The MIT Nuclear Reactor Lab’s Lin-wen Hu, David Carpenter, and Kaichao Sun are part of the team led by Oregon State University to work on “Computational and Experimental Benchmarking for Transient Fuel Testing”. Researchers will perform a benchmark of the Idaho National Laboratory’s Transient Reactor Test Facility (TREAT). TREAT is an air-cooled, graphite-moderated, thermal-spectrum test reactor which previously operated from 1959 until 1994. The TREAT was built to conduct transient reactor tests where materials are subjected to neutron pulses that can simulate conditions ranging from mild transients to severe reactor accidents. In 2014 The U.S. Department of Energy (DOE) decided to restart the TREAT facility in order to resume a program of transient testing. One of the planned uses for TREAT is to test new accident tolerant fuels for nuclear reactors. The MIT team will benchmark two steady state neutronic problems and two transient problems. Their work will include the design, construction and utilization of a full-scale representation of an in-pile flow loop prototype for TREAT, and numerical benchmarking against the experimental data gained from the experiment.
Office of Nuclear Energy
Resumption of Transient Testing Capability
APRIL 15, 2013
The Department of Energy (DOE) is proposing to re-establish the capability to conduct transient testing of nuclear fuels. Transient testing involves placing fuel or material into the core of a nuclear reactor and subjecting it to short bursts of intense, high-power radiation. After the experiment is completed, the fuel or material is analyzed to determine the effects of the radiation. The resulting information is then used to guide the development and improvement of advanced nuclear fuel designs, and to validate computer models of fuel and core behavior required for U.S. Nuclear Regulatory Commission (NRC) evaluation of nuclear power reactor design and safety evaluations.
Transient testing of nuclear fuels is needed to improve current nuclear power plant performance and sustainability, to make new generation reactors more affordable, to develop nuclear fuels that are easier to recycle, safer and more efficient, and fuels that can't be as easily diverted for use in making nuclear weapons.
BACKGROUND AND OVERVIEW OF THE PROCESS
JUSTIFICATION TO RESUME TRANSIENT TESTING
Q: What is the justification for resuming transient testing of nuclear fuel?
A: Transient testing of nuclear fuels is needed to develop and prove the safety basis for advanced reactors and fuels. The safety basis for a reactor system requires a complete understanding of what could happen to the reactor fuel if it were subjected to accident conditions such as large power increases and loss-of-cooling events. Demonstrating understanding of the safety basis means you can predict the behavior of the reactor and the fuel and thus limit operation to safe conditions.
Advanced reactor designs will require new fuel types. These fuels could be quite different from the ones that were tested in the past: different geometries to enhance their cooling, different compositions to help significantly reduce the amount of waste generated during the production of nuclear energy, and different materials to improve their thermal and safety performance. These new fuels need to be proof tested in a controlled environment and researched extensively in order to learn how they respond to accident conditions. This understanding will help guide the design of fuels with much better performance.
When the nuclear power industry started, engineers needed a way to determine the safety limits of nuclear reactor operations, such as the temperatures, pressures and power at which the reactors could be safely operated. One issue that had to be addressed was "under what conditions would the fuel in the reactor fail?" or "what happens when cooling is suddenly lost?" Similarly, engineers needed to develop computer models that could be used to predict what would happen when accidents occurred. In order to determine this, they used transient testing to expose full-sized reactor fuel rods to intense, very short duration power bursts or under-cooled conditions that simulated high power and loss-of-coolant accidents. These experiments told fuel designers, reactor operators and reactor regulators the safe limits for fuel design and operations.
Transient testing of nuclear fuels is also needed to improve current nuclear power plant performance and sustainability, to make new generation reactors more affordable, to develop nuclear fuels that are easier to recycle, and fuels that can't be as easily diverted for use in making nuclear weapons.
Q: Are there specific, identified customers who are willing to pay to use transient testing capability? If so, who?
A: While the DOE is responsible for several programs related to advanced nuclear fuel development, Accident Tolerant Fuel development is the most near term program that would benefit from the resumption of a transient testing capability. This program aims to design, develop and deploy new nuclear fuel designs for current generation nuclear power plants with the ability to mitigate the consequences of severe accidents through improved fuel performance. The development effort for these fuels will require a wide range of testing capabilities. The capability to conduct safety testing in a transient test reactor is a key component of the testing capability that must be added to meet this objective.
PROCESS / PLANNING
Q: When does DOE plan to resume transient testing?
A: In December 2010, the DOE determined that there is a mission-need for a domestic transient testing capability for developing nuclear fuels. If DOE decides to resume transient testing, it could resume as early as 2018. Over the past two years, the Department has conducted an alternatives analysis that examines multiple options for resuming transient testing to aid in determining the suite of reasonable alternatives. DOE is currently in the National Environmental Policy Act (NEPA) phase of planning. During this phase, DOE will evaluate the potential environmental impacts, if any, of resuming transient testing capabilities for two alternatives, TREAT or ACRR, as well as a no action alternative. After the NEPA analysis is completed, DOE will have a better understanding of the environmental impacts of resuming transient testing and will make a decision on the path forward.
