3 ms·
I think one of the most promising reactors in this area is the untegral molten salt reactor. It operates at low pressures, is passively cooled and has already m
by xorfish 7y ago
I think one of the most promising reactors in this area is the untegral molten salt reactor. It operates at low pressures, is passively cooled and has already mounted some regulatory hurdles.
- pfdietz 7y agoAnd if you let the fuel salt cool off enough, the radioactivity in it makes fluorine gas. Yum!
- xorfish 7y agoWhy would the radioactivity make fluorine gas?
- pfdietz 7y agoRadiolysis. https://www.osti.gov/servlets/purl/4109510 https://www.osti.gov/servlets/purl/4109510 The MSR saw some of the fluorine react with UF4 to make UF6, which is volatile. There is the potential for fuel to be volatilized and transported elsewhere in the reactor system, causing possible concern for criticality accidents.
- xorfish 7y agoApparently this only happens if the salt gets below 80°C. A temperature that the salt would reach around a year after every external heating is turned of. At this time the radioactivity will also be much lower. Furthermore uranium 235 has a very long halve life and radiates very little.
- pfdietz 7y agoYes, but consider what this means: in a MSR, reprocessing is not optional. Unlike a conventional oxide fueled reactor, the spent fuel cannot just be stored and ignored. So the cost of reprocessing has to be paid, even if it's not otherwise economically advantageous to have reprocessed the fuel, as it is not for today's reactors.
- xorfish 7y agoI don't understand the full implication of it. What exactly is the problem when a sealed used core starts to have some small quantities of UF6?
- pfdietz 7y agoThere are two implications. First, the free fluorine will cause corrosion of the structure in which the spent salt is stored. Second, this UF6 will be enriched, possibly mostly 233U if this is a thorium cycle reactor. If that condenses out somewhere you can achieve a critical mass. Unintentional nuclear chain reactions in spent fuel are a total no-no.
- xorfish 7y agoI mean it happens very slowly and only if the spent fuel is kept below 80° C. The vast majority of the waste decays in the first few years. This seems to be such a non-issue. Furthermore the IMSR isn't a thorium cycle reactor.