> Some analysts have expressed doubts that the EPR is the world's safest reactor. Their main concern is the spent fuel: The reactor's higher burn-up rate makes the waste more radioactive, raising concerns about proliferation.
They got this exactly backwards. Higher burn-up rate makes the spent fuel even harder to use for nuclear weapons, by screwing up the isotopic mix. The way you make weapons-grade plutonium is to construct special reactors designed for very low burn-up. And then I come to this gem:
> Despite its higher temperature, the reactor operates at one-fifth the power of a PWR. That reduced power density enhances overall safety. What's more, additional heat naturally increases the carbon's ability to absorb neutrons, so the carbon acts as a passive safety mechanism capable of shutting down the core.
First, the power of a reactor depends on its size and power density. Phrases like "one-fifth the power of a PWR" are meaningless. It's confusing power with power density.
Second, they say "additional heat" when they mean "additional temperature". Heat and temperature are completely different things, and you'd think the IEEE would know that.
Third, high temperatures make the non-fissile U-238 in the fuel more likely to absorb neutrons, not the carbon. The carbon is there as a structural component of the fuel, and to act as a moderator to slow down the neutrons.
Finally, it's not so much that it shuts down the core, as that it keeps the core at a roughly constant temperature. If you stop coolant circulation, then sure, the core is going to reduce its power output drastically; in some pebble bed research reactors they do this to turn it off at night. But the true beauty of this negative feedback loop is how it regulates the temperature, not some hypothetical "What if there's a stupendous accident?" application.
>"Because it's a fast reactor, the HPM doesn't consume vast amounts of water, making it attractive for areas where water is scarce or unavailable."
There's no reason a fast reactor should be different from an ordinary LWR in water use. A thermal power plant uses river or ocean water as a heat sink; nothing about a fast reactor changes the thermodynamic need for a heat engine to have a cold reservoir. Of course there's no longer water in the closed loop that cools the reactor core (which is what confuses them?).
No mention of pebble bed reactors[1] either, which is a shame, because AFAIK they are still the only ones that cannot melt down. They produce less energy the hotter they get and one can design them to, for instance, never exceed 1800K. If the cooling system fails, the system simply reaches a steady state at that temperature. There is thorium variety of this reactor.
[+] [-] pjscott|15 years ago|reply
> Some analysts have expressed doubts that the EPR is the world's safest reactor. Their main concern is the spent fuel: The reactor's higher burn-up rate makes the waste more radioactive, raising concerns about proliferation.
They got this exactly backwards. Higher burn-up rate makes the spent fuel even harder to use for nuclear weapons, by screwing up the isotopic mix. The way you make weapons-grade plutonium is to construct special reactors designed for very low burn-up. And then I come to this gem:
> Despite its higher temperature, the reactor operates at one-fifth the power of a PWR. That reduced power density enhances overall safety. What's more, additional heat naturally increases the carbon's ability to absorb neutrons, so the carbon acts as a passive safety mechanism capable of shutting down the core.
First, the power of a reactor depends on its size and power density. Phrases like "one-fifth the power of a PWR" are meaningless. It's confusing power with power density.
Second, they say "additional heat" when they mean "additional temperature". Heat and temperature are completely different things, and you'd think the IEEE would know that.
Third, high temperatures make the non-fissile U-238 in the fuel more likely to absorb neutrons, not the carbon. The carbon is there as a structural component of the fuel, and to act as a moderator to slow down the neutrons.
Finally, it's not so much that it shuts down the core, as that it keeps the core at a roughly constant temperature. If you stop coolant circulation, then sure, the core is going to reduce its power output drastically; in some pebble bed research reactors they do this to turn it off at night. But the true beauty of this negative feedback loop is how it regulates the temperature, not some hypothetical "What if there's a stupendous accident?" application.
[+] [-] uvdiv|15 years ago|reply
>"Because it's a fast reactor, the HPM doesn't consume vast amounts of water, making it attractive for areas where water is scarce or unavailable."
There's no reason a fast reactor should be different from an ordinary LWR in water use. A thermal power plant uses river or ocean water as a heat sink; nothing about a fast reactor changes the thermodynamic need for a heat engine to have a cold reservoir. Of course there's no longer water in the closed loop that cools the reactor core (which is what confuses them?).
[+] [-] Bdennyw|15 years ago|reply
[+] [-] unknown|15 years ago|reply
[deleted]
[+] [-] Confusion|15 years ago|reply
[1] http://en.wikipedia.org/wiki/Pebble_bed_reactor
[+] [-] neutronicus|15 years ago|reply
[+] [-] ars|15 years ago|reply
There are probably a few entities doing research, but I could not find any that actually had a schedule for submittion for approval.