The zirconium cladding which encloses the fuel pellets that were used at San Onofre (and every other light water nuclear reactor in America) will continue to degrade even after the fuel rods are crammed into their "dry casks", which are then welded and/or bolted shut and -- if the nuclear industry has its way -- forgotten about (until something goes wrong).
The loss of cladding integrity is a serious failure the nuclear industry needs to face, because a permanent solution to the waste problem is NOT on the horizon, but the fuel cladding degradation is very much on the horizon, and the horizon is getting closer every day.
The cladding may NOT degrade "gracefully," meaning, we may not see the failure coming, and won't be able to do anything about it until it happens. The nature of brittle-failure is that once a crack grows past a certain size it becomes dangerous. That size is unknown without lots and lots of testing, and each rod will behave differently. As the cracks form, stresses change throughout the rods.
Failure of even ONE rod among the hundreds of thousands of fuel rods can lead to a cascade effect and would be a significant environmental problem on its own. That cask would have to be resubmerged, opened, and the damaged fuel rod(s) "canned." "Canning is a process which isolates each fuel assembly (of approximately 150 fuel rods). But "canning" requires taking up additional space inside the dry cask. It also changes the thermal properties, and costs additional money to implement. Normally only fuel that is already obviously damaged in some way gets "canned." Without canning, fuel accumulations due to failed fuel rods have a greater potential to form a critical quantity.
Also, any radioactive releases that would have been kept in the can will escape into the rest of the dry cask and possibly out the cask's vents (yes, these casks have vents). A radioactive release inside the dry cask will also make handling that fuel in the future more difficult.
We could see, several decades down the road or maybe tomorrow, that all the fuel that seemed fine is now starting to crack. Failure rates can increase exponentially because small cracks are both harmless and invisible to the naked eye (not that you could get a naked eye close to a spent fuel rod without dying long before you got close). Over long periods of time, temperature has an enormous effect on fuel cladding integrity. With dense packing and mixing high burnup fuel with low burnup fuel, the average temperature of the oldest fuel will be significantly higher than it otherwise could be if the high burnup fuel were kept in the spent fuel pools longer and/or packed less densely.
Cracks tend to grow at roughly the same rate under the same conditions, so the fuel that is in the dry casks the longest is normally the fuel that is the most worrisome. However, some damage also is done in the pools and some occurs in the reactor during operation so the exact state of each fuel rod cannot be decided without very careful non-destructive testing and accurate estimating of the heat loads during operation and while inside the pools and the dry casks. Southern California Edison does not want to do ANY of this sort of testing. They just want to accept dry cask industry estimates as fact.
It appears that the reason Edison set up the Citizens advisory committee (known as the C.E.P.) is so that a few hand-picked elected officials and others, including one activist (Gene Stone of R.O.S.E.) among 18 members, will have a hand in rejecting expensive solutions to the problem, and will keep demanding someone, somehow, move the waste away from SoCal "as soon as possible." It is a hollow demand. There will never be, on this earth, a safe place to store nuclear waste (nor is there a safe or cost-effective way to get it into outer space, beyond earth's debris field). There will never be an energy efficient (and safe) way to neutralize all of the nuclear waste, even if some portion of it can be reused or reprocessed or fed into a breeder reactor or transmuted or anything. These problems are terminal and are not going away.
Stopping nuclear power is the #1 thing everyone should do.
Below is a transcript of a nuclear fuel suggestion by a friend of mine, a metallurgist who worked at the International Atomic Energy Agency, PSE&G, Westinghouse, etc.. for many years before a head injury put him on disability several decades ago.
Every suggestion I have heard for improving the storage of spent nuclear fuel costs enormous amounts of money. Earthen berms between each cask would enhance safety, as would thicker cement sarcophaguses, not to mention rebar. Less fuel in each cask enhances safety in some ways, but means there are many more dry casks. Not one of these questions is easy to answer, but the fact is: Southern California Edison's dry cask solutions are notorious. They will be the death of southern California if an airplane strikes them, or a terrorist.
During war, our pilots learn not to line up their airplanes in a row if the enemy is near, for example alongside the runway, because then one enemy fighter plane, in one straffing pass, can destroy an entire row of airplanes (this happened to our land-based bombers at Pearl Harbor). At San Onofre with our dry cask storage system, we have the same situation: Everything all lined up and packed in tight, UNDER MAJOR AIRLINE ROUTES, just a few miles from an open airstrip, and just a few hundred feet from rail, truck and passenger traffic to the tune of hundreds of thousands of trips per day.
To the best of my knowledge, San Onofre's dry cask storage system is the tightest-packed dry cask system anywhere in the country -- but all dry cask "farms" are as compact as possible. This decreases the "target size" for a terrorist but increases the damage if an airplane falls on it accidentally or on purpose. Nuclear waste needs to be stored either underground or under "no fly" zones. San Onofre's nuclear waste is neither.
This is an outrageous situation, but what can be done about it? Move the waste? To where? One activist, Roger Johnson, suggests the Chocolate Mountains military range as a temporary location, on the California border with Arizona. Personally, I do not believe a temporary solution is useful; it just enables the nuclear industry to claim that there is some solution at all! More useful is to point out to Diablo Canyon's local community (and Palo Verde's and others) that storing old nuclear waste isn't any fun, and the less of it, the better. Furthermore, we should make sure it's clear that storing it is going to be a lot more expensive than ANYONE had ever expected, and the cost will go up significantly with each new fuel rod accumulated at the site. Who's going to be paying for our waste to be stored when we are all dead and buried, and even our children, and our children's children, are all gone?
There is no solution but shutdown. Before anyone can properly even think about what to do with the waste, we need to shut down the operating reactors -- the waste production facilities. Prior to shutdown, the waste is a hidden part of the nuclear industry. Now, here in southern California, it's all we have, and we need to do SOMETHING with it.
Nuclear waste problems have been ignored for about 70 years, but now southern Californian residents are forced to grapple with the problem.
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