Environmental Engineering FOURTH EDITION

Radioactive Waste 331

Techniques now being applied to LLW include impervious packaging, compaction,

incineration, and stabilization in an asphalt or cement matrix. Compaction can achieve

volume reduction of about 8: 1 and incineration can reduce volumes by factors of 30 or

more. Incineration appears to be an excellent treatment option for mixed radioactive and

organic chemical wastes like liquid scintillators. Incineration emissions require careful

monitoring and decontamination factors of 10,000 or more. Air emission controls are

discussed further in Chap. 20.

The Low-Level Radioactive Waste Policy Act of 1980 as amended requires states

to form regional interstate compacts and site regional LLW disposal facilities. Siting

and operating these facilities will require careful environmental engineering.

TRANSPORTATION OF RADIOACTIVE WASTE

Some radioactive waste, particularly HLW, has such high activity that blocking all

external radiation during transportation would make the transport container far too

heavy for heavy truck transport or even for rail transport. As a result, transported

radioactive material is allowed a certain external dose by Nuclear Regulatory Commis-

sion regulation. This dose, called the Transport Index, is the dose rate in mremhour at a

perpendicular distance of 1 m from the outside edge of the vehicle or trailer. Transport

containers must also meet certain other regulatory requirements. For most LLW, the

container must be tested and certified to withstand the rigors and physical stresses of

normal transportation. For HLW, TRU, and some LLW, the container must be able to

withstand certain accident conditions, including combinations of fire and mechanical

stress.

CONCLUSION

Energy can be transferred from one place to another by direct radiation. Radiated

energy travels in straight lines and can be visualized either as a stream of particles or

as waves. In its wave formulation, energy forms a continuous spectrum from X-rays

at the very-short-wavelength end to radar and heat at the very-long-wavelength end.

Very-short-wavelength radiation can ionize atoms and molecules. Its source can be the

spontaneous process in which unstable atoms of an element emit excess energy from

their nuclei, as well as anthropogenic chain reactions in nuclear power facilities and

nuclear detonations.

This ionizing energy flux may have adverse impacts on biological matter.

Radiation sickness, cancer, shortened life, or immediate death may result from vary-

ing exposures. Radiation doses to living tissue are measured as grays or rads, units

of absorbed energy, and sieverts or rems, units of relative biological damage. These

units take into account the effects on living tissue of alpha, beta, gamma, and neutron

radiation.

The general concern of the environmental engineer is radiation from anthropogenic

sources, particularly the wastes from nuclear power plants, radiation from natural