The global trajectory of the nuclear power industry has fluctuated dramatically since the first power plant to produce usable electricity through atomic fission, Experimental Breeder Reactor #1 (EBR-1), illuminated four 200-watt light bulbs on December 20, 1951, in the Idaho desert.
This new technology was initially viewed as a game-changer that could “provide abundant electricity in power-starved areas of the world,” in the words of U.S. President Dwight Eisenhower. However, the past few decades have been an up-and-down story for the nuclear industry.
Meanwhile, global threats like war and climate change have forced policymakers to take a hard look at available energy choices. One result? In many circles, nuclear is getting a second look as an important potential contributor to future power-generation capacity. And within the industry, promising advances in reactor design are addressing issues of safety, sustainability, and economic feasibility. International cooperation surrounding these and other new technologies is helping to move the needle forward.
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For ASTM International, nuclear power has always been a relevant topic. The long-standing committees on nuclear technology and applications (E10, formed in 1951) and nuclear fuel cycle (C26, formed in 1969) have helped support the industry for decades by facilitating the development of important consensus standards. And with technologies continuing to change and evolve, their work continues.
Even as we examine the latest developments in nuclear technology and related standards, it’s important to note that, in many parts of the world, nuclear power never really went away. There are currently over 400 operable reactors in some 30 countries. And according to the International Atomic Energy Association (IAEA), nearly 60 more are under construction.
These statistics bolster the position of those who believe nuclear power, harnessed properly, should remain part of the energy equation. However, the fact that this option, opposed in some corners, is gaining new traction may well have as much to do with ripples in the international order as it does with a fundamental shift in public sentiment.
“The current state of the nuclear power industry is improving, to an extent, because of the war in Ukraine and climate change issues,” notes Bertrand Morel, who chairs the subcommittee on fuel and fertile material specifications (C26.02). He points out that nuclear continues to be a strong contributor to the power system in some countries, while others that have not heretofore embraced it are showing new levels of interest.
There are some on the other side of the fence, of course. “The world is having a mixed response on this issue,” says Pat Griffin, chair of the subcommittee on nuclear radiation metrology (E10.05) and a laboratory fellow at Sandia National Laboratories (SNL). “China and India are significantly expanding their nuclear power. Other countries are still closing their nuclear plants.”
To Griffin’s point, IAEA’s Power Reactor Information System (PRIS) database lists China (21 new units), India (8), Turkey (4), and South Korea (3) as the most active countries in terms of new reactor construction as of May 16, 2023. Conversely, several countries top the list of those who have permanently shut down reactors: the United States (41 units), the United Kingdom (36), Germany (33), and Japan (27).
To get a clearer picture of where the nuclear industry may be heading, it’s useful to focus on two distinct areas. The first, reactor technology, speaks to the ongoing quest for safer, more efficient alternatives to current designs. The second, decommissioning, addresses the question of how best to handle the phase-out of legacy nuclear power plants, as well as anticipating decommissioning procedures that may be required decades from now for next-generation reactors that haven’t even been built yet.
Turning first to the topic of reactor design, one of the most promising developments is Generation IV (Gen IV) technology. In 2001, the U.S. Department of Energy (DOE) spearheaded formation of the Generation IV International Forum (GIF), a consortium of countries with significant nuclear capacity and a belief that this form of power remains vital to their interests. They are also committed to shared R&D. Membership has fluctuated somewhat over the years, but major charter members — including Canada, France, Japan, South Korea, the U.K., and the U.S. — continue to participate.
After several years of discussion and examination of nearly 100 concepts, GIF selected six reactor technologies for further development: gas-cooled fast reactors (GFR), lead-cooled fast reactors (LFR), supercritical water-cooled reactors (SCWR), molten salt reactors (MSR), sodium-cooled fast reactors (SFR), and very high-temperature gas reactors (VHTR).
In the words of the World Nuclear Association, these technologies “were selected on the basis of being clean, safe, and cost-effective means of meeting increased energy demands on a sustainable basis, while being resistant to diversion of materials for weapons proliferation and secure from terrorist attacks.” DOE and its national laboratories are currently working with industry partners on the latter three options.
