Document: NUREG-0800
Document ID: db9f5ff5-cad8-4af5-848b-a22889b3fb51
Document Type: srp
Title: describes the design acceptance criteria for waste gas systems (as part of the
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070730056.pdf
Revision Date: 2023-06
Chapter: 11
Section ID: 11.3
CFR Part: 
CFR Title: 

Content:
GWMS). 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 assumes that the probability of occurrence is very small. It is recognized that the probability of an accidental release from the waste gas system is relatively high and that lower dose criteria are appropriate. Generally, the following two kinds of waste gas system failures have been designated as warranting evaluation: 1. Gross system failures, such as rupture of a decay tank (Regulatory Guide 1.24) or rupture of a line (Regulatory Guide 1.98); 2. Malfunctions, such as operator errors, valve misalignments, malfunction of attendant equipment, and active component failures; Both the probabilities and the consequences of a waste gas system leak or failure depend on the kind of accident considered and the characteristics of the system (as defined in Tables 15-1 and 15-4 in Section 15.7.1 of Regulatory Guide 1.70). Waste gas system design characteristics differ between plants, particularly between BWRs and PWRs, but the most important common characteristic among plants is that designs incorporate the guidance of Regulatory Guide 1.143 to withstand the effects of a hydrogen explosion and earthquakes for gaseous wastes produced during normal operation and anticipated operational occurrences. As a result, a gross failure of the waste gas system is considered highly unlikely, e.g., such as a failure involving the near total loss of the system’s inventory of radioactive materials. However, for present purposes, the most important aspect is that they have been designed in accordance with Regulatory Guide 1.143, and therefore, the NRC considered a higher dose criterion for evaluating gross failures of such fortified systems. The goal of this position paper is to minimize potential radiation exposures to the public and to provide reasonable assurance that the radiological consequences