ML093490942
| ML093490942 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 12/10/2009 |
| From: | Rad Z NRC Region 1 |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| 45559 | |
| Download: ML093490942 (4) | |
Text
1211012009 U.S. Nuclear Regulatory Commission Operations Center Event Report eaye I Power Reactor Event# 45559 Site: BELLEFONTE Notification Date ITime: 12/10/2009 16:23 (EST)
Unit: 1 2 Region: 2 State: AL Event Date ! Time: 12/10/2009 (CST)
Reactor Type: [11 B&W-R-LP (205),[2] B&W-R-LP (205) Last Modification: 12/10/2009 Containment Type:
NRC Notified by: ZACKERY RAD Notifications: REBECCA NEASE R2DO HQ Ops Officer: CHARLES TEAL Emergency Class: NON EMERGENCY 10 CFR Section:
50.55(e) CONSTRUCT DEFICIENCY Unit Scram Code RX Crit Init Power Initial RX Mode Curr Power Current RX Mode 1 N No 0 Decommissioned 10 Decommissioned 2 N No 0 Decommissioned 10 Decommissioned CONTAINMENT VERTICAL TENDON FAILED "Inspection of failed Unit 1 Reactor Building Containment Vertical Tendon V9 coupling indicates a potential for an unknown common mode failure mechanism for BLN Containment vertical tendon rock anchor couplings. Unit 1 Reactor Building Containment Vertical Tendon V9 experienced a failure of the rock anchor/tendon anchor coupling on August 17, 2009 at approximately 1400 CDT. The time of failure was identified based on a loud noise bang reported by several individuals. Initial investigation failed to reveal the source of the noise. The failed tendon was discovered on August 24, 2009 during a tour of Ul Tendon Gallery, elevation 607. Unsafe conditions previously precluded an inspection of the failed coupling for proper installation or component specific damage. The failed tendon coupling was inspected on 11/23/2009 and showed no signs of component specific damage or improper installation creating the potential for an unknown common mode failure.
"Safety significance:
"Until the mechanism of failure is identified the extent of [the] condition will not be known. If multiple containment tendons are found to be losing the capability to carry tendon design force and this condition was left uncorrected, this could jeopardize the ability of the containment structure to perform its design function.
"Causes of deficiency:
"The cause of this deficiency is unknown at this time. Further analysis is in progress and when completed, an update to this report will be provided.
"Interim progress:
12/10/2009 U.S. Nuclear Regulatory Commission OperationsCenter Event Report Page 2 Power Reactor Event # 45559 "Grease from the lower anchor head can has been analyzed for moisture content. Results were within vendor specifications. Additional samples have been sent for further analysis as described in Regulatory Guide 1.25 'In-service Inspection of Ungrouted Tendon in Prestressed Concrete Containments.'
"After successful safe securing of the tendon load, the failed coupling was visually inspected. The visual inspection of the failed coupling did not indicate a component-specific failure mechanism or indication of visually apparent common mode failure mechanism. Based on this inspection visual inspection of additional tendon coupling tendon couplers is not warranted at this time. The coupling has been removed from both the tendon anchorhead and the rock anchor tendon anchorhead and sent to the TVA Central Lab for metallurgical analysis.
"Records are being reviewed to identify previous non-conformance reports and certificates of compliances for the coupler. An extent of condition and extent of cause investigation will apply to vertical tendons are similar in design, these tendons do not utilize an anchorhead coupler in the design. However, these tendons will be considered in the analysis.
"Future updates:
"TVA plans to provide an update to this report by March 31, 2010 following the completion of the metallurgical analysis."
12/10/2009 16:21 2565748108 BLN CAB PAGE 01/02 NRC EVENT NOTIFICATION WORKSHEET Page I of 2 U.S. NUCLEAR REGULATORY COMMISSION OPERATIONS CENTER NRC EVENT NOTIFICATION WORKSHEET EN # 45559 NRC OPERATION TELEPHONE NUMBER: PRIMARY - 301-816-5100 OR 800-532-3469, BACKUP'- [1st] 301-951-0500 or 800-449-3894
[2nd] 301-415-0550 AND [3rd] 301-415-0553 NOTIFICATION TIME FACILITY OR ORGANIZATION I UNIT I NAME OF CALLER .. CALL BACK -
1602 est Bellefonte Nudlear PlantI 1& 2 Zeokery Red 2565749265 EVENT TIME &ZONE EVENT DATE POWER/MODE BEFORE POWER/MODE AFTER 11/23/2009 NIA N/A EVENT CLASSIFICATIONS 1-Hr Non-Emarnancy ¶0 CF. .sT2(b)(1i fl (XA) Safe s/o Capability AINA
[0 GENERAL EMERGENCY Gen/AAEC []7 TS Deviation ADEV fl (v)(,) RHR CapabIýiJ AINB O SITE AREA EMERG,,ENCY SITIAAEC 4-Hr Non-Emergency 10 CFR 50.72(b)(2) -f3 (vXC Control of Red Release AINO
[-1 ALERT ALE/AAC E] (I) T$ RIquIred 51D ASHU f,, v(v)(O)Accident Mitigation AIND I UNUSUAL EVENT UNUIAAEC [ flv)(A) EGGS Discharge to RCS ACCS j) X ,,.Offalte Medocal AMED oo 50.72 NON-EMERGENCY PHYSICAL SECURITY (73.71)
(see next columns)
DDOD El ED (xi) 1w)(RI).U'S Actuation (scram)
OfMIte Notification ARPS AFRE Ill)
X1 Lost CommlAsmtResp 60-Day Optional 10 CFR 60.7,(a)(1]
ACOM MATER1ALFEXPOSURE... B??? B-Hr Non-Emergency 10 CFR 50.?2(b)(3 -- ,,Q I Invalid Specified System Actuat*on AINV o FITNESS FOR DUTY HFITfi[d (NiXA) Degraded Condiltion ADEG Other Unspecified Requirement (Identllfy Other UnspecifledReqmt-m(lI)(B,)(seelast clumn) UnanalyzedCondition AUNA lecsoss e NONR
[] INFORMATION ONLY NINF I (Iv)(A) Specified System Actuation AESF NONR 1v Include: Systems affected", actuations &theirIintiating signals, onume, effect of event on plant, actrons tak<enor pla=nned, etc. (continue on page 2)'
Interim Report Description of Deficiency Inspection of failed Unit 1 Reactor Building Containment Vertical Tendon V9 coupling indicates a potential for an unknown common mode failure mechanism for BLN Containment vertical tendon rock anchor couplings. Unit 1 Reactor Building Containment Vertical Tendon V9 experienced a failure of the rock anchor/ tendon anchor coupling on August 17, 2009 at approximately 1400 CDT. The time of failure was Identified based on a loud noise being reported by several individuals. Initial investigation failed to reveal the source of the noise. The failed tendon was discovered on August 24, 2009 during a tour of the Ul Tendon Gallery, elevation 607. Unsafe conditions previously precluded an Inspection of the failed coupling for proper installation or component specific damage. The failed tendon coupling was Inspected on 1112312009 and showed no signs of component specific damage or improper Installation creating the potential for an unknown common mode failure.
