Document: NUREG-0800
Document ID: 65414bbc-012c-477d-8c25-466f94c1671f
Document Type: srp
Title: GASEOUS WASTE MANAGEMENT SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350105.pdf
Revision Date: 2023-06
Chapter: 11
Section ID: 11.3
CFR Part: 
CFR Title: 

Content:
s both locally and in the control room. 'High alarm" should be set approximately 2% and "High-high alarm'" should be set at a maximum of 4% hydrogen or oxygen. Control features to reduce potential for explosion should be auto- matically initiated at "High-high alarm" setting. The automatic control features should be as follows: (1) for systems designed to preclude explosions by maintaining either hydrogen or oxygen below 4%, the source of hydrogen or oxygen (as appropriate) should be automatically isolated from the system (valve should fail In closed position); (2) for systems using recombiners, if the downstream hydrogen and/or oxygen concentration exceeds 4% (as appropriate), acceptable control features include automatically switching to an alternate recombiner train and (3) injection of diluents to reduce concentrations below the limits specified herein. Systems designed to operate below 4% hydrogen and below 4% oxygen may be analyzed for either hydrogen or oxygen; systems designed to operate below 4% hydrogen only (no oxygen restrictions), should be analyzed for hydrogen; and systems designed to operate above 4% 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 operation). For PWR systems using recombiners, analysis for hydrogen and/or oxygen should be downstream of the recombiners. In addition, unless the system design features pre- clude explosive mixtures of hydrogen and oxygen upstream of the recombiners, analysis for hydrogen and/or oxygen (as appropriate) should be upstream of the recombiners as well. The number of gas 11.3-5 Rev. 2 - July 1981 analyzers and control features at each location should be in accordance with