Design of an in-situ measurement system for ortho and para liquid hydrogen fractions at ESS

Tatsumoto, H.; Sina, H.; Lyngh, D.; Kobayashi, H.; Hartl, M.; Lee, Y.; Beßler, Y.; Hasegawa, T.; Sakamoto, Y.

doi:10.1088/1757-899X/1240/1/012117

Journal Article

FZJ-2023-01673

Design of an in-situ measurement system for ortho and para liquid hydrogen fractions at ESS

Tatsumoto, H. (Corresponding author) ; Lyngh, D. ; Lee, Y. ; Hartl, M. ; Sina, H. ; Beßler, Y.FZJ* ; Kobayashi, H. ; Sakamoto, Y. ; Hasegawa, T.

2022
Institute of Physics London [u.a.]

IOP conference series / Materials science and engineering 1240(1), 012117 - (2022) [10.1088/1757-899X/1240/1/012117]

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Please use a persistent id in citations: doi:10.1088/1757-899X/1240/1/012117 doi:10.34734/FZJ-2023-01673

Abstract: The Cryogenic Moderator System (CMS) is equipped with a catalyst to convert hydrogen from the ortho state to the para state, to keep desirably high parahydrogen fractions in the cold moderators, which is required to deliver a high brightness cold neutron beams to the scientific instruments using neutron scattering. An in-situ measurement system for the ortho and para fractions of liquid hydrogen (OPMS) where a Raman spectroscopy will be used is being developed. The required measurement precision is 0.1% to detect an undesirable shift towards a high orthohydrogen fraction caused by neutron scattering driven para-to-ortho back conversion. The dedicated OPMS sampling line has been designed and is placed in a bypass line from and to the CMS to minimize the hydrogen inventory and to make it physically isolated from the CMS if a sapphire window failure happens. Accident analysis for a hydrogen leak due to the sapphire window failure was carried out using an inhouse-developed simulation code, and the required safety relief size has been determined.

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