Tag Archives: contamination

Root Cause Analysis - Incident Investigation

Kitty Litter Cause of Radiological Leak?

By ThinkReliability Staff

The rupture of a container filled with nuclear waste from Department of Energy (DOE) sites that resulted in the  radiological contamination of 21 workers appears to have resulted from a heat-producing reaction, possibly between the nuclear waste and the kitty litter used to stabilize the waste.

DOE photo of damaged container

Yes, you read that correctly. The same stuff you use for Fluffy’s “business” is also used to stabilize nuclear waste.  However, the kitty litter typically used is clay.  One of the sites that provides waste to the Waste Isolation Pilot Plant, where the release occurred, changed from clay kitty litter to organic kitty litter, which is made of plant material.  Although the reaction that resulted in the container’s rupture has not yet been determined, it is possible that it was due to the change in litter.

We can look at this incident in a Cause Map, or visual root cause analysis, to lay out both the effects and causes.  In this case, the effects were significant.  Twenty-one workers were found to have internal radiological contamination, impacting the safety goal.  A radiological release off-site impacted the environmental goal.  The waste repository has been shut down and is not accepting shipments, impacting both the customer service and production goals.  The release requires the investigation of a formal Accident Investigation Board, impacting the regulatory and labor goal.  Lastly, the damage to the container is an impact to the property goal.

The release was caused by the rupture of a container that stored radiological waste, including americium and plutonium.  The release was able to leave the underground storage facility due to a leak path in the ventilation system, which was by design because the ventilation system was not designed for containment because the safety analysis assumed that a release within the storage facility would result from a roof panel fall and was adequately prevented.

The rupture appears to have resulted from a heat-producing reaction. The constituents of that reaction have not yet been determined, but the change from clay to organic kitty litter has been identified as a possible cause.  (A possible cause indicates a cause for which evidence is not yet available.)  More research is being done to determine the actual reaction.  This will also allow a determination of which other waste containers may be at risk for rupture.

A solution that has already been implemented is to seal the leaks in the ventilation system with foam to reduce the risk of leak-by.  Other solutions that have been suggested are to add an additional heavy-duty containment around the affected casks, reclassify the ventilation system as containment, and perform an independent review of the safety analysis of the site.  Once appropriate solutions are determined and implemented, it’s hope the site will be able to reopen.

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

Root Cause Analysis - Incident Investigation

Cleaning up Fukushima Daiichi

By ThinkReliability Staff

The nuclear power plants at Fukushima Daiichi were damaged beyond repair during the earthquake and subsequent tsunami on March 11, 2011.  (Read more about the issues that resulted in the damage in our previous blog.)  Release of radioactivity as a result of these issues is ongoing and will end only after the plants have been decommissioned.  Decommissioning the nuclear power plants at Fukushima Daiichi will be a difficult and time consuming process.  Not only the process but the equipment being used are essentially being developed on the fly for this particular purpose.

Past nuclear incidents offer no help.  The reactor at Chernobyl which exploded was entombed in concrete, not dismantled as is the plan for the reactors at Fukushima Daiichi.  The reactor at Three Mile Island which overheated was defueled, but the pressure vessel and buildings in that case were not damaged, meaning the cleanup was of an entirely different magnitude.  Lake Barrett, the site director during the decommissioning process at Three Mile Island and a consultant on the Fukushima Daiichi cleanup, says that nothing like Fukushima has ever happened before.

An additional challenge?  Though the reactors have been shut down since March 2011, the radiation levels remain too high for human access (and will be for some time).  All access, including for inspection, has to be done by robot.

The decommissioning process involves 5 basic steps (though the completion of them will take decades).

First, an inspection of the site must be completed using robots.  These inspection robots aren’t your run-of-the-mill Roombas.  Because of the steel and concrete structures involved with nuclear power, wireless communication is difficult.  One type of robot used to survey got stuck in reactor 2 after its cable was entangled and damaged.   The next generation of survey robots unspools cable, takes up slack when it changes direction and plugs itself in for a recharge.  This last one is particularly important: not only can humans not access the reactor building, they can’t handle the robots after they’ve been in there.  The new robots should be able to perform about 100 missions before component failure, pretty impressive for access in a site where the hourly radiation dose can be the same as a cleanup worker’s annual limit (54 millisieverts an hour).

Second, internal surfaces will be decontaminated.  This requires even more robots, with different specialties.  One type of robot will clear a path for another type, which will be outfitted with water and dry ice, to be blasted at surfaces in order to remove the outer level, and the radiation with it.  The robots will them vacuum up and remove the radioactive sludge from the building.  The resulting sludge will have to be stored, though the plan for the storage is not yet clear.

