ML14128A512
| ML14128A512 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/09/2014 |
| From: | Werner G E NRC/RGN-IV/DRP/RPB-E |
| To: | Jeremy G. Browning Entergy Operations |
| Werner G E | |
| References | |
| EA-14-008 | |
| Download: ML14128A512 (111) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION IV 1600 E LAMAR BLVD ARLINGTON, TX 76011-4511 May 9, 2014 EA 14-008 Jeremy Browning, Site Vice President Arkansas Nuclear One Entergy Operations, Inc. 1448 SR 333 Russellville, AR 72802-0967
SUBJECT:
SUMMARY OF REGULATORY CONFERENCE TO DISCUSS SAFETY SIGNIFICANCE OF ARKANSAS NUCLEAR ONE UNIT 1 DROPPED STATOR
Dear Mr. Browning:
On May 1, 2014, members of the U.S. Nuclear Regulatory Commission (NRC) staff met with representatives of the Arkansas Nuclear One facility to discuss the apparent violation affecting both units related to the drop of the Unit 1 main generator stator as documented in NRC Inspection Report 05000313;368/2013012, issued on March 24, 2014 (ML14083A409). The focus of the regulatory conference was a discussion on the safety significance of the finding. The discussion included Unit 1 mitigating actions focusing on the use of temporary power to recover the electrical buses and Unit 2 procedural electrical power recovery actions. For Unit 1, three non-proceduralized and non-engineered success paths associated with recovery of electrical power were discussed, with the variation of Success Path 1 being actually used, after the event, to restore power to the vital buses within 6 days. Your staff indicated that this power was available for use within 4.4 days and could have been used in an emergency. The delay on re-energizing the vital buses with offsite power was based on completing and approving the engineering, installation, and operating procedures documentation. The three success paths all had estimated times to being available to re-energize the electrical buses of 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> or less. This information was discussed during your presentation on Slides 15 35. Your staff also discussed other recovery actions. Based on credit for the recovery options, your staff estimated the conditional core damage probability of 5.5E-6. For Unit 2, the focus was on procedurally directed electrical power recovery strategies. This information was discussed during your presentation on Slides 81 86. Based on these recovery options, your staff estimated the conditional core damage probability of 1.8E-6. The NRC staff asked questions during the Regulatory Conference, with some questions requiring additional information that you indicated you would supply to us by Friday, May 9. The NRC will continue to review the information that you provided during the Regulatory Conference and the subsequent information that was requested in order to reach a final significance determination. We are developing our final risk significance and will issue a final significance determination letter in June. A copy of your presentation slides is included as Enclosure 1. Copies of the NRC slides (Enclosure 2) and meeting attendance (Enclosures 3 and 4) are included. This regulatory conference was transcribed, and a copy of the transcription will be made available and placed into (ADAMS). This Category 1 public meeting was attended by 52 members of the public, both telephonically and in the Region IV office. enclosures will be available electr ADAMS is accessible from the NRC web site at http://www.nrc.gov/reading-rm/adams.html (The Public Electronic Reading Room). Sincerely, /RA/ Gregory E. Werner, Chief Project Branch E Division of Reactor Projects Docket Nos.: 50-313, 50-368 License Nos.: DPR-51, NPF-6
Enclosures:
- 1. ANO Presentation Slides 2. NRC Slides 3. Meeting Attendance at Region IV 4. Meeting Attendance by Phone
1Arkansas Nuclear One Regulatory ConferenceNuclear Regulatory Commission -Region IV Arlington, TXMay 1, 2014 2Agenda*Introduction of Participants*NRC Opening Remarks
- Licensee Presentation
- NRC Caucus
- Final Questions
- Closing Remarks
- Conference Adjournment
- Questions and Comments from Members of the Public