Speaker
Keisuke Mukai
(IAM-KWT)
Description
In a helium cooled pebble bed (HCPB) DEMO reactor, ceramic breeder pebbles are packed in EUROFER structural steel blanket and generate tritium as a consequence of the reactions between lithium and neutrons. As breeder pebbles and EUROFER are contacted at a high temperature for a long period during the operation, corrosive attack to EUROFER could occur even with the low activities of ceramic breeder materials. Additionally, traces of metals diffused from EUROFER into breeder pebbles could also have critical influence on activation property, resulting in a longer storage period for breeder recycling possibly. This study aims to investigate the compatibility between breeder material (Li4SiO4 with added Li2TiO3) and EUROFER steel under the blanket atmosphere by investigating corrosion layer near the surfaces.
In an atmosphere controllable tube furnace, alumina crucibles where a breeder pellet made from breeder pebbles is sandwiched by two EUROFER plates by using force from an Inconel spring, were heated under He with 0.1% H2 atmosphere for up to 1 month at both elevated temperatures and those expected within the blanket.
The results of surface XRD showed that the surfaces of EUROFER plates were partially oxidized, even in the reducing condition, and lithiated due to Li diffusion from the breeder pellet. On the other hand, diffusion of metals from EUROFER pellet was observed on the surface of breeder pellets. Effective diffusion coefficients estimated by measuring the thickness of corrosion layer after several heating periods will be also presented in the poster presentation in order to estimate possible diffusion length of the corrosion layer after the use under the blanket condition.
Co-authors
Keisuke Mukai
(IAM-KWT, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Build 575 76344 Eggenstein-Leopoldshafen, Germany)
Maria Gonzalez
(Materials for Fusion Group, CIEMAT, Avda. Complutense, 40. 28040 Madrid, Spain)
Regina Knitter
(IAM-KWT, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Build 575 76344 Eggenstein-Leopoldshafen, Germany)
Teresa Hernandez
(Materials for Fusion Group, CIEMAT, Avda. Complutense, 40. 28040 Madrid, Spain)
