Document: NUREG-0800
Document ID: 5cb19e99-a561-4571-92e5-2933a6181985
Document Type: srp
Title: CONTAINMENT SPRAY AS A FISSION'PRODUCT CLEANUP SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340761.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.2
CFR Part: 
CFR Title: 

Content:
bove expression represents a first-order approximation if a well-mixed droplet model is used for the spray efficiency. The expression is valid for As 6.5.2-10 Rev. 2 - December 1988 values equal to or greater than ten per hour. X is to be limited to 20 per hour to prevent extrapolation Beyond the existing data for boric acid solutions with a pH of 5 (Refs. 8 and 11). For A values less than ten per hour, analyses using a more sophisticated expression are recommended. (2) Elemental iodine removal during recirculation of sump solution The sump solution at the end of injection is assumed to contain fission products washed from the reactor core as well as those removed from the containment atmosphere. The radiation absorbed by the sump solution, if the solution is acidic, would generate hydrogen peroxide (Ref. 12) in sufficient amount to react with both iodide and iodate ions and raise the possibility of ele- mental iodine re-evolution (Ref. 5). For sump solutions having pH values less than 7, molecular iodine vapor should be conserva- tively assumed to evolve into the containment atmosphere (Ref. 15). Information on the partition coefficients for molecular iodine can be found in References 15, 16, and 17. The equilibrium partitioning of iodine between the sump liquid and the containment atmosphere is examined for the extreme additive concentrations determined in Section III.1.a.(2), in combination with the range of temperatures possible in the containment atmosphere and the sump solution. The reviewer should consider all known sources and sinks of acids and bases (e.g., alkaline earth and alkali metal oxides, nitric acid generated by radiolysis of nitrogen and water, alkaline salts or lye additives) in a post-accident containment environment. The minimum iodine partition coefficient determined for these conditions forms the basis of the ultimate iodine decontamination factor in the staff's analysis described in subsection III.4.d. (3) Organic iodides It is conservative