Tag Archives: Explosion

How Did a Cold War Nuclear Bomb Go Missing?

By ThinkReliability Staff

Is there a nuclear bomb lost just a few miles off the coast of Savannah, Georgia? It seems that we will never know, but theories abound. While it is easy to get caught up in the narrative of these theories, it is interesting to look at the facts of what actually happened to piece together the causes leading up to the event. This analysis may not tell us if the bomb is still under the murky Wassaw Sound waters, but it can tell us something about how the event happened.

Around 2 am on February 5, 1958, a training exercise was conducted off the coast of Georgia. This was during the most frigid period of the Cold war, and training was underway to practice attacking specific targets in Russia. During this particular training mission, Major Howard Richardson was flying a B-47 bomber carrying a Mark 15, Mod 0 Hydrogen bomb containing 400 pounds of conventional explosives and some quantity of uranium.

The realistic training mission also included F-86 ‘enemy’ fighter jets. Unfortunately, one of those jets, piloted by Lt. Clarence Stewart, did not see the bomber on his radar and accidentally maneuvered directly into the B-47. The damage to both planes was extensive. The collision destroyed the fighter jet, and severely damaged the fuel tanks, engine, and control mechanisms of the bomber.   Fortunately, Stewart was able to safely eject from the fighter jet. Richardson had a very difficult quest ahead of him: to get himself and his co-pilot safely on the ground without detonating his payload in a heavily damaged aircraft. He flew to the closest airfield; however, the runway was under construction, making the landing even more precarious for the two crew members and for the local community that would have been affected had the bomb exploded upon landing. Faced with an impossible situation, Richardson returned to sea, dropped the bomb over the water, observed that no detonation took place, and returned to carefully land the damaged bomber.

The Navy searched for the bomb for over two months, but bad weather and poor visibility did not make the search easy. On April 16, 1958, the search was ended without finding the bomb. The hypothesis was that the bomb was buried beneath 10 – 15 feet of silt and mud. Since then, other searches by interested locals and the government have still not identified the location of the bomb.   In 2001, the Air Force released an assessment which suggests two interesting points. First, the bomb was never loaded with a ‘detonation capsule’, making the bomb incapable of a nuclear explosion. (Until this time, conventional wisdom suggested that the detonation capsule was included with the bomb.) Second, the report concluded that it would be more dangerous to try to move the bomb than to leave the bomb in its resting place.

While we may never learn the location of the bomb, we can learn from the incident itself. Using a Cause Map, we can document the causes and effects resulting in this incident, providing a visual root cause analysis. Beginning with several ‘why’ questions, we can create a cause-effect chain. In the simplest Cause Map, the safety goal was impacted as a result of the danger to the pilots and to the nearby communities as the result of a potential nuclear bomb explosion. This risk was caused by the bomb being jettisoned from the plane, which was a result of the collision between the fighter jet and the bomber. The planes collided due to the fact that they were performing a training mission to simulate a combat scenario.

More details are uncovered as this event is further broken down to include more information and to document the impact to other goals. The property goal is impacted through the loss of aircraft and the bomb. The bomb is missing because it was jettisoned from the bomber AND because it was never found during the search. The bomb was jettisoned because the pilot was worried that the bomb might break loose during landing. This was due to the fact that the planes collided. The planes collided due to the fact that the F-86 descended onto the top of the B-47 AND because they were in the midst of a training exercise. The fighter jet crashed into the bomber because the bomber was not on radar. The planes were performing an exercise because they were simulating bombing a Russian target, because it was the middle of the Cold War. The search was unsuccessful because the bomb is probably buried deep in the mud AND because the weather and visibility were bad during the search.

Finally, the ‘customer service’ goal is impacted by the fact that the residents in nearby communities are nervous about the potential danger of explosion/radiation exposure. This nervousness is caused by the fact that the bomb is still missing AND the fact that the bomb contained radioactive material, which was due to routine protocol at the time.

