Professionalism/PEPCON Ammonium Perchlorate Plant Explosion


On May 4th, 1988, a series of strategic and tactical problems at the PEPCON chemical plant in Henderson, NV led to a fire and eventual explosion of approximately 4,000 tons of highly flammable ammonium perchlorate, with an equivalent impact on the surrounding area of a 1-kiloton arblast nuclear detonation. The explosion claimed 2 lives, injured around 370, and caused an estimated $100 million in damages[1].

For this case study in professionalism we will focus on PEPCON's disaster preparation, the response of government agencies, and underlying social and professional factors contributing to the disaster.


Ammonium perchlorate (AP) is an oxidizer than can be mixed with aluminum and other materials to create a solid propellant. PEPCON was one of two manufacturers of AP in the United States, and supplied AP to NASA for the Space Shuttle. After the Challenger disaster of January 28th, 1986, the Space Shuttle program was grounded while the investigation was ongoing [2]. The provider of solid rocket boosters for NASA, Morton Thiokol, therefore had no need for the propellant. However, the contract PEPCON had with Morton Thiokol to supply AP was not altered, and so PEPCON continued to produce AP and store it on site. By the time of the explosion in 1988, PEPCON had stockpiled over 4,000 tons of AP in various storage containers including aluminum bins and polyethylene drums. Lax housekeeping meant that dust had built up all around the warehouses, despite the danger of fire. Additionally, despite several fires PEPCON had not installed an alarm or a proper fire suppression system in the plant, instead relying on hoses to douse any flareup. At this time the US government considered AP an oxidizer, not an explosive, and correspondingly had fewer regulations concerning its production and storage [3]

On the day of the disaster, welding work was being performed near an area where AP was stored. Some sparks caught dust near bins of AP, which began to ignite. The dust fire spread to the AP stored in aluminum bins and polyethylene drums, feeding a volatile reaction that quickly got out of hand. A combination of 70% ammonium perchlorate, 15% aluminum, and 15% polyethylene is approximately the formula for a solid rocket booster, making the containers a compounding factor in the explosions [4]. Employees futilely fought the fire with a garden hose and soon enacted the disaster response plan for PEPCON, which essentially stated "flee the facility." Fortunately, all but 2 PEPCON employees were able to escape the facility; the two that remained were handicapped and unaccounted for in safety protocols. Although fire response teams braved the danger and headed towards the burning plant, they regrouped following an explosion that shattered their windows. Minutes later, over a third of PEPCON's ammonium perchlorate exploded at once, equivalent to a 1-kiloton nuclear explosion. The Kidd Marshmallow plant was obliterated, and the explosion's effects extended 10 miles. Furthermore, a gas main running underneath the plant exploded, burning for over an hour before being turned off [5].

The PEPCON disaster was precipitated by negligence on the part of PEPCON and its employees, and the response from national agencies was swift. The disaster affected more than just PEPCON, and the national agency response was swift. Other underlying attitudes towards response and readiness also impacted why so much ammonium perchlorate was being stored. Next, the participants and social/professional failures are covered in depth.


Although the blast caused a variety of damage in a 10 mile radius, only two people were killed. Both were PEPCON employees.[6] One of the employees, Roy Westerfield, stayed behind to call 911. Roy had been handicapped by polio and was not able to make the phone call and escape in time. The other employee killed was also handicapped. Their deaths raised questions regarding the evacuation procedures in place. The U.S Fire Administration, the Federal Emergency Management Agency (FEMA) and the National Fire Data Center released a report citing the need for improvement in the evacuation plans regarding both healthy and handicapped individuals, as well as the need for emergency triage procedures in nearby hospitals. The U.S. Fire Administration, FEMA, and the Department of Energy also released a report that called for better maintenance practices to ensure that AP residue did not build up on buildings and machinery. The report also called for the elimination of fuel sources around the facility and the implementation of ventilation systems, sprinkler systems, fire alarms, and fire-sensing systems. Aside from a sprinkler system in an administrative building, the PEPCON facility did not have these systems prior to the disaster.[1]

The blast also had effects outside of the plant and its employees. The Kidd Marshmallow factory which was just a couple miles away was completely destroyed by the compression waves given off by the blasts. An underground gas line controlled by Southwest Gas Company was ruptured, adding fuel to the fire. Luckily, the company shut the gas off quickly.[7]

Kerr-McGee, the only other producer of AP in the United States, was also located within the blast effect area. Although this could have lead to an even more disastrous explosion, the plant suffered only minor damages, including shattered windows and cracked walls.[7] While there were no casualties or resulting fires at Kerr-McGee, the threat of what could have happened if the fire spread that far initiated a push for better safety and prevention practices.[1]


There were several human errors in the PEPCON explosion which are specific to this particular case, there are however some things that seems to be related to human psychology, and transcend this particular case. The PEPCON disaster can be understood in terms of the surplus of stored Ammonium Perchlorate, as much as it can be understood in terms of negligence, so why was there so much unnecessary Ammonium Perchlorate?

This can be explained the phenomenon of standardization of deviance, and what we have called survivor overcompensation.

Standardization of devianceEdit

The phenomena of standardization of deviance is a psychological phenomena that occurs when an individual readjusts its expectations based on a long period of non catastrophic risky behavior. In other words, after a long time of engaging in risky behavior without consequences, an individual is more likely to raise the threshold of what he or she would considers risky. In the case of PEPCON, the company had been inappropriately storing Ammonium Perchlorate for a long period of time. This had not result in any incidents, and so the company kept doing it, inflating dramatically the consequences of a disaster if it was to occur.

Survivor overcompensationEdit

This is not a phenomena officially found in human psychology literature, but as described below, it has been useful in understanding the reasons behind the PEPCON disaster. Plenty of research has been done regarding different disorders that follow the surviving of traumatic experiences. Amongst these are PTSD, OCD and others[8]. However, it seems to be the case that after surviving a traumatic experience, the individual will readjust the threshold of preparedness that he or she originally had. In other words, if an individual has gone through a shortage of food, he or she is more likely to save more food than they would have saved previously. This phenomena, although still unnamed is particularly common amongst war survivors, who have a difficulty disposing things and justify keeping them by arguing that they might need it in the future. In relation to PEPCON disaster, the factory set their standards of production based on the needs of NASA, and after the Challenger disaster, they failed to readjust their production, and kept producing Ammonium Perchlorate based on what they might need as opposed to what they actually did. .