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:
s assumed to be released to the containment space are obtained from Regulatory Guide 1.3 (Ref. 6) or Regulatory Guide 1.4 (Ref. 7), as appropriate. The amounts of fis- sion product airborne inside the containment building depend upon plate-out on interior surfaces, removal by the spray and action of other engineered safety features present, radioactive decay, and outleakage from the containment building. b. The removal of fission products from the containment atmosphere by the spray is considered a first-order removal process. The removal coefficient A (lambda) for each of the sprayed regions of the con- tainment is computed. Removal coefficients representing time- dependent wall plate-out are also calculated. The coefficients for spray removal and wall plate-out are summed. The removal lambdas are input parameters of a computer model for dose calculation. c. Fission Product Cleanup Models The reviewer estimates the area of the interior surfaces of the containment building which could be washed by the spray system, the volume flow rate of the system (assuming single failure), the aver- age drop fall height and the mass-mean diameter of the spray drops, 6.5.2-9 Rev. 2 - December 1988 from inspection of the information in the SAR. The effectiveness of a containment spray system may be estimated by considering the chemical and physical processes that could occur during an accident in which the system operates. Models containing such considerations are reviewed on case-by-case bases. In the absence of detailed models, the following simplifications may be used: Experimental results (Refs. 8, 9, and 11) and computer simulations of the chemical kinetics involved (Ref. 10) show that an important factor determining the effectiveness of sprays against elemental iodine vapor is the concentration of iodine in the spray solution. Experiments with fresh sprays having no dissolved iodine were observed to be quite effective in the scrubbing of elemental iodine even at a pH as low