WCSAR-TR-AR3-9107-1 A Review of Helium-3 Resources and Acquisition for Use as Fusion Fuel [Published in Fusion Technology, Special Issue on DHe3 Fusion, Vol. 21 (4) 2230-2253]

A combination of man-made and natural resources on earth could provide sufficient He fuel for the technological development of D-He fusion reactors. Helium exists in natural gas wells; however, at the present rate of natural gas usage this resource would provide < 5 kg/yr of He. The radioactive decay of H produced in fission production reactors could yield 110 kg of He by the year 2000 if it were retained. Apparently, large amounts of He exist within the earth’s mantle but it is inaccessible. A significant quantity of He exists on the moon which could be imported to supply a fusion power industry on earth for hundreds of years. The solar wind has deposited more than a million tonnes of He in the fine regolith which covers the surface of the moon. The presence of this solar wind gas was confirmed by analyses of the lunar regolith samples brought to earth. A strong correlation is noted between the He retained and the TiO2 content of the regolith; consequently, remote sensing data showing high-Ti-bearing soils in the lunar maria areas have been used to locate potentially rich sites for He extraction. Surface photographs of Mare Tranquillitatis have shown that nearly 50% of this Mare may be minable and capable of supplying ∼ 10, 000 tonnes of He. A mobile mining vehicle is proposed for use in the excavation of the soil and the release of the He, and other solar wind gases. The evolved gases would be purified by a combination of permeators and cryogenic techniques to provide a rich resource of H2, He, CO2, H2O and N2, followed by He isotopic separation systems. The energy and financial payback from those operations are substantial when this fuel is utilized in a D-He fusion reactor located on earth. The implementation of this mining operation would have minimal impact upon the lunar environment. Several legal regimes insure that such a lunar enterprise can be implemented without severely disrupting international order.