Restart of the ILL reactor

As planned, the ILL reactor restarted on 27 February thanks to the completion of key maintenance and major upgrade work during 16 months. Modifications made to allow the reactor to restart after such a long shutdown prevent it from operating at nominal power to deliver the science programme. The reactor is therefore stopping with a view to resuming normal operation by the end of March.

This 16-month shutdown has seen the achievement of an extremely intense work programme - one of the richest and most complex that the ILL has ever seen, both for the reactor and for the experimental areas. It is also a great success: the entire technical programme has been successfully completed!

This great success is once again thanks to staff at the ILL.

The reactor

We had to meet safety requirements issued by the authorities to ensure continued reactor operation for the next 10 years. This long shutdown was necessary for long-term upgrade work. Among many others:

  • The periodic replacement of the H1-H2 beam tube, which gave its name to this shutdown, and the reactor fuel chimney. This was the 4th replacement of the H1-H2 beam tube; the last one dates back to 2005. The preparation took several years, and the project monopolised a whole team, from the manufacturing through to the installation. (See timelapse)
  • The replacement of the Fresh Air Intake and the testing of the new ventilation circuits, both of which are part of the commitments from the latest safety review.
  • At the end of the beam tube, the "Carter Pink" housing has also been replaced and the H1-H2 pool has been renovated.
  • In the reactor block, a new chimney for the fuel has been installed
  • The members of the Fluids group were actively involved in many projects. Among other things, they successfully oversaw the filling of the reactor block with light water so that the work could be carried out in the best possible conditions.
  • The H13 shutter has been repaired, which will allow the IN20 instrument to function.
  • The fresh air intake was one of the last post-Fukushima requirements.  It had to be made resistant to the reference "SND" earthquake which the reactor's hardened safety core of components are designed to withstand. Involving an enormous amount of work, this project lasted some 14 months.
  • Other seismic reinforcement work was carried out on the gaseous effluents circuit, the vertical cold source condenser, as well as the protective housing of the sensors of the emergency core reflood circuit (CRU).
  • Fire protection is currently one of the ASN's priorities. The project has progressed well with the installation of sprinkler systems in the casemates on Level B and A, a new dry riser and protection of various itemls of equipment which are important for nuclear safety, in particular the electrical and mechanical penetrations.
  • The ASN also asked the ILL to test the CRU, the emergency core reflood system, which allows light water to be injected into the reactor core in the event of an accident. This test cannot be carried out while the reactor is operating, so we had to take advantage of this long shutdown.
    See timelapse 
  • Many improvements have been made to the reactor's instrumentation and control systems, for example to the IABP (automatic insertion of control rod) system and certain emergency shutdown systems, not to mention the heat exchanger isolation system. These projects monopolised the entire Electricity/Electronics Service within the Reactor Division, as well as the colleagues temporarily transferred to this service.
  • Good progress has been made with the preliminary clean-up of the detritiation facility.
  • Finally, to prepare for the next shutdown, anchor points have been fixed to the reactor dome to enable the polar crane on Level D crane to be modified – an operation that will take place during the next shutdown.

The guide halls and the instruments

In the guide halls we can also see great achievements. The scientific users will be able to take full advantage of greatly improved performance, for instance:

  • Many of the ILL 7 instruments will benefit from increased flux, thanks to the ten-year replacement of guide sections (deteriorated by irradiation). 
  • The new H24 double guide is much more efficient, and its new D10+, XtremeD, IN13+ and CT2 instruments have started the « hot commissioning » phase with neutrons.
  • Two new imaging tomographs, NEXT and MOTO, are in place and NEXT is expected to deliver its first images early in this cycle.
  • D16 has a new detector
  • Panther has a new 'background noise' chopper system
  • The improved secondary spectro on IN20 will be commissioned after the successful intervention on the H13 plug
  • Fresnel coils on WASP have returned to mint condition

Let’s not forget the preparation of the experimental areas of the future Ricochet instrument and of the future position of FIPPS, and the primary guide of the future triple guide H15 project, with instrument commissioning scheduled in 2024.

This is a very impressive overall result, which will extend the limits of science carried out at the ILL for the next 10 years.