Evidence boxes are a helpful way to add information to the Cause Map that was discovered during the investigation. For example, an evidence box stating the evidence from the 2001 Air Force report that the bomb had no detonation capsule has been added to the Cause Map. A Cause Map is a useful tool to help separate the facts from the theories. Click on “Download PDF” above to see the full, detailed Cause Map.

The Force Was NOT With Them!

By Jon Bernardi

A long time ago, in a galaxy far, far away, the Empire tried to use their fancy Death Star to keep the member systems in line. This plan did not work out very well, as Death Star One (DS-1) was not able to fulfill its mission of empowering galactic domination! DS-1 had travelled across the galaxy to quell the rebellion at the rebel base on Yavin 4, but did not count on the über-Force of the Rebel Alliance. The Empire did not realize the power of the good side of the Force as the rebels overcame all odds and were able to destroy DS-1. We can do an analysis of the incident to determine the system of causes for the destruction and show those causes visually in a Cause Map.

As much as the Emperor and his minions would not like to see this published, we begin by looking at how the Empire’s goals were impacted. We start by developing an outline of the incident. You might suspect that different factions within the Empire see this problem differently! Some don’t believe there is such a thing as “The Force” and place their faith in the power of the machine. Others use the Dark Side to exploit the mortal weaknesses of the players. The goals of the Empire are impacted in a number of ways: DS-1 is ultimately destroyed, with loss of life, and loss of a dominant-style weapon. The Rebel Alliance has gained a toe-hold against the Empire! We use the impact to the goals as the first effects of our cause-and-effect relationships and will use the disparate view of “the problem” to help us with the branches of the Cause Map.

We already know that DS-1 had planet-busting capabilities, as demonstrated convincingly at Alderaan, Princess Leia’s adopted planet. This may have led the Empire’s power structure to doubt the “Power of the Force” and put their trust in a technological titan, “The ultimate power in the universe!” Even after the plans for the station had been obtained by the Rebellion, the commander of DS-1 still disregarded any concern of vulnerability in his unsinkable marvel. In a remarkable display of hubris, the Empire allows the small band of rebels aboard the Millennium Falcon to escape with the stolen plans for DS-1. The Empire intends to follow them, find the rebel base, and wipe out the rebellion once and for all!

Another branch of the Cause Map follows the path of the stolen plans and the re-awakening of the Force on the planet Tatooine. As we analyze this section of the map, we can see the convergence of causes that led to the technical experts of the Rebel Alliance finally obtaining the plans for DS-1, analyzing them and discovering the dreaded “thermal exhaust port” – (guess even a DS has to have a tailpipe!).

Even a long time ago, we see causes in multiple areas coming together to form the overall picture of the incident. The plucky Rebellion, had THE FORCE with them!

Runway Fire Forces Evacuation of Airplane

By ThinkReliability Staff

On September 8, 2015, an airplane caught fire during take-off from an airport in Las Vegas, Nevada. The pilot was able to stop the plane, reportedly in just 9 seconds after becoming aware of the fire. The crew then evacuated the 157 passengers, 27 of whom received minor injuries as a result of the evacuation by slide. Although the National Transportation Safety Board (NTSB) investigation is ongoing, information that is known, as well as potential causes that are under consideration, can be diagrammed in a Cause Map, or visual root cause analysis.

The first step of Cause Mapping is to define the problem by completing a problem outline. The problem outline captures the background information (what, when and where) of the problem, as well as the impact to the goals. In this case, the safety goal is impacted due to the passenger injuries. The evacuation of the airplane impacts the customer service goal. The NTSB investigation impacts the regulatory goal. The schedule goal is impacted by a temporary delay of flights in the area, and the property goal is impacted by the significant damage to the plane. The rescue, response and investigation is an impact to the labor goal.

The Cause Map is built by beginning with one of the impacted goals and asking “Why” questions to develop the cause-and-effect relationships that led to an issue.   In this case, the injuries were due to evacuation by slide (primarily abrasions, though some sources also said there were some injuries from smoke inhalation). These injuries were caused by the evacuation of the airplane. The airplane was evacuated due to an extensive fire. Another cause leading to the evacuation was that take-off was aborted.