New technologies have caused some to give nuclear power a second look.
Morel provides context, explaining that most currently operational nuclear facilities feature either boiling water reactors (BWR) or pressurized water reactors (PWR) that use solid fuel, water for cooling, and low temperatures. With Gen IV reactors, “You have some which are extremely high temperature, you have some which use liquid fuel, you have some which use sodium for cooling. We are talking really different systems.”
Small Modular Reactors
Another technological evolution that shows promise is advanced small modular reactors (SMRs). These units — whose power output can range from tens of megawatts to hundreds — are not necessarily unique in terms of how the reactor operates, with some relying on light-water cooling or well-established technologies. However, other designs do incorporate Gen IV technology, like gas or molten salt cooling. Physical footprint and economic viability are key differences.
“The nuclear power industry is very much in a state of transition,” says Mike Brisson, chair of the subcommittee on methods of test (C26.05). “It is shifting away from the large, expensive power plants that take decades to design and build, and moving toward smaller plants that can be brought online faster, with lower cost and easier waste management. The modular and smaller-scale designs reduce the amount of on-site installation work required.”
Griffin highlights the financial implications of SMR technology. “The cost of nuclear power was once very attractive,” he explains. “However, cost overruns in the construction of large, new nuclear plants are a negative. The potential offered by SMRs may address this concern. We have several different SMR designs and are waiting to see how they stand up to the U.S. Nuclear Regulatory Commission licensing and regulatory processes.”
Power generation is not the only potential use for SMRs; their smaller size makes them suitable for industrial applications like process heat and desalination as well. They also have the potential to bring electricity to remote locations and challenging topography where a larger nuclear facility is not feasible.
The nuclear fuel cycle committee, of which Brisson is first vice chair, has organized a conference in São Paolo, Brazil, this September (18-21) that will feature workshops on small modular and micro reactors, developments in analytical chemistry methods, and nondestructive analysis. Attendees are expected from the U.S. and Europe.
What are the event’s goals? “Standardization will be needed for small modular reactors and we hope to identify the opportunities there,” Brisson says. “New fuels are being developed that will need new or updated analysis methods. Finally, we hope to strengthen ASTM engagement from experts in South America.”
Uranium 235 is the most commonly used fissile isotope, producing energy during the chain reaction that takes place in a reactor’s core. However, SMRs and other nascent reactor technologies, because they represent new designs, will need new fuels.
Most such fuels fall into the category of high-assay, low-enriched uranium, or HALEU. The DOE defines HALEU as enriched between 5% and 20%, noting that it is “…required for most U.S. advanced reactors to achieve smaller designs that get more power per unit of volume. HALEU will also allow developers to optimize their systems for longer life cores, increased efficiencies, and better fuel utilization.”
C26 is revisiting existing standards and creating new ones to reflect the evolution of these fuels. One notable example is the standard specification for uranium hexafluoride enriched between 5 and 8% 235U (WK82821). This revision was in balloting at the time of this writing. “Today the standard for pressurized water reactors is 5%, but we think that there are capacities to increase the enrichment up to 8% in this standard,” Morel says. “We are also currently preparing a standard for up to 20% enrichment.”
The subcommittee on spent fuel and high level waste (C26.13) also just gained approval for a revised test method for measurement of glass dissolution rate using stirred dilute reactor conditions on monolithic samples (C1926). It describes a new technique for measuring the forward rate of glass corrosion using stirred reactor coupon analysis and will be used “to characterize aspects of glass corrosion that can be included in mechanistic models of long-term durability of glasses, including nuclear waste glasses.”
These new specifications build on the legacy of existing ASTM standards that are used all over the world, including the standard specification for uranium hexafluoride for enrichment (C787) and the standard specification for uranium hexafluoride enriched less than 5% 235U (C996).
