Moscow, Aug 2 (Reuters) - Russian scientists have proposed a method for a new neutron absorber for high-temperature gas-cooled nuclear reactors, which could help greatly improve the safety of such reactors developed since the mid-20th century.  The findings are in the journal Atomic Energy.  

Under relatively simple design and maintenance conditions, the HTGR is up to about 50% efficient, and the fuel efficiency is also very high, so it can operate for about ten years without charging.  Moreover, they may be relatively small in size.  These advantages make HTR the best solution to ensure the supply of energy and heat to settlements and businesses in hard-to-reach areas, such as the far North.  However, since the middle of the 20th century, a number of technical issues have remained unresolved, making its series production not economically cost-effective.  

Researchers at Tomsk University of Technology have developed a new method for monitoring the reactivity of high temperature gas-cooled reactors, greatly improving their safety.  It is based on the use of gaseous boron trifluoride as a neutron absorber released by nuclear fuel.  

Boron trifluoride makes it possible to quickly affect changes in the physical parameters of the reactor's neutrons when deviations occur, said Vladimir Kneshev, an assistant in the nuclear fuel cycle department at the university. Using the new absorber not only helps to control nuclear reactions more effectively, but its enriched version is also well suited for a safe emergency shutdown of the reactor.  The main advantage of boron trifluoride, he says, is its ability to remain in the gas phase at temperatures up to 1,000 ° C without disintegrating.  This compound is highly toxic but will be completely neutralized in ordinary water at room temperature.  

The research builds on a previously developed high-temperature gas-cooled reactor with helium thermal removal at Tomsk University of Technology. The reactor has a modular design that can be optimized to solve various energy problems.