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

Autor: Rizaal M; Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Naka-gun, Tokai-mura, Ibaraki 319-1195, Japan., Miwa S; Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Naka-gun, Tokai-mura, Ibaraki 319-1195, Japan., Suzuki E; Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Naka-gun, Tokai-mura, Ibaraki 319-1195, Japan., Imoto J; Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Naka-gun, Tokai-mura, Ibaraki 319-1195, Japan., Osaka M; Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirane, Shirakata, Naka-gun, Tokai-mura, Ibaraki 319-1195, Japan., Gouëllo M; VTT Technical Research Centre of Finland, P.O. Box 1000, Espoo FI-02044 VTT, Finland.
Jazyk: angličtina
Zdroj: ACS omega [ACS Omega] 2021 Nov 22; Vol. 6 (48), pp. 32695-32708. Date of Electronic Publication: 2021 Nov 22 (Print Publication: 2021).
DOI: 10.1021/acsomega.1c04441
Abstrakt: 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 (Cr 2 O 3 layer) to form Cs 2 CrO 4 . 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 (Cs 2 B 4 O 7 and CsB 5 O 8 ) 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.
Competing Interests: The authors declare no competing financial interest.
(© 2021 The Authors. Published by American Chemical Society.)
Databáze: MEDLINE
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