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Sunday, September 14, 2014

Duck and Cover: Children of the Cold War

Growing up, I can't recall a single instance of ever doing the "duck and cover" drill.



This lack of cold war education is a bit odd, because I grew up within a few miles of a nuclear missile launch complex.  The missile complex was taken out of service a few short years after it was built, while the US and USSR moved on to a paradigm of MAD, or Mutually Assured Destruction, so maybe the school board just assumed everyone on the planet would be vaporized by incoming nuke missiles.  In any event, I never performed a 'duck and cover' drill while at school.

I had heard rumors of the nearby missile complex when I was in high school, and it took a while after that before I could find someone who knew where it was located.  Boise, Idaho, where I grew up, is just off the top of the map below, and 569-C (near Orchard), is the nearby site I had a chance to explore.


Frankly it was a little intimidating driving up to the site, even with friends who had been there many times before.  It was fenced and posted "No Trespassing", and had various signs about being a felony to trespass, etc, etc.  The fence was in bad shape however, and the gate was askew. In we went...

In its heyday, the missile complex was part of the 569th Strategic Missile Squadron, based out of Mountain Home Air Force Base.  The missiles were deployed in a 3x3 arrangement - meaning three launch complexes with three missiles each.  Each of the above mapped "569" sites therefore would have three silos each containing a nuclear-tipped missile.

Below, a diagram of a three missile launch complex, showing the major components.  Note: Hydrazine was used on later missiles, so this likely a diagram for a Titan 2 missile complex.

The nearby launch complex was built around first-generation SM-68 Titan 1 missiles, and was only active for a very brief time before being superseded by more advanced missiles. The launch site was abandoned (rather than updated) at that time.  The 569th Strategic Missile Command was only active from June 1961 to April 1965 - a useful lifespan of under 4 years.  This must have been the only weapon system for nuclear deterrence with the longevity of a fruit fly.

Below, a Titan 1 missile, out of the silo.  Note the open blast doors and the Air Force markings.  This looks like it might be a commissioning ceremony, based on the contractor trailers and vehicles on site, as well as the tent adjacent to the silo.

The Titan 1 was the first true US intercontinental missile, having a range of 5500 nautical miles.  The arrangements required to launch the missiles were quite complex and time consuming, and this is very likely the reason that the system was abandoned so quickly, in addition to the rapid pace of rocket development in that era.

To begin with, the missile was a two-stage, liquid-fueled design.  The propellant was RP-1, essentially highly refined kerosene (a light oil) that was kept on board the missile.  The oxidizer, however, was liquid oxygen.  This had to be stored in an insulated and refrigerated cryogenic tank at the launch site, and pumped into tanks on board the missile immediately before launch, for both the first and second stages.

Further complicating matters, the silos were not designed with exhaust vents, so the blast doors had to be opened and the missile raised on an elevator out of the silo before launch could proceed.  There was no "quick launch" feature for this missile.  It took 15 minutes to launch the first one, and the other two would follow at 8 minute intervals.  Surely this would be an eternity in a nuclear exchange, particularly if you were not making the first strike.

The missile guidance system left a bit to be desired as well, being radio command.  Therefore this missile required radio signals from ground guidance to get where it was supposed to go.  The likelihood of intentional interference or Nuclear Electromagnetic Pulses (EMP) blocking this communication would be likely in the event of nuclear war.

What this missile could do however, was fling a W-38 thermonuclear weapon halfway around the globe and deliver a whopping 3.75 Megatons of destruction, with whatever level of accuracy the radio guidance system could provide.  Link to a Chinese video of a 3.3 Megaton airburst.

The missiles were pretty failure prone; of the 70 that were test launched, only 53 performed successfully - a success rate of about 76 percent.  That means that of two of the nine missiles from the 569th Strategic Missile Squadron probably wouldn't make it to the show - but those that did would make quite an impression ;)

And now, what you have been waiting for... the inside of the missile launch complex of the 1960s. (FYI: These are not photos that I took)

Below, a Google Earth image of the 569-C site near Boise.  The silos are to the upper left inside the fenced area.  The big pit in the center was dug to remove components from the complex when the site was abandoned.  It appears to be private property at this time.

