Radioactive permanent isolation

The work presented here enables us to get a clearer picture of the problems involved in permanent isolation of radioactive wastes from the environment. 

Over the last year or so, several papers have been published which have been concerned with the adequacy of the technology for providing for permanent isolation of radioactive wastes. In all cases the concerns that have been raised have focused on the second set of issues, rather than the first, so that the apparent dispute between those who say that there are no technical problems and those who say that there are still some to be solved is perhaps more a dispute as to what particular set of problems are being described. 

Clause (B) other highly radioactive material that NRC, consistent with existing law, determines by rule requires permanent isolation. 

The definition of high-level waste in Clause (B) of NWPA given above represents a potentially significant departure from previous definitions in that it allows the development of a generally applicable definition of high-level waste that is not based on the source of the waste. However, as in Clause (A), highly radioactive and requires permanent isolation in Clause (B) are not quantified. 

High-level waste is any waste that is highly radioactive and requires permanent isolation. 

Transuranic waste and equivalent is any waste that requires permanent isolation but is not highly radioactive. 

In these definitions, highly radioactive refers to high levels of decay heat and external radiation, due primarily to shorter-lived radionuclides, and requires permanent isolation refers to high concentrations of long-lived radionuclides i.e., these terms have the same interpretations as in the definitions of high-level waste in NWPA. 

HLW generally refers to materials requiring permanent isolation from the environment. It frequently arises as a by-product of nuclear power generation (reprocessing streams or spent fuel) or from the isolation of fissile radionuclides from irradiated materials to be used in nuclear weapons production. When nuclear fuel from reactor operations (civilian or defense) is chemically processed, the radioactive wastes include highly concentrated liquid solutions of nuclear fission products. Typically, these waste streams are solidified either in a glass (vitrification) or in another matrix. Both the liquid solutions and the vitrified solids are considered HLW. If the nuclear fuel is not processed, it too, is considered as HLW and must be dispositioned. The path most often proposed is direct, deep geologic isolation. 

Without going into great detail about the issues described in these papers, I would like to make the point that the response of the waste isolation program to these papers will be to use them to help us to design a technical program plan to ensure that these issues are adequately addressed, as indeed they must be, before we can commit radioactive waste to irretrievable permanent disposal. 

This experiment provides considerable confidence in the concept of waste immobilization in glass as one step toward isolating the long-lived radioactive by-products of nuclear power from man s environment. Of course, the immobilized material would not be placed deliberately in shallow ground water for permanent disposal. The consensus today is for deep underground disposal in a stable geological formation (21). 

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