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SIDEBAR 1.1:The definitions of HLW in the United States and Russia differ from each other.
Russia’s waste classes are based on the concentration of radioactivity in the waste (Rybal’chenko et al. 1998) or on the dose rate at the surface of the waste package (NAS 1990).
High-level waste (HLW)
Any liquid waste containing greater than or equal to one curie per liter (1 Ci/liter) is HLW. Any solid waste with a dose rate greater than or equal to 1 rad per hour (1 r/hr) due to gamma radiation on the surface of the waste package is HLW.
Intermediate-level waste (ILW)
1 Ci /liter>ILW>10-5 Ci/liter for liquids; 1 rad/hr>ILW>300 mrad/hr at the package surface for solids
Medium-level waste (MLW)
300 mrad/hr>MLW>30 mrad/hr at the package surface for solids
Low-level waste (LLW)
10-5 Ci/liter>LLW for liquids
30 mrad/hr>LLW at the package surface for solids
The United States’ definition is based on the process that produced the waste, although it allows for other wastes to be grouped with HLW on a case-by-case basis. High-level radioactive waste is
“(A) the highly radioactive material resulting from the reprocessing of spent nuclear fuel, including liquid waste produced directly in reprocessing and any solid material derived from such liquid waste that contains fission products in sufficient concentrations; and (B) other highly radioactive material that the (Nuclear Regulatory) Commission, consistent with existing law, determines by rule requires permanent isolation.” [42 U.S.C. § 10101]
The U.S. Nuclear Regulatory Commission has defined spent nuclear fuel as high-level waste [10 CFR 63]. Spent nuclear fuel is fuel that has been withdrawn from a nuclear reactor following irradiation.