Shielding Wall design complete, bidding begins

With the help of Dr. Mohamed Sawan of the University of Wisconsin, Madison, Dr. Subramanian and Mr. Lerner have completed the design of the shielding walls.

Design specs

The shielding walls will be 2.5 feet thick, and made of concrete enriched with 2.9% boron, the composition used in other fusion facilities.

Using the MCNP simulation program, we calculate that the shielding will reduce the biological dose of the neutron by a factor of very close to 3,000, and will essentially eliminate the gamma-ray and x-ray radiation.

This means that for the worst case of 10^13 neutrons per pulse and six pulses per hour, no one can be exposed to more than 1 mrem per hour, under the OSHA requirement of 2 mrem/hr.

For an annual average of 2,500 pulses, an optimistic figure, annual exposure will be under the background level of 500 mrem; even with the unrealistic assumption that all pulses produce the worst-case radiation.

Bidding begins

We are now getting bids from contractors to build the wall, lay a new concrete floor, upgrade the heating of the facility and install air-conditioning.

We still have to design and test the shielding for the narrow beams of neutrons that must be allowed out to the time-of –flight detectors, which will use the spread in velocity of the neutrons to determine their energy and thus the temperature of the ions that produce them.