Showing posts with label Radiation. Show all posts
Showing posts with label Radiation. Show all posts

Sunday, September 28, 2014

The Terrorist with a Demon Core

     Ever since the dissolution of the Soviet Union, there have been fears of 'terrorists' obtaining fissile material (plutonium or enriched uranium) and making a nuclear bomb. Getting their hands on enough of this type of radioactive material for a bomb is likely very difficult however. Some have speculated that a 'dirty bomb' could be developed, one which would not necessarily cause a nuclear explosion but which would spread radioactive contamination. Both these devices however (nuclear bomb and dirty bomb) require a delivery system (missile or large suitcase) as well as a 'trigger' (in the case of a 'suitcase' bomb) for detonation.

Terrorist Attack-World Trade Center
     But to create terror, the terrorist doesn't necessarily have to kill or even injure his victims. What better terrorist device is there, than one which simply disseminates terror?
     A relatively small amount of fissile material might be just what the terrorist needs for this purpose. A small amount of plutonium (in a backpack or in a 'suicide' vest) that is made to reach 'criticality' would have a dramatic effect, cause local injury and death and 'terrorize' the targets who would not know how much real damage was inflicted at the time nor what the future truly held for them.
     The nuclear weapons and the nuclear energy industries are subject to the normal range of accidents, from vehicle wrecks to falls from a height but there is one type of accident which is unique to these sectors, the criticality accident. This is an event where an amount of fissile material accidentally comes together into a supercritical amount. There is a sudden release of energy and deadly radiation.

The Atom
     It is all about the number of neutrons which are released. By definition, criticality is reached when conditions in a nuclear reactor are such that the fissionable material can sustain a chain reaction by itself. In effect, criticality is reached if each fission event causes, on average, exactly one other, resulting in a self-sustaining fission chain reaction (see post: Would You Prefer Plutonium or Uranium in Your Nuclear Weapon?).
     When a uranium-235 atom undergoes fission, it releases 2-3 neutrons (average 2.4). Therefore, criticality is reached if every released neutron has a 1/2.4 = 0.42 = 42% probability of causing another fission event as opposed to either being absorbed by a non-fission capture event or escaping from the fissile core.
     The criticality of a system can be calculated by comparing the rate at which neutrons are produced to the rate at which they are lost through absorption (boron-containing absorbing rods) and leakage out of the reactor core.

     A properly functioning nuclear reactor is a system that controls this criticality or balance of neutrons. When a reactor is said to have 'gone critical', it means it is in a stable configuration producing a constant power.
     'Subcritical' refers to a system where the loss rate of neutrons is greater than the production rate of neutrons and therefore the number of neutrons decreases as time goes on. During shutdown, the nuclear reactor is placed in a 'subcritical' configuration so that the neutron population and power decreases.
     'Supercritical' refers to a system where the production rate of neutrons is greater than the loss rate of neutrons and therefore the neutron population increases.
     It is when the neutron population remains constant that there is a perfect balance between production rate and loss rate, and the nuclear system is said to be 'critical'. The criticality of a system can be calculated by comparing the rate at which neutrons are produced, from fission and other sources, to the rate at which they are lost through absorption and leakage out of the reactor core. A nuclear reactor is a system that controls this criticality or balance of neutrons.
     A criticality accident is an unintentional increase of nuclear chain reactions (in enriched uranium or plutonium), releasing a surge of neutron radiation into the surroundings. Criticality accidents cannot reproduce the same conditions of an atomic bomb, so a nuclear explosion does not occur. The nuclear reaction however, does create heat which causes the fissile material to expand, so that, within a few seconds, the nuclear reaction becomes subcritical again.
     Since uses of atomic power were developed, at least 60 criticality accidents have occurred between 1945 and 2011 in collections of fissile materials many in facilities outside nuclear reactors. Many of these accidents related to nuclear weapons research conducted after the bombings of Hiroshima (August 6, 1945) and Nagasaki (August 9, 1945). Some of these accidents have resulted in death through radiation exposure of those close to the event. Other people further away from the source of radiation have suffered long-term effects and development of cancer years later.

Reactor-Idaho National Laboratory
     The SL-1 accident at the National Reactor Testing Station near Idaho Falls, USA on January 3, 1961 was a criticality accident that took place inside a military facility reactor (see post: Man-Made and Natural Nuclear Accidents).
     In the former Soviet Union, at the Mayak nuclear fuel processing center in central Russia an experiment with plutonium purification techniques was planned on December 10, 1968. Two operators apparently placed plutonium organic solution into an 'improvised' container. After most of the solution had been poured out, there was a flash of light and heat. The operator panicked, dropped the bottle and ran from the room.
Mayak Nuclear Fuel Reprocessing Center
     The complex was evacuated then the supervisor and radiation control supervisor re-entered the building. The shift supervisor then deceived the radiation control supervisor and entered the room of the incident and possibly attempted to pour the solution down a floor drain, causing a large nuclear reaction that irradiated the shift supervisor with a fatal dose of radiation.
      Mayak is located in the closed nuclear town of Ozersk, is still operational today and is Russia’s only operational facility for reprocessing spent nuclear fuel from VVER-440 type reactors and spent fuel from nuclear submarines, as well as fuel imported from other countries. Decades of spilling radioactive poison into the nearby Techa River Cascade and Lake Karachai have earned the site the moniker of being the most radioactively contaminated place on earth.
     On September 23, 1983, an operator at the RA-2 research reactor in Centro Atomico Constituyentes, Buenos Aires, Argentina died from a fatal radiation dose of 3700 rads (37 Gy) while changing the fuel rod configuration with moderating water in the reactor. Two other workers were injured.

