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:
eposition. Radiolytic destruction of iodomethane may be modeled, but the model must also consider radiolytic production. Engineered safety features designed to remove organic iodides are reviewed on a case-by-case basis. iv. Particulates The first-order removal coefficient for particulates, λp, can be determined by the method described in Reference 13, or estimated by: where h is the spray drop fall height, V is the containment building net free volume, F is the spray flow, and E/D is the ratio of a dimensionless collection efficiency E to the average spray drop diameter D. Since the removal of particulate material chiefly depends on the relative sizes of the particles and the spray drops, it is convenient to combine parameters that cannot be known. It is conservative to assume E/D to be 10 per meter initially (i.e., 1% efficiency for spray drops of 1 millimeter in diameter), changing abruptly to 1 spray drop per meter after the aerosol mass has been depleted by a factor of 50 (i.e., 98% of the suspended mass is 10 times more readily removed than the remaining 2%). D. The iodine decontamination factor, DF, is defined as the maximum iodine concentration in the containment atmosphere divided by the concentration of iodine in the containment atmosphere at some time after decontamination. The DF for the containment atmosphere achieved by the containment spray system is determined by the following equation: where H is the effective iodine partition coefficient, Vs is the volume of liquid in containment sump and sump overflow, and Vc is the containment building net free volume less Vs. 6.5.2-14 Revision 4 - March 2007 The effectiveness of the spray in removing elemental iodine is presumed to end when the maximum elemental iodine DF is reached. This value cannot exceed 200. Because the removal mechanisms for organic iodides and particulate iodines are significantly different from and slower than the mechanisms for elemental iodine, there is no need to limit the DF for