This was how you got into the complex - where crews had dug down and made a ramp to remove the components from inside the control room.  The other option was to rappel down into the silo on a rope.  Being a little acrophobic, I chose the former.

Below, a lot of dislodged heating and cooling ducts, as well as some stripped down electrical cabinets.  Not sure what part of the complex this is...

Below is my favorite.  Take a look at the massive shock springs at the left and right.  All the critical equipment was suspended by springs - in event the silo had to deal with a nuclear first strike.  The *hope* was that an incoming nuke would not score a direct hit, and that the launch complex could survive to retaliate.  Modern guidance systems do not offer this hope of a near-miss.

Cool stuff!


Saturday, September 13, 2014

Broken Arrows - USAF wins the trophy

"Broken Arrow" is the military term for an accidental event involving a nuclear weapon, but which does not create the risk for a nuclear war.  The 'accidental event' typically involves losing and/or damaging the weapon.

There have been 32 officially recognized "Broken Arrow" events in the United States since the dawn of nuclear weapons, as of Sept 2013.  Some of these events have been relatively minor, but others have been massive radiological accidents.  One accident with a large Hydrogen Bomb nearly made North Carolina uninhabitable... not that you would have seen THAT in the newspapers when it happened.  Apparently the news media were just as compliant in the 1950's as they are today.

I will go over a few of the more interesting Broken Arrow events.  Not surprisingly, most of these involve military aircraft crashing with weapons on board, as well as the intentional or inadvertent jettisoning of nuclear weapons.  All of these event descriptions are courtesy of Wikipedia.

Tuesday, September 09, 2014

Missing Radioactive Sources

Of all the goofy (and by that, I mean "unbelievably stupid") nuclear accidents that I read about, the worst are probably those that involve loss of custody/control of radioactive sources.


Radioactive sources are made by inserting a stable (non-radioactive) isotope of the desired material into a nuclear reactor and allowing enough time for neutron absorption to make that particular element radioactive.  Another technique is to process spent nuclear fuel and separate out the desired radioactive isotope.  Yet another is to bombard a sample in a particle accelerator, such as a cyclotron - although this last technique will only yield small quantities of material.

The vast majority of strong radioactive sources are made from Cobalt-60, Cesium-137, or Iridium-192.  Each of these are quite lethal gamma emitters when they are not shielded against.  Cesium also emits very hot beta radiation, so it's potentially quite a bit worse than the others.  Sources like these are used for cancer treatment, or to sterilize medical equipment - even simple and hardy micro-organisms cannot survive the harsh radiation these sources emit.  Radioactive sources are also used to make images of welds in very thick piping systems - piping that even an X-ray could not penetrate.

Here's what gets my goat though:  These things are exceedingly dangerous.  It shouldn't be too hard to keep tabs on this stuff and keep it out of the wrong hands.  ...And yet it happens fairly often.

Here is one recent example.  Synopsis:  A truck driver was asleep along a highway in Mexico, when he was awakened by men at gunpoint.  The truck was stolen along with the cargo.  The cargo was a shielded container with a Co-60 source for treating cancer patients. When the truck was located, the container had been broken into and the Co-60 source removed.

Here is another example.  Synopsis:  Workers at a paper mill in Vologodskaya Oblast, Russia reported on 1 September 2003 that a device containing the radioactive isotope cesium-137 had gone missing from a factory in the city of Sokol sometime during the summer months. The instrument, known as a BGI-75A, has a total mass of 85 kg, but it was not reported how much cesium the device contains. The Sokol region Chief of Police Sergey Turkin said the device was repaired in 2000, which may mean the radioactive core was replaced at that time with a fresh cesium-137 source. The plant's chief metrologist, Viktor Undozerov, said the instrument poses a danger only if one comes into close contact with it. The police are continuing to search for the stolen device.

Another very recent example.  This one is a neutron source.  Nasty.  Synopsis:  Oilfield truck loses the source in transit to a job.  Source is missing for a month, while Halliburton, Law Enforcement, and the NRC frantically search for it.  Don't leave a lethal item sitting on the fender when you drive off...

