The U.S. Chemical Safety and Hazard Investigation Board is “greatly concerned” by interim findings regarding the deadly white liquor tank implosion in May.

CSB’s investigation is still ongoing, and it’s expected to release its final report in spring 2027. 

The agency said in Friday’s update that it found NDP conducted two additional tank inspections, in October 2025 and February 2026, confirming the July 2025 conclusion that substantial portions of the tank’s shell were below the calculated minimum safe thickness. But NDP “still did not internally inspect or repair the tank shell, remove it from service, or reduce its operating conditions before it failed,” CSB said.

“Although the CSB’s investigation is still ongoing, we are greatly concerned that the tank was not promptly removed from service or properly repaired after the clear findings in the inspection report,” said CSB Chair Steve Owens in the update.

CSB members say they’re also investigating why NDP left the tank in service without repairing it or reducing its operations.

Nippon Dynawave was aware of tank wall concerns, CSB finds | Packaging Dive