A Model of Silver-Iodine Reactions in a Light Water Reactor Containment Sump Under Severe Accident Conditions
Metallic silver (Ag) and iodine (I) form insoluble AgI in the containment sump has a major impact on iodine volatility and hence on the source term to the environment. Resistance-in-series models are developed and validated against separate-effects tests. The reaction between I2 and Ag is limited by mass transfer in the liquid. The rate does not follow a parabolic law for the duration of the experiments. The extent of oxidation of the silver sample seems to play a decisive role for reactions with I- which proceed via a two-step process. The initial, rapid step is controlled by the reaction with the surface silver oxide with a contribution of mass transfer in the liquid. The subsequent, slow step is limited by reaction between I- and Ag+ at the solid-liquid interface. The reaction is probably negligible for pH>7 in the absence of oxidising conditions.
Bibliographic Reference: Article: Journal of Nuclear Materials 264 (1999) pp. 113-121
Record Number: 200012830 / Last updated on: 2000-11-03
Original language: en
Available languages: en