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
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CFR Title: 

Content:
d radiation monitor- ing, and control features. In all cases, the waste gas system is a radioactive gaseous waste management system required by 10 CFR Part 50, Section 50.34a, with system operation in accordance with Section 50.36a. The design accep- tance criteria for waste gas systems has been given in SRP Section 11.3. The basic criterion for reactor accidents, including waste gas system failures, is that offsite doses shall not exceed 25 rem to the whole body (10 CFR Part 100). However, that criterion is predicated on the assumption that the prob- ability of occurence is very small. At least since 1972, it has been recognized that the probability of an accidental release from the waste gas system is relatively high and that lower dose criteria are appropriate. Generally two kinds of waste gas system failures have been designated as warrenting evaluation. These are (1) gross system failures, such as rupture of a decay tank (Regulatory Guide 1.24, Rev. 0, March 1972) or rupture of a line (Regulatory Guide 1.98, For Comment, March 1976) and (2) malfunctions, such as operator errors, valve misalignments, malfunction of attendent equip- ment and active component failures. Both the probablities and the consequences of a waste gas system leak or failure depend on the kind of accident considered and the characteristics of the system (Regulatory Guide 1.70 Section 15.7.1, Rev. 3, November 1978). Waste gas systems characteristics differ between plants, particularly between BWRs and PWRs, but for present purposes the most important difference is between those systems designed to withstand the effects of a hydrogen explo- sion and earthquakes (Regulatory Guide 1.143) and those systems not so designed. Gross failure of the system is considered much less likely if the system is designed to withstand explosions snd earthquakes. Accordingly, higher dose 11.3-11 Rev. 0 - July 1981 criteria have been considered appropriate for evaluating gross failure of these fortified systems.