05000445/FIN-2017002-06
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Finding | |
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| Title | Unanalyzed Condition Involving Potential Moderate Energy Line Break |
| Description | Inspection Scope On September 13, 2016, based on initial observations by NRC inspectors, the licensee determined that pressurized fire protection piping in the service water intake structure was not properly shielded for moderate energy line break protection of service water components which resulted in inoperability of one train of service water for both Unit 1 and Unit 2. During extent of condition walk downs conducted on October 6, 2016, October 10, 2016, November 17, 2016, December 5, 2016, and December 22, 2016, additional piping in the Unit 1 and Unit 2 safeguards and auxiliary buildings was found to not be shielded correctly as well, resulting in inoperability of one train of various safety related equipment for both units. The licensee determined the most likely cause of this event was that the methodology used to conduct the initial moderate energy line break walk downs was flawed and allowed some threats to be missed. The licensees corrective actions include shielding the affected piping, performing a 100 percent walk down of rooms containing moderate energy line break piping identified for shielding, and revising the systems interaction program maintenance procedure. These activities constituted completion of one event follow -up sample, as defined in Inspection Procedure 71153. b. Findings Introduction. The inspectors identified a non- cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, associated with the licensees failure to assure that applicable regulatory requirements and the design bases, as defined in 10 CFR 50.2 and as specified in the license application, for those structure, systems and components to which this appendix applies, were correctly translated into specifications, drawings, procedures, and instructions. Specifically, from initial construction through March 2017, the licensee failed to fully incorporate applicable design requirements for components needed to ensure the capability to shut down the reactor and maintain it in a safe shutdown condition following a moderate energy line break. Description. On September 13, 2016, inspectors performed walkdowns in the service water intake structure and identified a vertical run of unshielded, pressurized fire protection piping that appeared to pose a moderate energy line break threat to the service water pumps. Inspectors determined that in the event of a moderate energy line break crack along any portion of the unshielded piping, the resultant spray had the potential to impact the function of any one of the four service water pumps. However, only one train would have been affected during the event due to the physical configuration/separation relative to the source line and target pumps and/or associated motor control centers that support pump operation. Inspectors informed the licensee of their concern. Engineering personnel performed a subsequent walkdown of the intake structure and determined that the identified piping was not correctly shielded and operability of the service water pumps was in question. The licensee took immediate action to isolate and depressurize the fire protection line in question which addressed the operability concern. The licensee entered this issue into the station corrective action program as Condition Report CR -2016 -008147 for resolution. Part of the licensees actions was to perform extent of condition walkdowns for unshielded moderate energy piping in the safeguards building for Unit 1 and 2. During the extent of condition walk downs conducted on October 6, 2016, October 10, 2016, November 17, 2016, December 5, 2016, and December 22, 2016, additional piping in the Unit 1 and Unit 2 safeguards and auxiliary buildings was found to not be appropriately shielded against a moderate energy line break, resulting in the inoperability of various safety related equipment for both units. Unit 2 Train B 480 VAC motor control center 2EB2- 1 (Unit 2 Train B emergency core cooling, battery charger, containment spray, and containment isolation valve equipment) Unit 1 Train B 480V MCC 1EB4- 2, and Unit 1 Train B Distribution Panel 1ED2- 2 (Unit 1 Train B safety -related pumps, panels, sequencer, and transformers) Unit 1 Train B 480V MCC 1 EB4- 1 (Unit 1 Train B safety -related pumps, valves, fans, battery chargers, and transformers) Unit 2 Train B 480V MCC 2E134- 1 (Unit 2 Train B safety -related pumps, valves, fans, battery chargers, and transformer) Unit 1, Train B 480V MCC 1E84- 1 (Unit 1 Train B safety -related pumps, valves, fans, battery chargers, and transformers) In each of these instances the licensee took prompt action to isolate and depressurize the identified moderate energy piping pending modification. The licensee subsequently determined that the most probable cause of the issue was the use of a flawed methodology during the initial moderate energy piping walkdowns conducted in 1989. The licensee reported this issue to NRC in Event Report 52239, and Licensee Event Report 16 -002- 00. Analyses. The failure to incorporate applicable design requirements into specifications for moderate energy line break protection was a performance deficiency. The performance deficiency was more than minor, and therefore a finding, because it was associated with the design control attribute of the Mitigating Systems cornerstone and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, from initial construction through March 2017, the licensee failed to fully incorporate applicable design requirements for components needed to ensure the capability to shut down the reactor and maintain it in a safe shutdown condition following a moderate energy line break. Using Inspection Manual Chapter 0609, Attachment 04, Initial Characterization of Findings, dated July 1, 2012, and Inspection Manual Chapter 0609, Appendix A , Significance Determination Process for Findings At -Power , Exhibit 2, Mitigating Systems Screening Questions, dated October 7, 2016, the inspectors determined the finding required a detailed risk evaluation because the finding involved a deficiency affecting the design and qualification of a mitigating structure, system, or component, and resulted in a loss of operability, and represented an actual loss of function of at least a single train for longer than its allowed out age time. A senior reactor analysts from Region IV performed a detailed risk evaluation and determined that the bounding increase in core damage frequency for this issue was 5.1E -8/year for Unit 1 and 2.9E -10/year for Unit 2 , and was therefore of very low safety significance (Green). Additional information is included in the detailed risk evaluation in Attachment 3 of this report. The inspectors did not assign a cross -cutting aspect because the performance deficiency was not reflective of present performance. Enforcement. Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, states, in part, that, measures shall be established to assure that applicable regulatory requirements and the design bases, as defined in 10 CFR 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies, are correctly translated into specifications, drawings, procedures, and instructions. Contrary to the above, measures established by the licensee did not assure that applicable regulatory requirements and the design bases, as defined in 10 CFR 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies, were correctly translated into specifications, drawings, procedures, and instructions. Specifically, from initial construction through March 2017, the licensee failed to fully incorporate applicable design requirements for components needed to ensure the capability to shut down the reactor and maintain it in a safe shutdown condition following a moderate energy line break. This issue does not represent an immediate safety concern because when the lines were identified the licensee took prompt action to isolate and depressurize them, and the licensee has implemented plant modifications. Since this violation was of very low safety significance (Green) and has been entered into the corrective action program as Condition Report CR- 2016- 008147, this violation is being treated as a non -cited violation consistent with Section 2.3.2 of the NRC Enforcement Policy. (NCV 05000445/2017002 -05; 05000446/2017002- 05, Failure to Translate Design Requirements Into the As Built Facility) |
| Site: | Comanche Peak  |
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| Report | IR 05000445/2017002 Section 4OA3 |
| Date counted | Jun 30, 2017 (2017Q2) |
| Type: | Violation: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71153 |
| Inspectors (proximate) | J Josey R Kumana S Janicki M Chambers L Carson J O'Donnell K Clayton I Anchandoj Joseyr Kumana S Janicki M Chambers L Carson J O'Donnell K Clayton I Anchondo M Haire |
| Violation of: | 10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control |
| INPO aspect | |
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Finding - Comanche Peak - IR 05000445/2017002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Comanche Peak) @ 2017Q2
Self-Identified List (Comanche Peak)
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