Archive for February, 2012

Radioactive Borders (part 4)

February 22, 2012

 

Tales from the Nuclear Age

Copyright © 2012 by Charles Glassmire

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Feb. 22, 2012

Radioactive Borders (part 4)

 

          On July 20, 2010, radiation inspector Enzo Montagna detected a shipping container on the dock near Genoa Italy emitting a life-threatening level of high radiation. The container manifest showed nothing irregular. Emergency personnel were summoned and it was decided to isolate the box by surrounding it with other shipping containers moved in by crane. Now the box sits quarantined on the Voltri dock surrounded by a barricade of stone and water-filled shipping containers; the radioactive source still remains unidentified.

          Additional surveying around the container determines the hottest spot to be in the center of the long side of the container and about 2 feet above ground(1). This exact center location is suspicious, for if someone were trying to hide a source, they would likely bury it at the middle of the container so as to be difficult to reach. It also suggests the container was NOT meddled with during transit. The remainder of the contents is 18 tons of copper wire, old radiators and other scrap metal. To place a source at the middle, 9 tons of metal would first need to be removed.

          Now there is time to direct attention to identifying the source. Many decaying radioisotopes give off a spectrum of gamma rays. This radiation is similar to visible light, but much more energetic in damaging human cells. If an isotope is present in its pure form, each one gives off gammas with a characteristic energy, wavelength and frequency. If there is a mixture of isotopes present, the problem becomes more complex. If the spectrum of the gamma field can be measured, it might be possible to identify the isotope in question.

          A very expensive scintillation counter is brought in – known as a pulse height analyzer. It should be able to measure the energy of the emitted gammas and hopefully classify the isotope. The gamma field is subsequently scanned and the data printed out. Two clear peaks appear at energy levels of 1.17 Million Electron Volts (Mev) and 1.33 Mev. These peaks identify the offender as Cobalt 60. The data is distinct from natural background radiation, and there seem to be no other isotopes present.

          How did such an active isotope get into this shipping container? Perhaps by accident? Not likely. The handler would probably be dead by now. An RDD? (Radiological Dispersion Device – dirty bomb)? This is a possibility. Cobalt 60 has a 5 year half life. It would linger in a dispersed area for a very long time – rendering the real estate unusable. Some observers object that it is a solid very hard metal, and difficult to “blow up”. A determined user however, could first machine it into a powdered form, then mix it with a common explosive.

          Cobalt 60 is fairly readily available especially around medical facilities. This is its most common use. Cobalt 60 is not found in nature. It must be created in a high flux nuclear reactor by irradiating the natural form, which is Cobalt 59. Normally the radioactive 60Co is then extracted for use in medical devices which emit intense radiation for treatments utilizing cancer therapy and other medical applications. There is also some use in industry for radiography of pipe metal welds, food irradiation etc. Cobalt 60 decays to a stable Nickel, and about 12.5% of the Cobalt isotope disappears each year.

          But if the origin of this material was medical or industrial, why would someone anonymously put it into a shipping container? The obvious answer is for terrorism purposes. But there are better sources to steal if one intends a dirty bomb. Perhaps the answer lies elsewhere.

          By United States law, 60Co sources are tracked carefully after manufacture, each one being assigned a serial number, and transport is required to use shipping containers weighing tons and tested to survive fire and crashes. This is not necessarily the case in foreign countries. For example, when the Soviet Union manufactured their nuclear weapons, each weapon was not issued a serial number. This makes it very difficult to track the devices. When Senator Lugar visited a few years ago, he found warehouses full of unnumbered bombs secured by underpaid guards, or padlocks and chain fences, and sometimes not guarded at all. We hope none have been sold clandestinely.

          Since the Cobalt eventually loses its potency (5.27 year half life) this raises a problem for the owner of the isotope. Eventually it becomes ineffective. So what to do with the source after its life expires?  Disposal turns out to be an expensive proposition. Until recently, The Department of Energy operated the Yucca Mountain repository in Nevada for safe deposit of nuclear waste materials. After an investment of billions, President Obama, at the urging of Harry Reid, closed the facility.

          Currently, the worldwide installed base of Cobalt 60 is estimated to be 260 million curies (a unit of radioactivity), disbursed to 170 gamma facilities(2). In the U.S., high-activity sources are uniquely numbered and tracked “cradle to grave”. In addition, the irradiator pays substantial upfront financial guarantees to cover anticipated disposal costs(2). Sometimes sources may be returned to the manufacturer, who mixes the depleted metal with newly activated to get a mix with appropriate strength. Disposal with shipping and fees of just one high level Cobalt source can cost the owner upwards of $130,000 (3). How much easier to avoid such costs in a less regulated foreign country, by just throwing the source in the garbage?

          On the dock at Voltri, alarm grows. The Stevedores are now refusing to handle or go near the container. The union blames port authorities for the week of unattended irradiation of passers-by. For 5 days in August 2010 the union strikes for 2 hours each day.  TV begins quoting local outrage. Painted signs begin to appear on the dock.   Genoese officials post signs   “Danger – Ionizing Radiation …

 (to be continued …)

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(1) “Mystery Box”, Andrew Curry, Wired Magazine, Nov. 2011.

