Document: NUREG-0800
Document ID: f03d2c71-27a1-41fd-9362-1e62c6142e13
Document Type: srp
Title: Containment Systems and Severe Accidents (Tier 1)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070653.pdf
Revision Date: 2023-06
Chapter: 14
Section ID: 14.3.11
CFR Part: 
CFR Title: 

Content:
etins and in some cases Information Notices. For example, degraded voltages have been highlighted. In addition, breaker coordination and short circuit protection have been also highlighted. 11. Policy issues raised for the standard designs. For the electrical area this includes the AAC source for SBO, second offsite source to non-Class 1E buses, and direct offsite feed to Class 1E buses. 12. New features in the design. For example, on the ABWR this includes the main generator breaker for back feed purposes; and the potential for harmonics introduced by new RIPs, MFW pump speed controllers and its potential effects on the Class 1E equipment. 13. PRA identified insights or key assumptions. In the electrical area this typically involves SBO which should already receive treatment in ITAAC because of the SBO rule (see DRAFT Rev. 0 - April 1996 14.3-54 above). As another example, in the case of CE it appears that their "split bus" arrangement is a significant or key assumption in their PRA and therefore in some cases it is important that within a Division a particular pump motor is on a particular bus. CE raised this to its ITAAC based on the PRA. NOTE: In some cases it may be possible to use PRA results to decide that some aspect does not need Tier 1 treatment, i.e. the PRA shows it is of little safety significance. 14. A severe accident feature has been added to the design. If there are such features it may turn out that an electrical support aspect may need an ITAAC. 15. Resolution of Generic Safety Issues (GSIs) have identified solutions that have resulted in design/operational features. For example, the resolution of GI-48/49 (as part of GI-128) identified treatment of "tie breakers." The figure showing the Class 1E distribution system should show this feature if it exists. Then any special features to deal with this feature should be covered. 16. Post TMI requirements - e.g., power to PORV block valve, Pressurizer heaters, etc. B. ITAAC ENTRIES (for the above