Document: NUREG-0800
Document ID: 1dda396e-398a-4b85-aa13-c5c1dbf82bc2
Document Type: srp
Title: MINIMUM CONTAINMENT PRESSURE ANALYSIS FOR EMERGENCY CORE COOLING SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340670.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.1.5
CFR Part: 
CFR Title: 

Content:
PERFORMANCE CAPABILITY STUDIES REVIEW RESPONSIBILITIES Primary - Containment Systems Branch (CSB) Secondary - None 1. AREAS OF REVIEW Following a loss-of-coolant accident in a pressurized water reactor (PWR) plant, the emergency core cooling system (ECCS) will supply water to the reactor vessel to reflood, and thereby cool the reactor core. The core flooding rate is governed by the capability of the ECCS water to displace the steam generated in the reactor vessel during the core reflooding period. For PWR plants, there is a direct depend- ence of core flooding rate on containment pressure; i.e., the core flooding rate will increase with increasing containment pressure. Therefore, as part of the overall evaluation of ECCS performance, the CSB reviews analyses of the minimum containment pressure that could exist during the period of time until the core is reflooded following a loss-of-coolant accident to confirm the validity of the containment pressure used in ECCS performance capability studies. The CSB reviews the assumptions made regarding the operation of engineered safety feature heat removal systems; the effectiveness of Structural heat sinks within the containment to remove energy from the containment atmosphere, and other heat removal processes, such as steam in the containment mixing with ECCS water spilling from the break in the reactor coolant system; and in the case of ice condenser containments, mixing with water from melted ice that drains into the lower containment volume. The review is done for all PWR containment types, i.e., dry, subatmospheric, and ice condenser containments. The CSB will coordinate the review with the Reactor Systems Branch (RSB), which is responsible for determining the acceptability of the mass and energy release data used in the minimum containment pressure analysis (see SRP Section 6.3). This information is derived from the applicant's evaluation of ECCS performance capa- bility in accordance with 10 CFR Part 50, §50.46 and