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:
oefficient 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 to assume that organic iodides are not removed by either spray or wall deposition. Radiolytic destruction of iodomethane may be modelled, but such a model must also consider radiolytic production (Ref. 18). Engineered safety features designed to remove organic iodides are reviewed on a case-by-case basis. (4) Particulates The first-order removal coefficient, A for particulates may be estimated by A _3hFE AP = 2VD where h is the fall height of the spray drops, V is the contain- ment building net free volume, F is the spray flow, and (E/D) is the ratio of a dimensionless collection efficiency E to the 6.5.2-11 Rev. 2 - December 1988 average spray drop diameter D. Since the removal of particulate material depends markedly upon the relative sizes of the particles and the spray drops, it is convenient to combine param- eters that cannot be known (Ref. 13). It is conservative to assume (E/D) to be 10 per meter initially (i.e., 1% efficiency for spray drops of one millimeter in diameter), changing abruptly to one per meter after the aerosol mass has been depleted by a factor of 50 (i.e., 98% of the suspended mass is ten 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. DF for the containment atmosphere achieved by the containment spray system is determined from the following equation (Ref. 4): V H DF = 1 + c c where H is the effective iodine partition coefficient, V is the volume of liquid in containment sump and sump overflow, and Vc is the containment building net free volume less Vs.c The maximum decontamination factor is 200 for elemental iodine. The