Design of nuclear power propulsion system for interplanetary flights
In the news, the following scheme of a nuclear electric missile tug is often encountered.
Most likely, drawing, as they say, in the artist's imagination, with physics and reality has little in common.
The main elements of space nuclear power plants include protection from the radiation of a nuclear reactor. How, I hope, most people know that when a uranium nucleus decays, 2-3 neutrons are formed. For further reaction, only one is needed, so 1-2 neutrons fly free into space. Plus other radiation. The outer space does not care, but the payload is not at all, especially if it is people. Hence the first requirement: protection is needed mainly for the payload.
It is also known that the withdrawal of any mass into Earth orbit is very expensive. A kilogram there is more than a kilogram of gold here. The best material to protect against radiation - lead - is not easy. Requirement two: the protection layout should ensure a minimum of its mass.
Based on our requirements, the optimum mass and degree of protection will be at the truncated cone.
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The mass of protection depends on the volume, where: the thickness directly depends on the distance to the payload, the shape of the angular size.
The first conclusion: there is no point in the arrangement of engines on a cruciform base. It is more logical to mark them on the circle.
It is desirable to remove the payload as much as possible, but not enough to get electricity, you need to transfer it to the engines. The megawatt is often mentioned. For example, take a household electrical network. For transmission of approximately 5 kW, copper wire with a cross section of 2.5 mm 2 is used . Accordingly, for a megawatt you need 200 times more - 500 mm 2 . With a length of 20 meters to weigh such entries will be almost 100 kg, but you need two of them. Plus, other difficulties like the extension of the structure after the launch into space. Immediately add that to reduce the current could increase the voltage, but in proportion to increase the mass of the insulation.
The second conclusion: there is no need to place the engines in the butt end of the planet.
And here is the optimal scheme of the entire system.
Most likely, drawing, as they say, in the artist's imagination, with physics and reality has little in common.
The main elements of space nuclear power plants include protection from the radiation of a nuclear reactor. How, I hope, most people know that when a uranium nucleus decays, 2-3 neutrons are formed. For further reaction, only one is needed, so 1-2 neutrons fly free into space. Plus other radiation. The outer space does not care, but the payload is not at all, especially if it is people. Hence the first requirement: protection is needed mainly for the payload.
It is also known that the withdrawal of any mass into Earth orbit is very expensive. A kilogram there is more than a kilogram of gold here. The best material to protect against radiation - lead - is not easy. Requirement two: the protection layout should ensure a minimum of its mass.
Based on our requirements, the optimum mass and degree of protection will be at the truncated cone.
')
The mass of protection depends on the volume, where: the thickness directly depends on the distance to the payload, the shape of the angular size.
The first conclusion: there is no point in the arrangement of engines on a cruciform base. It is more logical to mark them on the circle.
It is desirable to remove the payload as much as possible, but not enough to get electricity, you need to transfer it to the engines. The megawatt is often mentioned. For example, take a household electrical network. For transmission of approximately 5 kW, copper wire with a cross section of 2.5 mm 2 is used . Accordingly, for a megawatt you need 200 times more - 500 mm 2 . With a length of 20 meters to weigh such entries will be almost 100 kg, but you need two of them. Plus, other difficulties like the extension of the structure after the launch into space. Immediately add that to reduce the current could increase the voltage, but in proportion to increase the mass of the insulation.
The second conclusion: there is no need to place the engines in the butt end of the planet.
And here is the optimal scheme of the entire system.
Source: https://habr.com/ru/post/395437/
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