Safety Significance Until the mechanism of failure is identified the extent of condition will not be known. If multiple containment tendons are found to be losing the capability to carry tendon design force, and this condflon was left uncorrected, this could jeopardize the ability of the containment structure to perform its design function.
Cause of Deficiency The cause of this deficiency is unknown at this time, Further analysis is in progress and when completed, an update to this report will be provided interim Progress Grease from the lower anchor head can has been analyzed for moisture content, Results were within vendor specifications. Additional samples have been sent for further analysis as described In Regulatory Guide 1.35 "lnservice Inspection of Ungrouted Tendons In P3rsq4ra,5"ad ,-rmn4a rn^nfn u1... "
NOTIFICATIONS NRC RESLOENT STATE(s) .Di[]
YES jf NO WILL BE Q,.
Anythlng Unusual or Not Understood?
Od ANlSys.to;-s Function As 0 Yes (explainabove) 0 No LOCAL [ [ ,,, rI Required? As Yes [3 No(Explaln above)
OMIer Geov Agenciese Mode 01 Operation Estimated Additional INFO on page 2?
MOl/Prera Relnises Until Corrected: N/A Restart Oatsc NIA 1Yes -[ No Page 1 of 2 SPP-3.5-1 [04-13-2009]
12/10/2009 16:21 2565748108 BLN CAB PAGE 02/02 NRC EVENT NOTIFICATION WORKSHEET Page 2 of 2 RADIOLOGICAL RELEASES: CHECK OR PILL IN APPLICABLE ITEMS isoneelfie ddatllulnavnbnntlnnem ,hn~uld ha nua~mv4*in nvan4 dae,.*rlnfl.rii Liquid Release Gaseous Releese Unplanned Release 1 Plnned Release l Ongoin Terminated Monitored Unmonltored Offsite Release QTS. Exceeded I L] RM Alarms I Areas Evacuated
_* Personnel Exposed or Contaminated I Offrte Protective Actions Recommended *State release path In danerpton ..
Release Rate (Cllsec) % T. S. Limit HOC Guide Total Activity (CI) % T,S. Limit HOD Guide Noble Gas 0.1 Cl/se¢ 'I Boo CI Iodine 10 uCllaec 0.01 CI Parficulate 1 uCi/soc ' II mCI Uquid (excluding tritum 5 dissolved 10 uCilmin 0.1 CI noblvgases .....
Liquid (tritiumn) 0.2 CImln 5 CI Total Activity , "' '
to Monitor Radingls: Plant Stack' &CeMrserlAirEector Main Steam Line SO Blowdown Other Alarm Se"tpints:
_%T.S. Limit (.. icapplicean ) ......
RCS or SG Tube Leaks: Check or Fill In Applicable Items: (specific detatls/explanationsshould be covered In event description)
LOCATION OF THE LEAK (4)g., SG N valve, pipe, etc.)
LEAK RATE "UNITS: gpmigpd j T. S. LIMITS SUDDEN OR LONG TERM DEVELOPMENT LEAK START DATE TIME COOLANT PRIMARY - SECONDARY -
ACTIVITY & UNITS LIST OF SAFETY RELATED EQUIPMENT NOT OPERATIONAL
~flr*b.I1 .. fl111u5J5 lTVfl Page 1j After successful safe securing of the tendon load, the failed coupling was visually Inspected. The visual inspection of the failed coupling did not indicate a component-specific failure mechanism or indication of a visually apparent common mode failure mechanism. Based on this Inspection visual inspection of additional tendon couplers is not warranted at this time, The coupling has been removed from both the tendon anchorhead and the rock anchor tendon anchorhead and sent to the TVA Central Lab for metallurgical analysis.
Records are being reviewed to Identify previous non-conformance reports and certificates of compliance for the coupler. An extent of condition and extent of cause investigation will apply to vertical tendons in both Unit I and Unit 2 Reactor Buildings.
Although the dome tendons and horizontal tendons are similar In design, these tendons do not utilize an anchorhead coupler In the design. However, these tendons will be considered In the analysis.
Future Updates TVA plans to provide an update to this report by March 31, 2010 following the completion of the metallurgical analysis.
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