Tuesday, May 15, 2012

Kodak's Nuclear "Reactor" Explained

Correction: This blog post originally stated that Kodak's nuclear device was a nuclear reactor as was widely reported. This can be misleading. The device increased the output of neutrons from a radioactive source, but there was not enough material to initiate a chain reaction. The device was used in a very similar way to many research reactors found on university campuses. The post has been edited to reflect this.

This week, the Internet has been buzzing with news that Kodak had a nuclear facility housed in a basement at its Rochester, NY industrial park for over thirty years. Until 2007, Kodak used the device to check for impurities in samples, but the device wasn't widely known until the local Democrat and Chronicle newspaper ran an article late last week. Many have questioned why the company known for its photography products would need a nuclear device, and some alarmist articles have surfaced.

Gizmodo, for instance, began their article with extreme hyperbole while noting Kodak's recent bankruptcy:

"Kodak may be going under, but apparently they could have started their own nuclear war if they wanted, just six years ago."

Actually, Kodak didn't even have enough nuclear fuel to develop a single warhead. Refrigerator-sized nuclear devices like the one found in Kodak's basement have key differences with nuclear reactors found at power plants, and Kodak certainly couldn't have ignited World War III alone. In fact, the device is very similar to research reactors that can be found on several university campuses, and they are operated under strict guidelines without any nefarious intentions.

Researchers working at Kodak wanted to detect very small impurities in chemicals and impurities, and Neutron Activation Analysis (NAA) proved to be one of the best techniques to find these impurities. During NAA, samples are bombarded with neutrons, and elemental isotopes from the sample will absorb a small fraction of these neutrons.

Many of these stable elemental isotopes will become radioactive after gaining a new neutron; consequently, they will emit gamma rays. With the right equipment, researchers can measure the precise energy levels of this radiation and narrow down which elements are in the sample.

"For some elements, this is an exquisitely sensitive test," said Ken Shultis, a nuclear engineer at Kansas State University who works on the university's nuclear research reactor. "To do this [test], you need a source of neutrons."

For Kodak, that source was an isotope of Californium, a radioactive element first synthesized in 1950 with a cyclotron at the University of California Berkeley. Californium-252, the element's most common isotope, was initially used at Kodak as a neutron source by itself.

"Californium-252 is a poor man's reactor," said Shultis.

While a sample of this isotope will shed neutrons by itself, Kodak wanted more neutrons to increase the sensitivity of their analyses. That's where a small nuclear facility could help. The researchers could either collect a larger sample of Californium or use uranium plates to multiply the neutron flow from the source they already had. They opted for the uranium route.

With 3.5 pounds of uranium on-site, Kodak had far less than the roughly 100 pounds needed to develop a weapon. Strict security precautions were still taken, nonetheless.

But the device Kodak had and research reactors at universities don't pose the same safety risks as bigger nuclear reactors at power plants. Power plants produce much more fission products, and they require much more extensive cooling systems, according to Shultis.

"It's inherently much safer. There's no chance of a meltdown in our research reactors," Shultis said.

Radioactive materials used at research reactors still pose potential risks, according to Shultis. Consequently, researchers take great care when dealing with their samples. If samples become too radioactive, for instance, they can be left in the reactor pool until they decay enough to be safe.

Reactors like the one at Kansas State University and the decommissioned instrument at Kodak must meet strict guidelines determined by federal regulators. I wonder if those regulators were surprised when a photography company approached them many years ago with plans to use highly enriched uranium. It certainly caught many people by surprise this week.

Top image of Idaho National Laboratory's Advanced Test Reactor courtesy of Argonne National Laboratory.

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7 comments:

  1. At the time the reactor was build Eastman Kodak was pretty busy building KH-9 Hexagon spy sats for the CIA.

    So I wouldn't be surprised if the reactor was originally build to harden their films against space radiation.

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  2. So Californium-252 is a neutron source and Uranium-235 is a neutron amplifier? Not really a true reactor then.

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  3. Quote: "With 3.5 pounds of uranium on-site, the reactor had far less than the roughly 100 pounds needed to develop a weapon."
    That is just nonsense. The minimum uranium for a bomb is much less than 100 lbs., and even with the purest HEU, 3.5 lbs is not enough to run a nuclear reactor. Even Wikipedia has much better information.
    Call the IAEA inspectors! It's very suspicious^^

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  4. Anonymous/Eric Cartman: You are both correct that this was not a true nuclear reactor, and it certainly was not like the reactors found at nuclear power plants. I've added a correction to the blog post and updated the language.

    However, experts do agree that about 100 pounds of HEU is needed to develop "gun-type" nuclear weapons. Other devices can be made with less HEU, but they are much more technically difficult to make.
    Source: http://www.ucsusa.org/nuclear_weapons_and_global_security/nuclear_terrorism/technical_issues/fissile-materials-basics.html

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  5. and even with the purest HEU, 3.5 lbs is not enough to run a nuclear reactor.

    Much less uranium is needed for a chain reaction involving thermal neutrons than is needed for a bomb, since the fission cross section of 235U is much higher at thermal energies. This fact of physics is one reason why the Japanese had a criticality accident some years ago at a uranium processing plant. The accident involved enriched uranium compounds dissolved in water.

    The minimum critical mass for 100% enriched uranium in a water moderated/reflected system is less than 1 kilogram.

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  6. > The minimum uranium for a bomb is much less than 100 lbs.

    Technically correct; reality impaired. Fox News has trained you well.

    Whether the number is 100lbs (accepted number for the simplest practical bomb, the sort of thing achievable by people who'd bet their program on stealing fissionable out of a basement in Rochester, NY) or 33lbs (accepted number for medium tech device utilizing heavy neutron reflection) or 20lbs (accepted number for sophisticated (implosion) device), the bottom line is that instead of Kodak having 3.5% of the material needed for a bomb, they have 10-20% or less of what is needed.

    So...no bomb. Not even close. Which was the whole point. Can't argue the point, quibble over the details, and pretend they're what matters.

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  7. Put 3.5 lbs of uranium into a regular bomb as a "shrapnel" and generate shitload of hysterical news reports about "The atomic bomb". Standard media approach...

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