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Nuclear Reactor Digitization Project

Raymond L. Murray Reactor Project Notebook

Prepared for the North Carolina State University Science and Technology Electronic Text Center

The lineation of the manuscript has been maintained and all end-of-line hyphens have been preserved.

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A new estimate of the critical and operating mass of the

In summary: It is recommended that the reactor core be made with inside
diameter 10 3/4", inside height 11" (1.08" clearance at top), to accommodate

900 grams of U-235 at a hydrogen ratio of 400 (anhydrous uranyl sulfate l0% by

weight) solution density ≃ 1.1 g/cm

3.

The main differences between SUPO and our reactor are as follows:
SUP0

The number and dimensions of exposure tubes, control rod sheaths, etc., are
enough alike so that it is unprofitable to estimate differences due to them.

An analysis of the effects of changes listed above is given.

Shape. The critical volume (and mass) of a bare cylindrical reactor of given
hydrogen ratio is theoretically 1.14 times that of a bare spherical reactor. The

effect of a reflector is to reduce this discrepancy somewhat, so that this can be

Cooling Coil. In the conversion at
made of the worth of cooling coils that turned out to be quite accurate. The

addition of 157" (13.1') of cooling coil made an 80 gram increase in U-235

sary

cooling lengths is 33 ft., giving a predicted 200 gram charge. This value may be

Solution. The critical mass for a nitrate solution is quoted to be 70 grams

Estimate of Mass. Starting with the experimental critical mass of SUPO of 870
grams of U-235, the change to sulfate would bring it down to 800 grams. A change

in shape brings it to 1.14(800) = 915 grams, but the cooling coil difference

cuts it back to 215 - 200 =

715 grams for the critical mass. Adding 60 grams a for
the temperature coefficient and 15 grams for excess reactivity, gives a final

value of

790 grams for the operating mass.

In the design of the core provisions should be made for the possibility that
the effect of cooling length reduction is not as high as linear extrapolation

would predict, that the extra void at the top and the void between the bottom of the

used instead of sulfate.

Since it is preferable to err in the direction or too large a container size,
requiring that the actual solution used be of lower concentration, it is

mended

900 grams be assumed in establishing the core size.

Estimate of Reactor Size. The volume of container will be the sum of the necessary

By the applicable chemical relations, the solution volume is

bringing the total to 14,711 cm3 at h = 400, and M = 900 grams,33, or broken down as follows;3333 cm33

3.

For a bare cylindrical reactor, the optimum height is 1.8475 times the radius,
so that the volume is

2H = 5.804 R3

A space of approximately 1" between the solution and the inside of the top

The recommended fixed dimensions of the core are--Inside Diameter 10 3/4",

Inside Height 11".

Volume of top space