Installing a new component in a nuclear reactor could be compared to working in outer space repairing or replacing a part on the International Space Station.
The environment is unique, working conditions are difficult and awkward and all the extensive preparation cannot prepare you for all the unexpected. Like protocols in space, safety guides every action in the reactor environment.
The installation of a Cold Neutron Source (CNS), a component that reduces the energy and speed of the neutrons from a research reactor for use in scientific instruments, was successfully completed in September 2024.
The OPAL Reactor Manager said that since OPAL began operations, the successful installation of the CNS is the most significant achievement the group has made as team. It is a technical milestone with scientific, economic, and national significance. It confirms that OPAL is one of the best and most advanced reactors in the world and will continue to bring benefits in the peaceful uses of nuclear science and technology to Australia.
The new and improved cold neutron source offers ANSTO greater levels of scientific capability. Cold neutrons allow scientists to investigate the unique properties of larger molecules such as proteins and polymers.
Replacement of the cold neutron source is a major milestone for ANSTO, demonstrating our expertise in engineering design and major maintenance activities.
Chronology
.Planning and design activities commenced in 2015, working towards the 2024 shutdown timeline. The Cold Neutron Source was replaced over a shutdown period which extended from March to September 2024.
Andrew Eltobaji has been the project manager of the CNS upgrade since its conception, working closely with 20 core team members but drawing on the expertise of 30 to 40 more contributors from diverse disciplines across ANSTO.
The specialist Engineering, Maintenance and Operations team was made up of nuclear engineers, reactor managers and supervisors, technicians, welders, and radiation safety experts.
In the planning stages, the team reached out to several other international research reactors to identify what other facilities had undertaken similar major shutdown activities. This investigation quickly identified that the planned Cold Neutron Source replacement was a unique activity not undertaken by other research reactor facilities. This resulted in the majority of design development work and maintenance activities being undertaken by ANSTO engineering and maintenance experts.
To prepare technicians for the operation, a full-scale mock-up of the CNS and reactor environment was constructed to assist in the planning and training of supervisors and technicians. This allowed team members to undertake comprehensive training in conditions which mimicked the real environment.
The mock-up enabled the team to develop the process for replacing the CNS and develop the specialist tooling required.
The training mock-up facility was used to rehearse the CNS installation activities in a simulated environment and allowed them to complete tasks safely. A team of supervisors were trained using the mock-up to prepare them for their training of technicians.
During the engineering design process, every component in the installation was modelled in a 3D computer simulation. This was used to fabricate prototype components to initially build the full-scale mock-up then used to optimise the design of the CNS itself.
Prior to the commencement of the installation sequence, the level of water in the reactor pool was reduced and a number of reactor components, including pipework, had to be removed to allow access to the old CNS.
The CNS together with associated pipework were lifted out of the reactor and placed in a special shielded device with precision. This was done remotely using cameras and no direct interaction with technicians.
The replacement CNS structure was eight metres tall and had to be installed precisely vertical. Again, this was conducted remotely using cameras and required positioning accuracy to within a few millimetres. Once in place, the various pipes suppling either helium, deuterium or vacuum services were connected and tested.
The CNS Cryogenic refrigeration system cools helium down to -253°C, which in turn liquifies deuterium, which has a cooling effect on the neutrons.
Many measures were in place to ensure the safety of maintenance technicians.
Read more on ANSTO website
