Nuclear
Friday 4th August, 2006 11:58 Comments: 0
On today's letters page of The Register:
Counting the true cost of nuclear waste:
"The cost to the taxpayer of storing the waste, both short and long-term, is likely to be around £70bn over the next 40 years."
I wonder if they have factored in the cost of instituting and running a monitoring system for the next 100,000 years or so that it will take the radioactive waste to become safe. We wouldn't want it leaking into groundwater after 10,000 years because the gradual depredations of water corroded the containers and no-one noticed.
Tricky to cost though, I suppose. To get a sense of the time spans we're talking about, consider that 100,000 years ago Britain was buried beneath an ice sheet during (if memory serves) the last but one glacial period and modern human beings hadn't evolved yet.
Devising a storage facility that will be safe for that time period poses one or two technical challenges. Have we considered the geological changes that will be wrought by the next ice age and the implications for any post-glacial civilisation that will colonise Britain. Can we make warning signs that will last that long, or that will be intelligible to whatever intelligent species is around then?
Richard
I must admit, I hadn't looked into it before, but I was fairly certain that 100,000 years was a bit extreme. A quick Google later (so this may be slightly out?) and it looks like:
Final disposal of high-level waste is delayed to allow its radioactivity to decay. Forty years after removal from the reactor less than one thousandth of its initial radioactivity remains, and it is much easier to handle. Hence canisters of vitrified waste, or spent fuel assemblies, are stored under water in special ponds, or in dry concrete structures or casks for at least this length of time.
After being buried for about 1,000 years most of the radioactivity will have decayed. The amount of radioactivity then remaining would be similar to that of the naturally-occurring uranium ore from which the fuel originated, though it would be more concentrated.
To ensure that no significant environmental releases occur over periods of tens of thousands of years after disposal, a 'multiple barrier' disposal concept is used to immobilise the radioactive elements in high-level (and some intermediate-level) wastes and to isolate them from the biosphere.
I'm not a mathematician, but 1,000 years is a lot less than the 100,000 that Richard mentions in his letter. Scaremongerer.
PS There's meant to be an example in nature to suggest that final disposal of high-level wastes underground is safe. Two billion years ago at Oklo in Gabon, West Africa, chain reactions started spontaneously in concentrated deposits of uranium ore. The reactions continued for hundreds of thousands of years forming plutonium and all the highly radioactive waste products created today in a nuclear power reactor. Despite the existence at the time of large quantities of water in the area, these materials stayed where they were formed and eventually decayed into non-radioactive elements.
Counting the true cost of nuclear waste:
"The cost to the taxpayer of storing the waste, both short and long-term, is likely to be around £70bn over the next 40 years."
I wonder if they have factored in the cost of instituting and running a monitoring system for the next 100,000 years or so that it will take the radioactive waste to become safe. We wouldn't want it leaking into groundwater after 10,000 years because the gradual depredations of water corroded the containers and no-one noticed.
Tricky to cost though, I suppose. To get a sense of the time spans we're talking about, consider that 100,000 years ago Britain was buried beneath an ice sheet during (if memory serves) the last but one glacial period and modern human beings hadn't evolved yet.
Devising a storage facility that will be safe for that time period poses one or two technical challenges. Have we considered the geological changes that will be wrought by the next ice age and the implications for any post-glacial civilisation that will colonise Britain. Can we make warning signs that will last that long, or that will be intelligible to whatever intelligent species is around then?
Richard
I must admit, I hadn't looked into it before, but I was fairly certain that 100,000 years was a bit extreme. A quick Google later (so this may be slightly out?) and it looks like:
Final disposal of high-level waste is delayed to allow its radioactivity to decay. Forty years after removal from the reactor less than one thousandth of its initial radioactivity remains, and it is much easier to handle. Hence canisters of vitrified waste, or spent fuel assemblies, are stored under water in special ponds, or in dry concrete structures or casks for at least this length of time.
After being buried for about 1,000 years most of the radioactivity will have decayed. The amount of radioactivity then remaining would be similar to that of the naturally-occurring uranium ore from which the fuel originated, though it would be more concentrated.
To ensure that no significant environmental releases occur over periods of tens of thousands of years after disposal, a 'multiple barrier' disposal concept is used to immobilise the radioactive elements in high-level (and some intermediate-level) wastes and to isolate them from the biosphere.
I'm not a mathematician, but 1,000 years is a lot less than the 100,000 that Richard mentions in his letter. Scaremongerer.
PS There's meant to be an example in nature to suggest that final disposal of high-level wastes underground is safe. Two billion years ago at Oklo in Gabon, West Africa, chain reactions started spontaneously in concentrated deposits of uranium ore. The reactions continued for hundreds of thousands of years forming plutonium and all the highly radioactive waste products created today in a nuclear power reactor. Despite the existence at the time of large quantities of water in the area, these materials stayed where they were formed and eventually decayed into non-radioactive elements.