Third, spent fuel rods will be removed, further reducing the radiation within the buildings.  A shielded cask is lowered with a crane-like machine, which then packs the fuel assemblies into the cask.  The cask is then removed and transported to a common pool for storage.  (The fuel assemblies must remain in water due to the decay heat still being produced.)

Fourth, radioactive water must be contained.  An ongoing issue with the Fukushima Daiichi reactors is the flow of groundwater through contaminated buildings.  (Read more about the issues with water contamination in a previous blog.)  First, the flow of groundwater must be stopped.  The current plan is to freeze soil to create a wall of ice and put in a series of pumps to reroute the water.    Then, the leaks in the pressure vessels must be found and fixed.  If the leaks can’t be fixed, the entire system may be blocked off with concrete.

Another challenge is what to do with the radioactive water being collected.  So far, over 1,000 tanks have been installed.  But these tanks have had problems with leaks.    Public sentiment is against releasing the water into the ocean, though the contamination is low and of a form that poses a “negligible threat”.  The alternative would be using evaporation to dispose of the water over years, as was done after Three Mile Island.

Finally, the remaining damaged nuclear material must be removed.  More mapping is required, to determine the location of the melted fuel.  This fuel must then be broken up using long drills capable of withstanding the radiation that will still be present.  The debris will then be taken into more shielded casks to a storage facility, the location of which is yet to be determined.  The operator of the plant estimates this process will take at least 20 years.

To view the Process Map laid out visually, please click “Download PDF” above.  Or click here to read more.

Root Cause Analysis - Incident Investigation

300,000 Unable to Use Water after Chemical Spill in West Virginia

By Kim Smiley

Hundreds of thousands of West Virginians were unable to use their water for days after it was contaminated by a chemical spill on January 9, 2014. About 7,500 gallons of 4-methyl-cyclohexane-methanol, known as MCHM, leaked out of a storage tank and into the Elk River.   At the time of the spill, little information was known about MCHM, but officials ordered residents not to use the use the water because the chemical can cause vomiting, nausea, and skin, eye and throat irritation.  The ban on water usage obviously meant that residents should not drink the water, but they were also told not to cook, bathe, wash clothes or brush their teeth with it.

The investigation into this incident is still ongoing, but some information is available.  An initial Cause Map, or visual root cause analysis, can be built now and it can easily be expanded in the future.  A Cause Map is used to illustrate the cause-and-effect relationships between the many causes that contribute to any incident.  In this example, it is known that the MCHM leaked into the river because it was being stored in a tank near the river and the tank failed.  MCHM was being stored in a tank because it is used in coal processing and it was profitable for the company to sell it.

The cause of the tank failure hasn’t been officially determined, but the company who owned the facility has stated that an object punctured the tank after the ground under the tank froze.  (Suspected causes can be included on the Cause Map with a question mark to indicate that more evidence is needed to confirm their validity.)

The tank in question was older, built about 70 years ago.  There were no regulations that required the tank to be inspected while it was being used to store MCHM because the chemical is not currently legally considered a hazardous material.  The tank is also an atmospheric tank so it is exempt from current federal safety inspections because it is not under pressure, cooled or heated.

Many are asking questions about why a tank full of a chemical that can make people sick that was so close to the water supply had so little regulation and no required inspections.  The debate that has been sparked by this accident will force a close review of current regulations governing these types of facilities.

It’s also alarming how little was known about this chemical prior to this accident.  It’s still not well understood exactly how dangerous MCHM is.  Experts have stated that the long term impacts should be minimal, but it would be awfully reassuring to the people living in the area if there was more information about the chemical available.

Companies need to have a clear understanding of the risks involved in their operations if they hope to reduce the risk to the lowest reasonable level and develop effective emergency response plans to deal with any issues that do arise.  As the old saying goes – failure to plan is planning to fail.  Just ask the company involved.  Freedom Industries filed bankruptcy papers on January 17, 2013 as a direct result of this accident.

Root Cause Analysis - Incident Investigation

Issues at Fukushima Daiichi Unit 3

By ThinkReliability Staff

There are many complex events occurring with some of Japan’s nuclear power plants as a result of the earthquake and tsunami on March 11, 2011.  Although the issues are still very much ongoing, it is possible to begin a root cause analysis of the events and issues.  In order to clearly show one issue, our analysis within this blog is limited to the issues affecting Fukushima Daiichi Unit 3.  This is not to minimize the issues occurring at the other plants and units, but rather to clearly demonstrate the cause-and-effect within one small piece of the overall picture.

