SPECIAL REPORT | ACCIDENT TOLERANT FUEL
in 2021 and is ongoing. It includes a set of experiments with some participants providing samples to several laboratories. The experiments then provide data on a new set of ATFs. The results will be available in 2024. This CRP aims to address factors affecting the design,
fabrication and in-pile behaviour of currently operating and innovative nuclear fuels and materials for power reactors,
and to increase technology readiness. Objectives include: ● To perform experimental tests including single rod and bundle tests on ATFs’ performance under normal, Design Basis (DB) and Design Extension (DE) conditions
● To benchmark fuel codes against new test data either obtained during the CRP or from existing data relevant to advanced fuel and cladding concepts from member states’ experimental programmes
● To develop LOCA evaluation methodology for ATF performance with a view to NPP applications
● To look at part of the methodology for using ATF fuel in NPPs and to develop an open source library on the subject of ATF
ATF development progress Dr Nicolas Waeckel a former employee of Electricité de France (EDF) who worked for many years on ATF development told NEI: “We started to work on ATF together with US DOE right after Fukushima, participating in expert groups in IAEA and OECD.” He added: “I was in charge of developing a new safety standard to qualify this new type of fuel. When you develop a new type of fuel you cannot apply current standards. You have to develop new criteria, a new way of validating the material… and maybe even changing the way of thinking about safety for a type of fuel which can be very different from current fuel.” Since 2012, the US Department of Energy (DOE) has
supported the development of ATF concepts through its Enhanced Accident Tolerant Fuel (EATF) programme. DOE is currently funding research by France’s Framatome as well as GE Hitachi and Westinghouse. Russia is also currently testing its TVS-2M ATF at unit 2 of the Rostov nuclear plant. Waeckel pointed out that the DOE had received funding
from Congress to develop safer fuel “so all the fuel manufacturers and the researchers worked quite hard on development”. As a result, even before Fukushima, many laboratories and manufacturers “had on their shelves in the closet some exotic fuel under development, but on standby,” he said. “However, there was no demand, no real need to put this fuel in a reactor because the current fuel was behaving quite well.” He added: “People who developed the nuclear industry 15 years ago were pretty good, and they learned a lot from
their mistakes and some bad experiences so that now we have achieved very good optimisation.” That, argues Waeckel, is why the fuel concept did not change. “And now, all of a sudden, because of Fukushima, just because DOE had the great idea of saving the world, we are considering change. I think we have to be a bit more humble.” He said the driver to develop ATF used to be enhanced
performance and behaviour in accidents, “but we realised that this is not really achievable in the short term”. So now the focus is on other things – cladding, fuel cycle optimisation – a longer cycle and higher burn up. “This may be of some interest to the operators… improving plant economics – that is the motor,” said Waeckel. Among the multiple variants of ATF proposed by the
various fuel suppliers (see Figure 1), there are two main categories of fuel, with respect to their technology readiness level, which relates to the time and effort needed
to develop, qualify, and license the concepts. These are: ● Short-term evolutionary concepts, for example coated Zr-based claddings; stainless steel cladding (eg FeCrAl); high density fuel (eg U3 Cr doped)
Si2 ), and doped fuel pellets (eg
● Longer-term revolutionary concepts, such as refractory claddings (eg lined Mo), silicon carbide (SiC) claddings; microcells fuel; micro-encapsulated fuel pellet concepts; uranium nitride fuel
Key requirements for advanced fuels relate to in-reactor fuel performance, cladding performance, and compatibility with all system constraints. Waeckel stressed that developing a new type of fuel is
a long-term objective in terms of its qualification. “Putting new fuel in a reactor is not like putting a new app on your telephone. If the app doesn’t work you just dump it and the phone is still safe. But if you put the wrong fuel in a reactor it could be a nightmare for everyone. So, we have to be very prudent, very careful, think about everything that could happen. No operator in the world wants to experience bad surprises.” However, this caution is not necessarily a negative thing.
Right: ATFs mostly involve new cladding and fuel pellet designs that increase performance and accident response times
“For me, all this is very positive because it is motivating all the labs, all the researchers, and especially the young generation,” he said. “They see a vision for the future in developing this new type of fuel.” Some projects are very exotic and totally different from standard fuel while others are very similar - just fuel with a novel coating. Some of these evolutionary fuels are already under irradiation as part of the testing and qualification process. However, Waeckel cautioned the ultimate progress for these evolutionary fuels is limited. “What we are talking about is grace time – we are going to gain a couple of minutes. It is not a game changer. It is a small change and offers some benefit. Is it real accident tolerant fuel? Not really, but it is an improvement,” he said. Concluding, Waeckel said: “My main message is that development is always positive for the nuclear community because we are making progress in all areas – in research, in investigation techniques, in measurement techniques, in modelling, and all these improvements are beneficial for the nuclear industry as a whole,” he said, observing: “So even if the product itself is not going to be a magic answer or a magic solution, it is a platform for the young generation to think about safety, modelling, advanced modelling, advanced investigation.” ■
38 | January 2024 |
www.neimagazine.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45
