The use of water as a coolant raised the problem of corrosion and oxidation of the aluminum tubing. The Metallurgical Laboratory tested various additives to the water to determine their effect. It was found that corrosion was minimized when the water was slightly acidic, so dilute sulfuric acid was added to the water to give it a pH of 6.5. Other additives such as sodium silicate, sodium dichromate and oxalic acid were also introduced to the water to prevent a build up of film that could inhibit the circulation of the cooling water. The fuel slugs were given a jacket of aluminum to protect the uranium metal from corrosion that would occur if it came into contact with the water, and to prevent the venting of gaseous radioactive fission products that might be formed when they were irradiated. Aluminum was chosen because the cladding had to transmit heat but not absorb too many neutrons. The aluminum canning process was given close attention, as ruptured slugs could jam or damage the channels in the reactor, and the smallest holes could vent radioactive gases. The Metallurgical Laboratory investigated production and testing regimes for the canning process.