The issues surrounding Unit 3 are extremely complex.  In events such as these, where many events contribute to the issues, it can be helpful to make a timeline of events.  A timeline of the events so far can be seen by clicking “Download PDF” above.  A timeline can not only help to clarify the order of contributing events, it can also help create the Cause Map, or visual root cause analysis.  To show how the events on the timeline fit into the Cause Map, some of the entries are denoted with numbers, which are matched to the same events on the Cause Map.  Notice that in general, because Cause Maps build from right to left with time, earlier entries are found to the right of newer events.  For example, the earthquake was the cause of the tsunami, so the earthquake is to the right of the tsunami on the map.  Many of the timeline events are causes, but some are also solutions.  For example, the venting of the reactor is a solution to the high pressure.  (It also becomes a cause on the map.)

A similar analysis could be put together for all of the units affected by the earthquake, tsunami and resulting events.  Parts of this cause map could be reused as many of the issues affecting the other plants and units are     similar to the analysis shown here. It would also be possible to build a larger Cause Map including all impacts from the earthquake.

The impact to goals needs to be determined prior to building a Cause Map. As a direct result of the events at Unit 3, 7 workers were injured.  This is an impact to the worker safety goal.  There is the potential for health effects to the population, which is an impact to the public safety goal.  The environmental goal was impacted due to the release of radioactivity into the environment.  The customer service goal was impacted due to evacuations and rolling blackouts, caused by the loss of electrical production capacity, which is an impact to the production goal.  The loss of capacity was caused by catastrophic damage to the plant, which is an impact to the property goal.  Additionally, the massive effort to cool the reactor is an impact to the labor goal.

The worker safety and property goals were impacted because of a hydrogen explosion, which was caused by a buildup of pressure in the plant, caused by increasing reactor temperature.  Heat continues to be generated by a nuclear reactor, even after it is shutdown, as a natural part of the operating process.  In this case, the normal cooling supply was lost when external power lines were knocked down by the tsunami (which was caused by the earthquake).  The tsunami also apparently damaged the diesel generators which provided the emergency cooling system.  The backup to the emergency cooling supply stopped automatically and was unable to be restarted, for reasons that are as yet unknown.

The outline, timeline and cause map shown on the PDF are extremely simplified.  Part of this simplification is due to the fact that as the event is still ongoing and not all information is known, or has been released. Once more information becomes available, it can be added to the analysis, or the analysis can be revised.

To learn more about the reactor issues at Fukushima Daiichi, view our video summary.  To see a blog about the impact of the fallout on the health of babies in the US, see our healthcare blog.

Root Cause Analysis - Incident Investigation

Toxic Red Sludge Spill

By Kim Smiley

On Monday, October 4, 2010, a massive wave of red sludge flooded into four villages near Kilontar, Hungary when a storage reservoir burst.  Four were killed and at least 150 have needed medical treatment for their injuries.  The most common injuries reported are burns and eye ailments.

Red sludge is a highly caustic material that is produced during the aluminum manufacturing process.  Reports indicate that the sludge had a pH of 13 while stored in the reservoir.  All life has been killed in a 25 mile stretch of river and 16 square miles of land have been covered by the pollution.  Best estimates are that 158 million to 184 million gallons of sludge were released.  This first large scale release of red sludge in history.

Hungary’s top investigative agency is looking into the accident, but the cause for the reservoir barrier failure is not known at this time.

Even with the unknowns, a root cause analysis can be started by creating a Cause Map and documenting all available information.  Any new information can easily be incorporated into the existing Cause Map.

To build a Cause Map, we start with the impacted goals and ask “why” questions.  In this example, the two goals we will consider are the Safety goal and the Environmental goal.  Starting with the Safety goal we begin by asking – Why were people injured?  They were injured because they were exposed to caustic material because red sludge flooded into their villages.  Why?  Because red sludge was stored in a nearly reservoir and the barrier on the reservoir was breached.

Why the barrier failed isn’t known, but we can still add additional information that might be useful.  We know that the red sludge reservoir was near the villages and a little research reveals that this is common practice in the region and that there are a number of similar pools nearby.  This information may become relevant if the investigation determines that the other reservoirs are at risk for a similar failure so it’s worth recording on our Cause Map at this point. There is also information available about the environmental impact that can be added.

The investigation is still incomplete, but the Cause Map can grow as more information comes available.  Once the relevant information is added, the Cause Map can be used to develop solutions to help prevent similar accidents from occurring in the future.

Root Cause Analysis - Incident Investigation

Largest Egg Recall In US History

By Kim Smiley

Two Iowa farms have recently been at the center of the largest egg recall in US history.  Over half a billion eggs were recalled in August after more than 1,500 people were sickened by eggs tainted with salmonella.

How did this happen?  Where did the contamination come from?  How did tainted eggs make it onto supermarket shelves?

