by Sue Prent
When it comes to storage of spent nuclear fuel, the countries choosing to operate nuclear power plants are stuck between a rock and a hard place.
More than 50 years after the civilian population was persuaded to accept nuclear energy as a safe way to power modern living and commerce, nuclear scientists throughout the world have been unable to uncover a viable technological solution to the escalating problem of lethal nuclear waste.
According to a 2012 Congressional report, 67,000 metric tons of spent nuclear fuel is being “managed’ on-site at 77 different U.S. reactors. And with no solution in sight, another 2,000 metric tons is currently being added every year.
While the fission process inside a nuclear reactor releases the radioactive potential of the uranium pellets in the fuel, what goes into the reactor comes out as a lethal cocktail of radioactive rubble millions of times more radioactive than the original fuel. Here we are generating the most lethal material on earth and blithely creating it by the metric ton simply to run our air conditioners and heat our swimming pools and Jacuzzi’s.
There is no magic process by which we can make this mountain of highly radioactive waste simply disappear. The nuclear industry and government have failed to create a permanent waste repository. The government’s plan had been to bury this highly toxic nuclear waste very deep within the earth, but those plans came to a standstill due to hazards created by seismic instability, the real potential for radioactive contamination of precious aquifers, and significant citizen opposition.
So now, we are left with only two choices: allow the highly toxic spent fuel to remain indefinitely in the unshielded and overloaded spent fuel pools, or remove the partially cooled fuel as soon as it is cool enough to move and place it into onsite dry cask storage.
Do we really have much of a choice?
Even though the nuclear chain reaction is finished, the radioactive waste and rubble left behind remains hot. Preventing a nuclear meltdown in a spent fuel pool depends entirely on successfully maintaining the spent fuel pool-cooling bath of water, 24-7, for as long as the fuel remains in the pool. Under arbitrary NRC approvals that have saved the energy companies millions of dollars, spent fuel has already remained in pools for many, many decades so that the pools now hold more fuel than they were designed to hold. These jammed past capacity fuel pools create a number of possible scenarios, including operator error, mechanical failure, terrorist action and a host of outside forces that could compromise the ability of the spent fuel pool to keep the fuel cool thereby creating a fuel pool fire or meltdown I mentioned earlier.
For instance, at the Dresden Unit 1 reactor in Illinois, pipes froze and broke in the abandoned plant and drained the spent fuel pool of 60,000 gallons of precious cooling water. Over in Michigan, an errant raccoon once caused loss of power to the cooling pumps at the Fermi reactor. The likelihood of such wildlife misadventures increases substantially once a stand-alone reactor has been retired but left in the SAFSTOR mode as proposed for the Vermont Yankee plant. [Think grammar school English for pronunciation and read SAFSTOR like Sapstor, not the NRC nukespeak moniker that tries to make a 60-year sitting carcass appear safe.]
Some reactors, and again, Vermont Yankee is one of those, have their spent fuel pool positioned above the ground – five stories above –, leaving them at particularly high risk as targets for an airborne terrorist attack.
What then is the alternative?
Disturbingly, in the absence of any real possibility for entombment deep in the earth’s rocky substrata, dry cask storage has emerged as the only remaining solution. While it removes the necessity of perpetually keeping the spent fuel water-cooled, it comes with its own set of alarming problems.
There are many components to a dry cask storage system, any one of which has unique potential for errors or defects.
- The integrity of cask materials and their design and construction are a troublesome issue.
- Quality control can suffer under the pressure of tight work deadlines and cost constraints.
- Fleet buys that save corporations money may mean that a lesser quality cask or one not entirely appropriate for the storage site is used rather than one designed to protect the surrounding community.
The strength of concrete very much depends on high quality components and achieving a perfect chemical balance in the slurry; and some casks have been discovered as defective in that department. If the defects are only discovered after the fuel loading has begun, it is not a simple matter to reverse the loading process and return the fuel to the spent fuel pool. Doing so introduces a number of new risks of radiation releases and toxic contamination of the surrounding communities.
As for the long-term viability of concrete casks, the nuclear reactor containment systems themselves are showing early signs of concrete degradation due to an area’s salt, mineral, or moisture content. And the question remains as to what consequences may result from undetected concrete failure in loaded casks.
There have already been occasions when serious design flaws in the casks have only been discovered during loading; once rather spectacularly when a chemical explosion occurred inside the cask. Other mishaps have involved loose bolts, faulty o-rings, flaws in the neutron shielding material, cracked welds, etc.
Most recently at the Waste Isolation Storage Pilot Project in New Mexico, plutonium waste that had been properly packed for long-term storage and according to existing protocols, was discovered to haveexploded into the storage environment. When the protocols were reviewed to determine what might have caused the explosion, the most likely culprit was a change in the type of kitty litter that had been used as an absorbent.
It is thought that this kitty litter change may have triggered a chemical reaction that “blew” the seal on a canister sitting in storage.
Mistakes do happen, and they seem to happen more frequently in this aging industry that still, after 60-years, has no viable or workable long-term waste storage technology at hand.
Even the weight of the casks that runs to more than 100 tons each when fully loaded, represents a hazard; particularly in the case of reactors that have their spent fuel pools located five stories above the ground, as is the case at Vermont Yankee.
The loading process for retrieving the fuel from the spent fuel pool and securing it in the dry cask necessarily involves lowering the cask into the pool and then raising it out again once it has been fully loaded, drained and welded shut. The work must be done in the presence of all the other exposed fuel assemblies, so it is rife with hazards.
A slip of the loading gear, due to operator error or mechanical failure, could cause the cask to suddenly drop, sending all that weight crashing through the fuel pool with tremendous force, damaging fuel assemblies, destroying equipment, and breaching the water-tight containment. The result would most certainly be massive radiation release, with or without accompanying explosion and fire. The brake on the crane at Vermont Yankee failed several years ago… luckily the cask did not crash and damage other fuel or the pool itself. These aforementioned hazards are real, not made up.
The casks themselves have a limited life expectancy. If they cannot be consigned to deep earth entombment within the design life of the component parts, the spent fuel rods must be moved into new dry cask containers, which would involve a number of new risks for which no procedures or protocols exist.
Cask storage would represent more of an obstacle to terrorist exploitation than would storage in a spent fuel pool. However, if the goal was contamination rather than theft, even the strongest casks could be breached with high velocity armor piercing 50 caliber shells available on the Internet.
When you read that the NRC has determined that onsite cask storage is a safe method of spent fuel management, it must be understood that this is more of an actuarial judgment than an absolute scientific or engineering fact.
The NRC has simply weighed what it believes is the relatively small likelihood that a cask might be breached, or that a radiation release will occur due to an industrial accident or structural flaw, against the harsh reality that there truly is no other alternative for the hundreds of thousands of tons of spent fuel that the energy corporations have already accumulated.
We the people are powerless to change that bitter truth, but we have it within our power to draw a line under nuclear hubris, and promise our great-grandchildren that we will add no more to their toxic legacy.