Document: NUREG-0800
Document ID: 1c401e6c-8c2d-47df-b05f-2978939cbd15
Document Type: srp
Title: CONTROL ROOM HABITABILITY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550069.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.4
CFR Part: 
CFR Title: 

Content:
quantity or location of the toxic material is such as to need closer study is described in Regulatory Guide 1.78. This guide also discusses the methods for analyzing the degree of risk and states, in general terms, the various protective measures that could be instituted if the hazard is found to be too great. In the case of chlorine, specific acceptable protective provisions are provided in Regulatory Guide 1.78. In summary, the facility should include the following provisions or their equivalent for the emergency zone ventilation system: i. quick-acting toxic gas detectors, ii. automatic emergency zone isolation, iii. emergency zone leaktightness, iv. limited fresh air makeup rates, and v. breathing apparatus and associated bottled air supply. The best solution for a particular case will depend on the toxic gas in question and on the specific ventilation system design. C. Confined Area Releases. The reviewer in the organization responsible for the review of ventilation and air filtration studies the control building layout in relation to potential sources of radiation and toxic gases inside the control building or adjacent connected buildings. The following is considered: i. Storage location of CO2 or other firefighting materials should be such as to eliminate the possibility of significant quantities of the gases entering the emergency zone. The review will be coordinated with the organization responsible for the review of materials and chemical engineering. ii. The ventilation zones adjacent to the emergency zone should be configured and balanced to preclude airflow toward the emergency zone. iii. All pressurized equipment and piping (e.g., main steam lines and turbines) that could cause significant pressure gradients when failed inside buildings should be isolated from the emergency zone by multiple barriers such as multiple door vestibules or their equivalent. 6. Radiation Shielding. Control room operators as well as other plant personnel are protected from