NUCLEAR WASTE DISPOSAL

Our society does not have an impressive record for safe disposal of industrial wastes. We have polluted our water and air, and some land areas have become virtually uninhabitable because of the improper burial of chemical wastes. As a result, many people are wary about the radioactive wastes from nuclear reactors. The potential threats of cancer and genetic mutations make these materials especially frightening.

Because of its controversial nature, most of the nuclear waste generated over the past 50 years has been placed in temporary storage. However, in 1982 the U.S. Congress passed the Nuclear Waste Policy Act, which established a timetable for choosing and preparing sites for the deep underground disposal of radioactive materials.

The tentative disposal plan calls for incorporation of the spent nuclear fuel into blocks of glass that will be packed in corrosion-resistant metal containers and then buried in a deep, stable rock formation indicated by the rock layers.

There are indications that this method will isolate the waste until the radioactivity decays to safe levels. Some reassuring evidence comes from the natural fission “reactor” that was discovered at Oklo in Gabon, Africa (see “Celebrity Chemical: Uranium” on page 686). Spawned about 2 billion years ago when uranium in ore deposits there formed a critical mass, this “reactor” produced fission and fusion products for several thousand years. Although some of these products have migrated away from the site in the intervening 2 billion years, most have stayed in place.

In 1999 the Waste Isolation Pilot Plant (WIPP) in New Mexico began receiving nuclear waste. This facility employs tunnels carved into the salt beds of an ancient ocean. Once a repository room becomes full, the salt will collapse around the waste, encapsulating it forever.

Another waste depository, under Yucca Mountain in Nevada, is being contemplated. For nearly two decades, this area has been studied to determine its suitability for storage of high-level radioactive wastes. At present it looks to be a long time before this issue is settled.

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