Document: NUREG-0800
Document ID: 364356ce-150e-4dcb-865f-720ae91d37a7
Document Type: srp
Title: CONTAINMENT SPRAY AS A FISSION PRODUCT CLEANUP SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070473.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.2
CFR Part: 
CFR Title: 

Content:
ll spray coverage of the containment building volume, the following should be observed: (1) The spray nozzles should be located as high in the containment building as practicable to maximize the spray drop fall distance. (2) The layout of the spray nozzles and distribution headers should be such that the cross-sectional area of the containment building covered by the spray is as large as practicable and that a nearly homogeneous distribution of spray in the containment building space is produced. Unsprayed regions in the upper containment building and, in particular, an unsprayed annulus adjacent to the containment building liner should be avoided wherever possible. (3) In designing the layout of the spray nozzle positions and orientations, the effect of the post-accident atmosphere should be considered, including the effects of post-accident conditions that result in the maximum possible density of the containment atmosphere. c. Promotion of Containment Building Atmosphere Mixing Because the effectiveness of the containment spray system depends on a well-mixed containment atmosphere, all design features enhancing post-accident mixing should be considered. d. Spray Nozzles The nozzles used in the containment spray system should be of a design that minimizes the possibility of clogging while producing drop sizes effective for iodine absorption. The nozzles should not have internal moving parts such as swirl vanes, turbulence promoters, etc. They should not have orifices or internal restrictions which would narrow the flow passage to less than 0.64 cm (0.25 inch)one quarter of an inch in diameter. 16 e. Spray Solution The partition of iodine between liquid and gas phases is enhanced by the alkalinity of the solution. The spray system should be designed so that the spray solution is within material compatibility constraints. Iodine scrubbing credit is given for spray solutions whose chemistry, including any additives, has been demonstrated to be effective for iodine