Document: NUREG-0800
Document ID: 8c2fce42-281a-4a50-9de7-513df024f27c
Document Type: srp
Title: CONTROL ROOM HABITABILITY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340712.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.4
CFR Part: 
CFR Title: 

Content:
emergency zone is not normally considered a limiting problem. 6.4-6 Rev. 2 - July 1981 3. Ventilation System Layout and Functional Design The reviewer evaluates the control room ventilation system in order to establish appropriate parameters to be used in the control room dose calculations. The review is coordinated with the ASB which evaluates the control room ventilation system design and performance in accordance with SRP Section 9.4.1. The procedures are as follows: a. The type of system proposed is determined. The following types of protection provisions are currently being employed for boiling water. reactor (BWR) or pressurized water reactor (PWR) plants: (1) tone isolation, with the incoming air filtered and a positive pressure maintained by the ventilation system fans. This arrangement Is often provided for BWRs having high stacks. Air flow rates are between 400 and 4000 cfm. (2) Zone isolation, with filtered recirculated air. This arrange- ment is often provided for BWRs and PWRs with roof vents. Recirculation rates range from 2,000 to 30,000 cfm. (3) Zone isolation, with filtered recirculated air, and with a positive pressure maintained in the zone. This arrangement is essentially the same as that in (2), with the addition of the positive pressure provision. (4) Dual air Inlets for the emergency zone. In this arrangement two widely spaced inlets are located outboard, on opposite sides of potential toxic and radioactive gas sources. The arrangement guarantees at least one inlet being free of con- tamination, except under extreme no-wind conditions. It can be used in all types of plants. Makeup 'air supplied from the con- tamination-free inlet provides a positive pressure in the emergency zone and thus minimizes infiltration. (5) Bottled air supply for a limited time. In this arrangement a flow rate of 400 to 600 cfm is provided from compressed air containers for about one hour to prevent inleakage. It is used in systems having containments whose internal