Centro Atomico Constituyentes, Beunos Aires
     On September 30, 1999, at the Japanese uranium reprocessing facility in Tokai, Ibaraki Prefecture, workers put a mixture of uranyl nitrate solution into a precipitation tank which was not designed to dissolve this type of solution and caused an eventual critical mass to be formed, and resulted in two workers dying from radiation poisoning.
     There have been many more criticality accidents but the most infamous cases of criticality accidents occurred at the Los Alamos Laboratory in New Mexico while scientists worked with the 'demon core'. This type of investigation aimed at  creating a temporarily critical mass of fissionable material by sliding a slug of uranium-235 hydride through a larger mass of the same substance. They called it the 'Dragon Experiment'. These manual experiments continued with the hemispheres of plutonium used in the Trinity bomb, the first test of an atomic weapon (July 16, 1945), the Fatman, and the bombs used at Operation Crossroads in 1946.

Los Alamos National Laboratory, New Mexico
     Along with the successful tests, there were numerous criticality accidents with run-away output of energy and radiation. Within a year of the Trinity test, accidents would claim the lives of two members of the team that assembled the plutonium core at Trinity.
     It became known as the demon core, the 14 pound (6.2 kilogram) mass of plutonium which went critical in two separate events at the Los Alamos laboratory, New Mexico, the first in 1945 and the second in 1946. This same core was used in an atomic bomb test in 1946, five weeks after the second fatal accident. The explosion proved in practice to have a slightly increased yield over other cores which had not been subjected to criticality excursions.

The Trinity (Test) Detonation
    Harry Daghlian was a physicist who made a mistake while working alone performing neutron reflection experiments on the (demon) core. On the night of August 21, 1945, Daghlian was working alone but accompanied by a guard sitting 12 feet away making critical mass studies and measurements, stacking blocks of tamper material (tungsten carbide bricks) around the mass of fissionable material. The assembly was close to a critical configuration and Daghlian was lifting one last heavy piece of tamper material. As this piece approached the set-up, instruments warned that fission multiplication was imminent. He moved the block in hand to set it further from the pile and accidently let it slip, dropping it directly on top of the set-up.

Harry K. Daghlian
     There was a sudden 'blue glow' and Daghlian quickly disassembled the critical material and its tamper. Harry Daghlian absorbed huge doses of radiation, resulting in acute radiation poisoning and died less than 28 days later. The guard, sitting 12 feet away, suffered no obvious injury at the time. His estimated exposure was 0.31 Gy. He died of acute myelogenous leukemia 33 years later, age 62.
   
     Louis Slotin was a Canadian physicist from Manitoba working as a senior scientist at the Los Alamos Laboratory. On May 21, 1946, Slotin had already become the local expert, performing the same test almost a dozen separate times before, often in his trademark bluejeans and cowboy boots, in front of a roomful of observers.

Louis Slotin
     On this occasion, Slotin and seven other scientists were conducting the experiment to verify the exact point at which a subcritical mass of fissile material could be made critical by the positioning of neutron reflectors. The test was risky and known as 'tickling the dragon's tail'.

     Enrico Fermi had told Slotin and others that they would be 'dead within a year' if they continued performing it.
     The technique involved bringing a hollow hemisphere of beryllium (the neutron reflector) around a mass of fissionable material which was resting in a similar lower hollow hemisphere. The system was checked with two one-inch spacers between the upper hemisphere and the lower shell which contained the fissionable material; the system was subcritical at this time.

'Tickling the Dragon's Tail'
     The experiment required the operator to place the two half-spheres of beryllium around the core, manually lowering the top reflector over the core via a thumb hole on the top. As the reflectors were manually moved closer and farther away from each other, counters would measure the relative activity from the core. Allowing them to close completely would result in the instantaneous formation of a critical mass and a lethal power excursion.
     Spacers between the shells were removed so that one edge of the upper hemisphere rested on the lower shell while the other edge of the upper hemisphere was supported by a screwdriver.

