Document: NUREG-0800
Document ID: e3249d77-0411-430a-9793-06aea8669075
Document Type: srp
Title: FISSION PRODUCT CONTROL SYSTEMS AND STRUCTURES
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070474.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.3
CFR Part: 
CFR Title: 

Content:
aust and auxiliary building ventilation systems 84 fall under the purview of the ASBSCSB. The systems' ability to 85 maintain a negative pressure of sufficient margin under varying wind conditions and operational modes prior to a design basis accident is verified by the ASBSCSB. The AEB reviewer consults with the ASB 86 reviewer to verify also verifies to SCSB the design of that the systems have the capability to maintaining negative pressure following a design 87 basis accident. If an adequate negative differential pressure (0.6 cm, or88 0.25 in, water gauge) is achieved within 60 seconds from the time the accident, then no positive pressure time period need be assumed in the dose model. All positive pressure periods at any time in the secondary containment regions are treated as direct outleakage periods following an accident, and no credit is given for filters or recirculation systems. The CSBSCSB verifies the positive pressure periods. The large reactor 89 buildings around older BWR containments are usually maintained at a negative pressure during normal operation, and the dose model used for these cases has not assumed any positive pressure period. d. The exhaust systems used to maintain the negative pressure differential following the accident should be sized to meet the negative pressure criterion for the inleakage rate and the conservatively calculated heat load for the regions treated by each, and analyses to this effect should be presented by the applicant. The pressure response analyses are reviewed by the CSBSCSB. The functional capability of the filter design 90 associated with the exhaust system is reviewed by the ETSB under SRP 91 Section 6.5.1. Design guidance for postaccident cleanup air filtration and adsorption systems is provided in Regulatory Guide 1.52. The reviewer 92 should consult with ETSBPERB concerning filter system efficiencies. 93 The exhaust systems may be one of several designs. Common designs are: (1) Straight exhaust through