Chemical accident at PEPCON

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Violent explosion in the wake of the accident

The chemical accident at PEPCON was an industrial accident that occurred near Henderson in the US state of Nevada . The accident happened in the "Pacific Engineering Production Company Nevada" (PEPCON) on May 4, 1988. The fire and the following explosions killed two people, injured 372 other people and caused an estimated damage of 100 million US dollars. A radius of 16 km from Las Vegas was affected, the authorities started their disaster plans.

background

The PEPCON-operation was one of only two American manufacturers of ammonium perchlorate , an oxidizer that as APCP in the boosters of rocket is used and used for military weapons. The other producer, Kerr-McGee , was located less than 1.5 miles (1.5 miles) from PEPCON, i.e. within the area affected by the explosions. In addition, PEPCON Service manufactured a range of cleaning devices for the environment.

After the explosion of the space shuttle "Challenger" on January 28, 1986, the US government continued to produce rocket fuel from PEPCON. After the space program was stopped, there were no instructions from the government as to what to do with the fuel produced. Therefore, PEPCON stored a large amount of the ammonium perchlorate produced on site; an estimated 4,000 tons of the finished product were stored at the time of the accident.

course

The fire broke out between 11:30 a.m. and 11:40 a.m. in or around one of the drying facilities in the PEPCON facility. The steel frame with walls made of glass fiber reinforced plastic (GRP) and the roof structure had been damaged in a storm, and employees were initiating repairs. Presumably they used liquid tar and a welding machine for this . The fire spread quickly in the GRP material, accelerated by ammonium perchlorate residues in this area. However, since barrels were also stored in this area, which the employees used to sweep up the remains of the product in this area, a cigarette butt thrown into one of the containers could also have triggered the fire. According to a documentary entitled "Destruction in the Desert", the cause of the fire is still unclear. Jointly responsible for this accident is the following investigations according to bad housekeeping , i.e. H. contaminated residues of the end product, especially in the filling area.

Attempts by the staff to put out the fire were unsuccessful, and they abandoned their efforts when a number of 200 liter barrels exploded. The time between the first minor explosions and the first major explosion could not be precisely determined. It was probably between 10 and 20 minutes. After the attempts to extinguish the fire, the factory was evacuated. The employees ran or drove away. About 75 people were brought to safety. Only two were still in operation when the first explosion occurred. Both were killed. The first had stayed to brief the fire brigade over the phone, the other was the plant manager, who was unable to leave the premises.

The first of two main explosions occurred in the barrel storage area. The fire spread rapidly and reached the main warehouse, in which the aluminum containers ready for dispatch were stacked. This led to a strong explosion. The second major explosion occurred about four minutes later. After the second explosion, very little combustible material was left and the fire quickly subsided. However, a long-distance pipeline from a gasworks ran under the factory , which was broken in the explosion and provided additional food for the fire. The gas line was shut off by the gas company at a valve about 2 km away at 12:59 p.m.

These two explosions, when measured by the National Earthquake Information Center in Colorado , approximately 950 km away, were approximately 3.0 and 3.5 on the Richter scale . Over 4000 tons of ammonium perchlorate decomposed. A crater 4.5 m deep and over 60 m wide remained in place of the warehouse.

The Henderson Fire Department chief, who was in charge of the main fire station about 1.5 miles north of the factory, saw the column of smoke. He immediately gave the alarm, and a special unit drove towards the facility. The first explosion occurred when the unit was about 1.5 km from the factory. There was a fireball about 30 meters in diameter that was visible from afar. The shock wave destroyed the vehicle windows and broken glass injured the occupants. They were about to turn when the second, more violent explosion took place at 11:54 a.m. and further damaged the vehicle. Because of this and because of the size and type of fire, no direct attempts were made to extinguish the fire for safety reasons.

Subsequent investigations showed that ammonium perchlorate as a pure oxidizing agent is not flammable, let alone can trigger detonations of such force. It only becomes unstable when this substance is mixed with other materials or due to various impurities. The storage containers on the Pepcon site were made of plastic (polybins ) and so-called aluminum tote bins were made of aluminum with a larger capacity. Exactly these materials can be found - as added granules - in the booster propellant charges (solid charges) for rockets in the military field (weapon systems Hawk, Nike, Patriot) as in the boosters of the Space Shuttle until the program was discontinued by NASA in 1988.

Damage assessment

The PEPCON plant and a nearby marshmallow factory were destroyed. Damage within a radius of almost 2.5 km included wrecked cars, structural damage to buildings and destroyed power lines. Within 5 km there was damage to buildings such as broken windows, displaced walls or blown out door frames. At Las Vegas International Airport , seven miles away, windows were broken and doors were pushed open. In a Boeing 737 approaching Las Vegas International Airport, passengers and crew felt the shock caused by the pressure wave.

Recent analyzes of the explosion damage resulted in an estimated equivalent of 250 tons of TNT .

PEPCON changed its name to Western Electrochemical Corporation (WECCO) after the disaster and continues to produce ammonium perchlorate 14 miles outside of Cedar City , Utah . After another renaming, the company was taken over by Jon Huntsman senior in 2015 .

literature

Web links

supporting documents

  1. ↑ Summary of the report ( Memento of May 14, 2008 in the Internet Archive ) to the DOD Explosives Safety Board by Jack W. Reed and William H. Zehrt
  2. ↑ Huntsman family to acquire American Pacific's specialty chemicals business , November 16, 2015