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:
ecific 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 requirements need not be subject to the environmental qualification requirements of 10 CFR 50.49, quality assurance requirements of Appendix B to 10 CFR Part 50, and redundancy/diversity requirements of Appendix A to 10 CFR Part 50. Guidance such as that found in Appendices A and B of Regulatory Guide 1.155 (Ref. 4) is appropriate for equipment used to mitigate the consequences of severe accidents. This guidance was used to review the design of evolutionary and passive plant designs as documented in NUREG-1462 (Ref. 5), NUREG-1503 (Ref. 6), and NUREG-1512 (Ref. 7). The combustible gas control systems in all BWRs with Mark III-type containments and all PWRs with ice condenser type containments must meet the requirements in the Proposed Section 50.44. The staff considers that the combustible gas control systems installed and approved by the NRC as of the effective date of the rule are acceptable without modification. 2. OXYGEN AND HYDROGEN MONITORS 2.1 Hydrogen Monitors The Proposed Section 50.44 would require that equipment be provided for monitoring hydrogen in the containment. The equipment for monitoring hydrogen must be functional, reliable, and capable of continuously measuring the concentration of hydrogen in the containment atmosphere following a beyond-design-basis accident for accident management, including emergency planning. Safety-related hydrogen monitoring systems installed and approved by the NRC prior to the effective date of the rule are sufficient to meet these criteria. Non-safety-related commercial grade hydrogen monitors can also be used to meet these criteria if they: 1. Comply with the Category 3 design and qualification criteria of Regulatory Guide 1.97 (Ref. 8) for monitors used as diagnostic or backup indicators. 2. Comply with the Category 2