Partially Reflected Plutonium Sphere
     Under Slotin's unapproved protocol, the only thing preventing the energy surge was the blade of the standard flat-head screwdriver. This upper shell edge was permitted to approach the lower shell slowly. While one hand held the screwdriver, the other hand was holding the upper shell with the thumb placed in the opening at the polar point.
     Then the screwdriver slipped and the upper shell fell into position around the fissionable material. Of the eight people in the room, two were directly engaged in the work leading to this incident. The blue glow filled the room, a heat wave felt by all.

Exposure Victims in Slotin Criticality Event
     Realizing what had happened, Slotin knocked the two halves apart, stopping the chain reaction and likely saving the lives of the other men in the laboratory. His body positioning over the apparatus also shielded the others from much of the neutron radiation.
     Slotin received a lethal dose in under a second and died nine days later from acute radiation poisoning. The nearest physicist to Slotin, Alvin Graves, was watching over Slotin's shoulder and was thus partially shielded by him, receiving a high but non-lethal dose of radiation.
     Graves was hospitalized for several weeks with severe radiation poisoning, developed chronic neurological and vision problems as a result of the exposure, suffered a significant shortening of his lifespan and died of a radiation-induced heart attack 20 years later.
     The other six people in the room were far enough away from the assembly to avoid fatal injury, but they all suffered other complications as a result of the accident. Two suffered severe shortening of their lives and died years later from radiation-induced complications -  leukemia at age 42 for one observer (18 years after the accident) and the second died from aplastic anemia.
     The same demon core was later put to use in an atomic explosion  July 1, 1946, demonstrating that the criticality experiments of Daghlian and Slotin had increased the efficiency of the weapon.

Blue Glow of Criticality?
     Blue glow and heat are two sensory effects of a criticality accident.  Electric sparks in the air (lightening is an example) will often appear blue. This effect occurs due to the energy emission of excited molecules or atoms (mostly nitrogen and oxygen) falling back to their unexcited state.
     The cause of the heat effect experienced in a criticality accident is uncertain. It is either due to the realization by the observer of the terrible event which just took place (and its consequences) or possibly due to non-thermal stimulation of heat-sensing skin nerves by the energy of the radiation or by a true heat flux produced by the event. One other possible cause of this heat sensation is non-thermal damage done to tissue on the cellular level by the ionization and production of free radicals (see post: Low Dose Radiation and Its Effects) caused by exposure to intense radiation.

The Electromagnetic Spectrum
     There may also be relationship between the blue glow and the heat effect itself. Over 30% of the blue glow emissions are in the ultraviolet range, and about 45% are in the infrared range while only 25% are in the visible range. The skin feels infrared light directly as heat, and ultraviolet light is a cause of sunburn. Together, these phenomena can explain the heat wave observations.

     There is a characteristic blue glow associated with nuclear reactors called 'Cherenkov radiation'. This blue colour is due to electromagnetic radiation which is emitted when an electron or other charged particle passes through a medium such as water at a speed greater than the velocity of light usually seen in that medium. The charged particles polarize the molecules of the water which then turn back to their ground state, emitting radiation (the blue glow) in the process.

Cherenkov Radiation
     So, what if a terrorist did have a sphere of plutonium, 28 pounds (13 kilograms), a real demon core? If a portable setup could be developed where the sphere could be surrounded by a neutron reflector, the mass of plutonium required could be much less, perhaps as little as 11 pounds (5 kilograms).
     Thirteen kilograms or 5 kilograms...it's still not much to carry, under a vest or in a back pack. If there were a technique, a mechanism whereby the demon core could be brought to the edge of criticality, expose everyone within twenty feet to deadly doses of radiation, then settle back down, a terrorizing effect would be realized.

     The suicide wearer of the vest/back pack could wander the crowded city of New York or London, triggering the plutonium core towards criticality again and again until his exposure brings him to the edge of death.
     Exhausted, the terrorist could hand off the demon core to an associate who could continue the process, exposing hundreds, perhaps thousands to lethal radiation and maybe millions to the longer term effects of radiation exposure (leukemia, heart disease, other cancers).

     The only clue that anything might be amiss, would be the sensation of 'heat' pulses next to the terrorist and an intermittent, pale, 'divine' blue glow (see post: The Colors of Faith), signs that death, an unpleasant death, will soon upon you.

     Click on the link below to watch a dramatization of a fictionalized (but based on fact) Los Alamos criticality event.

