Mini-nuclear reactor with a 10 kW generator. Installation for power supply of bases on Mars and homes of the future

Previous articles on radioisotope nuclear installations have generated interest. I will indicate links to them at the end of the article. And since There are many developments in this area, so I propose to look at another promising installation: the RTG project from the USA called KiloPower.

This is a NASA project for power supply of interplanetary spacecraft, rovers and, in the future, bases on Mars and the Moon. Generator power - from 1 to 10 kW in electrical power (depending on the power of the core and the number of working cylinders of the Stirling engine).

Such indicators KiloPower are possible due to the use of not thermoelectric converters "heat-electricity" operating due to the temperature difference, but due to the use of the Stirling engine. This made it possible to increase the efficiency of converting heat into electricity. up to 25-30%. The installation also has a heat output. She 4 times higher than electrical. In theory, you can use it for other needs. And after debugging the technology, the efficiency can be even higher (for example, with additional installation of Peltier elements on the radiators).

The compact nuclear reactor generates heat. Is a cylinder from alloy: 7% molybdenum, and the rest is uranium-235. Inside there is a channel with a boron carbide rod. It is a chain reaction neutron absorber. As long as he is inside, there is no reaction. When the reactor starts up, it leaves the working area and it starts to warm up. But not to critical temperatures - there is no explosion hazard due to the calculated concentration of uranium in the alloy.

To reflect neutrons and to reduce the mass of uranium, the reactor is surrounded by beryllium oxide. It contains heat pipes with sodium. Coolant tubes heat the pistons of a Stirling engine. Generator coils are installed around the pistons. There is a magnet inside the piston. Those. generation comes from the reciprocating motion of the magnet in the coil. There are eight pistons. Each produces 125 watts electricity.

• How a simple Stirling engine works - article here

Plutonium-238 was not used in the reactor due to its high cost. It is 100 times more expensive than uranium-235 (35 kg - $ 500 thousand). Uranium alloy reactor cylinder size: diameter from 11 to 15 cm and length from 25 to 30 cm. Weight 28-35 kg. It all depends on the power received. Plus a beryllium shell. For spacecraft, the weight of the KiloPower RTG is 300 kg.

Scheme and testing of the KiloPower reactor by heating the tubes with heating elements in 2016 Later, in 2018. the installation was tested in the Nevada desert at the test site. She worked for 20 hours at full power. Even deliberate breakdowns did not lead to critical overheating of the reactor.

For spacecraft, radiation shielding is installed only towards the engine and electronics. But for installations on Mars, all-round protection of the reactor is needed. On Mars, these RTGs will look like this according to NASA specialists:

The umbrella is a radiator for cooling cold areas on the cylinders of a Stirling engine. The term of work is 10 years. This is the life of the Stirling engine itself, not the reactor. During this time, the reactor will develop 0.1% of its active mass. The half-life of uranium-235 is 710 million years.

Those. it is advisable to make the Stirling engine replaceable. Replacement after mechanical reliability or failure.

Three segments of radiation protection can be seen above the reactor. When used near biological objects, the protection should be all-round. This increases the mass of the installation at times. In an inactive state, the reactor is practically not radioactive - the background is less 1 Curie. The reaction starts after the rod is extended as described above. Therefore, unsuccessful missile launches will not pollute the ocean or land.

Reactor video KiloPower:

Can this technology and reactor be used for earthly needs? In theory, yes. For example, in the Arctic, in the mountains at remote bases or in underground or underwater autonomous objects. With up to 5 replaceable Stirling engines in stock, the service life of the unit can be increased to 50 years. But its cost is still high. The cost of uranium-235 for the reactor - 500 thousand $. And NASA spent on the development and creation of a pilot plant KiloPower $ 20 million.

Therefore, the use of such installations on Earth will be associated with particularly important objects. For individuals, this is too expensive and, due to the threat of misuse, they are unlikely to ever be produced on-line. Or this technology of the distant future.

Previous articles:

Radioisotope thermoelectric generators. Why they will never be available for private use

Compact nuclear power plants for power supply of villages

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