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lighthouse1234
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Are spent fuel rods radioactive and are the spent fuel rods cooling pools discharging radioactive water (tritium) into the environment?
Sure.lighthouse1234 said:Are spent fuel rods radioactive
There is nearly no tritium in the spent fuel pools, and the water is not getting into the environment unless there is an accident. There is no chain reaction happening in the spent fuel pool so the neutron flux is small. Traces of tritium can come from the fuel rods.lighthouse1234 said:and are the spent fuel rods cooling pools discharging radioactive water (tritium) into the environment?
Yes. Spent or used fuel contains the unused fuel, the fission products (2 atoms per fission), and the transmuted fuel and non-fuel components. In the early years of commercial nuclear energy, the fuel was discharge with burnups (GWD/tU) of about 25-33 GWd/tU, or roughly 2.5-3.3% FIMA (fissioned initial metal (U) atoms). In modern times, discharge burnups are at least 2x greater, with batch burnups being something like 50-60 GWd/tU (or 5 to 6% FIMA). Since there are regulatory/statutory limits on peak rod burnup, or peak pellet burnup, the actual discharge burnup is slightly less, although technically, the fuel could continue to higher burnups. Within a batch of fuel, there is a relatively broad range of burnup due to the axial and radial gradients in the core/fuel, with the most severe gradients being on the periphery of the core (typically one row in from the outermost assemblies and the corner assemblies in a PWR). The BWR situation is more complicated because control elements, which are inserted part-time in the core during operation for reactivity control, cause local radial and axial gradients in the fuel closest to the control elements (control blades).lighthouse1234 said:Are spent fuel rods radioactive
In the early days of the industry, before wide use of Zr alloys (Zircaloy-2 (in BWRs) and Zircaloy-4 (in PWRs)), cladding was often made of 304, 347 and 348 stainless steel. Tritium from fission would leak out of the fuel rods into the coolant, and into the spent fuel pool following discharge. Some older plants have had issues with tritium in ground water onsite. Since tritium decays over time (half life ~12.3 years), a lot of the tritium from 50-60 years ago has decayed, and otherwise at very low levels, generally less than regulatory limits.lighthouse1234 said:are the spent fuel rods cooling pools discharging radioactive water (tritium) into the environment?
I provided the context of LWR (both PWR/VVER and BWR), since that is the greatest volume of spent fuel in the US and Eu, but that could apply to CANDU. AGR and Magnox fuel is similar, but different, and of course there are fast reactor fuels and research reactor fuels.harborsparrow said:"Spent fuel rods" from exactly what kind of reactor? See https://en.citizendium.org/wiki/Nuclear_power_reconsidered for some of the options. A discussion without knowing exactly what reactor is kind of, well, makes me wonder.
Astronuc said:I provided the context of LWR (both PWR/VVER and BWR), since that is the greatest volume of spent fuel in the US and Eu, but that could apply to CANDU. AGR and Magnox fuel is similar, but different, and of course there are fast reactor fuels and research reactor fuels.
New fuel designs using different materials will have certain unique issues.
Thanks, I did not know this.Grelbr42 said:They then store it as metal hydrides. Canadian policy is we can't sell it to any country with a weapons program, so most of it is just sitting and decaying in storage.
The decay product 3He is quite valuable.Grelbr42 said:Canadian policy is we can't sell it to any country with a weapons program, so most of it is just sitting and decaying in storage.
You are correct. And there is apparently new needs for this isotope due to such things as fusion research, just for one. And, if I recall correctly, something about detectors for certain chemicals. (He deliberately avoids sensitive search terms. Having various nuclear things attached to my name is enough.)Astronuc said:The decay product 3He is quite valuable.
3He has interesting physical properties. It diffuses faster than 4He, and it is very hard to contain, unless in a hermetically sealed container.Grelbr42 said:However, I am unable to report what happens to the decay product. You have scratched my interest so I am going to ask around.
3He is the decay product (of tritium). It's used for refrigeration, neutron detectors, medical imaging and more.Grelbr42 said:However, I am unable to report what happens to the decay product.
I think the question was not about the general use of 3He, but whether it's actually collected at the deposit site.mfb said:3He is the decay product (of tritium).
When I lived in New England, I wanted to mix the pellets with asphalt and pave my driveway. No more shoveling!bob012345 said:To paraphrase Madison, if men were angels we could use spent fuel rods to power our cars.
Perhaps like in The Day of the Triffids.Vanadium 50 said:And the runoff into your garden would produce rare and interesting foliage.
Probably not.bob012345 said:To paraphrase Madison, if men were angels we could use spent fuel rods to power our cars.
Well, it was meant as humor but afterwards I thought cars require too much power but houses don't so from now on I'll downgrade my joke to say houses.Grelbr42 said:Probably not.
Immediately after the reactor shuts down, the decay heat is some few percent of the power of the reactor. In the range of 3 percent or so, depending on the specific design. Within a few minutes this has fallen to less than 1 percent. After a week it is down to less than 0.2 percent. It continues to decay after that, with the shorter lived isotopes gone, and the longer decaying at lower power.
A (very roughly) 50 kg fuel bundle from a CANDU is in the range of 500 kW during operation is down to 10 kW inside of a week after reactor shutdown. And it continues to fall as the isotopes decay.
If you wanted to run a steam engine and get 100 horse-power out, and putting in an arbitrary 30% efficiency, you would need round-about 1100 kg of fuel alone. That's over half the weight of a Tesla model S.
Plus the boiler and pistons and such. Plus some shielding to protect you from your fuel. And a Tesla S has either 695 hp or 1000 hp, depending on the specific configuration.
So, probably not going to be using spent fuel to power cars.
Yes, spent nuclear fuel rods are highly radioactive. They contain a mix of fission products, transuranic elements, and other radioactive isotopes that continue to emit radiation long after the fuel has been used in a reactor.
Spent nuclear fuel rods emit a variety of radiation types, including alpha particles, beta particles, and gamma rays. The gamma rays are particularly penetrating and require substantial shielding to protect human health and the environment.
Spent nuclear fuel rods remain radioactive for thousands of years. While the intensity of the radiation decreases over time, some isotopes have very long half-lives, meaning they will continue to pose a hazard for many generations.
Spent nuclear fuel rods are initially stored in large pools of water, known as spent fuel pools, which provide both cooling and radiation shielding. After cooling for several years, they can be transferred to dry cask storage, where they are encased in robust containers designed to contain radiation and prevent environmental contamination.
Yes, spent nuclear fuel rods can be reprocessed to extract usable materials such as plutonium and uranium, which can be fabricated into new fuel rods. However, the process is complex, expensive, and raises proliferation concerns. Some countries, like France, actively reprocess spent fuel, while others, like the United States, currently do not.