     *The risks of radiation: subject of research for the novel Whip the Dogs - Amazon Kindle




Sunday, May 4, 2014

How to Build a Dirty Bomb


     There are many different types of bombs which disperse ionizing radiation. The atomic bomb, in which a fission reaction results in a high energy output and extreme and direct destruction is the type of device that first comes to mind when discussing a 'nuclear' weapon. But there is a variety of radioactive weapons, bombs which kill, perhaps less dramatically than with one huge blast, but which potentially kill with just as deadly a force and perhaps with even more suffering. These bombs are called 'dirty' and 'dirty' is all about 'fallout'.
A Nuclear Explosion

     But 'fallout' usually refers to the 'residual radioactive material propelled into the upper atmosphere following a nuclear explosion', so-called because it 'falls out' of the sky after the explosion and energy pulse of the blast have passed. This radioactive dust and ash may also originate from a damaged nuclear plant. The radioactive dust consists of material either directly vaporized by a nuclear blast or charged by exposure and, whatever the source, results in contamination of soil and water supplies, possible leading to devastation of the exposed environment that lasts years after the event.
     With a dirty bomb, there is no true 'falling out' of dust from the sky but, in effect, the same result occurs in perhaps a more restricted area and possibly with more severe localized levels of radiation exposure.
Dirty Bomb

      The main difference between a nuclear blast and a dirty bomb is not necessarily the ultimate degree of radioactive damage inflicted but the fact that a dirty bomb is easier to make, easier to conceal, easier to transport and easier to detonate.
     A dirty bomb combines radioactive material (which can be obtained readily from multiple sources) with conventional explosives. The purpose of the weapon is to contaminate the area around the explosion site with radioactive material, hence the term 'dirty'.
     The dirty bomb is essentially a 'radiological dispersal device' (RDD). The explosion itself, using conventional explosives (dynamite) would likely have lethal effects, at least locally. Studies suggest that not enough radiation could be dispersed in high enough concentrations to cause severe illness or death.
A Simple Dirty Bomb with TNT

     A test explosion of a 'dirty bomb' and subsequent calculations done by the United States Department of Energy found that even if nothing is done to clean up the affected area and everyone stays in the affected area for one year, the radiation exposure would be high but not fatal.
     Analysis of the fallout from the Chernobyl disaster (see post: Man-Made and Natural Nuclear Disasters) shows that the effect on many people in the surrounding area, (although not those in close proximity) was extremely low.
     So is a dirty bomb a weapon of mass destruction or rather a weapon of mass terror? Certainly as a source of terror, a dirty bomb would be effective. The device would be high-profile (any blast would be noticed and investigated) but not insidious or stealthy as other terrorist techniques could be (see post: The Terrorist With a Demon Core). But, in the case of a dirty bomb,  time and money would be needed to address the contamination problem and there would always be the uncertainty of what the longer term future held for the people exposed.
     And what if multiple bombs were detonated in close proximity to one another, at or near the same time? Many devices could essentially create a true fallout effect, increasing the number of people exposed as well as possibly increasing the degree of their exposure.
     As of 2012, a dirty bomb is only a speculative radiological weapon in that no such device has ever been successfully deployed (yet). But since the attacks on the World Trade Center in New York City in September 2001, the fear that terrorist groups could use dirty bombs has increased significantly.
Izmaylovsky Park

     There have been a few cases of threatened dirty bombs. On two occasions, caesium-containing devices were found, neither of which was detonated.
     The first attempt of radiological terror was carried out in November 1995 by a group of Chechen separatists, who buried a mass of caesium-137,  wrapped in explosives at the Izmaylovsky Park in Moscow. A Chechen rebel leader alerted the media, the bomb was never activated.
Chechnya

    
     In December 1998, the Chechen Security Service, discovered a container filled with radioactive materials (caesium, once again) attached to an explosive mine, hidden near a railway line in the suburban area Argun, ten miles east of the Chechen capital of Grozny.
   In August, 2008, a large Iranian cargo ship, the MV Iran Deyanet was hijacked by Somali pirates. American government sources largely ignored the event but the hijacking became headline news in Russia. In the 21st century, Somalia, with its 1800 miles of coastline has become an international terrorist haven as well as a  safe haven for pirates plying their trade as far away as the coast of India.
Caesium Dirty Bomb-Russia

     On August 2, it was reported that three vessels, one Iranian, one Japanese and one German, along with 57 crew members were hijacked by pirates in the Gulf of Aden, the stretch of water connecting the Red Sea and the Indian Ocean near Somalia.
     The MV Iran Devant had departed Nanjing, China on July 28 and was headed to Rotterdam to deliver 42,500 tons of iron ore and other 'industrial products' to an unidentified German client.  The Iranian bulk carrier and its 29 crew members, belonged to the Islamic Republic of Iran Shipping Lines (IRISL), run by the Iranian Revolutionary Guard.
Somalia on the Horn of Africa

     Forty Somali pirates, armed with AK-47s and rocket-propelled grenades brought the MV Iran Deyanet to Eyl, a fishing village in northeastern Somalia where a larger contingent of pirates took control of the vessel – 50 on board and 50 patrolling on the beach.
     Attempts to inspect the ship's seven cargo containers failed, the pirates unable to break into the holds and the crew swearing they did not have access codes to the locks. The captain and engineer of the ship at first said the containers held crude oil then changed the story to say there were 'minerals' in the holds.
     After several efforts, the pirates succeeded in opening one of the containers and discovered packets of what was described as a 'powdery fine sandy soil'. Those exposed to the powder became sick and within days began to exhibit symptoms which looked like skin burns as well as hair loss. Sixteen of the pirates died.
The MV Iran Deyanet

