Page 84 - ILL Annual Report 2019

TECHNICAL AND COMPUTING DEVELOPMENTS
H16 guide renewal: a successful project to boost performance levels on IN5
Thanks to the ILL’s efficient project management system, the project
to overhaul the guide H16, which delivers neutrons to IN5, has been completed ahead of time and under budget, and has successfully achieved the targeted average gain of a factor of three on the flux.
Figure 1
H16 casemate and its guide during the replacement work.
AUTHORS
J. Beaucour, J. Bonnevaux, P. Cogo, E. Courraud, L. Didier, C. Dewhurst, R. Gandelli, Y. Gibert, B. Giroud, J. Halbwachs, B. Jary, P. Lachaume, C. Monon, M. Kreuz, J. Ollivier and F. Rencurel (ILL)
REFERENCES
[1] Project team: J. Beaucour, J. Bonnevaux, P. Cogo, E. Courraud, L. Didier, Ch. Dewhurst, R. Gandelli, Y. Gibert, B. Giroud, J. Halbwachs, B. Jary, P. Lachaume, C. Monon, M. Kreuz, J. Ollivier, F. Rencurel
[2] ‘The Endurance project IN5+: enhancing the potential of the IN5 spectrometer’, ILL Annual Report (2019) p. 78
IN5 is installed in the guide hall ILL7 at the end of the 45-metre long, curved cold guide H16. The guide’s main section (21 m long) was an obsolete M = 1 borkron guide installed in 1972. It was decided, in September 2017, to launch the execution phase of the ‘H16 guide renewal’ project ahead of the upcoming replacement of the H16 in-pile section, as part of the H1–H2 renewal project.
A dedicated project team was appointed, headed by B. Giroud as Technical Project Leader and with scientific support from J. Ollivier as Initiator Project Leader, in compliance with the ILL’s project management guidelines [1]. The design phase started in parallel with work to optimise neutron transport, with the aim of achieving a flux gain of a factor of three. The guide was optimised [2] in order to obtain the highest flux at the maximum divergence measurable by the geometry of IN5’s detection system and for a reduced sample size (30 x 15 mm2). Only 75 %
of the upstream guide section (200 mm x 30 mm) was necessary for
this maximum useable flux on IN5, leaving 25 % of the guide section available for a possible upgrade.
The design phase was carried out between May and October 2017. The decision to issue the call for tenders as early as June proved to
be good forward planning, since it allowed us to order the guide in December and receive all the parts and most of the guide components by July 2018. This in turn made it possible to prepare installation of
the guide during the winter shutdown. Unfortunately, on certain guide components the supermirror coating proved to be unstable, requiring the manufacturer to replace the most deteriorated parts between July and November 2018 in order to be ready for the installation phase. The manufacturer has undertaken to replace the final deteriorated parts in time for the long H1–H2 shutdown.
The guide installation and alignment phase started in early November 2018 during the winter shutdown and was successfully completed within the 10 weeks scheduled, thanks to the very efficient co-operation of all the teams involved. A four-week break in the installation work was necessary, however, to deal with the delamination issue with the manufacturer. Nevertheless, by the end of February 2019 the installation work was completed, ready for the restart of IN5 during the first reactor cycle of 2019.
The overall project lasted 16 months, from the start of the execution phase to commissioning, making it probably one of the fastest guide projects ever carried out at the ILL. On the budgetary side, it is worth noting that the final cost of the project for procurement and studies (820 k€) came in below the allocated budget as estimated at the end of the feasibility phase (900 k€).
During commissioning a background of high-energy neutrons was detected, transmitted, it transpired, by garland reflexion due to the high quality of the guide alignment. This could be corrected without affecting the flux gains by adding a 1 mm borated mask to the external lateral side of the guide. In the end, the anticipated average gain factor of three was achieved, along with an even higher gain for 1.5 Å neutrons not transported by the old M = 1 guide.
ANNUAL REPORT 2019