Declassified films expose dodgy nuclear test data
FROM the deserts of southern New Mexico and Nevada to islands in the Pacific Ocean, the US government conducted dozens of nuclear weapons tests from the 1940s until the early 1960s. Vintage rolls of film collected from high-security vaults across the country show some of the blasts sending incredible mushroom clouds into the sky and massive fireballs across the landscape. Others start with blinding flashes of light followed by rising columns of smoke in the distance.
A team from Lawrence Livermore National Laboratory has now published more than five dozen films of these tests, salvaged from government installations, where they had sat idle for years.
Lab physicist Greg Spriggs said the decades-old films were in danger of decomposing and being lost to history.
He called them a big part of the nation’s history and an important tool for providing better data to modern scientists, who now use computer codes to help certify that the US nuclear stockpile remains safe and effective.
‘‘We don’t have any experimental data for modern weapons in the atmosphere. The only data that we have are the old tests,’’ he said, noting that the manual methods used in the 1950s to analyse the blasts weren’t that accurate.
By scanning the films and reviewing them along with data sheets from the original tests, the team discovered that much of the data initially published were wrong. Some of the answers were off by 20 per cent.
‘‘One of the payoffs of this project is that we’re now getting very consistent answers,’’ he said.
Of the 10,000 or so films that are thought to have been made over the testing period, Spriggs and his team have located about 6500 of them.
Only a fraction of these have been reanalysed and declassified.
Some of the film cans had not been opened for decades. Some smelled of vinegar, indicating the decomposition process was under way and any more time would have left the material useless.
Some of the test films were located in a vault at Los Alamos National Laboratory, the northern New Mexico installation that played a large role in the Manhattan Project to develop the first atomic bomb.
Archivists and software developers worked together to determine the frame rates of the cameras used during the tests. This ensured an accurate measure of the growth of the fireball, the size of the shockwave and the overall yield. ‘‘It’s just unbelievable how much energy’s released,’’ Spriggs said.
It could take another two years to scan the rest of the films and even longer to complete the analysis and declassification, he said. AP