     According to Russian reports, the entire cargo was radioactive sand obtained by Iran from China in exchange for oil then sealed in containers. The plan had involved detonation of charges on the ship after the crew had escaped in life boats. The planned blast would have been taken high into the air where prevailing winds would then have pushed the highly dangerous and radioactive cloud ashore.
     The MV Iran Deyanet was, in effect, a huge floating dirty bomb, intended to detonate after exiting the Suez Canal at the eastern end of the Mediterranean and in proximity to the coastal cities of Israel.
     Because a dirty bomb has never been successfully used, there is disagreement as to how deadly or destructive the device would actually be. Many studies have suggested that a radiological dispersal device such as a dirty bomb would not physically harm nor kill many people. But one thing is certain. The detonation of a dirty bomb would have tremendous psychological impact as well as economic impact on the target population and country.
Goiania, Brazil

     But there have been 'accidental' dirty bombs - radiological accidents really, which spread radioactivity in a manner similar to that of a radiological dispersal device. One example is the accident which took place in Goiania, Brazil between September 1987 and March 1988.
     On September 13, 1987, two metal scavengers broke into the radiotherapy clinic of an abandoned city hospital and removed a radiotherapy source capsule containing powdered caesium-137 with a radioactivity of 50 T Bq. The two men took the component home and began to take it apart with the plan to sell it for scrap metal.
Goiania Radiotherapy Source Capsule

     Later that day both men began to show signs of radiation illness with vomiting, swollen hands and diarrhea. Work on the container continued and within a few days, one of the men punctured the 1 mm thick window of the capsule, allowing caesium chloride powder to leak out.
     The powder glowed blue in the dark and the man brought the container and powder back home to his family and friends to show them this curiosity. Within 2 weeks, spread by contact, contamination caused an increasing number of people to fall ill. Before the correct diagnosis of acute radiation sickness was made, 249 people had been contaminated, 151 of whom showed signs of both external (ex skin burns) and internal (vomiting, anemia). Twenty people became seriously ill and 5 people died. 
     The cleanup operation necessitated topsoil removal from several sites and the demolition of several homes. All the objects from within those houses were removed and examined. The Goiânia incident to some extent demonstrates a possible contamination pattern of radioactive dispersal, even without an explosive device. The incident also shows how fatal even very small amounts of ingested radioactive powder can be and raises concerns of how effective a 'dirty' device can be if a powdered alpha-emitting material (such as polonium-210; see post: Radiation to Cure, Radiation to Kill) is used.
     Although no dirty bomb has been detonated to date, it is well-known that terrorist groups are actively pursuing unsecured radiological material, and several of them may already possess dirty-bomb capabilities. Significant amounts of radioactive materials are stored in laboratories, food irradiation plants, oil drilling facilities, medical centers, and many other sites throughout the world.
     Cobalt-60 and caesium-137 are used in food disinfection, medical equipment sterilization, and cancer treatments. In the USA, nearly 1500 pieces of radioactive material went 'missing' between October 1996 and September 2001. The vast majority of the missing items contain tiny amounts of radioactive material and pose little threat but there have been several instances where hospital equipment has been lost or stolen, equipment that contains potentially lethal amounts of radioactive cobalt or cesium.
Training for Attack
With a Dirty Bomb

     The threat of a dirty bomb has been taken seriously by the US government. From June 5 to June 7, 2009, 400 New York Army and Air National Guardsmen as well as volunteers from the New York State Guard converged on Albany to practise their skills in responding to a dirty bomb attack on an American city.
     The three-day exercise involved the theoretical detonation of a high explosive device covered with radioactive material outside the New York State Capital, covering downtown Albany with radioactive contamination and forcing thousands of residents to shelter indoors for two days. Scenarios have been worked out as to explosion and wind distribution of radioactive materials from a dirty bomb.
     Dispersal of fine radioactive particles expose people down wind from the event and can cause contamination in several ways:
1. Inhalation of radioactive dust by the population directly exposed to the radiation cloud. Particles containing cobalt or caesium will stay in the body and result in long term exposure.
2. Exposure to settled dust after the radioactive cloud has passed. Caesium or cobalt-containing ground dust (gamma particles) results in on-going exposure for residents; dust containing americium (alpha particles) may be whipped into the air again by traffic or wind and inhaled resulting in internal radiation exposure.
3. Contaminated food and water especially in rural areas where water collection regions may be vast and monitoring more difficult.
Fukishima Dust Cloud

