test sites. A major cleanup operation codenamed Operation Brumby was conducted in 1967. Attempts were made to dilute the concentration of radioactive material by turning over and mixing the surface soil. Highly contaminated soil from Wewak was buried in the Marcoo crater, and the debris pits were capped. Over time, the short-lived isotopes decayed away, leaving plutonium, with its half-life of 24,100 years, as the main radioactive hazard. In January 1979, the British Government agreed to the "repatriation" of recoverable plutonium that had been buried at Maralinga. 1984 committee In 1984, the Minister for Resources and Energy established the Kerr Committee on 15 May 1984 to review fallout from the British nuclear tests in Australia. After receiving the report, and having discussions with John Symonds, who was commissioned to write an official history of the British nuclear tests, he decided to convene a royal commission into them. The McClelland Royal Commission delivered its report in late 1985, and found that significant radiation hazards still existed at many of the Maralinga test sites, particularly at Taranaki. The Australian Government accepted the findings of the royal commission, but rejected its recommendations that a Maralinga Commission be created, on the grounds that this was more properly a role for a department of state rather a statutory body, and that the British Government should pay all the costs of a cleanup. Instead, Cabinet decided that the British Government should be asked to make a significant contribution. Australian claims were put to the British Government in 1991, and in June 1993, it agreed to contribute an ex gratia sum of UK £20 million towards the costs of rehabilitation of the site. 2000 cleanup A Technical Assessment Group (TAG) was set up to advise on rehabilitation options, and a much more extensive clean-up program was initiated. The TAG Report plan was approved in 1991. Work commenced on site in 1996, and was completed in 2000 at a cost of $108 million. In the worst-contaminated areas, of soil and debris were removed from an area of more than , and buried in trenches. Eleven debris pits were also treated with in situ vitrification. Most of the site (approximately was rendered now safe for unrestricted access and approximately is considered safe for access but not "permanent occupancy". "A term", British historian Lorna Arnold noted, "that no one would have applied to these regions 30 or 40 years before".