Probably the worst event.   This one needs to be told in full (Courtesy of Wikipedia):

The Goiânia accident was a radioactive contamination accident that occurred on September 13, 1987, at Goiânia, in the Brazilian state of Goiás, after an old radiotherapy source was stolen from an abandoned hospital site in the city. 

Abandonment at the Hospital:
The Instituto Goiano de Radioterapia (IGR), a private radiotherapy institute in Goiânia, was just 1 km northwest of Praça Cívica, the administrative center of the city.  It moved to its new premises in 1985, leaving behind a cesium-137-based teletherapy unit that had been purchased in 1977.

The fate of the abandoned site was disputed in court between IGR and the Society of Saint Vincent de Paul, the owner of the premises.  On September 11, 1986, the Court of Goiás stated it had knowledge of the abandoned radioactive material in the building.

Four months before the theft, on May 4, 1987, Saura Taniguti, then director of Ipasgo, the institute of insurance for civil servants, used police force to prevent one of the owners of IGR, Carlos Figueiredo Bezerril, from removing the objects that were left behind.  Figueiredo then warned the president of Ipasgo, Lício Teixeira Borges, that he should take responsibility "for what would happen with the cesium bomb".

The court posted a security guard to protect the hazardous abandoned equipment.  Meanwhile, the owners of IGR wrote several letters to the National Nuclear Energy Commission, warning them about the danger of keeping a teletherapy unit at an abandoned site, but they could not remove the equipment by themselves once a court order prevented them from doing so.

Theft of the Source:
On September 13, 1987, the guard in charge of daytime security, Voudireinão da Silva, did not show up to work, using a sick day to attend a cinema screening of Herbie Goes Bananas with his family.

The same day, "scavengers" Roberto dos Santos Alves and Wagner Mota Pereira illegally entered the partially demolished facility, found the teletherapy unit – which they thought might have some scrap value – and placed it in a wheelbarrow, taking it to Alves's home, about 0.6 kilometres north of the clinic.  There, they began dismantling the equipment.

That same evening, they both began to vomit.  Nevertheless, they continued in their efforts.  The following day, Pereira began to experience diarrhea and dizziness and his left hand began to swell. He soon developed a burn on this hand in the same size and shape as the aperture - he eventually had partial amputation of several fingers.

On September 15, Pereira visited a local clinic where his symptoms were diagnosed as the result of something he had eaten, and he was told to return home and rest.  Alves, however, continued with his efforts to dismantle the equipment, which was now sitting under a mango tree in his back yard. In the course of this effort, he eventually freed the caesium capsule from its protective rotating head.  His prolonged exposure to the radioactive material led to his right forearm becoming ulcerated, requiring amputation.

The Source is partially broken:
On September 16, Alves succeeded in puncturing the capsule's aperture window with a screwdriver, allowing him to see a deep blue light coming from the tiny opening he had created.   He inserted the screwdriver and successfully scooped out some of the glowing substance.  Thinking it was perhaps a type of gunpowder, he tried to light it, but the powder would not ignite.  The exact mechanism by which the light was generated was not known at the time the IAEA report was written, though it was thought to be either fluorescence or Cerenkov radiation associated with the absorption of moisture by the source.

The Source is sold and dismantled:
On September 18, Alves sold the items to a nearby scrapyard. A scrapyard employee came to the house, loaded the contents into a wheelbarrow, transported them to the yard, and unloaded them.  That night, the owner of the scrapyard, Devair Alves Ferreira, who lived next door, went into the garage and noticed the blue glow from the punctured capsule.

Thinking the capsule's contents were either valuable or even supernatural, he immediately brought it into his house. Over the next three days, he invited friends and family to view the strange glowing substance and offered a reward to anyone who could free it from the capsule. He mentioned that he intended to make a ring out of it for his wife.

On September 21 at the scrapyard, a friend of Ferreira's succeeded in freeing several rice-sized grains of the glowing material from the capsule using a screwdriver. He shared some of these with his brother, claimed some for himself, and the rest remained in the hands of Devair Alves Ferreira, who began to share it with various friends and family members.  That same day, his wife, 37-year-old Gabriela Maria Ferreira, began to fall ill. On September 25, 1987, Devair Alves Ferreira sold the scrap metal to a second scrapyard.

