available. ORNL was the only Western source of californium-252. ORNL scientists lowered the immune systems of mice and performed the world's first successful bone marrow transplant. In the early 1960s there was a large push at ORNL to develop nuclear-powered desalination plants, where deserts met the sea, to provide water. The project, called Water for Peace, was backed by John F. Kennedy and Lyndon B. Johnson, and presented at a 1964 United Nations conference, but increases in the cost of construction and falling public confidence in nuclear power caused the plan to fail. The Health Physics Research Reactor built in 1962 was used for radiation exposure experiments leading to more accurate dosage limits and dosimeters, and improved radiation shielding. In 1964 the Molten-Salt Reactor Experiment began with the construction of the reactor. It was operated from 1966 until 1969 (with six months down time to move from U-235 to U-233 fuel), and proved the viability of molten salt reactors, while also producing fuel for other reactors as a byproduct of its own reaction. The High Flux Isotope Reactor built in 1965 had the highest neutron flux of any reactor at the time. It improved upon the work of the X-10 reactor, producing more medical isotopes, as well as allowing higher fidelity of materials research. Researchers in the Biology Division studied the effects of chemicals on mice, including petrol fumes, pesticides, and tobacco. In the late 1960s, cuts in funding led to the cancellation of plans for another particle accelerator, and the United States Atomic Energy Commission cut the breeder reactor program by two-thirds, leading to a downsizing in staff from 5000 to 3800. In the 1970s, the prospect of fusion power was strongly considered, sparking research at ORNL. A tokamak called ORMAK, made operational in 1971, was the first tokamak to achieve a plasma temperature of 20 million Kelvin. After the success of the fusion experiments, it was enlarged and renamed ORMAK II in 1973; however, the experiments ultimately failed to lead to fusion power plants. The US Atomic Energy Commission required improved safety standards in the early 1970s for nuclear reactors, so ORNL staff wrote almost 100 requirements covering many factors including fuel transport and earthquake resistance. In 1972 the AEC held a series of public hearings where emergency cooling requirements were highlighted and the safety requirements became more stringent. ORNL was involved in analysing the damage to the