Final design, fluid dynamic and structural mechanical analysis of a liquid hydrogen Moderator for the European Spallation Source

The ESS Design: Accelerator 6The ESS Design: Target 66The ESS Design: Controls 93The ESS Design: Conventional Facilities 109Physica ScriptaPhys. Scr. 93 (2018) 014001 (121pp) https://doi.org/10. 1088/1402-4896/aa9bff This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercialNoDerivs 3.0 licence. Content from this work may be used under the terms of the Creative Commons Attribution-NonCommercialNoDerivs 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Neutron scattering is a well-developed and extensively used means to get access to fundamental properties of biological matter as well as of physical materials. Until the end of the twentieth century that was mainly practiced with-and limited in performance by-the continuous flux of neutrons from ageing nuclear reactors (e.g. the Institut Laue-Langevin (ILL), the flagship of neutron research in Europe and in the world) [1]). Looking forward to the following two decades, an OECD report published in 1998 diagnosed the foreseeable decrease of the number of operational facilities [2] and the need to progress in performance. Considering the high scientific interest and the increasing importance of the subject for society at large, the report concluded by strongly recommending the construction of next generation neutron sources in America, Europe and Asia. Pulsed spallation neutron sources (SNS) using a proton beam power exceeding 1 MW were specifically mentioned as the most interesting high performance facilities in the future landscape of neutron laboratories.The USA was the first country to follow this advice by building the SNS in the Oak Ridge National Laboratory (ORNL) which started in 2006 [3, 4]. Japan followed in 2009 with the Japan Proton Accelerator Research Centre (J-PARC) in Tokai [5,6]. In Europe, the subject was part of a concerted effort to further develop the European world-leading largescale research infrastructures suite. In 2003, the European Strategy Forum for Research Infrastructures (ESFRI), set up by the Research Ministries of the Member States and associated countries, concluded that a 5 MW long-pulse, single target station layout with nominally 22 'public' instruments was the optimum technical reference design for an European Spallation Source (ESS) that would meet the needs of the European science community in the second quarter of the century [7].Six years later, in 2009, it materialised in a real project with the adoption of the site of Lund (Sweden). A preconstruction phase followed until the end of 2013 during which the design was finalised [8]. Construction then started with the first neutron beams planned to be available in 2019, and the ESS facility to be operational at full performance in 2025.2 Description 2.1 Principle and specifics. The high level parameters of ESS are shown in table 1. As at SNS and J-PARC, neutrons at ESS are produced by spallation, when the 2 GeV protons hit the meta...

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“…Page 80: Redundant reference in section 3.3.3. The [137,141] in the first paragraph should be corrected to [137], removing [137,141].…”

Section: Institutionmentioning

confidence: 99%

“…Figure 83 shows the fluid dynamic behaviour of the cold collimator system, over five beam pulses [137].…”

Section: Institutionmentioning

confidence: 99%

The European Spallation Source Design

et al. 2017

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“…( 1). Lehmann et al [8] reported that a transient heat flux for loss of insulation vacuum for LHe cryostat and LHe containers with MLI was 6 2 . In this analysis, the heat flux of 6 kW/m 2 is always applied to the process line, regardless of the vacuum pressure.…”

Section: 𝑚̇= 𝐶mentioning

confidence: 99%

“…In the beginning, the ESS will install two hydrogen moderators above the target wheel and the current plan is to replace them with four (two above and two below, respectively) in the future. Two flat butterfly shaped hydrogen moderator vessels have been designed and optimized to achieve a maximum neutron brightness under the condition of parahydrogen fraction higher than 99.5% [2]. A cryogenic moderator system (CMS) has been designed to continuously supply subcooled liquid hydrogen with a temperature of 17 K and a parahydrogen fraction of more than 99.5% to the moderators and to maintain an average temperature rise at the moderators within 3 K [3].…”

Section: Introductionmentioning

confidence: 99%

Failure analysis of leaks due to cracks in hydrogen transfer lines of ESS cryogenic moderator

Tatsumoto

Lyngh

Arnold

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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The ESS cryogenic Moderator System (CMS) has been designed to slow down the high-energy neutrons by means of two hydrogen moderators (to be increased to four in the future) by using forced flow of subcooled liquid hydrogen with a temperature of 17 K at 1.0 MPa. A liquid hydrogen leak is considered the most severe failure for the CMS. A leak scenario from the transfer line to its vacuum envelope through a crack have been analyzed and the expected results will be presented in this paper. An analysis code has been developed and calculated the pressure and temperature changes in the CMS process line and its vacuum envelope. The effect of the crack sizes is clarified. The consequential temperature changes along the vacuum envelope as well as the pressure drops were calculated. The required size of the safety relief device in the hydrogen transfer line and its vacuum envelope have thereby been determined and implemented.

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“…The cold moderators form a flat butterfly shape, which are optimized to achieve a high cold neutron brightness. The neutronic performance of the cold moderators degrades rapidly with the decreasing parahydrogen fraction below 99.5% [4]. The neutron collisions in the cold moderators increases the orthohydrogen fraction [5] if it is not compensated by the ortho-to parahydrogen conversion driven by the catalyst system.…”

Section: Introductionmentioning

confidence: 99%

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

Tatsumoto

Lyngh²,

Lee³

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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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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Final design, fluid dynamic and structural mechanical analysis of a liquid hydrogen Moderator for the European Spallation Source

Cited by 11 publications

References 1 publication

The European Spallation Source Design

The European Spallation Source Design

Failure analysis of leaks due to cracks in hydrogen transfer lines of ESS cryogenic moderator

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

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