Cause of the Port Neal ammonium nitrate plant explosion

Abstract

In 1994, an explosion in an ammonium nitrate neutralizer of a chemical processing plant in Port Neal, Iowa, resulted in fatalities, injuries, and widespread property damage. A lawsuit was brought by the plant operator against the neutralizer designer, and each party retained a team of scientists and engineers to determine the cause. The key question was whether the explosion initiated within or outside of the sparger that injected nitric acid into the ammonium nitrate solution. After extensive investigations and months of debate, an agreement could not be reached. To resolve this impasse, an independent expert was appointed by the ruling US District Court judge to review the evidence provided by the investigative teams, examine the recovered sparger fragments and test articles, and provide an opinion. This article presents the findings and conclusions from this investigation.