Chemical reactions of fission product deposits and iodine transport in primary circuit conditions

Jarmo Kalilainen (Corresponding Author), Teemu Kärkelä, Riitta Zilliacus, Unto Tapper, Ari Auvinen, Jorma Jokiniemi

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)

Abstract

The objective of this work was to examine the chemical reactions taking place on primary circuit surfaces and their effect on fission product transport in a severe nuclear reactor accident. Especially transport of gaseous and aerosol phase iodine was studied. Caesium iodide (CsI) was used as precursor material for iodine species. Also, effects of molybdenum and boron on transport of iodine were investigated. The experimental work showed that when CsI alone was used as a precursor, as much as 20% of the released iodine was in gaseous form and the rest as aerosol particles. Aerosol particles were most likely CsI. When the amount of hydrogen in the carrier gas was increased, the fraction of gaseous iodine decreased. When Boron was added to the precursor, a glassy caesium borate surface was formed on the crucible. Boron trapped most of the caesium and also a fraction of iodine, causing almost all released iodine to be in gaseous form. When Mo was introduced in the precursor, most of the iodine was again released in gaseous form. Oxidised Mo reacted with caesium releasing iodine from CsI. The effect of Mo on iodine transport depended much on H 2 concentration and was observed to be substantially greater on stainless steel surface. When stainless steel crucible was used, Mo was found in small amounts from aerosol particles, indicating that it was probably released as caesium molybdate or as molybdenum oxide
Original languageEnglish
Pages (from-to)140-147
JournalNuclear Engineering and Design
Volume267
DOIs
Publication statusPublished - 2014
MoE publication typeA1 Journal article-refereed

Fingerprint

fission products
Fission products
iodine
Iodine
chemical reaction
cesium
Chemical reactions
chemical reactions
Deposits
deposits
Cesium iodide
Networks (circuits)
cesium iodides
Cesium
iodide
Aerosols
Boron
aerosols
boron
aerosol

Cite this

Kalilainen, Jarmo ; Kärkelä, Teemu ; Zilliacus, Riitta ; Tapper, Unto ; Auvinen, Ari ; Jokiniemi, Jorma. / Chemical reactions of fission product deposits and iodine transport in primary circuit conditions. In: Nuclear Engineering and Design. 2014 ; Vol. 267. pp. 140-147.
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author = "Jarmo Kalilainen and Teemu K{\"a}rkel{\"a} and Riitta Zilliacus and Unto Tapper and Ari Auvinen and Jorma Jokiniemi",
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Chemical reactions of fission product deposits and iodine transport in primary circuit conditions. / Kalilainen, Jarmo (Corresponding Author); Kärkelä, Teemu; Zilliacus, Riitta; Tapper, Unto; Auvinen, Ari; Jokiniemi, Jorma.

In: Nuclear Engineering and Design, Vol. 267, 2014, p. 140-147.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Chemical reactions of fission product deposits and iodine transport in primary circuit conditions

AU - Kalilainen, Jarmo

AU - Kärkelä, Teemu

AU - Zilliacus, Riitta

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AU - Auvinen, Ari

AU - Jokiniemi, Jorma

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N2 - The objective of this work was to examine the chemical reactions taking place on primary circuit surfaces and their effect on fission product transport in a severe nuclear reactor accident. Especially transport of gaseous and aerosol phase iodine was studied. Caesium iodide (CsI) was used as precursor material for iodine species. Also, effects of molybdenum and boron on transport of iodine were investigated. The experimental work showed that when CsI alone was used as a precursor, as much as 20% of the released iodine was in gaseous form and the rest as aerosol particles. Aerosol particles were most likely CsI. When the amount of hydrogen in the carrier gas was increased, the fraction of gaseous iodine decreased. When Boron was added to the precursor, a glassy caesium borate surface was formed on the crucible. Boron trapped most of the caesium and also a fraction of iodine, causing almost all released iodine to be in gaseous form. When Mo was introduced in the precursor, most of the iodine was again released in gaseous form. Oxidised Mo reacted with caesium releasing iodine from CsI. The effect of Mo on iodine transport depended much on H 2 concentration and was observed to be substantially greater on stainless steel surface. When stainless steel crucible was used, Mo was found in small amounts from aerosol particles, indicating that it was probably released as caesium molybdate or as molybdenum oxide

AB - The objective of this work was to examine the chemical reactions taking place on primary circuit surfaces and their effect on fission product transport in a severe nuclear reactor accident. Especially transport of gaseous and aerosol phase iodine was studied. Caesium iodide (CsI) was used as precursor material for iodine species. Also, effects of molybdenum and boron on transport of iodine were investigated. The experimental work showed that when CsI alone was used as a precursor, as much as 20% of the released iodine was in gaseous form and the rest as aerosol particles. Aerosol particles were most likely CsI. When the amount of hydrogen in the carrier gas was increased, the fraction of gaseous iodine decreased. When Boron was added to the precursor, a glassy caesium borate surface was formed on the crucible. Boron trapped most of the caesium and also a fraction of iodine, causing almost all released iodine to be in gaseous form. When Mo was introduced in the precursor, most of the iodine was again released in gaseous form. Oxidised Mo reacted with caesium releasing iodine from CsI. The effect of Mo on iodine transport depended much on H 2 concentration and was observed to be substantially greater on stainless steel surface. When stainless steel crucible was used, Mo was found in small amounts from aerosol particles, indicating that it was probably released as caesium molybdate or as molybdenum oxide

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