Aircraft Reactor Experiment

W. B Cottrell et al. The Disassembly and Postoperative Examination of the Aircraft Reactor Experiment, ORNL-1868, Oak Ridge National Laboratory (1958). 

ORNL Aircraft Reactor Experiment 2.5 MW 882<>C Fuel Salt Na/Zr/F... 

The Aircraft Reactor Experiment, a 2.5-MW(th) reactor, operated in the 1950s with a NaF/ZrF4molten salt, while the Molten Salt Reactor Experiment, an 8-MW(th) reactor, operated in the 1960s with a EiF/BeF2 molten salt. In these reactors, the fuel was dissolved in the salt whereas the AHTR uses solid fuel with a clean molten salt. Detailed studies will be required to determine the preferred composition of the fluoride salt. All of the candidate fluoride salts have somewhat similar properties. Preliminary nuclear calculations used Ei2BeF4 because its properties are well known. 

Aircraft Reactor Experiment First Moiten Salt Reactor 2.5 MW 882°C Fuel Salt Na/Zr Fluoride... 

Aircraft Reactor Experiment (ARE) Successfuiiy Demonstrated Moiten Sait Reactor Technoiogy in 1954... 

These billion dollar programmes developed the technology base for use of liquid salts in nuclear systems. Two experimental reactors were built and successfully operated. The aircraft reactor experiment (ARE) was the first MSR. It was a 2.5 MW(th) reactor that was operated in 1954 at a peak temperature of 860°C and used a sodium-zirconium fluoride salt. This was followed in 1965 by the molten salt breeder reactor (MSBR) Experiment, an 8 MW(th) reactor that used a lithium-beryllium fluoride salt and demonstrated most of the key technologies for a power reactor. In addition, test loops with liquid salts were operated for hundreds of thousands of hours, materials of construction were code qualified to 750°C, and a detailed conceptual design of a 1000 MW(e) MSBR was developed. Over 1000 technical reports were produced. 

Molten Salt Reactor (MSR). The MSR [3] uses a liquid molten-fluoride salt as fuel and coolant. The uranium or plutonium fuel is dissolved in the molten salt. Two test reactors were built. In the 1950s, the Aircraft Reactor Experiment operated normally with molten salt exit temperatures of 815 C with peak operating temperatures up to 860 C and very low primary system pressures. Work continued on MSR technology for power applications until 1976. The reactor can be built in large sizes with passive safety systems. 

Equipment for Molten-Salt Reactor Heat-Transfer Systems 1C. Aircraft Reactor Experiment... 

The Oak Ridge National Laboratory, under the sponsorship of the U. S. Atomic Energy Commission, has engaged in research on molten salts as materials for use in high-temperature reactors for a number of years. The technology developed by this work was incorporated in the Aircraft Reactor Experiment and made available for purposes of civilian application. This earlier technology and the new information found in the. civilian power reactor effort is summarized in this part. 

Te.sts have also been made in which the fissioning fuel is pumped through a system in which a thermal gradient is maintained in the fluid. These tests included the Aircraft Reactor Experiment (described in Chapter 16) and three types of forced-circulation loop tests. A large loop, in which the pump was outside the reactor shield, was operated in a horizontal beam hole of the LITR, A smaller loop was operated in a vertical position in the LITR lattice with the pump just outside the lattice. A third loop was operated completely within a beam-hole of the MTR. f The operating conditions for these three loops are given in Table 12-8. 

Oxidizing nature of the fission process. The fission of a mole of UF.1 would yield more equivalents of cation than of anion if the noble gas isotopes of half-life greater than 10 min were lost and if all other elements formed fluorides of their lowe.st reported valence state. If this were the case the system would, presumably, retain cation-anion equivalence by reduction of fluorides of the most noble fission products to metal and perhaps by reduction of some U + to U +. If, however, all the elements of uncertain valence state listed in Article 12-6.2 deposit as metals, the balance would be in the opposite direction. Only about 3.2 equivalents of coml)iiicd cations result, and since the number of active anion equivalents is a minimum of 4 (from the four fluorines of UF4), the deficiency must 1)0 alleviated by oxidation of the container. The evidence from the Aircraft Reactor Experiment, the in-pile loops, and the in-pile capsules has not shown the fission process to cause serious oxidation of the container it is possible that these experiments burned too little uranium to yield significant results. If fission of UF4 is shown to be oxidizing, the detrimental effect could be overcome by deliberate and occasional addition of a reducing agent to create a small and stable concentration of soluble UF3 in the fuel mixture. 

Fig. 15-2. Sump-type centrifugal pump developed for the Aircraft Reactor Experiment.

The pump shown in Fig. 15 2 was developed for 2000-hr durabihty at very low irradiation levels and was used in the Aircraft Reactor Experiment for circulating molten salts and sodium at flow rates of 50 to 150 gpm, at heads up to 250 ft, and at temperatures up to 15.50°F. These pumps ha m been irtually trouble-free in operation, and many units in addition to those used in the Aircraft Reactor Experiment have been used in developmental tests of various components of molten-salt systems. 

The feasibility of the operation of a molten-sult-fueled reactor at a truly high temperature was demonstrated in 1954 in experiments with a reactor constructed at ORNL. The temperature of the fuel exiting from the core of this reactor was about 1500°E, and the temperature of the fuel at the inlet to the core was about 1200°E. The reactor was constructed before the mechanism and control of corrosion by molten salts had been fully explored, and therefore the experimental operation of the reactor was of short duration. Since the work was supported by the Aircraft Reactors Branch of the Atomic Energy Commission, the reactor was called the Aircraft Reactor Experiment (ARE). ... 

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