Document: NUREG-0800
Document ID: 9e3f4564-4ddf-4369-b699-a42709a80b66
Document Type: srp
Title: CONTAINMENT SPRAY AS A FISSION PRODUCT CLEANUP SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0701/ML070190178.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.2
CFR Part: 
CFR Title: 

Content:
ay, and outleakage from the containment building. If the value in Position C.1.a of Regulatory Guides 1.3 and 1.4 is used in the calculation of fission product removal, then deposition by plateout, as described in paragraph III.4.c of this SRP section, should not be considered as an additional removal mechanism. Deposition by plateout is already accounted for in the regulatory guide values. B. The removal of fission products from the containment atmosphere by the spray is considered a first-order removal process. The removal coefficient λ (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. 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 and computer simulations of the chemical kinetics 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. Solutions with dissolved iodine such as the sump solutions that recirculate after an accident