- #1
artis
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While reading about neutron interactions in a book I noticed that there is some amount of fast fission going on even in a thermal reactor with a water moderator/coolant. So essentially after each neutron that survives to the thermal range and manages to produce a fission event , on average 2 to 3 neutrons are born which at the first moment are born as fast neutrons of course.
Some of these fast neutrons before they leak out of the fuel manage to cause some fast fission events in the very fuel , after all they haven't been slowed down by scattering in the moderator yet.
Ok so theory aside here is my question/scenario.
Leaving out the practical aspects of engineering and more on a theoretical note.
Imagine a box filled with U fuel plates like the plates of a parallel plate capacitor, between each plate is a separation distance.
The plates and the distance between them are arranged such that each fuel plate is 2x as thick as each separation distance.
So let's say 1cm for fuel plate and 0.5cm for separation.
The separations are filled with water that acts as moderator/coolant. Now the idea is to have a 2:1 fuel to moderator ratio or thereabout , or in other words so that each fast neutron born in one fuel plate wouldn't get slowed down as fast before it enters at least 2 or 3 more adjacent fuel plates while still being "fast".
For this to happen the water layers between fuel plates need to be as thin as possible.
At the same time each fast neutron born in a fuel plate would either produce a fast fission in adjacent fuel plates or get slowed down whgile passing through more plates and water separations and become a slow neutron producing thermal fission. The way in which one could cool a reactor like this with such low water content is to say increase the flowrate of water through the box of plates , and allow the water to turn to steam at the end where it could be direct to a turbine , maybe even directly to a turbine very close by.
The only thing I'm not sure is whether the decrease in steam output temp would be compensated by the much larger amoutn of steam produced from the high flowrate and vaporization of the steam.
Just interested to hear has something like this been ever attempted in any form and is it even possible to produce a reactor which could utilize both thermal fission and fast fission at any considerable ration?
Some of these fast neutrons before they leak out of the fuel manage to cause some fast fission events in the very fuel , after all they haven't been slowed down by scattering in the moderator yet.
Ok so theory aside here is my question/scenario.
Leaving out the practical aspects of engineering and more on a theoretical note.
Imagine a box filled with U fuel plates like the plates of a parallel plate capacitor, between each plate is a separation distance.
The plates and the distance between them are arranged such that each fuel plate is 2x as thick as each separation distance.
So let's say 1cm for fuel plate and 0.5cm for separation.
The separations are filled with water that acts as moderator/coolant. Now the idea is to have a 2:1 fuel to moderator ratio or thereabout , or in other words so that each fast neutron born in one fuel plate wouldn't get slowed down as fast before it enters at least 2 or 3 more adjacent fuel plates while still being "fast".
For this to happen the water layers between fuel plates need to be as thin as possible.
At the same time each fast neutron born in a fuel plate would either produce a fast fission in adjacent fuel plates or get slowed down whgile passing through more plates and water separations and become a slow neutron producing thermal fission. The way in which one could cool a reactor like this with such low water content is to say increase the flowrate of water through the box of plates , and allow the water to turn to steam at the end where it could be direct to a turbine , maybe even directly to a turbine very close by.
The only thing I'm not sure is whether the decrease in steam output temp would be compensated by the much larger amoutn of steam produced from the high flowrate and vaporization of the steam.
Just interested to hear has something like this been ever attempted in any form and is it even possible to produce a reactor which could utilize both thermal fission and fast fission at any considerable ration?