Q: How will the decision be made on whether to resume transient testing?
A: DOE has initiated the NEPA review process that will help DOE decide whether or not to resume transient fuel testing by restarting TREAT or adapting ACRR. The decision to restart TREAT or adapt ACRR will be made only after the NEPA analysis and determination is completed. If the decision is made to resume transient testing capabilities, DOE will not resume actual testing until the requisite equipment replacements and refurbishments are completed and an extensive readiness preparation and review confirms safety and operational readiness.
Q: Will DOE perform an Environmental Impact Statement (EIS) prior to resuming transient testing? If not, why not?
A: DOE issued an Environmental Assessment Determination (EAD) in accordance with DOE Order 451.1B Change 2 "National Environmental Policy Act Compliance Program" in September 2011. The EAD concluded that an Environmental Assessment is the appropriate level of NEPA review in accordance with DOE and Council on Environmental Quality regulations. If we knew that the proposal would have significant environmental impacts the EIS would be the appropriate initial level of NEPA analysis. If the Environmental Assessment concludes with a Finding of No Significant Impact, an Environmental Impact Statement will not be required. If the analysis documents the potential for significant environmental impact, an EIS will be prepared.
Q: Which office will fund the refurbishment, restart and operation of TREAT, if the DOE decides to restart it, or the use of ACRR for transient testing?
A: The DOE Office of Nuclear Energy.
Q: What is TREAT and what was it used for?
A: The TREAT (Transient Reactor Test Facility) reactor at Idaho National Laboratory was used to conduct experiments investigating the effects of nuclear reactor transients, which are rapid and very short duration changes in power, on both water and sodium-cooled nuclear fuel systems. Much of the safety basis for fast reactors such as INL's Experimental Breeder Reactors I and II, the Pacific Northwest National Laboratory's Fast Flux Test Facility, the Japanese Joyo and Monju reactors, and the Westinghouse AP-600 light-water reactor is based on tests conducted at TREAT.
Q: What is ACRR and what is it used for?
A: The ACRR (Annular Core Research Reactor) is a water-moderated, pool-type research nuclear reactor (CAT-II) capable of steady-state, pulsed and tailored transient operations. It is currently used to support defense and nuclear testing of electronic equipment for the National Nuclear Security Administration (NNSA).
Q: When was ACRR built and how long has it been operating?
A: ACRR started operations in 1979 and has been in operation for more than 33 years.
Q: When was TREAT built and when was it last operated?
A: TREAT began operation on Feb. 23, 1959 and has been upgraded several times since then. It has not operated since early 1994 because there were no customers for the facility at that time. The Integral Fast Reactor Program (EBR-II) was canceled that same year and the commercial industry had well-established fuel performance that did not require an active transient testing capability.
Q: Were there any reactor accidents associated with TREAT during its operation?
A: No. TREAT is a steady state low-power reactor that can generate very short, high-power transients. During its 35-year operation, the TREAT reactor was used for 2,855 high-power transient experiments using a short burst of power lasting, often, mere milliseconds. The reactor rapidly shuts itself down because of the inherent self-limiting design of its core. Unlike most commercial power reactors that are cooled with water, TREAT is cooled using air at or slightly below atmospheric pressure.
Q: Were there any reactor accidents associated with ACRR during its operation?
A: No. In its more than 33 years of operation, ACRR has safely conducted more than 10,000 critical operations including irradiation of explosive components for defense programs and development, radioactive materials (e.g., fission products, tritium), nuclear and nuclear fuel materials (e.g., fissionable material as commercial, experimental, and space reactor fuel types), and nuclear fuel safety studies.
Q: Overall, what are the comparative costs of the two options (ACRR compared with TREAT)?
A: The NEPA process is designed to determine whether there are any significant environmental impacts associated with proposed actions. DOE is going through the EA process to determine the potential for environmental impacts of the two action alternatives. At the same time, DOE is compiling and will be examining the cost estimates for both alternatives. DOE will factor cost information into its decision on the best path forward.
On Aug. 8, John Bumgardner was honored with the Energy Innovator Award by the Partnership for Science and Technology (PST) for his innovative efforts in driving the TREAT restart effort and work on the new Fast Reactor program. The award ceremony was part of the Intermountain Energy Summit.
Each year the PST Board and Executive Board nominate and down select nominees for Energy Advocate Awards in various categories: National, Regional, Innovator and Educator. The PST was created, in part, by INL to advocate for nuclear energy both in Idaho and at the national level. The significant membership between businesses and individuals locally is able to take advantage of the Energy Communities Alliance and other groups to interact with DOE-HQ, the LINE Commission, and elected officials.
