CSB Releases Safety Video on NDK Crystal Explosion

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Rockford, Illinois —The U.S. Chemical Safety Board (CSB) has released “Falling through the Cracks,” a safety video on the 2009 explosion at NDK Crystal in Belvidere, Illinois, approximately 60 miles northwest of Chicago, which fatally injured a truck driver at a nearby gas station.

The video contains an animation which depicts the stress corrosion cracking that accumulated over time in the walls of the vessel where synthetic quartz crystals were manufactured under extremely high pressures and temperatures.

The video details CSB key findings and recommendations made by the board to prevent future accidents at NDK and to improve national pressure vessel codes and standards.

The accident occurred December 7, 2009, with a violent rupture in the Number 2 vessel. A combination of animation and surveillance video shows how one piece of steel from the building was blown 650 feet, striking a truck driver who was walking back to his vehicle. Another piece – a vessel fragment weighing over 8,000 pounds — tore through a wall at the facility, skipped across a neighboring parking lot and struck the wall of an automotive supply company where 70 people were working; but only one was injured.

CSB lead investigator Johnnie Banks said, “The video shows how cracking on and near the inner diameter of the vessel fragment reduced the vessel material toughness, which eventually led to large flaws resulting in the catastrophic failure.” CSB investigator Lucy Sciallo-Tyler added, “We hope operators in the chemical industry take away the clear message that warnings and near misses must be acted on immediately to prevent major accidents.”