Document: NUREG-0800
Document ID: 47be7233-5326-4a7d-a9c5-f3b91d565a72
Document Type: srp
Title: MINIMUM CONTAINMENT PRESSURE ANALYSIS FOR EMERGENCY CORE
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070492.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.1.5
CFR Part: 
CFR Title: 

Content:
COOLING SYSTEM PERFORMANCE CAPABILITY STUDIES REVIEW RESPONSIBILITIES Primary - Containment Systems and Severe Accident Branch (SCSB)1 Secondary - None I. 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 dependence 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 SCSB 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 SCSB reviews the assumptions made regarding the 2 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. DRAFT Rev. 3 - April 1996 6.2.1.5-2 It should be noted that the minimum containment pressure analysis done in connection with ECCS performance evaluation differs from the containment functional performance analysis, in that the conservatisms and margins are taken in opposite directions in the two cases. Thus, the minimum containment