Ivo and his daughter: (this is the saddest part of this awful event)
The day before the sale to the second scrapyard, on September 24, Ivo, Devair's brother, successfully scraped some additional dust out of the source and took it to his house a short distance away.  There he spread some of it on the cement floor.  His six-year-old daughter, Leide das Neves Ferreira, later ate a sandwich while sitting on this floor.  She was also fascinated by the blue glow of the powder, applying it to her body and showing it off to her mother.  Dust from the powder fell on the sandwich she was consuming; she eventually absorbed 1.0 GBq, total dose 6.0 Gy, which is roughly equal to 13 Sv, more than a fatal dose even with treatment.

Gabriela Maria Ferreira notifies the authorites:
Gabriela Maria Ferreira had been the first to notice that many people around her had become severely sick at the same time. Her actions from that point on probably saved lives.  She first suspected the culprit was a beverage they had shared, but an analysis of the juice showed nothing untoward.  On September 28, 1987 — 15 days after the item was found - Gabriela went with one of her scrapyard employees to the rival scrapyard which was then in possession of the materials.  She reclaimed them and transported them by bus in a plastic bag to a hospital. 

There, physician Paulo Roberto Monteiro rightly suspected that it was dangerous.  He placed it in his garden on a chair to increase the distance between himself and the materials.  Because the remains of the source were kept in a plastic bag, the level of contamination at the hospital was low.

Radioactive Contaminatin Confirmed:
In the morning of September 29, 1987 a visiting medical physicist, Walter Mendes Ferreira (no relation to the aforementioned family; "Ferreira" is a common surname equivalent to "Smith"), used a scintillation counter borrowed from NUCLEBRAS (a national government agency which is involved in the nuclear fuel cycle, including searching for uranium ore) to confirm the presence of radioactivity. He spent most of the day confirming the dangerous levels of radiation and persuading the authorities to take immediate action. The city, state, and national governments were all aware of the incident by the end of the day, and the accident response started that evening.

Health outcomes:
About 130,000 people overwhelmed hospitals.  Of those, 250 people, some with radioactive residue still on their skin, were found, through the use of Geiger counters, to be contaminated.  Eventually, 20 people showed signs of radiation sickness and required treatment.

Fatalities:




  • Leide das Neves Ferreira, aged 6 (6.0 Gy, 6 Sv), was the daughter of Ivo Ferreira. Initially, when an international team arrived to treat her, she was confined to an isolated room in the hospital because the hospital staff were afraid to go near her. She gradually developed swelling in the upper body, hair loss, kidney and lung damage, and internal bleeding. She died on October 23, 1987, of "septicemia and generalized infection" at the Marcilio Dias Navy Hospital, in Rio de Janeiro, due to the contamination.  She was buried in a common cemetery in Goiânia, in a special fiberglass coffin lined with lead to prevent the spread of radiation.  Despite these measures, there was still a riot in the cemetery where over 2,000 people, fearing that her corpse would poison the surrounding area, tried to prevent her burial by using stones and bricks to block the cemetery roadway.





  • Gabriela Maria Ferreira, aged 37 (5.7 Gy, 5.5 Sv), wife of junkyard owner Devair Ferreira, became sick about three days after coming into contact with the substance.  Her condition worsened, and she developed internal bleeding, especially in the limbs, eyes, and digestive tract, and suffered from hair loss.  She died October 23, 1987, about a month after exposure.





  • Israel Baptista dos Santos, aged 22 (4.5 Gy, 4.5 Sv), was an employee of Devair Ferreira who worked on the radioactive source primarily to extract the lead.  He developed serious respiratory and lymphatic complications, was eventually admitted to hospital, and died six days later on October 27, 1987.





  • Admilson Alves de Souza, aged 18 (5.3 Gy, 5 Sv), was also an employee of Devair Ferreira who worked on the radioactive source.  He developed lung damage, internal bleeding, and heart damage, and died October 18, 1987.

