Document: NUREG-0800
Document ID: 23331bab-fa00-40fd-8357-d8db908b4532
Document Type: srp
Title: GASEOUS WASTE MANAGEMENT SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070710366.pdf
Revision Date: 2023-06
Chapter: 11
Section ID: 11.3
CFR Part: 
CFR Title: 

Content:
nt gas analyzers continuously operating and providing two independent measurements verifying that hydrogen and/or oxygen are not present in potentially explosive concentrations) with automatic control functions are required to preclude the formation or buildup of 11.3-8 Revision 3 - March 2007 explosive hydrogen/oxygen mixtures. Gas analyzers should annunciate alarms both locally and in the control room. Analyzer “high alarm” setpoints should be set at approximately 2 percent and “high-high alarm” setpoints should be set at a maximum of 4 percent hydrogen or oxygen. Control features to reduce the potential for explosion should be automatically initiated at the “high-high alarm” setting. The automatic control features should be as follows: i. For systems designed to preclude explosions by maintaining either hydrogen or oxygen below 4 percent, the source of hydrogen or oxygen (as appropriate) should be automatically isolated from the system (valves should fail in closed position). ii. For systems using recombiners, if the downstream hydrogen and/or oxygen concentration exceeds 4 percent (as appropriate), acceptable control features include automatic switching to an alternate recombiner train. iii. Injection of diluents to reduce concentrations below the limits specified herein. Systems designed to operate below 4 percent hydrogen and below 4 percent oxygen may be analyzed for either hydrogen or oxygen; systems designed to operate below 4 percent hydrogen only (no oxygen restrictions) should be analyzed for hydrogen; and systems designed to operate above 4 percent hydrogen should be analyzed for oxygen. For BWR systems with steam dilution upstream of the recombiners, analysis for hydrogen (oxygen is not an acceptable alternative) should be downstream of the recombiners and upstream of the delay portions of the system (analysis upstream of the recombiners is not required if the system is designed to assure the availability of dilution steam during