CHARLESTON, W.Va. — A report by the National Transportation Safety Board says the design of a railcar that leaked chlorine at a New Martinsville plant had been under scrutiny.

The NTSB issued the preliminary report Monday detailing the Aug. 27 chlorine gas spill at the Axiall Natrium plant, according to media reports.

The report describes a 46-inch-long crack on one end of the tank car that leaked. The crack opened up on a reinforcement pad for part of the car’s underframe called the sub sill.

“During the 2½ hours after the crack developed, the entire 90-ton load of chlorine released from the crack and formed a large vapor cloud that migrated south from the Axiall facility along the Ohio River valley,” the report said.

The tank built in 1981 had a particular type of sub sill that the Federal Railroad Administration had issued a safety advisory for in 2006. The advisory noted defects including cracks in some tank cars equipped with the sub sills. A series of solutions to the problem have been recommended.

Asked if the railcar involved in the Axiall leak had been retrofitted to match the recommended fixes, an NTSB spokesman told the Charleston Gazette-Mail (, “That is some of the information we are gathering as part of our investigation.”

The NTSB’s report did show that the car involved had received a routine, five-year interior inspection in January 2016.

Axiall Corp. spokesman Chip Swearingen said the company is fully cooperating with the NTSB.