Morel notes the challenge of coming up with a standard specification for fuels when so many different types of reactors are in development. Another hurdle is the unstable nature of fissile material. “When you enrich uranium, it’s very difficult to exactly predict the behavior of all the impurities. How do you take what is known by the industry for enrichment up to 5% and extrapolate to higher values like 8%?” he asks.
ASTM standards are often established prior to actual implementation of the industrial processes they are designed to support. WK82821 is a prime example of this phenomenon. “Nobody today is transporting 6% or 8%, but we are getting ready,” Morel states. “We will have a standard that is a consensus document, so it can be used in transportation, it can be used by the NRC to give approval for plants. The standard will absolutely be needed in advance so that everybody has agreed on what is inside.”
Even as exciting developments in new reactor technologies and fuel standards move forward, there has also been unprecedented growth in the number of existing nuclear facilities being mothballed. As chair of the subcommittee on radiological protection for decontamination and decommissioning of nuclear facilities and components (E10.03), Joe Sinicrope and his fellow members have had a front row seat.
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“From our perspective you see this tremendous forecasted effort in decommissioning of nuclear facilities,” he says. “You may see a little bit of the opposite occurring in China and in Asia, where it’s still looked at as a pretty viable way to meet energy requirements. But at least in North America and Europe, you’re seeing growth in decommissioning, not in bringing up new reactors.”
E10.03 is responsible for 16 standards that range from the foundational (standard guide for radiation protection program for decommissioning operations [E1167]) to the deeply technical (standard specification for permanent foaming fixatives used to mitigate spread of radioactive contamination [E3191]). Many of these were developed in the context of earlier reactor designs, but Sinicrope points out that new options like small modular units will themselves someday need to be closed down.
“For our subcommittee, those 16 standards are mostly associated with decommissioning efforts for current operational and/or about-to-expire existing nuclear technologies,” he says, noting that his subcommittee has added six new standards in the last three years that fall into this category. “But SMRs may very well present new issues that will require new guides and specifications to be created, implemented, and updated to deal with the back end of the nuclear cycle: the waste and the decommissioning processes.”
Many industry observers view waste as the most vexing issue confronting the nuclear industry. Russell DePriest, chair of the subcommittee on radiation dosimetry for radiation effects on materials and devices (E10.07), says “I believe the primary issue is spent fuel waste disposal or recycling.” Sinicrope calls waste the industry’s “Achilles heel,” while Griffin wonders whether nuclear power’s “green-ness” in terms of CO2 emissions is enough to offset concerns over disposition of spent fuel rods and other radioactive materials.
Though his subcommittee’s work centers around dosimetry – the measurement and assessment of radiation doses absorbed by an object (often, but not exclusively, the human body) during exposure to radioactive materials – DePriest believes it has an important role to play in any future resurgence of nuclear power.
“The focus of E10.07 tends to be more toward understanding the radiation environment experienced by objects in a test facility,” he says. “But standards within our subcommittee that could be important for a nuclear revival are 1.) practices that provide metrics to understand both neutron and gamma irradiation of materials used in reactors; and 2.) practices to characterize the energy distribution of particles in the radiation field. The subcommittee has been maintaining these standards for some time now, and most of our effort is to make certain that we stay abreast of new technologies that could improve our current characterization activities.”
DePriest points out that most of the nuclear technology and applications committee standards related to nuclear power come under the jurisdiction of subcommittees E10.02 and E10.05. These, he says, will be crucial to planning dosimetry protocols for new reactors — which may boast service lives as long as 80 years — as well as those currently operating that are being extended past their original 40-year design life.
Whether the focus is decommissioning of legacy designs or implementation of new technologies, one thing is certain: the work of the individuals who volunteer on E10, C26, and other ASTM committees will be crucial to its success.
As DePriest puts it, “I think it is particularly important to develop and foster younger engineers and scientists in the standards-development process. The members of E10 are enthusiastic about mentorship, sponsoring the first ASTM student chapter at Florida International University. We are hopeful that students will take advantage of the opportunity to participate and benefit from the collective experience in the nuclear field that we have in E10.” ■
Jack Maxwell is a freelance writer based in Westmont, N.J.