CONTAIN code calculations of the effects on the source term of CsI to I2 conversion due to severe hydrogen burns

Preliminary experiments have been conducted at Sandia National Laboratories simulating degraded-core accidents. One notable result of these preliminary tests is the observation of the conversion of cesium iodide (CsI) to its elemental form (I2) following a hydrogen burn. To evaluate some of the implications of the iodide conversion for the source term, computational simulations of the Surry TML and TMLB' accident sequences using experimental data on near-stoichiometric burns were conducted with the CONTAIN code. CONTAIN is the NRC's general-purpose computer code for modeling containment response to a severe accident. The results provide qualitative insights on a few of the more important sensitivities of the source term to the form of radioactive iodine in containment, and can be used to guide further experimental and theoretical developments in assessing the consequences of iodide conversion