Ambient office = 115 nanosieverts per hour

Ambient outside = 73 nanosieverts per hour

Soil exposed to rain water = 72 nanosieverts per hour

Lemon from Central Market = 110 nanosieverts per hour

Tap water = 152 nanosieverts per hour

Filter water = 138 nanosieverts per hour

Ambient office = 140 nanosieverts per hour

Ambient outside = 122 nanosieverts per hour

Soil exposed to rain water = 117 nanosieverts per hour

Romaine lettuce from Central Market = 85 nanosieverts per hour

Tap water = 90 nanosieverts per hour

Filter water = 85 nanosieverts per hour

Ambient office = 128 nanosieverts per hour

Ambient outside = 111 nanosieverts per hour

Soil exposed to rain water = 110 nanosieverts per hour

Ginger root from Central Market = 86 nanosieverts per hour

Tap water = 96 nanosieverts per hour

Filter water = 80 nanosieverts per house

Dover sole = 106 nanosieverts per hour

     New research by Texas A&M University scientists could help boost the efficiency of nuclear power reactors in the near future. Utilizing a combination of physics-based modeling and advanced simulations, they found the key underlying factors that cause radiation damage to nuclear reactors.
     Karim Ahmed is assistant professor in the Department of Nuclear Engineering. “Reactors need to run at either higher power or use fuels longer to increase their performance. But then, at these settings, the risk of wear and tear also increases. So, there is a pressing need to come up with better reactor designs, and a way to achieve this goal is by optimizing the materials used to build the nuclear reactors.” The Texas A&M research was reported in the journal Frontiers in Materials. Abdurrahman Ozturk is a research assistant in the nuclear engineering department who was the lead author of the report. Merve Gencturk is a graduate student in the nuclear engineering department who also contributed to the research.
     According to the U.S. Department of Energy (DoE), nuclear energy surpasses all other natural resources in power output and accounts for twenty percent of U.S. electricity generation. The source of commercial nucleal power is the nuclear fission reaction. In this process, isotopes of uranium split into daughter elements after being hit by fast-moving neutrons. Enormous heat is generated by fission reactions. This means that parts of nuclear reactors, especially the pumps and pipes, are constructed from materials possessing exceptional strength and resistance to corrosion.
      Fission reactions also produce intense radiation that damages the nuclear reactors structural materials. At the atomic level, when energetic radiation penetrates these materials, it can either knock atoms away from their normal location which causes point defects or force atoms to take the vacant spots which form interstitial defects in the atoms. Both of these types of imperfections disrupt the regular arrangement of atoms within the crystalline metal structure. What begins as tiny imperfections grow to form voids and dislocation loops, compromising the mechanical properties of the materials as time passes.
      There is some understanding of the type of defect which occur in these materials when they are exposed to radiation. Ahmed said that it has been very difficult to model how radiation and other factors such as the high temperature of the reactor and the microstructure of the materials together contribute to the formation of defects and their growth.
      Ahmed said, “The challenge is the computational cost. In the past, simulations have been limited to specific materials and for regions spanning a few microns across, but if the domain size is increased to even 10s of microns, the computational load drastically jumps.”
     The researchers said that in order to accommodate larger domain sizes, previous studies have compromised on the number of parameters within the simulation’s differential equations. However, an undesirable result of ignoring some parameters over other is an inaccurate description of radiation damage.
     In order to deal with these limitations, Ahmed and his team designed their simulation with all of the parameters involved. No assumptions were made on whether one of them was more pertinent than the other. In addition, to perform the now computationally heavy tasks, they used the resources provided by the Texas A&M High Performance Research Computing group.
     When the simulation was run, the analysis revealed that using all the parameters in nonlinear combination yields an accurate description of radiation damage. In addition to the microstructure of the materials in the reactor, the radiation conditions in the reactor, the reactor design and the operational temperatures are also important in predicting the instability in materials caused by radiation.
     In additions to finding about radiation damage, the Texas A&M also revealed why some specialized nanomaterials are more tolerant to voids and dislocation loops. They found that instabilities are only triggered when the border around the cluster of co-oriented atomic crystals, or grain boundary, is above a specific critical size. Nanomaterials with their extremely fine grain sizes suppress instabilities, which makes them more radiation tolerant.
     Ahmed said, “Although ours is a fundamental theoretical and modeling study, we think it will help the nuclear community to optimize materials for different types of nuclear energy applications, especially new materials for reactors that are safer, more efficient and economical. This progress will eventually increase our clean, carbon-free energy contribution.”

