Editing Project Pluto (section)

== Tory II-A==
In 1957, the Livermore Laboratory began working on a prototype reactor called Tory II-A to test the proposed design.{{sfn|Hadley|1959|pp=18–19}} It was initially intended to build two Tory II-A test reactors, which were designated IIA-1 and IIA-2; ultimately only one was built. Its purpose was to test the design under conditions similar to that in a ramjet engine. To save time, money, and reduce its complexity, Tory II-A had a diameter about a third of that required for the engine, a much smaller diameter than the final design. To allow it to still reach [[criticality (status)|criticality]] with reduced fuel, the core was surrounded by a thick [[nuclear graphite]] neutron reflector.{{sfn|Hadley|1963|pp=1–2}}

The Tory II-A design process was completed by early 1960. During the summer and early fall of that year,{{sfn|Hadley|1963|pp=1–2}} the core was assembled at Livermore inside a special fixture in a shielded containment building. It reached criticality on 7 October with the control vanes rotated 90° from the full shutdown position. A test was then carried out with the cooling passages of the core and neutron reflector filled with water. Instead of the predicted increase in reactivity, there was a drop, and the reactor could not go critical at all. The water was replaced with [[heavy water]], but it was barely able to reach criticality. It was therefore concluded that additional fuel would be required to attain the required margin for error when more components were installed.{{sfn|Hadley|1963|pp=17–22}}

[[File:Tory II-A reactor.jpg|left|thumb|The Tory-IIA prototype]]
The reactor was shipped to the Nevada Test Site for a series of dry runs and zero- or low-power tests. Another layer of {{convert|4|in|cm|order=flip|adj=on|sp=us}} fuel elements was added.{{sfn|Hadley|1963|pp=17–22}} The reactor was mounted on the test vehicle and, with heavy water for coolant, reached criticality during a test run on 9 December, with the control vanes at 65°. It was estimated that without the heavy water, 71° would have been required. Boron rods were then inserted into the six central tie tubes. This lowered the reactivity of the core, and the vanes had to be turned to 132° before criticality was achieved. Oralloy foils were placed in the core tubes, and the reactor was run at 150 W for ten minutes.{{sfn|Hadley|1963|pp=17–22}}

The next set of tests involved blowing air through the reactor while it was subcritical to test the integrity of the components under conditions of strain and vibration. On 17 and 18 December, air flow rates of {{convert|60|,|75|,|100|and|330|lb/s|kg/s|order=flip|sp=us}} for 30 seconds.{{sfn|Hadley|1963|pp=26–32}} During what was intended to be the final qualification test on 11 January 1961, with an air flow rate of {{convert|720|lb/s|kg/s|order=flip|sp=us}} and a core temperature of {{convert|1060|F|C|order=flip}}, the clamp holding the exit nozzle to the air duct on the test vehicle broke, and the nozzle flew {{convert|480|ft|m|order=flip|sp=us}} through the air. Following this mishap, it was decided to conduct a test of radio-controlled disconnection and removal of the reactor from the test vehicle. During this test the electrically controlled coupler between the locomotive and the test vehicle suddenly opened, and the test vehicle careered down the track and violently struck the concrete face of the test pad bunker at the end. The test vehicle was extensively damaged, and had to be stripped down and rebuilt. All the reactor components had to be checked for cracks.{{sfn|Hadley|1963|pp=26–32}}

With repairs completed, the Tory II-A was returned to the test pad for another series of tests. It was found that without cooling water, the reactor reached criticality with the control vanes at 75°; with heavy water for coolant it was reached with them at 67°. With hot air flowing through the reactor, the core temperature was raised to {{convert|220|F|C}}, then to {{convert|440|F|C}}, and finally to {{convert|635|F|C}}. It was then operated at 10 KW for 60 seconds at {{convert|643|F|C}}.{{sfn|Hadley|1963|pp=26–32}} A final test was conducted on 3 May, with an air flow rate of {{convert|120|lb/s|kg/s|order=flip|sp=us}}, a core temperature of {{convert|400|F|C|order=flip}} and no incidents.{{sfn|Hadley|1963|p=35}}

Tory II-A was operated at its designed value on 14 May, when it reached a power output of 46 MW with a core temperature of {{convert|2580|F|C|order=flip}}. Three high power test runs were conducted on 28 September, 5 October and 6 October. These reached power levels of 144, 166 and 162 MW with core temperatures of {{convert|2330|,|2300|and|2640|F|C|order=flip}} respectively.{{sfn|Hadley|1963|pp=44–45}} With the tests conducted successfully, the reactor was dissembled between December 1961 and September 1962.{{sfn|Hadley|1963|pp=1–2}}