The large amount of explosive mixture that killed a government scientist when it spontaneously combusted had not been through the usual small-scale tests in advance, an inquest has heard.
Terry Jupp, 46, died after the accident involving 10kg of the mixture at a weapons testing range in Essex in 2002.
The ongoing inquest in Southend heard there was no record of small-scale testing that should have taken place.
Mr Jupp had been carrying out secret anti-terrorism research on explosives.
He died six days after suffering burns to 75% of his body in the accident at the range near Shoeburyness.
Laboratory testing of very small amounts of potentially dangerous materials should take place before large-scale trials, the inquest was told by William Warren, research and development manager at Qinetiq, the private contractor which operates the testing range.
He said that he had checked his database covering 40 years of tests, and found no record of small-scale testing on the mixture of substances that killed Mr Jupp.
After Mr Jupp's death, his own laboratory experiment involved placing just 30g of the mixture in an armoured cabinet, where it again spontaneously combusted.
That was like a firework going off, another researcher told the inquest, adding that he could not understand how anyone could have worked with larger quantities of the materials.
Mr Jupp had been working for the Defence, Scientific and Technology Laboratory.
At the time of his death, almost a year after the 11 September 2001 attacks, he was part of a joint US-UK team researching terrorist groups' capabilities to combine certain materials into home-made bombs.
Mr Jupp's family believe that the secret national security experiments were conducted without the Ministry of Defence taking adequate precautions against the possibility of an accident.
In its investigation, the Health and Safety Executive said that the "root cause" of Mr Jupp's death had been "significant failures of the management auditing system to recognise that risk assessment had not identified and addressed the hazards".
Two government employees charged over Mr Jupp's death were later cleared.