05000456/LER-2015-002, Regarding Indication in Control Rod Drive Mechanism Nozzle Weld Due to Embedded Flaws Opening Up from Thermal and Pressure Stresses During Operation

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Regarding Indication in Control Rod Drive Mechanism Nozzle Weld Due to Embedded Flaws Opening Up from Thermal and Pressure Stresses During Operation
ML15153A398
Person / Time
Site: Braidwood 
Issue date: 06/02/2015
From: Raush P
Exelon Generation Co
To:
Office of Nuclear Reactor Regulation
Shared Package
ML15153A396 List:
References
BW150050 LER 15-002-00
Download: ML15153A398 (3)


LER-2015-002, Regarding Indication in Control Rod Drive Mechanism Nozzle Weld Due to Embedded Flaws Opening Up from Thermal and Pressure Stresses During Operation
Event date:
Report date:
Reporting criterion: 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)(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

10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4562015002R00 - NRC Website

text

NRCFORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 1/31/2017 (02-2014)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

13' PAGE Braidwood Station, Unit 1 05000456 1of3

~-TITLE Indication in Control Rod Drive Mechanism Nozzle Weld due to Embedded Flaws Opening Up from Thermal and Pressure Stresses during Operation

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 N/A N/A FACILITY NAME DOCKET NUMBER 04 03 2015 2015 - 002 -

00 06 02 2015 N/A N/A

9. OPERATING MODE
11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 6 D 20.2201(b)

D 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C)

D 50.73(a)(2)(vii)

D 20.2201 (ct)

D 20.2203(a)(3)(ii) 181 50.73(a)(2)(ii)(A)

D 50.73(a)(2)(viii)(A)

D 20.2203(a)(1)

D 20.2203(a)(4)

D 50.73(a)(2)(ii)(B)

D 50.73(a)(2)(viii)(B)

D 20.2203(a)(2)(i) 0 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) 000 D 20.2203(a)(2)(iv)

D 50.46(a)(3)(ii)

D 50.73(a)(2)(v)(B)

D 73.71(a)(5)

D 20.2203(a)(2)(v)

D 50.73(a)(2)(i)(A)

D 50.73(a)(2)(v)(C) 0 OTHER D 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)

D 50. 73( a)(2)(v)(D)

Specify in Abstract below or in

O. Safety Consequences

This condition had no actual safety consequences impacting plant or public safety.

The flaw was identified in a timely manner and repaired. The flaw was identified as part of a required periodic inspection. Potentially, if the flaw remained undetected, it could have over time, propagated through the embedded flaw repair to form a leak path through the reactor coolant pressure boundary.

Based on the A1R18 documented characteristics and dimensions of the observed PT indication, there was no Safety Significant functional failure (i.e., loss of safety function) as a result of these indications. The primary coolant pressure boundary was maintained and capable of preventing the release of radioactive material.

The Rod Drive system remained functional and there was no impact to structural integrity.

I:. Corrective Actions:

The identified indication was reduced to an acceptable dimension by mechanical means (manual grinding) and verified to be within the acceptance standard by liquid penetrant.

Develop and implement a corrective action plan that includes consideration of a long term Alloy 600 mitigation and other acceptable alternatives for the remaining acceptable, but unrepaired penetrations on the Braidwood Units' 1 and 2 RPV closure heads.

i:

Previous Occurrences

Previous Licensee Event Reports were made in April 2012 and November 2013 at Braidwood Station Unit 1 for indications on CROM penetration 69 (LER 2012-002-00 and LER 2013-002-00).

G. Component Failure Data

Manufacturer Westinghouse Nomenclature Reactor Vessel Integrated Head Package Termination 1718E72 Mfg. Part Number N/A