The investigation is still ongoing, but we can begin a root cause analysis of this problem by building a Cause Map.  A Cause Map provides a simple visual explanation of all the causes that were required to produce the incident.  A good place to start building a Cause Map is to identify the impacts to the organizational goals.  Causes are then added to the map by asking “why” questions.  (Click on the “Download PDF” button to view a Cause Map of this issue.)

In this example, we’ll consider the safety goal first.  The safety goal was impacted because nearly 1,500 people got sick because they consumed eggs that were contaminated with salmonella.  Why did they eat contaminated eggs?  Contaminated eggs were eaten because they were sold.  Why?  Because the eggs were contaminated at some point and there was inadequate regulation to prevent them from being sold.

Investigators are still determining the exact source of the contamination, but there is significant information available that can be added to the Cause Map.  The eggs were contaminated with salmonella because the hens laying the eggs were contaminated. (This strain of bacteria can be found inside a chicken’s ovaries and is passed on to eggs.)  The exact source that contaminated the hens is still being determined, but testing by the FDA has determined that the hens were likely contaminated after arriving at the farms.  FDA investigators have found a number of sanitation violations, including rodents which are a known carrier of salmonella.  Salmonella is not passed from hen to hen, but is typically passed from rodent droppings to chickens.

As more information comes available we can add to the Cause Map.  Hopefully, the investigation will result in solutions that can be applied and prevent this situation from occurring again.

Root Cause Analysis - Incident Investigation

Impure Injections Used

By Kim Smiley

Research is been suspended at a prominent brain-imaging center associated with Columbia University.  Food and Drug Administration investigations found that the Kreitchman PET (positron emission tomography) Center has injected mental patients with drugs that contained potentially harmful impurities repeatedly over the past four years.

Investigations by the lab determined that no patients were harmed from the impurities, but this is still a significant issue in a nationally renown laboratory.

How did this happen?

This issue can be investigated by building a root cause analysis as a Cause Map.  To start a Cause Map, the impact to the organization goals is determined.  In this example, this issue is obviously an impact to safety because there was potential to harm patients.  It is also an impact to the production-schedule goal because research has been suspended.  Additionally, this problem is an impact to the customer service goal because this issue raises questions about the validity of research results.

To build a Cause Map, select one goal and start asking “why” questions to add causes.  In this case, the first goal considered will be the safety goal.  There was a potential for injury.  Why?  Because impure injections were given to patients.  Why?  Because the injections are necessary for research, because the labs typically prepare the compounds themselves and because the lab prepared the compounds incorrectly.  When there is more than one causes that contributed, the causes are added vertically with an “and” between them.

Each impacted goal needs to eventually connect to the same Cause Map.  If they do not, the impacted goal may not be caused by the same problem and the goals should be revisited.

To continue building the Cause Map, keep asking “why” questions for each added cause until the level of detail is sufficient.

A Cause Map can be as high level or as detailed as needed.  The more significant the impact to the goals, the more likely a detailed Cause Map will be warranted.  Once the Cause Map is completed, it can be used to develop solutions to help prevent the problem from reoccurring.

In this example, the lab is currently changing management and reorganizing procedures to help prevent the similar problems in the future.

To view an initial Cause Map for this issue, please click the “Download PDF” button above.

Root Cause Analysis - Incident Investigation

Contaminated Drinking Water

By Kim Smiley

In 1922 the United Nations designated March 22 as World Water Day.  In honor of the occasion, a report titled “Sick Water” was published this week detailing issues with water pollution throughout the globe.

According to the report, two billion tons of pollution consisting of human and animal waste and industrial chemicals are dumped into waterways every day.  Almost 80 percent of sewage around the globe goes into waterways untreated.

Millions of people lack basic infrastructure including access to clean water, sanitation systems and water treatment facilities. The massive water pollution that results from this situation kills nearly 1.5 million children under age 5 every year.  Over half of the hospital beds in the world are occupied by people with illnesses caused by drinking contaminated water.

Even in developed nations, water pollution is a problem because many chemicals aren’t removed by the water treatments that kill the pathogens from sewage.  Chemicals from antidepressants, birth control, illegal drugs, sunscreen, and insect repellent are just some of the pollutants that have been found in US drinking supplies.

In addition to human illnesses caused by dirty water, water pollution has a large scale impact on the environment.  Over two billion tons of water is polluted daily, resulting in death of fish and choked coral reefs.

While the problem of water pollution isn’t a problem that is traditionally approached by root cause analysis, a Cause Map can be built to examine the causes of a wide range of issues.  Click on the “Download PDF” button to view a high level Cause Map of this issue.  The Cause Map could be expanded to incorporate as many causes as desired.