The wife of a scientist killed by an explosion during a Ministry of Defence experiment has told his inquest how she had to watch him slowly die.
Terry Jupp lost his life after his secret national security research into explosives went wrong in 2002.
In a statement, Pat Jupp said her husband was so burned that she could not hold his hand to comfort him during the six days he clung to life.
Mr Jupp suffered 60% to 90% burns at a range near Shoeburyness in Essex.
The 46-year-old scientist worked for the Defence, Scientific and Technology Laboratory. This elite research team investigates explosives, including devices used in terrorist attacks or against British military forces overseas.
At the time of his death, a year after the 9/11 attacks, Mr Jupp was in a joint US-UK team investigating the capabilities of some terrorist groups to use a number of unnamed materials to make home made bombs.
At the opening of the inquest in Southend, Coroner Peter Dean read out statements from Mr Jupp's family describing him as "instrumental" in saving many lives.
In her statement, Mrs Jupp said: "The last memory of my husband will be him lying in hospital on full medical support. At first it was not thought his injuries were as grave as they turned out to be."
Mrs Jupp said she realised how serious the situation was when one of her husband's colleagues telephoned her to say that Mr Jupp had said: "Tell my wife I love her very much."
She said: "I knew things were serious at this point as Terry was not the kind of person to use words like that. He showed his affection in other ways.
"I couldn't hold his hand, I couldn't kiss him. I found I couldn't even sit there and stroke his face."
The couple had been childhood sweethearts who had married in 1980 and had two children, aged 15 and 11 at the time of Mr Jupp's death.
"I made a promise to Terry on his deathbed that I would be strong and not let him down. This has been a hard promise to keep as there have been a lot more bad days than good days."
Mr Jupp's family believe that the secret national security experiments were being conducted without proper safety checks in place.
They say that Mr Jupp's department of the Ministry of Defence had taken inadequate 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 who were charged over Mr Jupp's death were later cleared.
Coroner Dr Dean told the jury that some of the hearings would not be held in open court to protect national security. The inquest is expected to last four weeks.