Document: NUREG-0800
Document ID: 91a12934-f0d9-4573-ad3b-553ab75dabc0
Document Type: srp
Title: FISSION PRODUCT CONTROL SYSTEMS AND STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0636/ML063600408.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.3
CFR Part: 
CFR Title: 

Content:
be sized to meet the negative pressure criterion for the inleakage rate and the conservatively calculated heat load for the regions 6.5.3-9 Revision 3 - March 2007 served by each rate, and analyses to this effect should be presented by the applicant. The pressure response analyses are reviewed by the organization responsible for the review of reactor accident consequence assessment, specifically design basis containment and ventilation performance. The functional capability of the filter design associated with the exhaust system is reviewed by the organization responsible for radiation protection under SRP Section 6.5.1. Design guidance for postaccident cleanup air filtration and adsorption systems is provided in Regulatory Guide 1.52. The reviewer should consult with the organization responsible for radiation protection concerning filter system efficiencies. The exhaust systems may be one of several designs. Common designs are: i. Straight exhaust through charcoal and high-efficiency particulate air (HEPA) filters. Primary containment leakage to these regions is assumed to go directly to the filter with no mixing or holdup in the region being filtered. ii. Recirculation system with split inflow (some exhausted through filters and some recirculated to the region being served). Primary containment leakage to the region being serviced is assumed to occur directly to the intake of the recirculation fan. There, a fraction of the leakage (the ratio of exhaust to total flow) is exhausted through the filters; the balance is then assumed to return to the region being serviced. The placement of the system intake and return headers is examined to determine that return flow from the fans does not have a direct path to the intake again. Credit for mixing in 50% of the region is given for fission products returned by the recirculation system to the secondary volume if the header placement is satisfactory. iii. Other variations on the recirculation system are (a) filters in the