water during accident conditions. The CS ring header piping is unique when compared to other SI piping, thereby limiting the extent of condition. Other containment cooling systems such as CCW are closed loop systems that are filled with water.
An EOC was also completed to ensure that there were no additional discrepancies with this CS piping and supports inside containment.
NRC FORM 366 (02-2014)
An evaluation has been conducted by the station. The results of the evaluation conclude that containment spray and containment systems prior to the discovery of the issue were capable of performing their intended safety functions during a postulated MSLB or LOCA without modification. In addition, only one pipe support exceeds the code allowable stresses of ASME BPVC Section III Appendix F.
This report is being submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) and 50.73(a)(2)(v)(B).
CONCLUSION The large bore CS piping inside containment had never undergone an extensive design review due to the location of the piping (Containment dome). This review required tools previously not available (3D Laser Scan).
A cause analysis was performed and determined that thermal expansion was never considered for the containment riser supports. This is a flaw in the original design of the CS header and rings inside containment.
The material discrepancies identified as part of the EOC walkdown/3D Laser Scan were determined to be caused by poor configuration control during original construction.
CORRECTIVE ACTIONS
An EOC, previously mentioned, was completed using 3D Laser Scanning and walkdown of the containment. This evaluation determined that one of the CS piping supports SIS-110 was missing one U-Bolt, SIH-283 and SIS-284 were missing kickers and SIS-230 had gaps larger than specified.
An operability evaluation was completed in support of plant operation. The operability evaluation, utilizing calculation FC08434, conclude that the piping and pipe supports of the CS System as well as the Containment liner are capable of performing their intended safety functions per the operability criteria of ASME BPVC Section III Appendix F following modifications completed under Engineering Changes (EC) 65926.
Final corrective actions to fully qualify the CS system will be completed under the stations corrective action program.
NRC FORM 366 (02-2014)
SAFETY SIGNIFICANCE
An evaluation has been conducted by the station. The results of the evaluation conclude that containment spray and containment systems prior to the discovery of the issue were capable of performing their intended safety functions during a postulated MSLB or LOCA without modification. In addition, only one pipe support exceeds the code allowable stresses of ASME BPVC Section III Appendix F. Although code allowable stresses were exceeded, the affected train would have delivered design flow during design basis events.
SAFETY SYSTEM FUNCTIONAL FAILURE This does represent a safety system functional failure in accordance with NEI 99-02, revision 7.
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