Document: 10 CFR Part 50
Document ID: e5e51d71-6583-44f4-85e4-1d59c4ed1c3c
Document Type: cfr
Title: Combustible gas control for nuclear power reactors.
Source: 10 CFR Part 50
Source URL: https://www.ecfr.gov/current/title-10/part-50/section-50.44
Revision Date: 
Chapter: 
Section ID: 50.44
CFR Part: 50
CFR Title: 10

Content:
§ 50.44 Combustible gas control for nuclear power reactors. ( a ) Definitions — ( 1 ) Inerted atmosphere means a containment atmosphere with less than 4 percent oxygen by volume. ( 2 ) Mixed atmosphere means that the concentration of combustible gases in any part of the containment is below a level that supports combustion or detonation that could cause loss of containment integrity. ( b ) Requirements for currently-licensed reactors. Each boiling or pressurized water nuclear power reactor with an operating license on October 16, 2003, except for those facilities for which the certifications required under § 50.82(a)(1) have been submitted, must comply with the following requirements, as applicable: ( 1 ) Mixed atmosphere. All containments must have a capability for ensuring a mixed atmosphere. ( 2 ) Combustible gas control. ( i ) All boiling water reactors with Mark I or Mark II type containments must have an inerted atmosphere. ( ii ) All boiling water reactors with Mark III type containments and all pressurized water reactors with ice condenser containments must have the capability for controlling combustible gas generated from a metal-water reaction involving 75 percent 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. ( 3 ) Equipment survivability. All boiling water reactors with Mark III containments and all pressurized water reactors with ice condenser containments that do not rely upon an inerted atmosphere inside containment to control combustible gases must be able to establish and maintain safe shutdown and containment structural integrity with systems and components capable of performing their functions during and after exposure to the environmental conditions created by the burning of hydrogen. Environmental conditions caused by local detonations of hydrogen must also be included, unless such detonations can be shown unlikely to