Document: NUREG-0800
Document ID: 7c5a6f62-3fbc-4bde-8062-2eb15eeb6d45
Document Type: srp
Title: UNCONTROLLED CONTROL ROD. ASSEMBLY WITHDRAWAL FROM A SUBCRITICAL OR LOW POWER
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350326.pdf
Revision Date: 2023-06
Chapter: 15
Section ID: 15.4.1
CFR Part: 
CFR Title: 

Content:
be exceeded. These require- ments have been met by comparing the resulting extreme operating conditions and response for the fuel (i.e., fuel duty) with the acceptance criteria for fuel damage (e.g., critical heat flux, fuel temperatures, and clad strain limits should not be exceeded), to assure that fuel rod failure will be precluded for this event. The basis for acceptance in the staff review is that the applicant's analyses of the maximum transients for single error control rod withdrawal from a subcritical or low-power condition have been confirmed, that the analytical methods and input data are reasonably conservative and that specified acceptable fuel design limits will not be exceeded. For BWR/6 Designs The possibilities for single failures of the reactor control system which could result in uncontrolled withdrawal of control rods under low power startup conditions have been reviewed. The staff concludes that the requirements of General Design Criteria 10, 20, and 25 have been met. This conclusion is based on the following: The applicant has met the requirements of GDC 10 that the specified acceptable fuel design limits are not exceeded, GDC 20 that the reactivity control systems are automatically initiated so that specified acceptable fuel design limits are not exceeded, and GDC 25 that single malfunctions in the reactivity control system will not cause the specified acceptable fuel design limits to be exceeded. These require- ments have been met since the system design contains a Rod Pattern Control System. This system has been reviewed and found acceptable because single failures in the reactor control system which could result in uncontrolled withdrawal of control rods under low-power conditions have been precluded. The scope of the review has included the design features, which act to prevent such withdrawals. This review has shown that no single failure will permit an uncontrolled rod withdrawal that could lead to reactivity insertions greater than