Document: NRC Regulatory Guide
Document ID: 7bdfde6b-2c09-49db-8a3f-863eab24747e
Document Type: regulatory_guide
Title: Control of Combustible Gas Concentrations in Containment + HISTORY - HISTORY 08/2002 – DG-1117 , Proposed Revision 3 Prior to the issuance of DG-1117, RG 1.7 was entitled "Control of Combustible Gas Concentrations in Containment Following a Loss-of-Coolant Accident," to reflect its narrower original scope
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0222/ML022210067.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.7
CFR Part: 
CFR Title: 

Content:
egrity. The combustible gas control systems, the atmosphere mixing systems, and the provisions for measuring and sampling that would be required by Section 50.44 are risk- significant as they have the ability to mitigate the risk associated with combustible gas generation caused by beyond-design-basis accidents. The recommended treatments for those systems are delineated in the Regulatory Position. C. REGULATORY POSITION 1. COMBUSTIBLE GAS CONTROL SYSTEMS For all construction permits or operating licenses under 10 CFR Part 50, and to all design approvals, design certifications, combined licenses, or manufacturing licenses under 10 CFR Part 52, that are issued after the effective date of the rule, the following design guidance is applicable to combustible gas control systems installed to mitigate the risk associated with combustible gas generation due to beyond design basis accidents. Structures, systems, and components (SSCs) installed to mitigate the hazard from the generation of combustible gas in containment should be designed to provide reasonable assurance that they will operate in the severe accident environment for which they are intended and over the time span for which they are needed. Equipment survivability expectations under severe accident conditions should consider the circumstances of applicable initiating events (such as station blackout1 or earthquakes) and the 4 environment (including pressure, temperature, and radiation) in which the equipment is relied upon to function. This guidance was contained in SECY-93-087, "Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs," dated April 2, 1993 (Ref. 3). The required system performance criteria will be based on the results of design- specific reviews that include probabilistic risk-assessment as required by 10 CFR 52.47(a)(v). Because these requirements address beyond-design-basis combustible gas control, SSCs provided to meet these