The fact that take-off was able to be aborted, for which the pilot has been hailed as a hero, is actually a positive cause. Had the take-off been unable to be aborted, the result would likely have been far worse. In the case of the Concorde accident, a piece of debris on the runway ruptured a tire, which caused damage to the fuel tank, leading to a fire after the point where take-off could be aborted. Instead, the aircraft stalled and crashed into a hotel, killing all onboard the craft and 4 in the hotel. The pilot’s ability to quickly save the plane almost certainly saved many lives.

The fire is thought to have been initiated by an explosion in the left engine due a catastrophic uncontained explosion of the high-pressure compressor. This assessment is based on the compressor fragments that were found on the runway. This likely resulted from either a bird strike (as happened in the case of US Airways flight 1549), or a strike from other debris on the runway (as occurred with the Concorde), or fatigue failure of the engine components due to age. This is the first uncontained failure of this type of engine, so some consider fatigue failure to be less likely. (Reports of an airworthiness directive after cracks were detected in weld joints of compressors were in engines with different parts and a different compressor configuration.)

In this incident, the fire was unable to be put out without assistance from responding firefighters. This is potentially due to an ongoing leak of fuel if fuel lines were ruptured and the failure of the airplane’s fire suppression system, which reportedly deployed but did not extinguish the fire. Both the fuel lines and fire suppression system were likely damaged when the engine exploded. The engine’s outer casing is not strong enough to contain an engine explosion by design, based on the weight and cost of providing that strength.

The NTSB investigation is examining airplane parts and the flight data and cockpit voice recorders in order to provide a full accounting of what happened in the incident. Once these results are known, it will be determined whether this is considered an anomaly or whether changes to all planes using a similar design and configuration need to take action to prevent against a similar event recurring.

To view the initial investigation information on a one-page downloadable PDF, please click “Download PDF” above.


Explosions raise concern over hazardous material storage

By ThinkReliability Staff

On August 12, a fire began at a storage warehouse in Tianjin, China. More than a thousand firefighters were sent in to fight the fire. About an hour after the firefighters went in, two huge explosions registered on the earthquake measurement scale (2.3 and 2.9, respectively). Follow-on explosions continued and at least 114 firefighters, workers and area residents have been reported dead so far, with 57 still missing (at this point, most are presumed dead).

Little is known for sure about what caused the initial fire and continuing explosions. What is known is that the fire, explosions and release of hazardous chemicals that were stored on site have caused significant impacts to the surrounding population and rescuers. These impacts can be used to develop cause-and-effect relationships to determine the causes that contributed to an event. It’s particularly important in an issue like this – where so many were adversely affected – to find effective solutions to reduce the risk of a similar incident recurring in the future.

Even with so much information unavailable, an initial root cause analysis can identify many issues that led to an adverse event. In this case, the cause of the initial fire is still unknown, but the site was licensed to handle calcium carbide, which releases flammable gases when exposed to water. If the chemical was present on site, the fire would have continued to spread when firefighters attempted to fight it using water. Contract firefighters, who are described as being young and inexperienced, have said that they weren’t adequately trained for the hazards they faced. Once the fire started, it likely ignited explosive chemicals, including the 800 tons of ammonium nitrate and 500 tons of potassium nitrate stored on site.

Damage to the site released those and other hazardous chemicals. More than 700 tons of sodium cyanide were reported to be stored at the site, though it was only permitted 10 tons at a time. Sodium cyanide is a particular problem for human safety. Says David Leggett, a chemical risk consultant, “Sodium cyanide is a very toxic chemical. It would take about a quarter of teaspoon to kill you. Another problem with sodium cyanide is that it can change into prussic acid, which is even more deadly.”

