Part 2 of 2 Parts (Please read Part 1 first)
There is a great deal of research into new designs for nuclear reactors. Even some environmental activists believe that nuclear power can be a low-carbon source of energy along with hydropower, wind and solar. Part of this research is aimed at the creation of smaller, safer, modular and even mobile next generation nuclear reactors. Some of the uses suggested for this next generation of nuclear reactors include use in the engines of spacecraft, burning recycled nuclear fuel and even as portable generators that could be easily delivered to the site of disasters to provide power when the grid is down.
One particular design that is gaining momentum in the nuclear industry is molten salt reactors (MSR). These reactors use fuel mixed with molten salts which helps prevent meltdowns. Of course, before any of these next generation nuclear reactor designs become actual commercial sources of energy, they will need to undergo many rounds of safety and operational testing.
The difficult task of reactor improvement and testing has just been made easier due to innovations at the Pacific National Nuclear Laboratory (PNNL). These new developments combine remote, real-time testing and continuous monitoring of off-gas byproducts during the operation of nuclear reactors. A new software package aimed at nuclear power plant operators has also been developed at PNNL. When combined with the new testing system from PNNL, these innovations help lay a solid foundation for remote, nearly instantaneous monitoring in this new era of reactor design.
Amanda Lines is a PNNL chemist. She said, “Real-time monitoring is a valuable tool, particularly in the development of next-generation reactors. This can help designers more efficiently and effectively design and test flow loops, mechanisms, or processes. Also, when they ultimately deploy their reactor systems, this gives operators a tool to better understand and control those processes.”
One of the main off-gas byproducts of nuclear power generation is iodine which is produced in several different forms. In liquid-fuel molten salt reactors, iodine compounds are currently monitored by taking samples at operating reactors and analyzing them in a remote laboratory. This method is slow and expensive. In addition, there are added safety challenges and complexities involved when analyzing radioactive samples in a laboratory. Real-time monitoring employs no direct human interaction with the samples and it offers a less risky, more efficient alternative. Lines said, “It's a real game-changer in terms of the steps you have to go through, and the timeline to sample iodine and other chemical species.”
Off-gas fission products are generated in all nuclear reactors. There is special concern about iodine gas because it is radiotoxic. It can easily vaporize, and if released, it becomes airborne. The operation of molten salt reactors would require that iodine be treated and scrubbed from the system as it is produced in real time. This is not necessary in conventional light water reactors because the iodine is trapped inside the fuel rods. In order to enable the real-time scrubbing of iodine in a molten salt reactor, operators will need real-time information about iodine levels.
Existing processes for tracking radioactive iodine levels are complex and expensive. It involves examining chemical behavior at the molecular level because iodine can continually morph by binding with other elements, creating new molecules with different properties.
The research team at PNNL focused its attention on two common forms of iodine. These are iodine monochloride and elemental iodine. The goal was to find chemical “fingerprints” for each type of iodine produced using two common chemical analysis techniques. These are Raman spectroscopy and Fourier-transform infrared spectroscopy.
While the spectroscopy readings are useful to researchers, it was important to convert that data into information that would be useful to operators. Lines said, “We want an output that is easily understandable, especially for someone who hasn't spent years of their life staring at spectrometry data.”
The PNNL team has developed software that can take highly sensitive spectroscopy light readings from existing, off-the-shelf technology and transforms that data into real-time information that can be used by plant operators. Next, the PNNL team plans to take what they have learned from their studies and expand it to other byproduct gases.
Sam Bryan is a PNNL laboratory fellow and chemist. He said, “Ultimately these are tools that can help expand research and development efforts, particularly in terms of next-generation reactor design and testing. Real-time monitoring can enable new types of reactors by solving problems on the front end.”