Document: NUREG-0800
Document ID: 936f16a2-5593-4498-8533-ddca55910376
Document Type: srp
Title: COMBUSTIBLE GAS CONTROL IN CONTAINMENT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340704.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.5
CFR Part: 
CFR Title: 

Content:
ent penetrations needed for plants that utilize external recombiners to assure the single failure criteria outlined in Item II.E.4.1 of NUREG-0737 or NUREG-0718 are met. 7. CSB reviews analyses of the functional capability of the systems provided to mix combustible gases within the containment. CSB reviews the support- ing information in the safety analysis report which should include eleva- tion drawings of the containment showing the routing of ductwork and the circulation patterns caused by fans, sprays, or thermal convection. Special attention is paid to interior compartments to assure that combustible gases cannot collect in them without mixing with the bulk containment atmosphere. CSB ensures that interior compartments are identified in the safety analy- sis report and the provisions made to assure circulation within them are discussed. Systems provided to mix the combustible gases within the containment may also be used for containment heat removal, e.g., the fan cooler and spray systems. The acceptability of the design of these systems is considered in the review of the containment heat removal systems in SRP Section 6.2.2. 8. CSB reviews the manner in which the systems provided to reduce combustible gas concentrations will be operated. The concentration at which the system is actuated (the control point) will be determined from the safety analysis report. The margin between the control point and the hydrogen or oxygen concentration limits specified in Table 1 of Regulatory Guide 1.7 is checked. CSB determines whether the uncertainty in measuring combustible gas concentrations and the time lag in making the system operational after reaching the control point have been covered by the minimum allowable mar- gin specified in the acceptance criteria. IV. EVALUATION FINDINGS The reviewer verifies that sufficient information has been provided and that his evaluation supports conclusions of the following type, to be included in the staff's safety evaluation report: