Document: NUREG-0800
Document ID: b761625e-90fd-41e3-a3ae-acaea1aabf84
Document Type: srp
Title: should still be met.
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0520/ML052070476.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.5.1
CFR Part: 
CFR Title: 

Content:
DRAFT Rev. 4 - April 1996 6.5.4-4 Technical Rationale:16 The technical rationale for application of the above acceptance criteria to the ice condenser as a fission product cleanup system is discussed in the following paragraphs. 1. GDC 41 establishes requirements regarding the containment atmosphere cleanup systems being designed to control fission products released into the reactor containment to reduce the concentration and quality of fission products released to the environment following postulated accidents. The ice condenser systems are relied upon, in part, to provide an effective means for removal of fission product iodine released to the reactor containment during the design basis accident. Requiring the ice condenser system ice to contain a quantity of the proposed chemical additive sufficient to ensure that the pH of the post- accident recirculating solution is above 7 enhances the dissolution and retention of iodine in the ice melt. Tests have shown an alkaline additive in the ice, such as sodium tetraborate, improves the dissolution and retention of iodine in the ice melt through hydrolysis reactions (Reference 8). The deposition of volatile iodine on the surfaces of the ice provides a means of iodine removal that is highly efficient in a steam condensing environment. Ice without any additives has been shown to not function as well as ice containing an alkaline additive. In addition, ensuring the pH of the post-accident recirculating solution is above 7 ensures that the iodine remains fixed in the recirculation water. Under acid conditions (pH less than 7), the iodine is completely dissolved but will be available for stripping by air flow, resulting in a refluxing action that returns the iodine to the containment atmosphere. Enhancing dissolution and retention of radioactive iodine in the ice melt limits the quantity of radioactive iodine available in the containment atmosphere, thereby mitigating the potential release of fission products to the