(2) “Cost-Benefit Analysis for Potential Alternative Technologies for Category 1 and 2 Radioactive Sources”, ICF Incorporated, L.L.C., August 31, 2009.

(3) “Radiation Source Use and Replacement”, http://www.nap.edu/openbook.php?record_id=11976&page=27.

Radioactive Borders (part 3)

February 4, 2012

Tales from the Nuclear Age

Copyright © 2012 by Charles Glassmire

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Feb. 4, 2012

Radioactive Borders (part 3)

          It is now the 20th of July 2010 near Genoa on the Italian coast.  Radiation inspector Enzo Montagna stands on the Voltri shipping dock, beside a rusty red cargo container off-loaded on the 13th from a ship. The Geiger Counter he holds is detecting a radiation level sufficient to kill an exposed human within eight hours. Something inside the 20 foot long sealed metal box is giving off a very high intensity gamma field. (1)  His problem now is how to determine what it is without opening the container. The possibilities are ominous. 

          Nuclear weapons are now designed to be small enough to fit inside a heavy back pack.  Such a device would take up only a small space mixed in with other elements of the cargo, listed on the manifest as “scrap metal…” Detonated on the dock, such a device could decimate a 10 mile radius of the city, and destroy all shipping activity for a period of five to ten years into the future. In addition to the large loss of life and physical wreckage, it would be an economic disaster.  But the device might also be an RDD (Radiological Dispersion Device) i.e. a “dirty bomb”. This is a conventional explosive mixed with a radioisotope. When such a device detonates the physical damage is relatively local but it distributes wind-born contamination over a large area, instilling panic and denying use of the area for long periods.

          In order to check his  body dose, Enzo removes a six-inch pencil-thin cylinder from his shirt pocket and holds it to his eye.  Reading through the lens in the end, he sees a small hairline scale which is recording his total whole body gamma dose since he zero’d it before leaving for work early this morning.  The device is called a Dosimeter, and every radiation worker the world around knows its life-saving capability.

          Enzo knows his time is very limited in this high radiation field, so the safest course is to move away quickly. The radiation intensity will decrease as the square of the distance he moves away.

          But the situation is life-threatening. He calls the facility supervisor, and they declare a radiation emergency. An urgent call is placed summoning two radiation inspectors from the Regional Environmental Agency. (1) They arrive within a few hours, meters in hand. Circling the container, they verify his readings and also note that the field intensity is not decreasing. This is a long-lived gamma source.  The question is what kind? A terrorist could booby-trap the doors to trigger a device when the container is opened. If the material is loose inside, opening the container could presumably spread the radioactive material across the entire area, exposing everyone to contamination, stopping all shipping, and causing an uncontrolled emergency.  The container must remain sealed.

          However, on the positive side, because the radiation level is so high this implies there is probably not a nuclear weapon inside. Radiation from an unexploded weapon is comprised of lower level Alpha and Beta particles with only smaller amounts of Gamma. Also, a nuclear bomb presence would imply a terrorist objective and it is likely that such a device would be carefully shielded so as to avoid discovery. But this does not rule out the presence of an RDD.

          Now a search is begun for the origin of the box’s contents.  Officials  find the  container was leased in April 2010 from Textainer (maker of the box) to a large Geneva based conglomerate, the Mediterranean Shipping Company.(1  Subsequently the box was “stuffed” in Saudi Arabia under auspices of a scrap dealer, Sun Metal Casting. The sealed container was then trucked to a dock, loaded aboard ship and finally transshipped onto a second vessel in a southern Italian seaport. The destination is a foundry in a small town north of Genoa.(1). Experts know that sealed containers can be broken into during transit.  The manifest shows no record of any radioactive contents.

          Three years earlier (2007) the United States Congress passed a bill requiring that Department of Homeland Security scan all cargo containers for radiation before they are permitted to enter the U.S.(1) Estimates vary on this number but it is possibly 50,000 containers each day entering our borders. Skeptics scoff politely at DHS’s claim that 99% of all containers entering each day are scanned for radiation.  DHS has now proposed an alternative plan of scanning before the containers arrive. If documentation indicates something suspicious, and if there is a U.S. Customs agent on duty at the foreign port, the container is scanned before setting sail to America.

          Now that the possibility of a Nuclear Bomb is eliminated, local officials are summoned, and in turn, call – who else? The Fire Department! As the level of officialdom increases, the amount of confusion also seems to increase. What should be done? With hand waving and excited discussion options are examined. Close the Port? Evacuate everyone, redirect the surrounding highway traffic, do nothing?  Or perhaps burn all the contents? It is politely pointed out that fire does not destroy radiation. All you get by incineration is very radioactive  smoke drifting uncontrolled up into the sky!

          Finally a crane is brought in to stack other containers around the box to block some of the emissions and keep others away to create an exclusion zone of safety. This gives the radiation experts a little breathing room to further probe this very mysterious source …

(to be continued …)

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(1) “Mystery Box”, Andrew Curry, Wired Magazine, Nov. 2011.