ML051220293
| ML051220293 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 10/16/2003 |
| From: | Schin R NRC/RGN-II |
| To: | Ellen Brown, Gallucci R, Qualls P Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2004-0277 | |
| Download: ML051220293 (1) | |
Text
From:
Robert Schin PA To:
Brown, Eva; Gallucci, Ray; Qualls, PhilŽm Date:
Thursday, October 16, 2003 1:25PM
Subject:
Comments on NEI 00-01 Here are some comments on the the attached file "Enclosure 2", "NEI Responses to NRC Comments on Draft Revision D of NEI 00-01"
- 1. In item 2, NEI states that "The risk significance of MCC, panel, and switchgear fires is generally low because they typically affect only one train of hot shutdown eguipment.
That was not the case at Shearon Harris and is likely not the case at other plants. Many MCCs there contained breakers that affected both trains of hot shutdown equipment. The MCCs were designed with separation for FSAR Chapter 15 events, not with separation for Appendix R fire events. For Chapter 15 events, many flowpaths have two MOVs in series (one A train & one B train) with a safety function to close. Examples include containment isolation valves for all ECCS and charging systems, VCT outlet valves, and charging pump cross-connect valves. For Appendix R fire events, the hot shutdown function of these valves may be to both remain open.
Consequently, each of the two MOVs in series will have a post-fire hot shutdown function to support both an A-train shutdown and a B-train shutdown. For example, one will be powered from a B train MCC, (along with other B train post-fire hot shutdown equipment) but will be relied upon to remain open to support A train post-fire safe hot shutdown. At Shearon Harris, most of the 480V MCCs contained breakers that affected both trains of hot shutdown equipment.
- 2. Item 2 also states that "ignition and propogation of cabinet fires in qualified cables are less likely." However, cables inside cabinets and MCCs are likely to not be IEEE 383 qualified.
- 3. In item 3, the statement is made that "Feed and bleed is one method for accomplishing safe shutdown recognized in plant procedures and risk analysis. Therefore, it may be used for post-fire safe shutdown..."
This is an erroneous conclusion. Feed and bleed is in plant EOPs and in PRA analyses, but generally only for outside of design basis events. Typically the pressurizer PORVs and safety valves do not have the required QA to be relied upon for feed and bleed for design basis events. FSAR Chapter 15 events typically involve only a few lifts while passing steam. The pressurizer PORVs and safety valves are generally not designed or tested to assure that they can open and close many times in rapid succession or while passing water.
CC:
O'Donohue, Kathleen; Ogle, Charles R.; Payne, Charlie