by lpetrich
Just my luck. I found this news story: Mini nuclear plants to power 20,000 homes: £13m shed-size reactors will be delivered by lorry
It seems like the reactor will function as long as it is cooled, so it needs a good coolant system. It can heat 167 kg of water each second by 100 C, something that Hyperion's site leaves out. Scaling down to a 3-megawatt locomotive requires 8 megawatts of heat rejection, or heating 20 kg of water per second by 100 C. This would require a sizable radiator, complete with fans capable of sending a similar mass of air past it each second.
Boiling water requires a heat-energy input of 5.5 times the amount necessary to heat that water from 0 C to 100 C, so the full-size reactor would boil 30 kg of water per second and a locomotive-sized one 3.6 kg/s, a little less than 1 gallon/s. So if the water is allowed to boil, it will reduce the necessary water flux, though not the air flux.
An alternative to using a radiator is to release the steam without trying to recover it, which is what most steam locomotives are designed to do. A nuclear-powered locomotive would thus need an onboard water tank, or else get its water from a water-tank railcar.
I could find nothing in Hyperion's site about how that reactor's electricity is generated, but "no moving parts" suggests that it generates electricity with thermocouples or some similar system. Also, that reactor only needs refueling every 7 to 10 years if in continual use, and it would be sent back to the factory for refueling.
ETA: the Hyperion reactor's design is much like the TRIGA research-reactor design; TRIGA reactors have been used for years, and they have had a good safety record.
Nuclear power plants smaller than a garden shed and able to power 20,000 homes will be on sale within five years, say scientists at Los Alamos, the US government laboratory which developed the first atomic bomb.The company is Hyperion Power Generation, its reactor's size is about 3 m, and its power generation is 70 megawatts of heat and 25 megawatts of electricity. The reactor has some fail-safety built in; uranium in it is combined with hydrogen, making uranium hydride. The hydrogen acts as a "moderator", which slows down the neutrons so that they will react more easily. If the reactor overheats, the uranium hydride decomposes, and the hydrogen departs from the uranium, letting the neutrons through and slowing down the reaction. When the reactor cools down again, the hydrogen and uranium recombine, making uranium hydride again.
The miniature reactors will be factory-sealed, contain no weapons-grade material, have no moving parts and will be nearly impossible to steal because they will be encased in concrete and buried underground.
It seems like the reactor will function as long as it is cooled, so it needs a good coolant system. It can heat 167 kg of water each second by 100 C, something that Hyperion's site leaves out. Scaling down to a 3-megawatt locomotive requires 8 megawatts of heat rejection, or heating 20 kg of water per second by 100 C. This would require a sizable radiator, complete with fans capable of sending a similar mass of air past it each second.
Boiling water requires a heat-energy input of 5.5 times the amount necessary to heat that water from 0 C to 100 C, so the full-size reactor would boil 30 kg of water per second and a locomotive-sized one 3.6 kg/s, a little less than 1 gallon/s. So if the water is allowed to boil, it will reduce the necessary water flux, though not the air flux.
An alternative to using a radiator is to release the steam without trying to recover it, which is what most steam locomotives are designed to do. A nuclear-powered locomotive would thus need an onboard water tank, or else get its water from a water-tank railcar.
I could find nothing in Hyperion's site about how that reactor's electricity is generated, but "no moving parts" suggests that it generates electricity with thermocouples or some similar system. Also, that reactor only needs refueling every 7 to 10 years if in continual use, and it would be sent back to the factory for refueling.
ETA: the Hyperion reactor's design is much like the TRIGA research-reactor design; TRIGA reactors have been used for years, and they have had a good safety record.