ML121010577

Request for Additional Information Re E-mail, Relief Request VR-01 from Requirements of ASME OM Code Mandatory Appendix I, One-time Extension Replacement of Main Steam Isolation Valve Actuator Rupture Disks

ML121010577
Person / Time
Site:	Callaway
Issue date:	04/05/2012
From:	Thadani M Plant Licensing Branch IV
To:	Elwood T, Maglio S Union Electric Co
Thadani, M C, NRR/DORL/LP4, 415-1476
References
TAC ME8319
Download: ML121010577 (2)

Text

From: Thadani, Mohan Sent: Thursday, April 05, 2012 1:18 PM To: Maglio, Scott A; Elwood, Thomas B Cc: Billerbeck, John; McMurtray, Anthony; Billerbeck, John; Gardocki, Stanley; Casto, Greg; Wang, Alan; Thadani, Mohan; Singal, Balwant

Subject:

RAIs for Callaway re/rupture disk replacement frequency Scott/Tom:

This is a follow-up to our 11:00 Oclock relief request RR VR-01 phone call, regarding your request for relief from requirements of ASME OM Code Mandatory Appendix, I-1360 for periodic replacement of Class 2 and 3 non-reclosing pressure relief devices. As the NRC staff stated during the call, the NRC staff has identified the following request for additional information, in order to support you relief request.

Please provide your responses to the following questions at your earliest convenience to facilitate NRC staffs expeditious review for timely resolutions of the issues discussed during the call..

If you have any questions, please do not hesitate to contact me.

Request for Additional Information

1. Can Callaway supply a sketch of the MSIV/actuator showing the rupture disk and describing its function?

2. Please discuss the credible rupture disk failure modes (e.g., leakage, burst early, fail to burst) and their effect on MSIV functionality and the transients / events / analyzed accidents for which the MSIVs are either credited or which MSIV may cause.

3. Are there any spare rupture disks from the same lot number available for testing? Or old rupture disks that were previously removed available for testing? Can at least a visual exam be performed on the installed rupture disks?

4. Has the rupture disk material, service conditions and environment, stress history (pressure and temperature cycles), visible condition (corrosion, leakage, etc.) been determined and considered?

5. What rupture disk vendor information or data are available concerning expected service life?

And expected failure rate?

6. Describe rupture disk storage and handling controls and work controls during installation (e.g., torque, thread lubrication, gasketing).

7. What are the design requirements for this rupture disk installation? For instance,

• Is it, in fact, an overpressure protection device?

• Is it required to be there by BPV Section III?

• Is the rupture disk code stamped per Section III?

• Is it protecting a code vessel? Which code? What are that codes test/inspection/replacement requirements?

• Is it properly scoped in the IST Program? Does it meet the applicability requirements of 50.55a, ISTA-1100, ISTC-1100, Mand. App. I-1100?

8. Why were the rupture disks not replaced at the last outage?

9. Has the ANII been consulted on this issue? Does he have an opinion?

Mohan C Thadani Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation (301) 415-1476 Mohan.Thadani@nrc.gov