But cleaning up the mess is necessary, especially because there are residents living within 2,000 ft. of the site, despite regulations that hazardous sites are a minimum of 3,200 ft. away from residential areas. Developers who built an apartment building within the exclusion zone say they were told the site stored only common goods. Rain could make the situation worse, both by spreading the chemicals and because of the potential that the released chemicals will react with water.

The military has taken over the response and cleanup. Major General Shi Luze, chief of the general staff of the military region, said, “After on-site inspection, we have found several hundred tons of cyanide material at two locations. If the blasts have ripped the barrels open, we neutralize it with hydrogen peroxide or other even better methods. If a large quantity is already mixed with other debris, which may be dangerous, we have built 1-meter-high walls around it to contain the material — in case of chemical reactions if it rains. If we find barrels that remain intact, we collect them and have police transport them to the owners.”

In addition to sending in a team of hazardous materials experts to neutralize and/or contain the chemicals and limiting the public from the area in hopes to limit further impact to public safety, the state media had said they were trying to prevent rain from falling, presumably using the same strategies developed to ensure clear skies for the 2008 Summer Olympics. Whether it worked or not hasn’t been said, but it did rain on August 18, nearly a week after the blast, leaving white foam that residents have said creates a burning or itchy sensation with contact.

View an initial Cause Map of the incident by clicking on “Download PDF” above.

ISS Supply Mission Fails

By Kim Smiley

An unmanned Progress supply capsule failed to reach the International Space Station (ISS) and is expected to burn up during reentry in the atmosphere along with 3 tons of cargo.  Extra supplies are stored on the ISS and the astronauts onboard are in no immediate danger, but the failure of this supply mission is another in a string of high-profile issues with space technology.

This issue can be analyzed by building a Cause Map, a visual format of root cause analysis.  A Cause Map intuitively lays out the causes that contributed to an issue to show the cause-and-effect relationships.  To build a Cause Map, “why” questions are asked and the answers are documented on the Cause Map along with any relevant evidence to support the cause.

So why did the supply mission fail? The mission failed because the supply capsule was unable to dock with the ISS because mission control was unable to communicate with the spacecraft.  The Progress is an unmanned Russian expendable cargo  capsule that cannot safely dock with a space station without communication with mission control.  Mission control needs to be able to verify that all systems are functional after launch and needs a communication link to navigate the unmanned capsule through docking.

Images of the capsule showed that two of the five antennas failed to unfold leading to the communication issues.  Debris spotted around the capsule while it was in orbit indicates a possible explosion.  No further information has been released about what might have caused the explosion and it may be difficult to decisively determine the cause since the capsule will be destroyed in orbit.

The ISS recycles oxygen and water to an impressive degree and food is the first supply that would run out on the ISS, but NASA has stated that there are at least four months of food onboard at this time.  The failure of this mission may mean that the cargo for future missions will need to be altered to include more basic necessities and less scientific equipment, but astronaut safety is not a concern at this time. The failure of this mission does put additional pressure on the next resupply mission scheduled to be done by SpaceX in June in addition to creating more bad press for space programs that are already struggling during a turbulent time.

To view a intermediate Cause Map of this issue, click on “Download PDF” above.

Early Problems with Mark 14 Torpedoes

By Kim Smiley

The problems with Mark 14 torpedoes at the start of World War II are a classic example that illustrates the important of robust testing.  The Mark 14 design included brand new, carefully guarded technology and was developed during a time of economic austerity following the Great Depression.  The desire to minimize costs and to protect the new exploder design led to such a limited test program that not a single live-fire test with a production model was done prior to deploying the Mark 14.

The Mark 14 torpedo design was a step change in torpedo technology. The new Mark VI exploder was a magnetic exploder designed to detonate under a ship where there was little to no armor and where the damage would be greatest.  The new exploder was tested using specially instrumented test torpedoes, but never a standard torpedo. Not particularly shocking given the lack of testing, the torpedoes routinely failed to function as designed once deployed.

