7794

7294

TO:

FROM:

CC:

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 lb ^{a1}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/ton ^{b}Colemanite $60/ton Estimated shipping cost $15/ton ^{c}

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

7.2% of the mix, and 20% of the cost, so it would probably be worth the

ment

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.

Notes:

^{a}Letter of

^{b}Based on

^{c}Freight agent,

Barytes: | Ba 41.9% |

O 31 | |

S 9.9 | |

Fe 8.7 | |

Co 4.5 | |

Si 1.7 | |

other 3.3 | |

100 |

^{d}Quoted by