Safe Made in China reactor

chiny24.com 10 months ago

Safe reactor

Scientists from TsingHua University (chin. 清华大学) in Beijing (pinyin: BeiJing, chin. 北京) successfully conducted a passive cooling test in a 105 MW atomic reactor designed to halt working in an emergency situation without allowing the reactor core to melt down. It is the world's first reactor of this type. investigation on the solution has been ongoing since 2016. The intent of the investigation was to make a reactor that, passively cooled, utilizing natural cooling methods, would prevent the melting of the cores in case of failure. This was the case in Chernobyl.

How cool are atomic reactors?

Existing atomic reactors require externally powered cooling systems. The nature of these systems may vary depending on the reactor plan – most usage water, but any usage coolants specified as CO2, helium, molten metals or melted salts. But they all fundamentally do the same thing: they drain excess heat from the reactor core.

It is known that water cooling systems supply advanced power density, which translates into better thermal efficiency (essentially the ratio of output power to full heat consumption in the system), but this has its drawbacks. For example, there is always a hazard of detonation if the reactor melts. This is due to the fact that if water pumps lose power, heat from the reactor fuel rods can separate water into explosive hydrogen and oxygen.

It was this problem that contributed to the Fukushima atomic disaster in 2011, erstwhile the power failure meant overheating of fuel rods that were flooded with water, which led to the explosion.

Gas-cooled reactors are little likely to detonate than their water-cooled counterparts, but usually besides have lower heat efficiency.

However, regardless of the kind of cooling strategy used, in case of failure, human intervention is needed to shut down the reactor and prevent the disaster. This is usually due to the fact that cooling systems are based on external power sources.

What's peculiar about the fresh reactor structure?

One of the fresh types of reactors, known as the gravel deposit reactor (PBR), may be a solution to the problems associated with older structures. These reactors are "passively" safe, so they can control off themselves if there is any problem with the cooling system.

In contrast to another reactors based on high-energy fuel rods, PBRs usage smaller low-energy fuel density pebbles in more numbers. Although they contain little uranium than conventional fuel rods, there are more. They are besides surrounded by graphite, which is utilized to average neutron activity in the core. This helps slow down atomic reactions, resulting in little heat.

Therefore, the lower energy density means that excess heat can be distributed into pebbles and can be more easy discharged.

Until recently, the only existing PBR reactors were prototypes in Germany and China. It turns out that China built a full-sized gravel-cooled reactor module with advanced temperature gas (HTR-PM) that was commercially launched in December 2023 and is equipped with fresh safety systems. To test them, engineers shut down both HTR-PM modules at a time erstwhile they operated with full power.

The results that have just been published show that HTR-PM cooled itself down, reaching unchangeable temperature within 35 hours of the power cut.

The ability to test a working atomic reactor by disconnecting its cooling power is unusual. Only thanks to the unique HTR-PM strategy was this possible at all and although further investigating will be essential to guarantee that the strategy works properly, all indicates that the solution will service as a model for future reactors constructed in China.

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