The Mark 14 torpedoes tended to run too deep and often failed to detonate near the target. One of the problems was that the live torpedoes were heavier than the test torpedoes so they behaved differently. There were also issues with the torpedo’s depth sensor.  The pressure tap for the sensor was in the rear cone section where the measured pressure was substantially less than the hydrostatic pressure when the torpedo was traveling through the water.  This meant that the depth sensor read too shallow and resulted in the torpedo running at deeper depths than its set point.  Eventually the design of the torpedo was changed to move the depth sensor tap to the mid-body of the torpedo where the readings were more accurate.

The Mark 14 design also had issues with premature explosions.  The magnetic exploder was intended to explode near a ship without actually contacting it.  It used small changes in the magnetic field to identify the location of a target. The magnetic exploder had been designed and tested at higher latitudes and it wasn’t as accurate closer to the equator where the earth’s magnetic field is slightly different.

In desperation, many crews disabled the magnetic exploder on Mark 14 torpedoes even before official orders to do so came in July 1943.  Use of the traditional contact exploder revealed yet another design flaw in the Mark 14 torpedoes.  A significant number of torpedoes failed to explode even during a direct hit on a target.  The conventional contact exploder that was initially used on the Mark 14 torpedo had been designed for earlier, slower torpedoes.  The firing pin sometimes missed the exploder cap in the faster Mark 14 design.

The early technical issues of the Mark 14 torpedoes were eventually fixed and the torpedo went on to play a major role in World War II.  Mark 14 torpedoes were used by the US Navy for nearly 40 years despite the early issues.  But there is no doubt that it would have been far more effective and less painful to identify the technical issues during testing rather than in the field during war time.  There are times when thorough testing may seem too expensive and time consuming, but having to fix a problem later is generally much more difficult.  No one wants to waste effort on unnecessary tests, but a reasonable test program that verifies performance under realistic conditions is almost always worth the investment.

To view a high level Cause Map of the early issues of the Mark 14 torpedoes, click “Download PDF”.

You can also learn more about the torpedoes by clicking here and here.

Antares Cargo Rocket Explodes Seconds After Launch

By Kim Smiley

On October 28, 2014 an Antares cargo rocket bound for the International Space Station (ISS) catastrophically exploded seconds after launch.  The $200 million rocket was planned to be one of eight supply missions to the ISS that Orbital Sciences has a $1.9 billion contract to provide.  The investigation is still underway, but initial findings indicate that there may have been a problem with the engines, which were initially built in the 1960s and early 1970s by the Soviet space program.

Whenever NASA launches a rocket, it is observed by safety personnel with the ability to cause the rocket to self-destruct if it appears to be malfunctioning to minimize potential injuries and property damage. Reports by NASA have indicated that this flight-termination system was engaged shortly after liftoff in this case because the rocket malfunctioned shortly after takeoff.

Video of the launch and the subsequent explosion show the plume from one engine changing shape a second before the massive explosion.  The change in the plume has led to speculation that a turbopump failed shortly after liftoff and suggests that the engines were the source of the malfunction.  Investigators are currently reviewing the video of the launch, telemetry readings from the rocket, and studying the debris to learn as many details as possible about this failure.

The engines in question are NK-33 rocket engines that were initially built (not just designed, but actually manufactured) more than 4 decades ago. So how did engines from the Apollo era end up on a rocket decades later in 2014?  The one-word answer is money.

These engines were originally designed to support the Soviet space program which was disbanded in 1974.  For years, these engines were warehoused with no real purpose.  In 1990, these engines were sold to a company called Aerojet, reportedly for the bargain price of a cool million each.  The engines were refurbished and renamed Aerojet AJ-26s.  The cost of using these older engines was significantly less than developing a brand new rocket design.  In addition to being expensive, a new rocket design requires a significant time investment.  There are also limited alternatives available, partly due to NASA’s shrinking budget.

Orbital Sciences has announced that they will source a different engine and no longer use the AJ-26s, but it’s worth nothing that these rockets have been used successfully in recent years. They have launched Cygnus supply spacecraft three times without incident.

