Scientists have developed safe material for "nuclear batteries"
The "battery" is a solid-state ceramic matrix with a high-energy radionuclide strontium-90 (90Sr) immobilized inside. The material is built via the method of spark plasma sintering-reactive synthesis and meets the requirements for solidified radioactive waste (Government Standard 50926-96). It can serve as a reliable radioactive source of autonomous power supply for navigation equipment (lighthouses, radio beacons, light signs) and weather stations of the Northern Sea Route. A related article appears in Nuclear Engineering and Technology.
A network of autonomous marine navigation devices operating on the radioisotope heat source (RHS) is able to secure a stable throughput and navigation accuracy on the Northern Sea Route. The most promising RHSs are based on the high-energy radionuclide strontium-90 (90Sr) which radioactive decay is converted into electrical energy by radioisotope thermoelectric generators (RTGs).
Scientists from Far Eastern Federal University (FEFU) and the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS, Institute of Chemistry) have developed a ceramic material with high mechanical strength, microhardness, and thermal stability that are necessary for the safe immobilization of strontium-90 cores, not endangering the environment. "Isotope battery" made from developed ceramics is an example of the peaceful application of nuclear technology.
"RHS -90 is a sealed source of ionizing radiation, where strontium borosilicate glass (90SrTiO3) is an active composition being not an ideal candidate material since it is subject to vitrification with subsequent mechanical destruction. Despite the protection of the capsule with the core from external influences, the existing RHS-90 managing system does not guarantee physical protection of the RHS element. An accident, unauthorized extraction, or a terrorist act can lead to the destruction of the RHS core, release of 90Sr into the environment, including seawater. Thus, the radionuclide can be involved in the food chain "bottom microorganisms—algae—fish". The ceramic matrix composition developed by the Far Eastern Federal University and the Far Eastern Branch of the Russian Academy of Sciences reliably protects the core with strontium-90, no matter what happens", explains Ivan Tananaev one of the work authors, Director of the School of Natural Sciences of Far Eastern Federal University.
Scientists recalled, that strontium-90 accumulates in radiolaria, unicellular plankton, which concentrate it in spicule-outgrowths, some green algae, all types of brown algae, in crustacean shells and shells of mollusks.
Cooperative Threat Reduction plan of the US Congress, which has been in operation since 1991, considers RHSs a risk factor of the spreading of radioactive materials for a "dirty bomb". The IAEA classifies them as high-risk elements because a single RHS-90 can be hazardous for more than 1000 years.
FEFU and FEB RAS research team led by Evgeniy Papynov (Institute of Chemistry, FEB RAS), have obtained a stable composition of a ceramic matrix that reliably protects the strontium-90 core. The matrix is capable of "holding" radiation even in the case of an accident, preventing the RHS element from getting into the environment, including fresh and seawater.
That development becomes possible due to the method of reaction spark plasma sintering (SPS) of mineral-like ceramic systems. The SPS approach means the consolidation of powder materials due to high-speed heating and compression. The technique allows one to preserve the micro granular structure of the final material, hardness, strength, and low rate of radionuclide leaching in environments with different acidity. FEFU and FEB RAS Institute of Chemistry specialists collaborate on joint advancement of the technological approach.
According to the researchers, the obtained ceramic material can also be recommended as sources of ionizing radiation based on 90Sr.
New materials for different areas of application are one of the priority research areas of FEFU. Recently, university scientists have developed ceramic materials for high-power LED systems.
More information:
E.K. Papynov et al. SrAl2Si2O8 ceramic matrices for 90Sr immobilization obtained via spark plasma sintering-reactive synthesis, Nuclear Engineering and Technology (2021). DOI: 10.1016/j.net.2021.01.024
Provided by Far Eastern Federal University