     Dust clouds from nuclear accidents (similar to a dirty bomb) have been seen. Following the Fukishima accident in 2011, scientists performed testing which showed nuclear radiation raining down on Tokyo from incinerators that were burning radioactive sludge and other materials contaminated with radiation from the damaged nuclear plant in Fukishima 65 kilometers away.
     In the United States, aside from radioactive devices used in medicine and industry, there is at least one other potential source of radioactive material that may be useful to build a dirty bomb.
     The Gammator was a gamma irradiator made by the Radiation Machinery Corporation during the U.S. Atoms for Peace project of the 1950s and 1960s (see post: Nuclear Waste). The Gammator was distributed by the Atomic Energy Commission to schools, hospitals, and private firms to promote 'nuclear understanding'. About 120-140 Gammators were distributed throughout the U.S. and the whereabouts of several of them remain unknown.
The Gammator

     The Gammator weighed about 1,850 pounds and contained  caesium-137  in a pen-sized pellet (400 curies of radioactivity). The device was well-shielded and safe when used as intended (school science experiments) but the amount of nuclear material was large enough to cause significant problems if used as the radioactive component in a dirty bomb.
     Between 120 and 140 Gammators were distributed to schools across the country. Since the attacks of September 11, 2001,  the US Department of Energy has been trying to retrieve these devices. In 2004, Massachusetts Congressman Edward Markey claimed that six Gammators had 'gone missing'.
     So, how do you build a dirty bomb?
     A terrorist organization (or even a disaffected former employee) must first obtain radioactive material by stealing it or buying it (legally or illegally). Radioactive material could come from the millions of radioactive sources used worldwide in industry, for medical purposes (Goiania, Brazil is a good example) and in research institutions.
     Few of these sources provide the isotopes (caesium-137, cobalt-60, americium-241, californium-252, iridium-192, plutonium-238, polonium-210 (see post: Radiation to Cure, Radiation to Kill), radium-226, strontium-90) which would be useful for this type of terrorist weapon. It has estimated that within the U.S., approximately one source of these isotopes are lost, abandoned or stolen every day of the year. Within the countries of the European Union, the annual estimate is 70.
Russian Radioisotope Thermo-Electric Generator

     There exist thousands of such lost or abandoned sources scattered throughout the world. There are also thousands of 'orphaned' sources in Russia, lost following the collapse of the Soviet Union. Especially worrisome are  the Russian strong beta-emitting strontium-90 sources used as radioisotope thermo-electric generators used in beacons in lighthouses in remote areas. 
     In December 2001, three woodcutters in Georgia (former republic of the Soviet Union) found one such power generator and dragged it back to their camp site to use it as a heat source. Within hours they suffered from acute radiation sickness and required hospitalization. The generator contained approximately 40 kilocuries of strontium,equivalent to the amount of radiation released immediately after the Chernobyl accident (see post: Man-Made and Natural Nuclear Disasters).
Twin Towers, September 9, 2011

     There have been several incidents of alleged intent to make and detonate a dirty bomb. many of these cases are linked to Al-Qaeda since the airline bombing of the Twin Towers in New York City in 2001.
     On 8 May 2002, Jose Padilla (a.k.a. Abdulla al-Muhajir) was arrested on suspicion that he was an Al-Qaeda terrorist planning to detonate a dirty bomb in the US. Padilla had not obtained radioactive material or explosives at the time of arrest but authorities did uncover evidence that he was on reconnaissance for usable radioactive material and possible locations for detonation. Later, the charges against José Padilla were dropped.
Jose Padilla

     In 2006, Dhiren Barot of North London pleaded guilty of conspiring to murder innocent people in both the United Kingdom and the USA. using a dirty bomb. He had planned to target underground parking lots in British and American cities. Experts say if the plot to use the dirty bomb had been carried out it would have been 'unlikely to cause deaths, but was designed to affect about 500 people'.
     In January 2009, an FBI report described the results of a search of the Belfast, Maine home of white supremacist, James G. Cummings, who had been shot and killed by his wife.

Dhiren Barot
     Investigators found four one-gallon containers of 35 percent hydrogen peroxide, uranium, thorium, lithium metal, aluminum powder, beryllium, boron, black iron oxide and magnesium as well as literature on how to build dirty bombs and information about cesium-137, strontium-90 and cobalt-60, radioactive materials.

     In April 2009, the Security Service of Ukraine arrested a legislator and two businessmen from the Ternopil Oblast region. The security service seized in the undercover 3.7 kilograms of what was claimed by the suspects during the sale as plutonium-239, used mostly in nuclear reactors and nuclear weapons, but was determined by experts to likely be americium, a radioactive material commonly used in amounts of less than 1 milligram in smoke detectors but which can also be used in a dirty bomb. 
James G. Cummings

     The suspects reportedly wanted 10 million US dollars for the material, which had been produced in Russia and smuggled into Ukraine through a neighboring country.

