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assemblies. So, initially they start out in the reactor, they move to the spent fuel pool, after five
<br /> years, you have the option — not a requirement, but the option to move them into dry casks.
<br /> So, that's where the fuel assemblies are. Where are they vulnerable? Well, they
<br /> are vulnerable when they are in the reactor core, they're vulnerable when they are in the spent
<br /> fuel pool, and they're vulnerable when they are in dry casks. I'm going to talk a little bit about
<br /> what those vulnerabilities are. They are vulnerable from the outside or from the inside. They
<br /> are vulnerable to external forces that can break apart the metal tubes and cause the radiation to
<br /> be released. They are also vulnerable from internal forces that can cause the metal tubes to
<br /> heat up, overheat, and be damaged from that way. The difference is kind of like what happened
<br /> on 9/11. Two jets hit the World Trade Center, but it was not the impact from the jets that
<br /> toppled the towers, it was the burning of the jet fuel that weakened the steel girders that caused
<br /> the collapse. So, the external forces would have been if the towers were knocked over by the
<br /> jet impact, the internal forces are the follow up effects that can happen later on. I'm going to talk
<br /> a little bit about how those follow up effects can affect the fuel assemblies. The external forces
<br /> are pretty simple, they are the blasts from an explosive device that can cause the fuel rods to
<br /> break open, also if they are hit by bullets. Any outside force can break them apart. There is
<br /> some protection; I don't want to make them sound too vulnerable. The internal forces are
<br /> basically the heat that is produced by the unstable byproducts when they decay. They release
<br /> radiation and they also release a large amount of heat. That heat continues to be hot enough to
<br /> cause either meltdown or fire for many years after the fuel is taken out of the reactor core. The
<br /> problem does not stop when it is taken out of the reactor core. So, those are the internal forces,
<br /> whether they are in the reactor, spent fuel pool, or in dry casks.
<br /> How can these internal forces affect the fuel when they are in the reactor core?
<br /> This is a schematic of a plant like Shearon Harris. You'll see that there are a number of safety
<br /> systems to provide cooling for this reactor core. If something were to disable the control room,
<br /> where all the instruments are controlled, then the system stops working. It is kind of like the
<br /> brain, if you knock out the brain, it does not really matter if the heart and the liver and everything
<br /> else are functional. If you knock out the brain then the body does not have a long period of
<br /> time. A nuclear power plant is the same way, if you are able to knock out the control room, the
<br /> plant timeline is not long. Once you move the fuel assemblies to the spent fuel pool, they are
<br /> also vulnerable to internal forces. The water in the spent fuel pool must be continuously cooled;
<br /> otherwise it heats up, overheats, and causes damage to the pool. If that water disappears for
<br /> any reason, if you crack the side of the pool, allow the water to drain out, that in itself does not
<br /> cause the fuel to be damaged, but the internal forces will lead to that fuel being overheated and
<br /> damaged due to either meltdown or fire. Likewise, the dry casks, normally it is a passive
<br /> system and there are no moving parts, if everything is working right. If the outside surface of
<br /> the container is ruptured, it allows air to get inside or damage, then the cooling mechanism for
<br /> the cask can be disrupted and the fuel inside can overheat and be damaged.
<br /> A couple of things I would like to point out here is that when the fuel is in the
<br /> reactor, it is protected against sabotage and terrorist attack as long as the terrorists come by
<br /> ground. If they fly in, it is not protected. But if they do not have an airplane, it is somewhat
<br /> protected; although Dr. Lyman will talk about some of the deficiencies in that protection. Once
<br /> the fuel moves to the spent fuel pool or to dry casks, the security protection drops off. It is really
<br /> not protected in the spent fuel pool, because it is never tested to ensure that security is
<br /> adequate. When it moves to the dry casks, it is never even considered, let alone tested. The
<br /> good news is that the number of fuel assemblies, the amount of materials that is able to be
<br /> released is least when it is in the dry casks; it is most when it is in the spent fuel pool. At
<br /> Shearon Harris, the reactor core contains 157 fuel assemblies. The spent fuel pools contain
<br /> 4,000 fuel assemblies, or five times as much. The dry casks hold less than 50. So if there is a
<br /> successful attack or sabotage, you have 157 things releasing radiation, 4,000 things releasing
<br /> radiation, or less than 50, unless you damage more than one cask. As Jim Warren is fond of
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