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:
iven 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 recirculation line, (b) filters in both the recirculation line and the exhaust line, and (c) high exhaust flow to reduce the negative pressure to several centimeters (inches) water gauge, and then no exhaust with recirculation only for some time period. C. The sizing of the system fans for the volumes they are maintaining at a negative pressure may be critical in determining the ratio of exhaust flow to recirculation flow. Past history shows that secondary containment structures are considerably more leaky than applicants anticipated (2 to 5 times as great as anticipated), and fan exhaust flows have been increased after testing to account for this. (When identical flow rates are predicted for two volumes that differ by a factor of 10 or more, it is difficult to believe that the negative pressure differential will be the same for both volumes.) The flow rates, negative pressure differential, and volumes are noted, and the organization responsible for the review of reactor accident consequence assessment (specifically design basis containment and ventilation performance, pressure response only) is consulted for verification before performing dose calculations. D. The systems should be reviewed to determine volumes exhausted, system operation, fan flow rates, and filter efficiencies. All the applicant's claims should 6.5.3-10 Revision 3 - March 2007 be verified by appropriate staff members as noted in Table 6.5.3-2 of this SRP section. Leakage fractions from the primary containment to each volume should be identified and stated in the technical specifications. Completeness of information, adequacy of technical specifications and testing methods, and the adequacy and maintenance of the integrity of the secondary containment negative pressure considering failures of