ML121010488
| ML121010488 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 04/10/2012 |
| From: | Balwant Singal Plant Licensing Branch IV |
| To: | Elwood T Union Electric Co |
| Singal, B K, NRR/DORL, 301-415-301 | |
| Shared Package | |
| ML121010488 | List: |
| References | |
| TAC ME8319 | |
| Download: ML121010488 (2) | |
Text
From:
Singal, Balwant Sent:
Tuesday, April 10, 2012 2:07 PM To:
Elwood, Thomas B Cc:
Maglio, Scott A; Thadani, Mohan; Billerbeck, John; McMurtray, Anthony; Casto, Greg; Gardocki, Stanley; Markley, Michael
Subject:
Request for Additional Information (RAI) - Main Steam Isolation Valve (MSIV)
Actuator Rupture Disks Replacement Interval Relief Request - TAC ME8319 Attachments:
FW: responses to NRC RAIs Sorry. Forgot to attach your e-mail dated April 9, 2012.
Tom:
After review of your application dated March 30, 2012 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12090A501), we have earlier forwarded you the request for additional information for the subject relief request via e-mail on April 5, 2012.
The request contained 9 questions. We were provided with an e-mail response to these questions April 9, 2012. Based on further review of your e-mail responses dated April 9, 2012 (copy attached), we have the following additional questions:
- 10. Please provide additional technical justification for the argument that the rupture disks will not burst at higher than design pressure.
- 11. Are the rupture disk cyclic failure test results provided by Continental Disc Corporation to the Hatch Nuclear Plant (Hatch) for their High Pressure Coolant Injections (HPCI) system rupture disks applicable (or scalable) to the Callaway Plant, Unit 1 (Callaway) rupture disks? Please indicate if a life cycle argument similar to the Hatch argument be made for the Callaway rupture disks?
- 12. Several failure detection monitoring activities were described in your previous Attachment 3 to e-mail dated April 9, 2012. Please indicate if Callaway intend to implement these measures?
- 13. Attachment 3 referenced in Question 12 addresses the rupture disk leaking and rupture disk bursts at lower pressure failure modes. Please confirm that under either of these failure modes, the MSIV will perform its safety function to close?
- 14. Your application dated March 30, 2012 indicates that the rupture disks will be replaced at the June 2013 Refueling 19 outage. Please indicate if Callaway will replace the rupture disks sooner, if plant conditions permit?
- 15. In your e-mail response dated April 9, 2012, the following response was provided to Question 8:
The work was removed from the scope of the last refueling outage based on an initial determination that the work could be done with the plant on-line subsequent to the outage.
However, when the work was evaluated by Operations management for on-line performance and scheduling after the outage, it was determined that the plant risk was too high, particularly in light of the estimated time for completing the work relative to the allowed
outage time (Completion Time) specified in the Technical Specifications for an inoperable MSIV.
This question was discussed during the phone call on April 5, 2012 with your staff. Your staff stated that the replacement time for the rupture disc was about 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, which is 1/2 of the AOT. Additionally, the licensee referred to a Condition Report (CR) that discussed this issue. Please provide a copy of the CR and an explanation on the difference between the reasons provided in the phone call and what was included above.
Please confirm if you performed an operability assessment to address the impact, if the rupture disc is not replaced. Additionally, U.S. Nuclear Regulatory Commission (NRC) staff would like to know the results of your operability assessment, if it was performed.
- 16. From a system configuration point of view, please confirm the correct operation of the components. Drawing M-628-00094 provided as Attachment 1 to your e-mail dated April 9, 2012 shows check valve ABHV0011V6 installed in an opposite direction from what is stated in the Final Safety Analysis Report (FSAR). The drawing shows the check valve allows flow from the bonnet area through the 3 way valve into the lower piston area. However, the FSAR states that after 120 seconds the 3 way valve energizes to allow residual steam and condensate to flow from the lower piston area to the bonnet. Please confirm if the drawing is incorrect, the check valves are installed incorrectly, or the FSAR is incorrect.
Please treat this e-mail as a formal request for additional information. Also, please note that verbal authorization cannot be provided based on your e-mail responses and you are requested to submit your responses formally. A timely and complete response will enable NRC staff to process your request more efficiently.
Please let me know if you have any questions.
Balwant K. Singal Senior Project Manager (Comanche Peak, STP, and Palo Verde)
Nuclear Regulatory Commission Division of Operating Reactor Licensing Balwant.Singal@nrc.gov Tel: (301) 415-3016 Fax: (301) 415-1222