Tommy Holschuh earned his doctorate in nuclear engineering from the Oregon State School of Nuclear Science and Engineering in June 2017. In August, he, along with Abdalla Abou Jaoude from the Georgia Institute of Technology, was named one of two inaugural recipients of the Idaho National Laboratory’s (INL) Deslonde de Boisblanc distinguished postdoctoral appointment. INL is the nation’s preeminent nuclear energy lab, and Holschuh will be using a novel method he developed at Oregon State to support the modeling of its Transient Reactor Test Facility (TREAT).
Deslonde de Boisblanc was an early influential scientist at INL and designed the unique serpentine core of INL’s Advanced Test Reactor. According to INL’s press release, the appointment is “competitively awarded to early career researchers who embody the spirit of ingenuity of de Boisblanc and who have leadership potential.”
A Nuclear Energy University Partnership Fellow during his doctoral studies at Oregon State, Holschuh developed a methodology and a detection system to quantify the Cherenkov radiation, or light, emitted by a reactor to determine reactor kinetics parameters. He calls it the Cherenkov Radiation Assay for Nuclear Kinetics (CRANK) system, which he describes in his dissertation. Holschuh used the Oregon State TRIGA Reactor for his research.
“The overall goal is that this might be used as an inspection tool by International Atomic Energy Agency (IAEA) inspectors,” Holschuh said. “During an official inspection of a reactor facility under IAEA safeguards, the inspectors could utilize the CRANK system to measure a reactor pulse and be able to obtain information about that reactor to verify the facility’s activities.”
Holschuh’s detection system fits in a briefcase-size hard case and consists of a photodiode connected to the end of a fiber optics cable, which connects to signal processing software. The photodiode is lowered into a reactor and measures the Cherenkov light. The software and components are off the shelf and altogether cost about $15,000. Other systems used by the IAEA for similar purposes cost $250,000 just for the cameras they utilize, according to Holschuh.
To interpret the data from the Cherenkov light and determine the reactor’s parameters, Holschuh developed a mathematical formula to put into the software. “The most difficult part was determining how to interpret the pulses. Reactor pulses, or large power changes over a short period of time, are inherently different for every reactor. Every aspect of the reactor alters the shape of the pulse -- the changing reactivity with temperature, the heat capacity of the reactor, the facility design,” he said. “I was able to obtain a method that combined many of those aspects into a single variable that scaled between two unique reactor pulses.” (See video of the Cherenkov light emitted during a pulse at the Oregon State Triga Reactor.)
This means that his method and system can be used for virtually any reactor that has the capability to perform a large power transient.
At INL, Holschuh will utilize this method for reactor safety rather than standard reactor safeguards. “As part of the deBoisblanc postdoctoral appointment, I will attempt to use that methodology and measure reactor pulses at the TREAT Facility,” he said. Shut down since 1994, TREAT is in the process of being restarted—an effort involving Oregon State. It will be used to test nuclear fuel assemblies for power-generating reactors.
“The last time its reactor parameters were measured, experimentally, was in 1960,” said Holschuh. “By obtaining more accurate experimental results for reactor kinetics parameters, it provides more representative values for the INL staff members who perform modeling and simulation for the TREAT facility. The pulse shape, and subsequent energy deposition into the fuel types being tested, are greatly influenced by the reactor kinetics parameters, so by knowing them more accurately you can more accurately determine the effects on the fuel being tested.”
Holschuh completed two internships at INL during his graduate studies and will be working under the supervision of Dan Wachs, who earned his master’s in both nuclear and mechanical engineering at Oregon State before earning his doctorate in mechanical engineering at the University of Idaho.
“We’ve been working with Tommy for several years and are looking forward to his return to INL,” said Dr. David Chichester, according to the press release. Chichester is an INL directorate fellow and was Holschuh’s graduate intern mentor at INL. “With key skills in reactor physics and radiation science, he’s going to be making important contributions to our nuclear energy and nuclear nonproliferation research programs.”
— Jens Odegaard.
Thursday, September 14, 2017
INL Graduate Fellow Ari Foley adjusting the tungsten bremsstrahlung radiator at the end of the 0 degree port of the 25 MeV accelerator at the Idaho Accelerator Center. Photo credit: INL Nuclear Physicist Matt Kinlaw.
Idaho National Laboratory is the premier nuclear research lab in the country and maintains close ties with Oregon State. The selection of Oregon State graduate students Ari Foley and Musa Moussaoui as two of the inaugural class of INL Graduate Fellows promises to continue strengthening the partnership. They will be contributing to nuclear nonproliferation and security programs as well as next-generation nuclear power technology.
