Document: NUREG-0800
Document ID: 9f13abda-ee55-4fa1-8276-db55ac2094ef
Document Type: srp
Title: CONTROL ROOM HABITABILITY SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070449.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.4
CFR Part: 
CFR Title: 

Content:
ir through two open inlets. (ii) Dual inlet designs with manual selection control - equation (6) of Reference 9 may be used with respect to the more favorable inlet location to estimate the X/Q's. The estimated values can be reduced by a factor of 4 to account for dilution effects associated with a dual inlet configuration and the relative probability that the operator will make the proper inlet selection. The reduction factor is contingent upon having redundant radiation detectors within each air inlet. The reduction factor is based on the judgment that trained control room operators, in conjunction with radiation alarm indication, will select and close the contaminated air inlet. (iii) Dual inlet designs with automatic selection control features - equation (6) of Reference 9 may be used with respect to the more favorable inlet location to estimate the X/Q's. The estimated values can be reduced by about a factor of 10 to account for the ability to select a "clean" air inlet. The actual factor may be somewhat higher if the inlet configuration begins to approach the remote air inlet concept such that the probability of having one clean air inlet is relatively high. Plant configuration and meteorological conditions should be used as the principal basis for reduction factors greater than 10. The reduction factor of 10 or more is contingent upon having redundant detectors in each inlet and the provisions of acceptable control logic which would be used in the automatic selection of a clean air inlet. Because damage to the ducting might seriously affect the system capability to protect the operators, the ducting should be seismic Category I and should be protected against tornado missiles. In addition, the number and placement of dampers must be such as to assureensure both flow and isolation in each inlet assuming one single active 6.4-15 DRAFT Rev. 3 - April 1996 component-failure (see Appendix A for information on the damper repair alternative). The location of the