Karl Herchenroeder
RW Monitor
1/8/2016
A reaction from rainwater and material from corroded steel drums led to an industrial fire in October at a closed low-level radioactive waste dump 115 miles northwest of Las Vegas, according to the Nevada State Fire Marshal.
The agency released this and other details Wednesday concerning an investigation led by the fire marshal, the Nevada Division of Environmental Protection, and the state Department of Health and Human Services Radiation Control Program. The fire marshal also concluded that the incident at the state-managed site resulted in no personnel injuries, the fire was contained to the site, and there was no release of radioactive materials.
“As detailed in our report, this investigation found corrosion of the steel drums containing the metallic sodium over time allowed the packing fluid to seep out leaving the metallic sodium exposed to the underground elements,” Nevada State Fire Marshal Chief Peter Mulvihill said in a statement. “Heavier than normal rainfall seeped into the ground reaching the metallic sodium through a compromised cover causing the fire.”
The fire burned from Oct. 18-19 in Beatty, Nev., at a permanently shuttered waste site formerly managed by US Ecology, and resulted in the expulsion of several 55-gallon drums. Officials allowed the fire to burn itself out.
Nevada acquired the site in 1961 for disposal of low-level radioactive waste, which was buried there from 1962 until 1992, when the site was closed. Materials were buried and covered with earth fill in a number of trenches. The incident occurred in a trench near the east perimeter of the disposal site.
The fire marshal’s report lays out a series of events that the department believes, “with a reasonable level of confidence,” led to the explosion. Waste materials have been buried at the site in a variety of containers, including steel drums, cardboard boxes, and wooden crates. The fire marshal contends that some of those containers deteriorated and collapsed over the course of multiple decades, resulting in a “settlement of the fill and cover material in several areas at the site.”
During the investigation, crews collected metallic sodium packed in oil-filled steel drums from three different sources buried in an east-end trench at the site. Sources included: two 1970s-era drums originating from a U.S. Bureau of Mines research center in Boulder City, Nev.; 22 drums from Gulf-United Nuclear in Elmsford, N.Y.; and 92 drums from GE Nuclear Energy Division-SEFOR in Fayetteville, Ark.
Two weeks before the event, the Desert Research Institute recorded 1.29 inches of rainfall at the site over a two-day period. On the day of the incident, the organization reported another half-inch of rainfall. The fire marshal report states that rainwater reached the metallic sodium through compromised earth cover and caused an exothermic reaction, igniting combustible metals and resulting in the fire.
“The reaction produced a large amount of heat and generated quantities of hydrogen gas,” the report states. “The volume of gas produced caused the eruption of the ground, expelling dirt, buried and corroded drums, and the products of the sodium-water reaction, primarily sodium hydroxide.”
