ePubs

The open archive for STFC research publications

Full Record Details

DOI 10.5286/stfctr.2024001
Persistent URL http://purl.org/net/epubs/work/56532016
Record Status Checked
Record Id 56532016
Title Monitoring the neutronic stability of the liquid methane moderator on ISIS Target Station 1
Contributors
Abstract The stability of the output from the liquid methane moderator on ISIS Target Station 1 is investigated through analysing close to 3 million µAmps of historical neutron data collected on the PEARL diffractometer over the period September 2015 to June 2021. The fundamentals of neutron moderation are introduced, and the requirements for moderator output stability for the diffraction instruments are discussed. It is found that while the thermometry of the moderator may indicate stability, the neutronic output from the moderator can indicate otherwise, if over-exposed to radiation with time. Analysis of the shift in peak-flux from the moderator over long durations suggests an upper critical limit for accumulative neutron irradiation between 250,000 and 300,000 Amps, prior to degradation beyond an acceptable tolerance. The rate of change of degradation shows potential for continuous monitoring of the moderator output, to better inform decisions on operation and replacement of the moderator. Implications for understanding the new methane moderator assembly, post the major refurbishment of TS1, are discussed.
Organisation ISIS , STFC
Keywords
Funding Information
Related Research Object(s):
Licence Information: Creative Commons Attribution 4.0 International (CC BY 4.0)
Language English (EN)
Type Details URI(s) Local file(s) Year
Report STFC Technical Reports STFC-TR-2024-001. STFC, 2024. STFC-TR-2024-001.pdf 2024