Foley and Moussaoui are both graduates of the Oregon State College of Engineering's School of Nuclear Science and Engineering (NSE), receiving their bachelor's degrees in nuclear engineering in 2016 and 2017 respectively. As INL Graduate Fellows, they will pursue their doctoral degrees at NSE while conducting research at INL.
"The graduate fellowship is mutually beneficial for the student, their university, and INL," said Foley's mentor at INL, Nuclear Physicist Matt Kinlaw. "The fellowship gives the student an opportunity to access unique national laboratory facilities and capabilities to conduct their graduate research, while also providing the university and INL an opportunity to develop and strengthen ongoing collaborative efforts."
Oregon State is one of five universities partnered with INL under the National University Consortium (NUC). The NUC's goal is to further "the nation's strategic nuclear energy objectives, clean energy initiatives, and critical infrastructure security goals," according to the NUC website. Students from NUC schools, like Moussaoui and Foley, were targeted as candidates for the INL Graduate Fellowship Program.
"Over the years, the mutual benefits of the NUC has been demonstrated through the alignment of research interests among Oregon State faculty and INL staff, numerous patents, a vein of well-qualified staff to the lab resulting from recent Oregon State graduates, named national laboratory fellows, joint faculty appointments, and the most recently added benefit is the creation of this INL Graduate Fellowship program," said Wade Marcum, associate professor of nuclear engineering and NUC program lead at Oregon State.
Foley interned at INL in the Nuclear Nonproliferation division in both the summers of 2016 and 2017. She plans on pursuing nonproliferation and security related research as a graduate fellow. "The research focuses on the determination of short-lived fission product yields through the precise measurement and analysis of delayed gamma-ray signatures immediately following photon-induced fission (photofission)," she said. "This is motivated by a need for improved nuclear data and novel isotope production methods to support the nonproliferation and nuclear forensics communities."
According to Kinlaw, "her research is anticipated to have a significant, direct impact on several ongoing nonproliferation and homeland security programs at INL."
Moussaoui, on the other hand, will be tackling research related to next-generation nuclear power at INL's recently reactivated Transient Reactor Test Facility (TREAT). "TREAT will now be the foundation for studying the performance of advanced nuclear fuel designs under simulated accident conditions," said Moussaoui's mentor at INL, Dan Wachs. He is INL's National Technical Lead for Fuel Safety Testing and an Oregon State alumnus in both nuclear and mechanical engineering. "In particular, new 'accident tolerant nuclear fuel' technology is being collaboratively developed by the U.S. national laboratories and commercial nuclear fuel vendors to mitigate the consequences of low probability accidents like those experienced at the Fukushimi-Daichi nuclear plants after they were struck by the Great Tohoko earthquake and tsunami."
Moussaoui will be helping develop experimental devices needed to conduct these accident simulations at TREAT. "It's really a terrific opportunity," said Wachs. "Musa is at the forefront of a new generation of scientists and engineers that will apply modern experimental methods coupled with state-of-the-art modeling and simulation tools to lead this critical area of study. He'll be working with some of the world's premier experts in the field."
Both Moussaoui and Foley plan to pursue careers at national labs after completing their doctoral degrees. "I endeavor for my career to directly support the development of novel and robust nuclear power technology," said Moussaoui. "Much of the most impactful research is produced by Department of Energy national labs; thus, after graduation, I see myself at INL conducting applied research."
— Jens Odegaard.
Idaho National Laboratory (INL) recently released footage of a new experiment that simulates what happens to a nuclear fuel pin when it starts to overheat. The new series of tests will ultimately help researchers better understand the safety limits of nuclear fuel.
INL conducted the experiments at its Transient Reactor Test Facility (TREAT) using a first-of-a-kind device that can detect and study the critical heat flux of a nuclear fuel rod. Critical heat flux is the physical phenomenon that occurs when a fuel rod first begins to overheat and can no longer transfer additional heat to the water. This leads to excessive boiling around the surface of the pin and could potentially cause excessive fuel damage.
A Unique Look
The slow-motion video by INL shows the progression of boiling leading up to the point where critical heat flux is reached, when large quantities of water vapor bubbles touch the surface of the fuel rod. The experiment was conducted outside of the test reactor in a specially-designed water-filled capsule that used an electrically heated fuel pin to simulate the conditions. The entire experiment lasted one second, but provided unique insights into this phenomenon.
“Critical heat flux is an important parameter that regulators use to determine the safety limits of nuclear fuel,” said Dr. Colby Jensen, the Transient Testing Technical Leader. “These experiments will help us better understand fuel behavior and to demonstrate how robust safety features of advanced fuel designs will allow more efficient use of those designs.”
Check out this INL experiment to explore how nuclear fuel rods perform when pushed to their limits.
Learn more here.
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