     To make a dirty bomb, therefore, would not be easy but certainly easier than building an atomic bomb.
     A dirty bomb would require a radioactive source that was 'sufficiently' radioactive to create direct radiological damage at the explosion or at least to perform societal damage or disruption (a Russian thermo-electric generator would work).
Security Service of Ukraine

     The device would need to be be transportable with enough shielding to protect the carrier, but not so much that it will be too heavy to manoeuver (strontium-90 in the back pack of a suicide 'bomber' would work).

     Finally, the source would need to be sufficiently dispersible to effectively contaminate the area around the explosion ('powdered' strontium-90 or caesium-137 has already been shown to be effective).
     It seems then that it really only involves three (rather simple) steps:
1. obtain the radioactive material (ex. strontium-90);
2. transport the radioactive material to the target site (in a sealed and protected box or trunk); 3. pack the radioactive material around a detonation source (simple dynamite will do).
Dirty Bomb in a Briefcase
     And what do you do if (or when) a dirty bomb is detonated nearby?
     Get out of the way of the dispersal cloud.
     Move across or up wind to escape the area.
     If in a house or car, stay inside, turn off the air conditioning and heat and close the windows. If near the blast, take cover inside in a lower inside room away from doors and windows.
     Use a filter mask or breathe through clothing and avoid breathing through a jacket which may be contaminated with radioactive dust.
Dirty Bomb in a Backpack

     Click on the link below for a PBS video on dirty bombs.
   
     *Terrorism and radiation: subject of research for the novel Whip the Dogs - Amazon Kindle

Wednesday, June 12, 2013

Radiation from the Sun


     In the event of a coronal mass ejection (CME), the earth
coronal mass ejection
is hit by 'solar energetic particles' (protons, electrons, heavy ionized particles). The initial wave of the strike creates a 'geomagnetic storm' warping the planet's protective magnetosphere, essentially thinning it on the side receiving the brunt of the blast. Extreme auroral events are triggered and 'electrification' of the atmosphere occurs (see post: The Carrington Event).

     But this, alone, with exploding electrical transformers and disruption of navigation and communication systems may be a relatively minor problem for human-kind. This non-ionizing form of radiation (which includes visible light, thermal radiation, radio waves) is not powerful enough to 'knock out' electrons from atoms or molecules (thus, non-ionizing).
Electromagnetic Spectrum

     But the geomagnetic storm is not the entire punch of a CME. The more threatening tempest associated with a CME event occurs in areas where life forms are unprotected. Astronauts in orbit or populations on 'day-time' areas of the planet (the surface where the magnetic shield has been thinned or stripped) face the full force of the 'second' phase of the assault, the plasma eruption from the sun.
     Within the sun's ejectile are high-energy particles including protons, resulting in ionizing radiation (a 'solar proton event'), knocking out electrons from the atoms of their targets. This can destroy electronic circuits and, being an electrically-charged particle mass, will also cause extreme auroras. But it is the effect on living tissue by this ionizing radiation that is most dangerous - DNA changes, breakdown of cell-wall integrity, all leading to 'radiation poisoning' and rapid death or the triggering of cancerous transformation. This results in the destruction of ALL living things in its path - plants, animals, microbes. Nothing to eat. Only radio-active water to drink.
     X-rays, gamma-rays and neutrons (other forms of ionizing radiation, some more penetrating than others) all make up the plasma that our star can spew towards the earth during a coronal mass ejection.

     It would take a large coronal mass ejection and probably one that would have to be a direct hit on the planet for complete stripping of our magnetic shield and penetration of the ionizing particles down to the planet's surface.
     But what if this does occur? What do you do? Where do you hide? What do you eat? How do you survive?
   
     *Solar radiation: subject of research for the novel  The Tao of the Thirteenth God - Amazon Kindle.

Friday, May 24, 2013

You Have Been Warned


     Our society today has grown dependent on its communication systems, its guidance/navigation systems, its electronically-monitored economic system...The list goes on and on.
   
Coronal Mass Ejection
     One effect of a direct hit by a CME (coronal mass ejection) would be similar to the blast of a nuclear bomb in the lower atmosphere, causing electro-magnetic disruption of power supplies that would pull down land-line as well as mobile phone systems, internet and cable communications. The complex electronics of orbiting communications satellites would be destroyed, resulting in malfunctioning or complete shut down of global positioning and aircraft navigation systems. The orbit of satellites would begin to degrade, eventually leading to their re-entry into and 'burning up' in the atmosphere.
   


     High altitude air travel (such as most long distance commercial flights) would result in significantly increased exposure of passengers and crew to ionizing radiation, especially if the flight were to cross over either of the earth's poles where the magnetosphere (part of earth's radiation shield) has been thinned, warped or even removed by the pulse of the CME.
     Any astronaut unfortunate enough to be in orbit (even within the spaceship or space station) would be exposed to even more radiation, likely a lethal dose.

     On the ground, the electrical grid would see transmission relays explode, spontaneous ignition of flammable material (ex telephone poles) and melting of metal wiring.
Disruption of the Magnetosphere by a CME
     Another perhaps more far-fetched result of a direct hit by a CME is the 'flipping' of earth's own magnetic poles and the triggering of wide-spread volcanic eruption throughout the world.
   

