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:
ctor is directly proportional to recirculation flow rate multiplied by efficiency. 6.4-12 Revision 3 - March 2007 time-integrated concentration of iodine outside over the time-integrated concentration within the emergency zone, of 20 to 100 for filters built, maintained, and operated according to Regulatory Guide 1.52. An IPF of 100 needs deep bed filters. Such systems are likely to provide a sufficient reduction in iodine concentration only if the source is at some distance from the inlets. Thus, the staff consider that in most cases, only plants with high stacks (about 100 meters) would meet GDC 19 with this system. ii. Zone isolation with filtered recirculated air. These systems have a greater potential for controlling iodine than those having once-through filters. IPFs ranging from 20 to over 150 can be achieved. These are the usual designs for plants having vents located at containment roof level. A system having a recirculation rate of 2400 L/s (5000 cfm) and a filter efficiency of 95% would be rated as follows: Infiltration L/s (cfm) IPF3 100 (200) 25 50 (100) 49 24 (50) 96 12 (25) 191 Infiltration should be determined conservatively. Measured gross leakage is used to determine the infiltration rate that will be applied in the evaluation of the radiological consequences of postulated accidents. This rate is determined in accordance with the guidance of Regulatory Guide 1.197. “Demonstrating Control Room Envelope Integrity at Nuclear Power Reactors,” May 2003. The base infiltration rate is augmented by adding to it the estimated contribution from opening and closing of doors associated with such activities in accordance with by the plant emergency plans and procedures. Normally, 5 L/s (10 cfm) is used for this additional contribution. iii. Zone isolation with filtered recirculated air and a positive pressure. This system is essentially the same as the preceding one. However, an additional operational mode is possible. Makeup air for pressurization is