INSTRUMENTATION AND CONTROL | NEUTRON DETECTION
Above: The Reuter-Stokes and Paragon partnership will supply neutron detection systems to NuScale for its SMR
Below: A proportional counter relies on ionisation to produce a signal
V bit of engineering work to custom fit our detectors to that specific technology. They’re potentially each going to need a separate design and qualification effort.” For example, on the large gigawatt-scale reactors all of the Reuter-Stokes detectors are of the fission chamber type. However, for small modular reactors, because of the differing technical parameters like temperature and neutron flux, it is possible to use ionization chambers in some instances as well. Because ionization chambers do not contain uranium they don’t require special nuclear material considerations that affect things like logistics regulations. That potentially is another benefit particularly associated with SMR technologies which are designed to be easily transported to site. Nonetheless, the challenge of new reactor designs new market entrants is picked up by Martinez, who says: “They’ve done a lot of research, but are now in a commercialization phase addressing the challenges and developing the sciences to deliver an SMR facility and all the benefits that brings. We are helping these companies design what they actually need for their particular reactor design from a sensor side with practical experience. We’re already well established and we can help to make the discovery phase and design phase a bit easier. Luckily, that’s one of our sweet spots.”
Phased detector development To ease the design and qualification process, Reuter- Stokes has launched a three phase programme for SMR developers. “We’ve developed this phased process to try to help in terms of risk management and cost management,” says Schreiner. The problem is that SMR developers don’t always have all the answers when considering neutron detection. “We can’t go directly into detailed design without really understanding what the requirements are for these detectors, the technical specifications and the acceptance criteria for example,” Schreiner says. However, he adds: “Since we’ve been in business for so long, we do have a large catalogue. We have thousands of different detector designs that are both fission chamber-based and also ionization chamber types. When a new customer comes in and details the neutron flux, the temperature, and the sensitivity required our physicists can go into this database and find two or three detectors that are close. We can use that as the foundation for a custom product offering. We’re not starting from scratch with detailed engineering, we’re starting from maybe anywhere from the 60 to 80 percent complete phase.” This allows a two to six month front-end engineering
effort to be launched – phase one preliminary design – working with the SMR developer and the SMR fuels engineer and talking directly to detector physicists to explore issues such as the location of the detector, what the environment looks like at that specific location and then which detectors from the catalogue could work for this application. “Once that process is complete now both sides have
a really good understanding of what this technical specification looks like. Then the SMR developer can publish its technical specification and we’ll provide a fixed-term quote on phase two, which is detailed design and building a prototype detector to validate all of the physics models and manufacturing processes,” says Schreiner. Once phase two is complete the process can move
to qualification with the relevant nuclear regulatory authorities. “It’s a very rigorous and methodical qualification process for a nuclear safety-related detector to ensure that the detector has been qualified for the safe operation start up and shut down of a nuclear reactor. It’s a huge investment both in design and time and in dollars to get that qualification. Reuter-Stokes’ experience of going through the qualification process helps when it comes to new designs and new types of sensors,” explains Schreiner. He concludes: “It’s mitigating risk and making sure that we control costs as we progress through the phases so that we’re constantly incorporating the lessons learned as we continue to work on the project with the customer”. The pressure is on all SMR developers to keep costs
down as low as possible and Martinez makes a key observation: “The most important thing in terms of making things cheaper is you got to think about it early in the process. If we can have our detector physicists talking directly to the fuels engineer and they can work out where these detectors go before the SMR design is locked in that allows the widest range of detectors that we can choose from our off the shelf database.” It’s simple steps like this that will ensure the supply
chain can support SMR development in making its ambitions a reality. ■
20 | February 2023 |
www.neimagazine.com
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