     The pulse of the coronal mass ejection would not be felt on the side of the earth facing away from the sun (that is, the night side of the planet). But the exposed side of the globe, if the blast is strong enough to (temporarily) sweep the magnetosphere aside, would receive extreme doses of ionizing radiation, destroying the membranes of cell bodies and disrupting DNA, killing any and all unprotected living thing that may be in its path.

     *Solar radiation: subject of research for the novel  The Tao of the Thirteenth God - Amazon Kindle.

Sunday, May 12, 2013

When the Sun Grows Angry


     The 'solar cycle' reflects magnetic changes in our star, seen in the change of position as well as magnetic polarity of sunspots. It was discovered and first described by German astronomer Samuel Heinrich Schwabe in 1843. This cycle waxes and wanes every 11 (earth) years. The last solar cycle (cycle 23, by human count) peaked in 2000-2002 then decayed to its low in 2008. A new cycle (solar cycle 24) began in that year. The 'solar maximum' is expected to occur sometime in 2012 (2013?).
   
Samuel Heinrich Schwabe
     A 'solar maximum' implies increased solar magnetic activity - more sunspot changes, more solar flares and possibly a 'solar storm'. To what degree a solar storm affects our planet depends on the severity of the storm itself as well as whether the storm on the sun takes place on an area that directly faces the earth or at an angle, either resulting in a 'direct hit' of our planet or simply a glancing blow.
   
     In early 2012, a mild solar storm hit our planet resulting in brilliant auroras at both poles - electromagnetic radiation of a benign nature that showed us once again the beauty of nature (see post: Fire in the Sky).
   
   
Solar  Flares ('Storms')
     Solar storms launch energy into space in three pulses: 1. electromagnetic radiation (much like an atmospheric nuclear blast) that results in effects on the earth's magnetosphere causing remarkable auroras and, in more extreme cases, warping or thinning of our protective shield. 2. proton (ionizing) radiation from deeper inside the sun. Space-bound astronauts, unprotected by our atmosphere may be at risk of exposure to these 'deadly rays'. 3. 'Coronal Mass Ejection' (CME) - expulsion of the sun's plasma that strikes our planet.

   
'Coronal Mass Ejection' (CME)
     These pulses can travel at speeds of up to 4 million miles per hour. With the earth only 93 million miles from its star, that gives us less than 25 minutes once a first pulse is launched!
     In the year 2012, our planet was hit by severe solar storms. During the week of March 5, 2012, the earth was witness to increased solar 'rage'. But a big one? Has our lonely blue planet ever been struck by a large CME? A direct hit? What happened?
       

     *Solar radiation: subject of research for the novel The Tao of the Thirteenth God - Amazon Kindle.




Wednesday, April 24, 2013

The Winds of the Sun


     A Brief Summary of Sun Activity: Our sun is a star, a roiling mass of magnetism, chemistry and physics. It creates the 'solar wind', a normal flow of electrically-charged particles (electron, protons) that stream out from the corona (the sun's upper atmosphere) at over 1 million miles per hour.
 The 'Solar Wind'

     Our earth itself behaves much likes a large magnet as well, its own magnetic field (magnetosphere) extending from pole to pole, protecting the planet from the assault of the solar wind and the radiation pulsed out from the sun itself.
     'Sunspots' are points on the solar surface, darker than the surrounding regions, triggered by the sun's own intense magnetic activity. 'Solar flares' are bright spots on the sun's surface (usually located in the area of sunspots) which release huge masses of energy (electrically charged particles and radiation, from radio waves to gamma waves) through the corona and into space.
Sunspots
   
     The 'solar (magnetic) cycle' is a variation in solar sunspot activity, cycling through 11 years. The cycle results in a change in frequency and pattern of sunspots which relate to a change in the type and amount of irradiation launched from the sun towards the earth. It is the presence of the earth's magnetic 'shield' which protects us from most of the harmful effects of the sun's discharge.
     'Space weather' is the change in environment (charged particles, radiation) in the space between the atmospheres of the sun and the earth.
     In 364 BC, Chinese astronomers were the first to document sunspots. In ancient Greece of 300 BC, Theophrastis recorded the strange activity on the sun's surface. Throughout the Middle Ages, further observations were made but it wasn't until Galileo that it was understood that these 'spots' were signs of activity on the sun itself; an important point since, up until then, scientific and religious thought had held that all celestial bodies were 'perfect and unchanging spheres'.
Cosmic Rays Changing the Magnetosphere


     So then, what happens when 'space weather' changes? When 'solar flares' become more active? If the magnetospheric shield of the planet is altered?...What happens when the 'Winds of the Sun' turn fierce?
   
     *Solar radiation: subject of research for the novel  The Tao of the Thirteenth God - Amazon Kindle.