Document: NUREG-0800
Document ID: 848ab24d-ac9b-4ec5-85ff-099e13b769c3
Document Type: srp
Title: CONTAINMENT SPRAY AS A FISSION PRODUCT CLEANUP SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0601/ML060150001.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.2
CFR Part: 
CFR Title: 

Content:
cess. The removal coefficient 8 (lambda) for each of the sprayed regions of the containment is computed. Removal coefficients for time-dependent wall plateout are also calculated. The coefficients for spray removal and wall plateout are summed. The removal lambdas are the input parameters of a computer model for dose calculation. 6.5.2-11 Rev. 3 - December 2005 c. Fission Product Cleanup Models Based on the information in the SAR, the reviewer estimates how large an area of the interior surfaces of the containment building could be washed by the spray system, the volume flow rate of the system (assuming a single failure), the average spray drop fall height and the mass-mean diameter of the spray drops. The effectiveness of a containment spray system may be estimated by considering the chemical and physical processes that can occur during an accident during which the system operates. Models that consider such process are reviewed on a case-by-case basis. In the absence of detailed models, reviewers should use the following simplifications. Experimental results (References 16, 18, and 15) and computer simulations of the chemical kinetics (Reference 10) show that an important factor in determining the effectiveness of sprays against elemental iodine vapor is the concentration of iodine in the spray solution. Experiments with fresh sprays with no dissolved iodine were found to be quite effective at scrubbing elemental iodine at a pH as low as 5 (References 18 and 15). Solutions with dissolved iodine such as the sump solutions that recirculate after an accident may revolatilize iodine if the solutions are acidic (References 17 and 10). Chemical additives in the spray solution have no significant effect on aerosol particle removal because this removal process is largely mechanical. (1) Elemental iodine removal during spraying of fresh solution During injection, the removal of elemental iodine by wall deposition can be estimated by the equation Where, 8w is the first-order