Facility Details: BESSEL

Organization / Localization: VTT
Country: Finland
Facility Description: Glass cylinder, volume 5 l.
Test Identification: BESSEL tests
SA-Related Topics / Phenomena: Bessel facility was developed to study radiolytical oxidation of gaseous iodine by β-radiation. Materials, including fission product aerosols may be exposed to beta-radiation in the vicinity of core debris pool on the containment floor. In the BESSEL tests the β-source was phosphorus-32, located at the bottom of test chamber.
Measured Parameters: Radiation dose rate, airborne particle gas concentration, CH3I concentration, particle number size distribution
Modelling: The irradiated material was methyl-iodide (CH3I) in O2 and N2 atmospheric mixtures. The size of the detected IOx particles were a 10-100 nm. The particles dissolved easily to humidity in air. The reaction was mainly diagnosed from formation of CO2 after at least 1 day exposure time.
Simulation Code: Monte Carlo NParticle Transport Code (MCNP)
Experimental Research Program: Finnish SAFIR2014 program
Link to PIRT: WP-1.5 ST-25
References: [1] Teemu Kärkelä, Ari Auvinen, Tommi Kekki, Jussi Lyyränen, Jorma Jokiniemi, ”Radiolytical oxidation of gaseous iodine by beta radiation”, Radiochim. Acta 2015; 103 (10): 719 – 728.
[2] Proceedings of Conference7th Conference on Severe Accident Research, ERMSAR 2015, 24-26 March 2015, Marseille, France.
[3] X-5 Monte Carlo Team: MCNP – A general Monte Carlo Nparticle transport code, version 5 volume I: MCNP overview and theory. Report No. LA-UR-03-1987, Los Alamos National Laboratory, New Mexico (2003).




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