Case history – European Spallation Source
Enabling cutting edge neutron research through advanced cooling solutions


The European Spallation Source is a multi-disciplinary research facility outside Lund, Sweden, with a vision to build and operate the most powerful pulsed neutron source in the world. Neutron research enables the detailed study of matter, with the potential to unlock breakthroughs in energy science, environmental technology, healthcare and fundamental physics.

At ESS, the process of creating neutrons begins with a linear proton accelerator. Protons are guided into the linear accelerator, which focuses a proton beam towards the neutron source: a custom-built tungsten target. This process, called ‘spallation’, causes a collision between protons and the nuclei of the tungsten target which triggers high energy neutrons to be scattered. The scattered neutrons are then examined at a series of experimental stations to investigate the nature of materials.

Cryogenic cooling systems
Cryogenic cooling system


The linear proton accelerator which begins the spallation process generates excess heat in the production of ion source protons. This requires careful management within tight parameters to protect the valuable electrical instrumentation.

ESS required a bespoke cooling system to:

  • Maintain a nominal temperature set point within the range 15-25°C with a strict tolerance of ±1 °C
  • Manage the flow rate, conductivity and outlet pressure of the coolant within specified parameters
  • Function as a standalone system and also integrate with the ESS master control system
  • Operate ‘out of the box’

There was no pre-existing cooling solution to meet the demanding requirements of the new technology used at ESS, so a competitive tender invitation was issued. GRE was awarded the contract on the merits of its proposal which included detailed specifications for a bespoke technical construction, a high level of quality control, and many examples of how the GRE team steps beyond the role of subcontractor, to become an integrated project partner.


With extensive experience in creating highly specialised ultra-pure water systems, GRE’s engineers were fully prepared to meet the client’s meticulous requirements. Our team designed and manufactured a completely custom-made ultra-pure water cooling system that maintains a nominal set point of 20°C with a tolerance of ±0.5 °C, which exceeds the client’s specification.

Our open skid frame design included everything that is required to deliver ultra-pure water to the circuit and maintain:

  • fluid flow – the user has the option to control this via the HMI by either:
    • volumetric flow rate (typically at 300Lpm); or
    • pressure (typically 7.0 barg)
  • conductivity at <0.2 µS/cm
  • oxygen content <50 parts per billion

The system was engineered and manufactured at our Devon facility, including the development of a customised controls system, managed by a colour touchscreen HMI (human machine interface). As a standalone system, the unit features fully automated run and standby pumps to ensure performance continuity during any faults, which are reported via the control system, and scheduled changeover to even out mechanical wear on the pumps. Our software also provides seamless integration with ESS’ parent control system.

Temperature Control
Throughout the project, GRE maintained continuous communication with the team at ESS. At the outset of the project, engineers from GRE travelled to Lund to meet key ESS personnel and establish a close working relationship.

This strong partnership, coupled with GRE’s solution-focused approach, was key to the success of this project as ESS’ rigorous specification continued to evolve throughout the project. During development, GRE created design drawings in line with ESS’ standard protocol, adapted the design to incorporate components from ESS’ preferred suppliers, and accommodated several client requests for changes to the skid and control system.

At the testing stage, three members of the ESS team travelled from Sweden to attend a full day of factory acceptance testing (FAT) at GRE. During extensive testing of all functions of the equipment and controls, GRE implemented further design changes to support system operation by ESS engineers. Following delivery to ESS at Lund, GRE team members attended to oversee site acceptance testing (SAT), during which a further control feature was introduced at the request of the ESS engineers, prior to successful client sign-off.


GRE’s ability to meet ESS’ stringent requirements both for system configuration and delivery method, was essential to the successful completion of the ultra-pure water skid frame. The unit, installed and brought into commission by GRE engineers, enables mission-critical operation of the linear accelerator, without which the neutron source cannot function.

Throughout the project, GRE’s responsiveness to the evolving specification ensured that the client ultimately received a unit that operates perfectly in line with operational need.

GRE is currently developing a second, larger ultra-pure water unit to be installed at ESS, which will be delivered in early 2019.

Client Comment

“GRE presented a very impressive tender submission and were the clear choice for us based on their ability to get under the skin of ESS and work with us as a true partner. From start to finish, GRE’s engineers have been diligent and responsive, going the extra mile to ensure that the system we have is not just what we asked for; it’s what we need. We have been highly impressed with GRE’s attention to detail and quality which is evident in every aspect of the system, right down to the intuitive touchscreen controls. Inviting us on site to join the FAT process gave us great confidence that we would be pleased with the results and is a great example of GRE’s personal approach. We look forward to continuing our relationship with GRE for many years.” 

Anton Lundmark, Project Engineer, ESS