High demands on ESS - testing systems with a nuclear mindset
The technical systems for the European Spallation Source (ESS) research facility in Lund are currently undergoing tests to meet the strict requirements. FVB’s Robert Wahlgren is responsible for four of the systems.
ESS has been under construction since 2014 and is expected to be commissioned in 2027. Between two and three thousand scientists and researchers are expected at the facility annually, where they will study the structure and behaviour of a range of materials at the atomic level. Examples include proteins for medicines and materials used in batteries. One of the world’s most powerful neutron sources will be used for this purpose. One of the big advantages of using neutrons is that they can penetrate deep into a material without damaging it.
“In simple terms, the facility will act as a giant microscope when it’s completed. The scientists will be able to analyse different materials using neutrons at their research stations and see what they look like at an atomic and molecular level,” explains Jaime Arriagada, responsible for commissioning the target station, where the actual neutrons will be produced.
Neutron production is done by spallation, which involves accelerating protons to extremely high energy levels and bombarding a wheel made of wolfram, a process that releases neutrons. The process generates a lot of heat, and the wolfram block is cooled by helium. Cooling is essential, otherwise the temperature would be so high that the material would be damaged. Residual heat will be used for Kraftringen’s district heating grid, and ESS is expected to account for around 25% of the city of Lund's entire heating needs in the future. Some of the residual heat will be used in Kraftringen’s new low-temperature system for district heating, which can utilise lower temperatures than normal.
ESS will use a lot of energy, expected to be up to 270 GWh per annum, equivalent to the consumption of a small town. The biggest consumers are the particle accelerator, which propels protons to very high speeds, and the spallation process, which releases the neutrons. The cooling system will also require a lot of electricity to deal with the heat generated.
“Scientists from all over the world will be coming to perform their research for periods of 1–2 days or longer, which makes it extremely important that all technical systems work, otherwise it can take over two years before they get another chance, as the research slots are in extremely high demand,” says Arriagada, and adds:
“Availability is therefore very important, which is why we are now testing all the systems. We also intend to build a strong maintenance team able to look after the facility.”
Testing of the technical systems for electricity, heat, helium etc., is currently in progress at the target station. It’s incredibly important the everything works all the time, as even short disruptions can affect an experiment and damage sensitive instrumentation.
The tests are being conducted by a number of specialists from various consultancy firms. Robert Wahlgren at FVB is responsible for testing four of the systems and is the Test Engineer on another two. He has over 25 years of experience working with nuclear power and has also worked at a district heating company before joining FVB. This is experience he can really draw on in his role at ESS.
“ESS simply has to be stable and safe. We want to achieve the same mindset found at nuclear power stations with regard to safety and redundancy of various systems,” he explains.
The implementation of safety measures similar to those found in nuclear power stations is due to the radioactive radiation generated in the production of neutrons. The target station is a building similar to a bunker, to ensure that radiation is safely contained.
One of the major challenges for the technical systems is that many components were installed several years ago, but could not be tested at the time, as the systems are so interdependent. It’s only now that the whole system is ready. There have also been delays caused by the COVID-19 pandemic and by problems with manufacturing and design.
“Now that testing is starting, planning the whole schedule is very important due to the high level of system interdependency. What's more, some of the specialists can only be here for limited periods to run the tests,” says Wahlgren.
The tests currently being run do not involve neutron production. That will not start until the autumn.
“Even though we’re not actually producing neutrons and there is therefore no radioactivity, we still need to check that all the machinery and electronics work,” says Arriagada.
He emphasises the importance of having experienced personnel to run the tests, as this is a highly complex facility, which is in fact the only one of its kind.
“Our specialists and experts are extremely valuable. They are also objective and good at identifying any shortcomings we have. These are things I appreciate, as this is our opportunity to deal with any faults and weaknesses. Having a team drawn from a range of disciplines with experience from projects all over the world is a massive advantage,” concludes Arriagada.
More information:
Robert Wahlgren, 040-40 98 95, FVB Sverige AB.
Jaime Arriagada, 046-888 30 00, ESS.
