Verlag des Forschungszentrums Jülich
JUEL-3967
This report discusses the technical feasibility of solid methane moderators.
Methods to tailor the neutron output by adding absorption materials ( decouplers
or poisons ) are not considered here, neither are composite moderators.
ßased on the given target-moderator-reflector assembly of the ESS project a
concept for the ESS cold methane moderators has been developed and is being
examined at the Forschungszentrum Jülich.
Barnert-Wiemer, Heidrun
Conceptual design of a cold methane moderator system for the European Spallation Source (ESS)
56 S., 2002
As part of the work for the target station of the planned European Spallation
Source (ESS) the Central Department of Technology at the Forschungszentrum
Jülich GmbH is also concerned with the moderators, particular attention being
given to the development of cold methane moderators.
According to this moderator concept the moderator is a fixed bed of small spheres,
which makes moderator container filling homogeneous and reproducible. Since
spheres form a defined packed bed, cooling of the moderator bed by H2 is reliable.
The process of filling the moderator container and of removing the pellets is
batchwise to ensure complete removal of the pellets, so that no spent methane
pellets accumulate in the system. For removal of the moderator spheres the fixed
bed in the moderator container is fiuidized with subsequent hydraulic transport of
the pellets.
The spent methane pellets are separated from the transport fluid and the methane
is released over the stack or purified and reused. Depending on the kind and
amount of the radioactive isotopes present these may have to be separated and
stored.
Neuerscheinungen
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Heike Lexis
+49 2461 61-5367
zb-publikation@fz-juelich.de