To view a high level Cause Map, a visual root cause analysis, of this incident, click on “Download PDF” above.

50 Presumed Dead in Canadian Train Disaster

By ThinkReliability Staff

A tragic accident devastated the Canadian town of Lac-Mégantic, Quebec on July 6, 2013.  Much about the issue is still unknown.  When investigating an incident such as this, it can be helpful to identify what is known and information that still needs to be determined.

What is known: a 73-car train was parked in Nantes, Quebec, uphill from Lac-Mégantic.  Of the cars, 72 contained crude oil.  The train was left unattended and late the evening of July 5, 2013, a fire broke out in the locomotive.  While the fire department of Nantes was putting out the fire, they turned off the train’s main engine.  Less than two hours later, the train rolled down the track and derailed in Lac-Mégantic.  After subsequent explosions and long-burning fires, 24 people have been confirmed dead.  26 more are missing.   Much of the town and the train – and the evidence in it – is destroyed.

What is not known: The cause of the initial fire on the train is not known.  Whether or not the fire department should have explicitly notified the train engineer that the main engine had been shut off is not known.  What happened that allowed the train to roll downhill is unknown.

With this number of unknowns, it is helpful to visually lay out the cause-and-effect relationships that occurred, and what impact they had on those affected.  This can allow us to see the holes in our analysis and identify where more evidence is needed.  Once as much evidence as possible has been obtained, additional detail can be added to the cause-and-effect relationships.  Ensuring that all causes related to the incident are included will provide the largest number of solutions, allowing us to choose the most effective.  We can do all this in a Cause Map, or visual root cause analysis.

The first step in using any problem solving methodology is to determine the impact caused by the incident.  In this case, the deaths (and assumed deaths) are our most significant impact.  Also addressed should be the crude oil leakage (though much of it was likely burned off), the high potential for lawsuits, the possible impact on rail shipments, the destruction of the town and the train, and the response and cleanup efforts.  These form the initial “effects” for our cause-and-effect analysis.

Asking “Why” questions allows us to further develop the cause-and-effect relationships.  We know that for the train to roll backwards down the hill, both sets of brakes had to be ineffective.  The railway company has stated that the air brakes released because the main engine had been shutdown.  However, according to the New York Times, “since the 19th century, railways in North America have used an air-braking system that applies, rather than releases, freight car brakes as a safety measure when it loses pressure.”  This certainly makes more sense than having brakes be dependent on engine power.

The hand brakes functioned as backup brakes.  The number of cars (which, when on a hill, affects the force pulling on the train) determines the number of handbrakes required.  In this case, the engineer claims to have set 11 handbrakes, but the rail company has now stated that they no longer believe this.  No other information – or evidence that could help demonstrate what happened to either sets of brakes – has been released.

Also of concern are the style of train cars – believed to be the same that the NTSB identified in a report on a previous train accident as “subject to damage and catastrophic loss of hazardous materials”.

In a tragedy such as this one, the first priority is to save and preserve human lives in every way possible.  However, once that mission is complete, evidence-gathering to determine what happened is the next priority.  As evidence becomes available it is added directly to the Cause Map, below the cause it supports or refutes.  Additional causes are added as necessary with the goal of determining all the cause-and-effect relationships to provide the largest supply of possible solutions to choose from.

The company involved has already stated it will no longer leave trains unattended.  That should be a big help but, given the consequences of this event, other solutions should be considered as well.

To view the Outline and Cause Map, please click “Download PDF” above.  Or click here to read more.

Chemical Plant Explosion Kills 2 and Injures Dozens in LA

By Kim Smiley

On June 13, 2013, an explosion at a chemical plant in Louisiana killed two and injured more than seventy others.  The cause of the explosion is still unknown, but the federal Occupational Safety and Health Administration and the U.S. Chemical Safety Board are investigating the accident.

