Application to a Heavy-water-moderated Reactor

A detailed report on the CP-5 reactor is given in the Atomic Energy Commission document Research Reactors a few of its principal characteristics are summarized here. The reactor core proper is an upright cylinder of D2O 2 ft high and 2 ft in diameter in which are immersed MTR-type aluminum fuel elements (see Fig. 5.28). The sides and bottom of the core are reflected by 2 ft of D2O, and this region in turn is surrounded by 2 ft of graphite. The top of the core is reflected by 2J ft of D2O alone. The fuel elements, of which there are 16, consist of boxlike arrays of fuel plates fabricated of a uranium-aluminum alloy, composed of 17.5 per cent aluminum and 82.5 per cent uranium. For computational purposes we will assume that the volume fraction of aluminum in the core is Vax = 0.0688 and that of D2O, Vdio = 0.914. The reactor was designed to produce 1,000 kw of heat, and at this power level the temperature of the D2O is 49 C. 

If the core of this reactor were entirely bare, we could use Eq. (6.80) directly to determine the critical fuel concentration. Since the present configuration is completely reflected, we require a modified relation which will take into account the effect of the reflector. We observed in Chap. 1 that the purpose of the reflector is to decrease the neutron escapes from the core and thereby reduce the critical fuel concentration of the system. Clearly, if we were to ignore the reflector altogether, our estimate of the 

On the basis of the selected bare-core configuration, we estimate the buckling to be 

For the proposed calculations we will also use the following data  

The fast nonleakage probability based on these data may be computed from Eq. (6.79) it is found to be th = 0.7364. 

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