"LOW-LEVEL" RADIOACTIVE WASTE

Source: http://www.nirs.org/factsheets/llwfct.htm

"Low-Level" Radioactive Waste is one of the most misleading terms ever created. In the U.S., it is all nuclear waste that is not legally high-level waste, some transuranic waste, or mill tailings.

High-Level Radioactive Waste is: the irradiated fuel from the cores of nuclear reactors, the liquid and sludge wastes that are left over after irradiated fuel has been reprocessed (a procedure used to extract uranium and plutonium), the solid that would result from efforts to solidify that liquid and sludge from reprocessing.

Transuranic Waste is material contaminated with radioactive elements heavier than uranium, such as plutonium, neptunium, americium and curium. These elements: have extremely long hazardous lives--hundreds of thousands to millions of years and emit alpha radiation a type of radiation that is especially dangerous if inhaled or swallowed. Some transuranic waste is allowed in the "low-level" radioactive waste category. In 1983, when the Nuclear Regulatory Commission (NRC) adopted regulations on land disposal of radioactive waste (lOCFR61), it increased the allowable concentration of transuranics in "low-level" radioactive waste.

Uranium Mill tailings, resulting from mining and milling uranium for weapons and commercial reactors, are not usually included in the "low-level" waste category, but may be handled with it in some states. The large volumes of these wastes, which will emit radiation for centuries, pose serious health problems.

WHAT IS "LOW-LEVEL" RADIOACTIVE WASTE?

"Low-Level" Radioactive Waste includes:

Irradiated Components and Piping: reactor hardware and pipes that are in continual contact with highly radioactive water for the 20 to 30 years the reactor operates. The metal becomes "activated" or radioactive itself from bombardment by neutrons that are released when energy is produced. Also called Irradiated Primary System Components.

Control Rods: from the core of nuclear power plants--rods that regulate and stop the nuclear reactions in the reactor core.

Poison Curtains: which absorb neutrons from the water in the reactor core and irradiated fuel (high level waste) pool.

Resins, Sludges, Filters and Evaporator Bottoms: from cleansing the water that circulates around the irradiated fuel in the reactor vessel and in the fuel pool, which holds the irradiated fuel when it is removed from the core.

Entire Nuclear Power Plants if and when they are dismantled. This includes, for example, from a typical 1,000 megawatt nuclear reactor building floor: over 13,000 tons of contaminated concrete and over 1,400 tons of contaminated reinforcing steel bar.

The highly radioactive and long-lived reactor wastes are included in the "low-level" waste category along with the much less concentrated and generally much shorter-lived wastes from medical treatment and diagnosis and some types of scientific research.

RADIOACTIVE CONCENTRATION vs VOLUME

The nuclear industry and government commonly describe "low-level" waste in terms of volume although there can be a tremendous concentration of radioactivity in a small package and a small concentration in a big package. The amount of radioactivity, measured in CURIES, indicates how much radioactive energy is being emitted by the waste. (1 Curie = 37,000,000,000 or 37 Billion disintegrations or radioactive emissions per second from a radioactive material.)

The medical waste from diagnosis and treatment shipped in one year from most states usually gives off a fraction of one curie of radiation. In contrast, each nuclear reactor generates hundreds and thousands of curies in "low-level" waste every year.

Nuclear reactor waste is concentrated: Solidified liquid emits about 2 curies per cubic meter; Filter/Demineralizer sludges emit about 10 curies per cubic meter; Cartridge filters emit about 20 curies per cubic meter; Demineralizer resins emit about 160 curies per cubic meter. Primary Components average 1000 to 5000 curies per cubic meter.

All of this material is legally considered low-level.

HALF-LIFE and HAZARDOUS LIFE

Radioactive elements decay by emitting energy in the form of radioactive particles and rays. As radiation is given off, other elements (some radioactive and some stable) are formed.

The Half-Life is the time it takes for HALF of the radioactive element to decay (give off half of its radioactivity). Different radioactive elements have different half-lives.

The Hazardous Life of a radioactive element is about 10 or 20 Half-Lives. (It is best to measure the amount of radiation after 10 or 20 half-lives before releasing waste from active controls.)

Reactor waste remains hazardous for a very long time. Most medical waste from treatment and diagnosis is hazardous for a very short time. Research and industrial waste can contain small amounts of some long-lived radioactive materials.

Among the radioactive elements commonly found in nuclear reactor "low-level" waste are: Tritium, with a half-life of 12 years and a hazardous life of 120-240 years; Iodine-131, half-life of 8 days, hazardous life of 80-160 days; Strontium-90, half life of 28 years, hazardous life of 280-560 years; Nickel-59, half life of 76,000 years, hazardous life of 760,000-1,520,000 years, and Iodine-129, half-life of sixteen million years, hazardous life of160-320 million years.

By contrast, common medical waste elements include Technetium-99m, with a half-life of 6 hours and a hazardous life of 2.5-5 days; Galium-67, half-life of 78 hours and hazardous life of 1-2 months; and Iodine-131, with its half-life of 8 days and hazardous life of 80-160 days.

The vast majority of medical waste is hazardous for less than 8 months. Yet, it is in the same category as reactor waste that will be hazardous for hundreds of thousands to millions of years.

Clearly, the definition of "low-level radioactive waste" must be changed. It would make sense to redefine the more concentrated and/or longer-lived waste as high-level. Active recontainerization and operational control must be provided for the entire hazardous life of the waste, yet the NRC requires only 100 years of passive institutional control. Thus, waste hazardous longer than 100 years could be forgotten. Retrievability is essential.

PLANNED LEAKAGE AND "ACCEPTABLE" RISK

Waste containers and forms will not last as long as some waste remains hazardous. Therefore, waste should be placed in a manner which will facilitate recontainerization and make continued isolation from the environment possible in the future. If the waste is "disposed of" as the NRC currently requires, it will not be isolated from the environment. "Planned leakage will occur at (what NRC considers) an "acceptable" leak rate leading to "acceptable" public radiation exposures and health risks. The allowable leak rates and exposure levels are determined by federal agencies, not those experiencing the risk.

To avoid leakage, above-ground, engineered storage at or near the source of generation could allow responsible routine monitoring and repair.

STATES' AUTHORITY

States have the right and responsibility to protect their citizens' health. In 1980, Congress gave states the responsibility for "low-level" radioactive waste. How and whether states choose to take on that responsibility will be reflected indefinitely into the future.

Source: http://www.nirs.org/factsheets/llwfct.htm