  • Devair Ferreira himself survived despite receiving 7 Gy of radiation.  He died in 1994 of cirrhosis aggravated by depression and binge drinking.

    A great deal of cleanup was necessary afterwards; several houses were razed and buried, and tons of topsoil removed.  The biological waste of victims who had become contaminated was treated and the radioactive cesium was removed from that.  They were injected with Prussian Blue dye (which reacts chemically with Cesium and is expelled in the waste).  The remnants of the source were siezed and the (now decontaminated) container is on display.

    This is a horrific and very sad story, but it seems like every year somebody attempts a repeat :(

    Monday, September 08, 2014

    I am the gamma ray shielding...

    In any system filled with water, there will be corrosion.  It's inevitable.  Water is a highly polar molecule, and so it has a tendency to dissolve/corrode almost everything.  All you can do is attempt to minimize the amount of corrosion through careful chemistry control.  Even so, you will still get some corrosion.

    In the primary coolant system of a nuclear reactor, what this means is that you will have a few (hopefully not many!) metal atoms suspended in the coolant.  These metal atoms will pass through the reactor core and absorb a neutron, and sometime become radioactive, depending on the metal.

    Some components in the primary coolant system are made from Stellite, a Cobalt-Chromium alloy that has excellent wear and corrosion resistance.  Unfortunately even Stellite corrodes, and it also erodes over time due to wear.  For this reason there will always be some of these Cobalt, Chromium, and Iron atoms carried through the reactor core, suspended within the primary coolant.

    The biggest nuisance among these metal atoms is Cobalt.  Cobalt-59 atoms that flake or corrode off the Stellite can absorb a neutron, and become radioactive Cobalt-60.  Co-60 has a half-life of 5.3 years, and decays by emitting two gamma rays at energies of 1.17 and 1.31 Million Electron Volts.

    Eventually these now-radioactive atoms will find an eddy and come to rest in a low-flow point and settle out, much like silt behind a large dam in a river.  These low-turbulence points where the radioactive atoms settle out will now emit quite a bit of gamma radiation, due to internal contamination.  This stuff has a name: CRUD.

    On the submarine, there were a number valves connected to the primary coolant system which were located outside of the reactor compartment, so that they could be opened or closed if necessary without having to go near the reactor.   One such system on the ship was for emergency cooling; if all electrical power were lost, we still had to be able to remove decay heat from the reactor core.

    As a result of performing the required testing on this emergency cooling system over the years, several of the valves outside of the reactor compartment had accumulated a fair amount of CRUD in them - enough to deserve posting signage and discouraging loitering.
    On to the story... one day in port, some routine maintenance inside the reactor compartment was being performed, and I was the control point watch.  That job meant I that I had to control access in and out of the reactor compartment, to ensure nothing bad happened to the guy in there, and to ensure he didn't bring any nasty radioactive crap out that was clinging to his suit.

    To ensure the last, I had a very sensitive detector for sensing contamination.  It looked like this:
     
    This meter is a Geiger type detector, with an attached "Pancake Probe".  The probe is heavily shielded on all sides but one, so that it will directionally detect radiation.  The open side has a thin mica window, protected from puncture by a mesh screen.  The radiation can pass through the mica and into the detector, which will provide a reading on the meter.  A selector knob allows you to choose a multiplier for the level of contamination you are dealing with, to keep the needle on-scale.  It reads out in counts/minute (times the multiplier).

    Geiger-Mueller detectors work by maintaining a very high voltage across a low pressure gas.  This voltage is just slightly less than would be needed to cause all the gas to ionize and begin conducting continuously like a neon lamp. 

    If a gamma ray or beta particle enters the tube, and reacts with a gas molecule, it will ionize it that molecule.  Next, the very high voltage immediately accelerates the positive and negative ions, causing them to bang into other atoms, ionizing them in turn.  Eventually the entire tube becomes ionized in a massive (but very brief) cascade, and you get one audible "click".  The gas in the Gieger tube immediately resets (because the voltage is slightly too low to keep the gas ionized) and the process repeats for every radiation event inside the tube.

