Question: Ammonium perchlorate was used in the disaster that occurred in what city?
Context: Perchloric acid is a mineral acid with the formula HClO.  Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric and nitric acid.  It is a powerful oxidizer when hot, but its aqueous solutions up to approximately 70% by weight at room temperature are generally safe, only showing strong acid features and no oxidizing properties.  Perchloric acid is useful for preparing perchlorate salts, especially ammonium perchlorate, an important rocket fuel component.  Perchloric acid is dangerously corrosive and readily forms potentially explosive mixtures. Potassium perchlorate is the inorganic salt with the chemical formula KClO.  Like other perchlorates, this salt is a strong oxidizer although it usually reacts very slowly with organic substances.  This usually obtained as a colorless, crystalline solid is a common oxidizer used in fireworks, ammunition percussion caps, explosive primers, and is used variously in propellants, flash compositions, stars, and sparklers.  It has been used as a solid rocket propellant, although in that application it has mostly been replaced by the higher performance ammonium perchlorate.  KClO has the lowest solubility of the alkali metal perchlorates (1.5 g in 100 mL of water at 25 °C). Ammonium perchlorate composite propellant (APCP) is a modern solid-fuel rocket used in rocket vehicles.  It differs from many traditional solid rocket propellants such as black powder or zinc-sulfur, not only in chemical composition and overall performance, but also by the nature of how it is processed.  APCP is cast into shape, as opposed to powder pressing as with black powder.  This provides manufacturing regularity and repeatability, which are necessary requirements for use in the aerospace industry. The Kyshtym disaster was a radioactive contamination accident that occurred on 29 September 1957 at Mayak, a plutonium production site in Russia for nuclear weapons and nuclear fuel reprocessing plant of the Soviet Union.  It measured as a Level 6 disaster on the International Nuclear Event Scale (INES), making it the third-most serious nuclear accident ever recorded, behind the Fukushima Daiichi nuclear disaster and the Chernobyl disaster (both Level 7 on the INES).  The event occurred in Ozyorsk, Chelyabinsk Oblast, a closed city built around the Mayak plant, and spread hot particles over more than 20,000 sqmi , where at least 270,000 people lived, with 300 immediate deaths among the villagers nearby.  Since Ozyorsk/Mayak (named Chelyabinsk-40, then Chelyabinsk-65, until 1994) was not marked on maps, the disaster was named after Kyshtym, the nearest known town. Ammonium perchlorate ("AP") is an inorganic compound with the formula NHClO.  It is a colorless or white solid that is soluble in water.  Perchlorate is a powerful oxidizer and ammonium is a good fuel.  This combination explains the usefulness of this material as a rocket propellant.  Its instability has involved it in a number of accidents, such as the PEPCON disaster. The PEPCON disaster was an industrial disaster that occurred in Henderson, Nevada on May 4, 1988 at the Pacific Engineering and Production Company of Nevada (PEPCON) plant.  The conflagration and subsequent explosions killed two people, injured 372 others, and caused an estimated US$100 million of damage.  A large portion of the Las Vegas Valley within a 10 mi radius of the plant was affected, and several agencies activated disaster plans. Tannerite is the brand name of a patented exploding target used for firearms practice, sold in kit form and containing the components of a binary explosive.  The explosive comprises a combination of ammonium nitrate and/or ammonium perchlorate (oxidizers), and a fuel - primarily aluminum powder - that is supplied as two separate powders that are mixed by the user.  The combination is relatively stable when subjected to forces less severe than a high-velocity bullet impact, such as a hammer blow, being dropped, or impact from a low-velocity bullet or shotgun blast.  It is also not flammable – an explosion cannot be created by a burning fuse or electricity.  Because it is sold as two separate powders, it can be transported and sold in many places without the legal restrictions that would otherwise apply to explosives.  The target system as a whole is the patented, trademarked product called Tannerite, although the term is often used to refer to the explosive mixture itself, and other combination explosives are often generically referred to as Tannerite. The Texas City disaster was an industrial accident that occurred April 16, 1947, in the Port of Texas City.  It was the deadliest industrial accident in U.S. history, and one of the largest non-nuclear explosions.  Originating with a mid-morning fire on board the French-registered vessel SS "Grandcamp" (docked in the port), her cargo of approximately 2,200 tons (approximately 2,100 metric tons) of ammonium nitrate detonated, with the initial blast and subsequent chain-reaction of further fires and explosions in other ships and nearby oil-storage facilities.  It killed at least 581 people, including all but one member of the Texas City fire department.  The disaster triggered the first ever class action lawsuit against the United States government, under the then-recently enacted Federal Tort Claims Act (FTCA), on behalf of 8,485 victims. When heated, ammonium nitrate decomposes non-explosively into gases including oxygen; however, it can be induced to decompose explosively by detonation.  Large stockpiles of the material can be a major fire risk due to their supporting oxidation, and may also detonate, as happened in the Texas City disaster of 1947, which led to major changes in the regulations for storage and handling. The 1924 Nixon Nitration Works disaster was an explosion and fire that claimed many lives and destroyed several square miles of New Jersey factories.  It began on Saturday morning, March 1, 1924, when an explosion destroyed a building in Nixon, New Jersey (an area within present-day Edison, New Jersey) used for processing ammonium nitrate.  The 11:15 a.m. explosion touched off fires in surrounding buildings in the Nixon Nitration Works that contained other highly flammable materials.  The disaster killed twenty people, destroyed forty buildings, and demolished the “tiny industrial town of Nixon, New Jersey.”
Answer: Henderson, Nevada