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:
th 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 may revolatilize iodine if the solutions are acidic. Chemical additives in the spray solution have no significant effect on aerosol particle removal because this removal process is largely mechanical. i. 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, λw is the first-order removal coefficient by wall deposition, A is the wetted-surface area, V is the containment building net free volume, and 6.5.2-12 Revision 4 - March 2007 Kw is a mass-transfer coefficient. All available experimental data are conservatively bounded if Kw is taken to be 4.9 meters per hour. During injection, the effectiveness of the spray against elemental iodine vapor is chiefly determined by the rate at which fresh-solution surface area is introduced into the containment building atmosphere. The rate of solution surface created per unit gas volume in the containment atmosphere can be estimated as 6F/VD, where F is the volume flow rate of the spray pump, V is the containment building net free volume, and D is the mass-mean diameter of the spray drops. The first-order removal coefficient by spray, λs, may be taken to be where Kg is the gas-phase mass-transfer coefficient and T is the time of fall of the drops, which may be estimated by the ratio of the average fall height to the terminal velocity of the mass-mean drop. This equation represents a first-order approximation if a well-mixed droplet model is used for the spray efficiency. The equation is valid for λs values equal to or greater than 10 per hour. λs must be limited to 20 per hour to prevent extrapolation beyond the existing data for boric acid solutions with a pH of 5. For λs values less than 10 per hour, analyses using