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:
ilable upon restoration of power. Additional guidance concerning the availability of deliberate ignition systems during station blackout sequences is being developed as part of the staff’s review of Generic Safety Issue 189, “Susceptibility of Ice Condenser and Mark III Containments to Early Failure from Hydrogen Combustion During a Severe Accident.” 3 2. All BWRs with Mark III type containments and all PWRs with ice condenser type containments must have the capability to control combustible gas generated from a metal-water reaction involving 75% of the fuel cladding surrounding the active fuel region (excluding the cladding surrounding the plenum volume) so that there is no loss of containment structural integrity. The deliberate ignition systems provided to meet this existing hydrogen source term are capable of safely accommodating even greater amounts of hydrogen associated with even more severe core melt sequences that fail the reactor vessel and involve molten core-concrete interaction. Deliberate ignition systems, if available, generally consume the hydrogen before it reaches concentrations that can be detrimental to containment integrity. 3. For all applicants for and holders of a construction permit or operating license under 10 CFR Part 50, and all applicants for a design approval, design certification, or combined license under 10 CFR Part 52 that are issued after the effective date of the rule, the following requirement applies. All containments must have an inerted atmosphere or limit hydrogen concentrations in containment during and following an accident that releases an equivalent amount of hydrogen as would be generated from a 100% fuel-clad coolant reaction, uniformly distributed, to less than 10% and must maintain containment structural integrity. 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