Tempi Train Crash: NTUA Report Sheds Light on Fireball Phenomenon

A comprehensive 132-page report from the National Technical University of Athens (NTUA), authored by Professor Dimitris Karonis of the Fuels and Lubricants Technology Laboratory, has been submitted to the investigating judge probing the tragic Tempi railway disaster.

The report addresses the catastrophic collision of two trains that claimed numerous lives and focuses on the mysterious "fireball" captured on surveillance cameras during the incident.

Key Findings on the Fireball

The report investigates the fireball phenomenon, exploring its origins and the mechanisms behind its formation. Professor Karonis concludes that silicone oil (M50 EL), used in the cooling systems of train transformers, does not typically form a fireball under normal conditions. However, the report highlights a critical factor: the presence of an electrical arc, as evidenced by three intense flashes recorded in videos analysed by the Greek railway accident investigation body (EODASAAM).

Under high-intensity electrical arc conditions, silicone oil can break down into highly flammable gases such as hydrogen, methane, ethane, ethylene, acetylene, and carbon monoxide. The report notes that hydrogen and acetylene have low ignition energy and wide flammability limits, making them prone to ignition even from minor sparks, such as those caused by friction between train wheels and tracks. This breakdown likely occurred when the passenger train’s transformer, the only one to ignite, ruptured during the collision, releasing both silicone oil and these combustible gases.

Conditions for Ignition

The report clarifies that silicone oil requires temperatures exceeding 300°C to ignite, far above the normal operating temperature of around 90°C in the transformer’s cooling liquid. However, the extreme heat generated post-collision, coupled with the fireball’s development, likely enabled the oil to contribute to the fire. The analysis rules out the possibility of other volatile materials on the freight train causing the fireball, as no evidence of such cargo was found in police inspections, Hellenic Train documents, or recent video footage. To produce a fireball of the observed magnitude, an estimated 2,300 to 3,100 kg of flammable material would have been required, which was not present.

Implications for the Investigation

The NTUA report provides crucial insights into the Tempi disaster, suggesting that the fireball was a result of specific conditions involving electrical arcs and the decomposition of silicone oil. These findings may guide ongoing investigations into the causes of the tragedy and inform future safety measures for Greece’s railway network.

For the full report in Greek, click here.

(Source: In.gr)