Even though the investigation is still ongoing, an initial Cause Map, or visual root cause analysis can be built for this issue.  The initial Cause Map can document what is known at this point and can easily be expanded to incorporate more details as they become available.  The first step in the Cause Mapping process is to fill in an Outline with the basic background information for the accident (such as the location, time and date) as well as document what overall goals were impacted by the incident.

In this case, the safety goal was obviously impacted because of the fatalities and injuries.  The damage to the plant is an impact to the material goal and the time the plant is shut down is an impact to the schedule goal.  Once the Outline is complete, including the impacts to the goal, the Cause Map is built by asking “why” questions.  For example, we would ask “why” people were killed and injured and would add that there was an explosion at the chemical plant to the Cause Map.

What caused the explosion isn’t known, but every explosion requires oxygen, a spark and fuel so these basic facts can be added to the Cause Map.  The plant housed a large amount of flammable material because it manufactures polymer grade propylene which is used to make plastics.  If investigators are able to determine what created the spark that information could be added as well as any other relevant information that comes to light.

The Outline also has space to document anything that is different or unusual at the time of the accident.  Anything unusual about the situation when the accident occurred is often a good starting point in an investigation because it may have played a role in the accident.  In this example, the plant was being expanded at the time of the accident and there were many contract workers on site.  If this is found to have played a role in the accident, this information would be incorporated onto the Cause Map as well as the Outline.

The final step of the Cause Mapping process is to use the Cause Map to develop solutions that can be implemented to help prevent a similar problem from occurring in the future.  Once a final Cause Map is built that incorporates all the findings from the investigation, it will be helpful in understanding any lessons to be learned and discussing potential solutions.

To view a high level Cause Map and an Outline for this accident, click on “Download PDF” above.

Deadly Explosion at Texas Fertilizer Plant

By ThinkReliability Staff

An explosion at a fertilizer plant in West, Texas, destroyed much of the town and killed between 5-15 people.   (Search and rescue is still ongoing.)  At least 160 were injured but that number may increase.  The material involved in the explosion was ammonium nitrate, a popular fertilizer.

Capturing the impacts to the goals as a result of an issue is essential to understanding the true effect.  In this case, the fatalities and injuries were severe.  The property damage, which included the plant, as well as the homes of more than 100 families, was also extensive.  An environmental impact resulted from the release of ammonia, which is a respiratory irritant. There was some level of evacuation, which can be considered an impact to the customer service goal, though the high number of injuries has led some to believe the evacuation was not widespread enough.  Additionally, ongoing search and rescue, and firefighting operations are an impact to the labor goal.

These goals were all impacted due to the explosion at the fertilizer plant.  Ammonium nitrate can explode when ignited at very high temperatures.  In this case, a fire provided the high heat.  We can capture these causes in a Cause Map, or a visual form of root cause analysis.  The cause of the fire itself is as yet unknown, though if that is determined we can add it to the Cause Map as well.

What is known is that efforts to prevent explosion were ineffective.  The plant did not believe that an explosion was possible.  Its internal safety review had a worst-case scenario of a ten-minute ammonia release, causing no injuries.  It is fairly rare that ammonia nitrate explodes; only 17 known cases of unintended ammonia nitrate explosions resulting in fatalities have occurred since 1921.  Firefighters were on scene fighting the fire when the explosion occurred, leading to many responder fatalities and injuries.  Oversight at the facility was limited; OSHA has not inspected the facility for at least the last five years.

It is worth exploring why large amounts of ammonium nitrate were present.  Ammonium nitrate is an inexpensive, effective fertilizer.  It is particularly good at delivering nitrogen to food-bearing plants, like fruit trees.  The use of nitrogen greatly increases the yield of food from these plants.  (It is said to increase the carrying capacity, or number of people who can be supported by a hectare of land – from 1.9 to 4.3.)  Given the shortage of food-growing land, this is certainly important.   However, the benefits must be considered alongside the risk and certainly in the future more oversight of these types of facilities may be needed to protect the public from the process as they benefit from the results.

To view the Outline and Cause Map, please click “Download PDF” above.