Revaporization Behavior of Cesium and Iodine Compounds from Their Deposits in the Steam−Boron Atmosphere

Muhammad Rizaal*, Shuhei Miwa, Eriko Suzuki, Junpei Imoto, Masahiko Osaka, Melany Gouello

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)

Abstract

This paper presents our investigation on cesium and iodine revaporization from cesium iodide (CsI) deposits on stainless steel type 304L, which were initiated by boron and/or steam flow. A dedicated basic experimental facility with a thermal gradient tube (TGT) having a temperature range of 1000–400 K was used for simulating the phenomena. In the absence of boron, it was found that the initially deposited CsI at 850 K could be revaporized as CsI vapor/aerosol or reacted with the carrier gas and stainless steel (Cr2O3 layer) to form Cs2CrO4. The latter mechanism consequently released gaseous iodine that was later accumulated downstream. After introducing boron to the steam flow, a severe revaporization occurred. This, in addition to the revaporized CsI vapor/aerosol, was caused by cesium borate (Cs2B4O7 and CsB5O8) formation, which then largely released gaseous iodine that was capable of reaching the TGT outlet (<400 K). In the case of a nuclear severe accident, our study has demonstrated that an increase of gaseous iodine in the colder region of a reactor could occur after late release of boron or a subsequent steam flow after refloods of the reactor, thus posing its inherent risk once leaked to the environment.
Original languageEnglish
Pages (from-to)32695–32708
JournalACS Omega
Volume6
Issue number48
DOIs
Publication statusPublished - 7 Dec 2021
MoE publication typeA1 Journal article-refereed

Funding

This work was done in the framework of collaboration between JAEA and VTT under the support of the Academy of Finland (grant number 294995).

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