Why does the lunar base have to use nuclear power? This time, Ma Jun will talk to you about the nuclear power plant on the moon and see why it should be built and what kind of reactor it should be built.
This problem was mentioned by Ma Jun in an article about nuclear batteries before: The moon is tidal locking by the earth, and its rotation period is the same as that of period of revolution, which is 28 days, that is to say, the moonlit night is half a month long! This is an extremely cold night of MINUS 180 degrees. If you don't want to hibernate, you should not only use electricity, but also provide heat, otherwise it will freeze into a frozen throne! However, the electricity generated by solar energy during the day is basically unable to support the consumption of moonlight and night, or the cost is unbearable. In this case, it is the turn of nuclear energy to do heavy work.
Using nuclear energy to generate electricity on the moon, you can choose to use reactors or isotope batteries. However, the power of isotope batteries is small, and the key point is that materials such as plutonium 238 are really expensive. It is no problem to drive a small device, and it is really unbearable to realize large-scale power generation. Although nuclear reactors are not cheap, uranium fuel is easy to get, and the power can be made relatively large. It is absolutely necessary to supply power to the moon!
But not all reactors can be used on the moon, such as the common pressurized water reactor nuclear power plant, which needs to be replenished frequently and take away the residual heat by air or seawater. These conditions are simply not available on the moon. Therefore, it is necessary to use specially designed space reactors to realize "unsupported" power generation without relying on water supply or cooling conditions.
There are many options for the types of space reactors. At present, the heat pipe reactor is popular, which uses the phase change of liquid metal in the heat pipe to take away the heat from the core and transfer it to the thermoelectric conversion element or Stirling engine to realize the conversion from thermal energy to electrical energy. The thousands of power space reactors in the United States use Stirling engines with relatively high efficiency. Unlike internal combustion engines and steam turbines, this kind of engine is an external combustion engine. Using helium as working medium, it can generate 1 to 10 kW of electricity. You know, the power of the nuclear battery carried by Curiosity is only 125 watts, which is much larger or even larger than the power generated by space reactors.
Intentional netizens will still have questions: no matter which power generation method is used, the efficiency is not high, and there is still a lot of waste heat to be discharged. Nuclear power plants on earth can use air or seawater to discharge waste heat. There is a vacuum on the moon. Where can the residual heat of the reactor be discharged? There is only one way: radiation. According to the law of blackbody radiation, as long as there is temperature, it will radiate heat outward, and the larger the area, the stronger the heat dissipation ability. There is no way to conduct heat in vacuum, so a very large radiation radiator should be built. The greater the power, the larger the radiator. So you will see that there is a huge "mushroom head" in the space pile, which is the radiator.
A friend asked, building a reactor on the moon is too sci-fi, it should be a very distant thing! Ma Jun once thought so, but now things have changed: the United States has begun an ambitious "Artemis" program, which intends to return to the moon in 2024. After all, the United States spent $25 billion on manned landing on the moon in the 1960 s, but now it is suspected of fraud by countless hostages. This evil spirit can't be swallowed. In addition, with the rapid development of space flight in China, NASA began to feel anxious. It would be a shame if China took the lead in manned landing on the moon.
At that time, the Apollo program came here to visit, except that the lunar module worked as a lunar station for several years, leaving nothing behind. This time, the "Artemis" plan is obviously ambitious and will establish a long-term existence on the moon. A few days ago, the United States has signed a memorandum to study space reactors, hoping to build nuclear power plants on the surface of the moon by the end of 2027. In fact, the purpose of building nuclear power plants is to support the lunar base, and once the United States has built a lunar base, it means that it has successfully implemented the good intentions of "staking the land".
Of course, it is not easy to build a lunar nuclear power plant. The launch vehicle needs to do at least two things: the transportation capacity should be large enough and the safety factor should be high enough. KiloPower reactor weighs as much as 1.6 tons, a moon or Mars base needs four, and it needs to be equipped with a lander to land on the surface of the moon, which is very demanding for rockets. More importantly, it contains real nuclear fuel. Once the launch fails and falls to the earth, it will be more than one bargained for! So rockets must be extremely reliable. At present, the SLS giant rocket built by NASA to return to the moon has gradually taken shape. Maybe in a few years, there will be real nuclear power plants on the moon! So the question is, should China follow suit?