    I was sitting at control point, and got bored.  I decided to point the pancake probe (a very sensitive instrument for detecting minute amounts of contamination) directly at the CRUD-filled valves that were emitting a modest gamma radiation field.

    The instrument went from clicking every second or so, to screaming.  I had place it on the highest range while pointing pancake probe at the internally contaminated valves, even from across the room.

    Out of idle curiousity, I placed my body between the pancake probe and the valves, and the meter stopped screaming.  I was absorbing the gamma radiation that was making the meter swing!  On that day I shielded the sensitive probe from 10 mr/hr worth of gamma rays.  It was a little unnerving realizing that I was absorbing so much gamma radiation, just by being in the room with it. 

    Meh.  I didn't even get an image for that exposure...
     

    Sunday, September 07, 2014

    Radon - a radioactive hazard for everyone

    Radon-222 is a radioactive gas that is heavier than air.  As such, it tends to settle at low points.  It is a "noble" gas, meaning that it doesn't react chemically all that much, because it has 8 electrons in the outer shell.  In this respect it is unlike Radium, which tends to mimic Calcium, and accumulate in bones, causing bone cancers.

    Below is a diagram showing that Radon-222 is element 86 (has 86 protons), has 136 neutrons, and 86 electrons, with a full 8 in the outer shell, making it pretty much inert chemically.



    Radon, although it is chemicall inert, and therefore doesn't bio-accumulate through a chemical process, is still extremely dangerous from a radioactive standpoint.  Radon is a type of "NORM", a.k.a. "Naturally Occurring Radioactive Material", and anyone can easily be receiving dangerous levels of radiation exposure without even realizing it.

    Below is a diagram of the decay chain for U-238, and the portion that interests us begins in the middle, at Radon-222 (Rn).  There are several very damaging radioactive decays that will occur before a stable (non-radioactive) state is reached.  Thus one inhaled Radon atom can inflict biological damage over a series of radioactive decays.  All of these decays are internal, and therefore the alpha and beta particles are absorbed into living tissue inside the lung.



    Uranium-238 at the top of our decay chain, tends to be more concentrated in granite than in other soils and rocks.  Below is a map showing the estimated prevalance of Radon-222 within the US.



    Radon is particularly nasty because due to its density, it tends to accumulate in basements, where there is often little air circulation.  If an atom of Radon decays while in the lungs, it becomes a radioactive atom of lead, which is no longer a gas, and will therefore not be exhaled.  The radioactive particle will very likely stay in the lung.  Afterwards, the radioactive lead atom(s) will continue to decay in a series of events, damaging the DNA in the lungs.

    Below are the some statistics on a variety of causes of deaths annually.  Clearly Radon is a hazard that should be taken very seriously.

    Prior to moving into our new house, we requested a Radon test, and the result was 215 pCi/L (picoCuries per Liter).  The limit is 4 pCi/L.  The concentration of Radon in our basement was about 53 times the limit.

    The biological damage inflicted by the radiation of 4.0 pCi/L of Radon (continuous exposure, annualized) is equal to the biological damage from 100 chest x-rays.

    In equivalent biological damage for cigarettes, 4 pCi/L is equal to 10 cigarettes a day.  So the Radon in our basement had the biological damage equivalent to 530 cigarettes a day or 5300 chest X-Rays per year.  Not good.

    The corrective measures for Radon however are pretty simple and inexpensive.  The basement (particularly penetrations for utilities) is sealed up, the dirt in the crawlspace is covered with a plastic liner.

    A continuously-operating fan is installed that takes suction from underneath the liner and from underneath the floor in the basement.  This ensures any Radon will be swept away and vented before leaking into the house. 

    After remediation, a follow-up test showed that our Radon levels had been reduced to 0.5 pCi/L, or about 1-1/4 cigarette per day, if you never leave the basement.  If I can live in Bakesfield air for 8 years, I can certainly deal with that! :)

    Below, a Radon fan.  These come equipped with an alarm that sounds should the fan fail.

    I highly recommend that anyone who has a basement have their home tested for Radon.  It's cheap. The test is definitely less expensive, painful, and deadly than getting lung cancer.