Ambient office = 115 nanosieverts per hour

Ambient outside = 112 nanosieverts per hour

Soil exposed to rain water = 114 nanosieverts per hour

Tomato from Central Market = 108 nanosieverts per hour

Tap water = 98 nanosieverts per hour

Filter water = 93 nanosieverts per hour

     The U.S. Department of Energy (DoE) Office of Environmental Management (EM) is celebrating thirty years of cleanup work at the Idaho National Laboratory site. This work has been carried out to ensure the protection and safety of the underlying Snake Rive Plain aquifer in compliance with state and federal regulations.
     The eight hundred and ninety square mile site is located on the ancestral lands of the Shoshone and Bannock Tribes in southeast Idaho. It was established in 1949 to design, build and test nuclear reactors for land, sea and air applications. Fifty-two reactors have been built at the site, most of which were first-of-a-kind. This includes the U.S. Navy’s first prototype nuclear propulsion plant and Experimental Breeder Reactor No. 1 which is the first reactor to produce a usable quantity of electricity from nuclear fission. This reactor is now registered as a National Historical Landmark open to the public.
     Four of the fifty-two reactors constructed at the INL are still in operation today: the Advanced Test Reactor (ATR), the ATR Critical Facility, the Neutron Radiography Reactor, and the Transient Reactor Test Facility. The INL is part of the DoE’s complex of national laboratories. They carry out research and development of nuclear energy. The site has also been chosen by NuScale Power and Utah Associated Municipal Systems for the deployment of a small modular reactor plant by the end of this decade.
     In December of 1991, the DoE, Idaho, and the Environmental Protection Agency signed a Federal Facility Agreement and Consent Order which outlined a plan to investigate and clean up, if necessary, more than five hundred individual waste area inside the site. The agreement provides the regulatory framework that is still in use for the cleanup of legacy waste that includes contamination from World War II and Cold War-era conventional weapons testing, plus wastes from government-owned research and power-reactor development and testing, used nuclear fuel reprocessing, laboratory research and defense mission at INL other government sites.
     Waste sites at the INL consisting of unlined wastewater disposal ponds, debris piles, radioactive groundwater plumes, buried barrels and boxes of radioactive and hazardous waste and even unexploded ordnance, have all been evaluated and most of the cleanup has been completed.
      Two of the cleanup projects were explicitly designed to protect the aquifer which lies five hundred and eighty-five feet below the surface. These two projects were the removal of forty-nine thousand drums of radioactive and hazardous waste for an unlined Cold War Landfill known as the Subsurface Disposal Area and the use of vacuum-extraction units to remove solvent vapors from beneath the landfill. The vacuum extraction project was completed early, and the waste removal project is now expected to be completed eighteen months ahead of schedule.
     At the northern end of the INL site, more than eight hundred twenty-five gallons of water have been treated with a pump-and-treat system over the last twenty years, and bioremediation is ongoing. This consists of injecting sodium lactate or a similar product into a contaminant plume in the aquifer to create conditions favorable for naturally occurring microorganism to “feed” on the waste.
     Construction of the five hundred thousand cubic yard Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Disposal Facility in the early 2000s has allowed waste material from many areas of the site to be consolidated into a single managed landfill that includes several feet of impermeable liners as well as a leachate collection system and lined disposal ponds.
     Exhumation of buried waste from the area of the landfill that posed the greatest danger to people and the environment is expected to be complete within the coming weeks.
     Fred Hughes is the program manager for EM INL Site contractor Fluor Idaho. He said, “The amount of environmental cleanup work that crews have completed is impressive. The progress is visible, and the aquifer is benefitting from a host of waste remediation projects.”