TO: Dr. Clifford K. Beck
FROM: R. L. Murray
CC: A. C. Menius, Newton Underwood

This note answers your request for calculations on the heavy concrete.

The composition of Barytes mix, according to the Carbide purchasing agent^a is,
per yd³,

• Barytes	3970 lba1	72.0
  Colemanite	400 lb	7.3
  Portland cement	830 lb	15.1
  Water	310 lb (37.5 gallons)	5.6
  Total mix	5510 lb	100.0

Since the Colemanite consists of

• B2O3	44%
  CaO	27%
  H2O	28%

The boron content at the final mix is almost exactly 1%, as computed below:

The density of the concrete is
or its specific gravity is

The ORNL figures for this concrete are 1% Boron, 3.5 specific gravity. The
neutron flux data show that in a 6 foot shield, the attenuation with the 1% B
concrete is 100 times that for Barytes without B.

The minimum cost figures quoted by CCC&D are

• Barytes aggregate $20/ton	Estimated shipping cost $4/tonb
  Colemanite $60/ton	Estimated shipping cost $15/tonc

The fractions of each in the mix are Barytes 3970/5510 = 0.72, Colemanite 400/5510 = 0.072.
Assuming a figure of $16 a ton for Portland Cement^d, with 830/5510 = 0.15 required,
the cost is
[(0.72)(24) + 0.072(75) + (0.15)(18)] 5510/2000 = $70/yd³

A good estimate for the volume of concrete in the shield^e is 107 yd³, so that the
cost would be ($70)(107)= $7500. Of this, the critical item so far as shipping
(from California) is the 21.4 tons of Colemanite. However, it only constitutes
7.2% of the mix, and 20% of the cost, so it would probably be worth the invest-
ment to achieve the full degree of shielding, rather than using an inner lining
of the Boron cement. Special forms might be needed also, which would run up
the construction cost. The cost estimates for a 4 ft inside lining corresponding
to 1440 ft³ = 53 yd³ are computed for consideration, anyway. This is half the
reactor volume. Substituting Barytes for Colemanite would reduce the yd³ cost to
only $65 and the total concrete to $7000.

^aLetter of Feb. 23, 1951 - R. N. Reams to C. K. Beck

^bBased on Mr. Stainback's figures on W. Va. coal shipping

^cFreight agent, Seaboard Railway

^a1

Barytes:	Ba 41.9%
	O 31
	S 9.9
	Fe 8.7
	Co 4.5
	Si 1.7
	other 3.3
	100

^dQuoted by N. C. State Products Corp.

^e