The fissile material is the material constituted of the heavy atoms such as Uranium or Plutonium that will ultimately be fissioned in a reactor to extract energy while the fuel cycle is the ensemble of processes that the fissile material is undergoing before, during and after being burned in the reactor. Viewing the whole set of nuclear related industries and technologies as being part of a fuel cycle where fissile material is continuously flowing through can be very useful for issues related to nuclear security such as non-proliferation and disarmament. Using such an approach the problem reduces to a problem of continuously managing and knowing the isotopic distribution of the fissile material flow.
Many software have been developed to model different processes throughout the fuel cycle (Scale, MCNP, Serpent, CASMO) and have been essential tools in the advance of nuclear technologies. Nonetheless, many of these codes are now getting old and are not able to provide proper simulation for new concepts of nuclear technologies. In addition, they also present limitations in their scope of use since their original raison d’être is closely connected to the civil and military nuclear industry. Hence, our capacity to use computers to have accurate and reliable information on the isotopic distribution of the fissile material throughout the fuel cycle in the context of nuclear security is far from being satisfying.
This is why we are currently developing an open source isotopic evolution software that will have the following main features:
Modeling the most recent nuclear technologies: While the technologies and processes constitutive of the fuel cycle evolve, the traditional software that simulate them tend to lag behind. We want our software to be able to model the latest technological innovations that are going to be part of the nuclear fuel cycle. For instance, reactors where fuel is not fix but circulates are very promising concepts that can’t be currently simulated with the available set of neutronics software. We are currently working on innovative ways to simulate circulating fuel reactors and integrating these methods into a neutronics code to provide a numerical module that would be fully adapted for circulating fuel systems.
Rewinding the fuel cycle time line: As a tool for the nuclear industry, numerical software were developed to predict, among other purposes, the isotopic evolution of the fissile material. In the Nuclear Futures Laboratory we believe that numerical simulation should also serve to investigate in the service of nuclear security and disarmament. A rather new and promising tool for nuclear security and disarmament is what is called Nuclear Archaeology. As its name indicates, Nuclear Archaeology aims at going backward in time in the fuel cycle time line. Using information like measured isotopic ratio from “back end” fuel cycle material, Nuclear Archaeology’s goal is to reconstruct the history of the fissile material in the fuel cycle. This can be used to reconstruct the plutonium production throughout the fuel cycle when no information on the initial parameters of the fissile material are available. This possibility would be very helpful within any non-proliferation or disarmament project as it would yield an independent and reliable way to check the plutonium stock declaration of the parties involved. One of our goal is to develop a “backward depletion” package that would let the user input data from “back end” material and rewind the fuel cycle timeline to reconstruct the fissile material history.
Open source: We want each of the software we develop to be open source. The nuclear industry and the nuclear security scholarship would gain a lot by having access to an open-source software that would investigate fissile material isotopic content throughout the fuel cycle. Many people around the world have a lot of ideas and different approaches to deal with the issues of disarmament or non-proliferation but will often be slowed down or even discouraged in their research by the lack of access they have to key-element tools such as depletion codes. Developing an open-source depletion software and sharing it will double the numbers of good ideas and even bring new people aboard.