ML14034A415: Difference between revisions

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{{Adams
#REDIRECT [[DCL-14-009, Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01]]
| number = ML14034A415
| issue date = 02/03/2014
| title = Diablo Canyon, Units 1 and 2, Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01
| author name = Allen B S
| author affiliation = Pacific Gas & Electric Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000275, 05000323
| license number = DPR-080, DPR-082
| contact person =
| case reference number = BL-12-001, DCL-14-009
| document type = Letter
| page count = 5
}}
 
=Text=
{{#Wiki_filter:Pacific Gas and Electric Company February 3, 2014 PG&E Letter DCL-14-009 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal:
691.4888 Fax: 805.545.6445 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 10 CFR 50.54(f)
Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01
 
==References:==
: 1. NRC Letter, "Bulletin 2012-01,
'Design Vulnerability In Electric Power System,"'
dated July 27, 2012 2. PG&E Letter DCL-12-1 04, "Ninety-Day Response to NRC Bulletin 2012-01:
'Design Vulnerability In Electric Power System,"'
dated October 25, 2012 3. NRC Letter, "Request for Additional Information Regarding Response to Bulletin 2012-01,
'Design Vulnerability in Electric Power System,"'
dated December 20, 2013 Dear Commissioners and Staff: In Reference 1, the NRC issued Bulletin 2012-01 to request information from licensees regarding open phase impacts on electric power system designs and verify compliance with regulatory requirements.
PG&E provided a response in Reference
: 2. The NRC has requested additional information in Reference 3 to verify that licensees have completed interim corrective actions and compensatory
: measures, and to determine the status of licensee's long-term corrective actions.
Pacific Gas and Electric's (PG&E) response is provided in the Enclosure to this letter. PG&E is making a regulatory commitment (as defined by NEI 99-04) in this letter. The commitment is identified in the Enclosure to this letter. If you have any questions, or require additional information, please contact Mr. Tom Baldwin at (805) 545-4720.
A member of the STARS (Strategic Teaming and Resource Sharing)
Alliance Callaway
* Comanche Peak
* Diablo Canyon
* Palo Verde
* Wolf Creek m Document Control Desk February 3, 2014 & Page 2 PG&E Letter DCL-14-009 I state under penalty of perjury that the foregoing is true and correct.
Executed on February 3, 2014. Sincerely, 5. A&___ Barrys2 Site Vice President mjrm/4557/50601137 Enclosure cc Diablo Distribution cc/enc: Brian J. Benney, NRR Project Manager Marc L. Dapas, NRC Region IV Administrator Thomas R. Hipschman, NRC, Senior Resident Inspector Gonzalo L. Perez, Branch Chief, California Department of Public Health A member of the STARS (Strategic Teaming and Resource Sharing)
Alliance Callaway
* Comanche Peak
* Diablo Canyon
* Palo Verde
* Wolf Creek Enclosure PG&E Letter DCL-14-009 Response to NRC Request for Additional, Information Regarding Response to NRC Bulletin 2012-01 Enclosure PG&E Letter DCL-14-009 Response to NRC Request for Additional Information Regarding Response to NRC Bulletin 2012-01 NRC Request 1 Provide a summary of all interim corrective actions that have been taken since the January 30, 2012, event at Byron Station, Unit 2, to ensure that plant operators can promptly diagnose and respond to open phase conditions on the offsite power circuits for Class-1 E vital buses until permanent corrective actions are completed.
Pacific Gas and Electric (PG&E) Response Lessons learned from the events at Byron station were reviewed and various interim corrective actions evaluated for safety and efficiency at Diablo Canyon Nuclear Power Plant (DCPP). Based on the plant's offsite power configuration, electrical design details, and lessons learned, the following actions were taken to ensure plant operators can promptly diagnose and respond to open phase conditions (OPC):
* Interim Corrective Actions o As an interim measure, DCPP performs a daily visual inspection of the 230 kV tie-line for an open phase. The scope of the inspection includes the line termination at the standby I startup transformers of each unit up to switchyard disconnect switches (i.e., interface with the 230 kV busses).
o PG&E's system protection group performed an informal study to evaluate the effects of single open phase on DCPP's 230 kV offsite power source and concluded that for heavy loading levels on the standby startup source, existing relaying would detect the condition and provide alarms in the control room. o Operating instructions were reviewed and procedures for annunciator responses were revised to provide guidance for operators to diagnose and respond to an OPC. o Training has been provided to operations personnel on the OPC event and the procedural changes.
o PG&E has performed a study to determine the voltage imbalance tolerance of a selected sample of engineered safety feature motors. This is similar to, but more limited in scope than, the NEI guidance document for the OPC initiative.
PG&E determined that a more detailed analysis is required.
1 NRC Request 2 Enclosure PG&E Letter DCL-14-009 Provide a status and schedule for completion of plant design changes and modifications to resolve issues with an open phase of electric power." PG&E Response
* Status o PG&E is monitoring and evaluating industry efforts and options being researched and developed by several vendors to detect OPC faults. There is currently no generic, off-the-shelf technology that has been proven to detect all the required open phase fault conditions for all plant and transformer designs.
o PG&E is monitoring and/or participating in the development of the NEI OPC guidance
: document, as well as development of enhancements to software tools being used to analyze OPC faults. o Prior to implementation, new OPC technology will need to be thoroughly evaluated, tested, and analyzed.
* Schedule o PG&E will be performing a detailed study of OPC faults beginning in February of 2014. PG&E anticipates the results in the third quarter of 2014. o Based on the results of the above study, PG&E will determine any design changes necessary to address OPCs, and the schedule for implementation, taking into account refueling outage schedules, software and hardware availability, manufacturer's delivery capabilities, licensing delays, and etc. PG&E is making the following regulatory commitment:
o Based on the results of the study being performed in 2014 for DCPP, PG&E will submit a supplement to the NRC by December 31, 2014. The supplement will identify any changes to current actions taken to address OPCs, and will provide details of any additional actions needed including proposed design changes and their planned schedule for completion.
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