Management of Commercially Generated Radioactive Waste - U.S. ...

H.1
APPENDIX H
HAZARD INDICES
The total quantity of radioactive material to be isolated can be compared to the iso-
tope quantities that naturally occur in the earth's crust (Winegardner and Jansen 1974,
Smith 1975). This comparison can be used to indicate the relative hazard that may result
from the burial of radioactive waste (i.e., geologic isolation). Early efforts to develop
safety perspectives on geologic isolation led to the development of hazard indices. These
indices attempted to combine those parameters that characterize waste isolation into an
index on public health and safety. The indices use one or more of the following parameters:
quantity of radioactive material, specific activity, decay properties, chemical and physical
form, packaging, toxicity, time behavior, and pathways.
Some hazard indices that have been developed are listed and defined in Table H.O.1.
Studies in which they have been used include: the comparison of the toxic content of high-
level waste to the toxic content of the uranium ore and tailings from which it came (Cohen
1976, 1977); the. comparison of the toxic level of Pu sent to high-level waste against the
toxic level of lead sent to waste (Cohen 1975); The Reactor Safety Study (NRC 1975) (risk
of nuclear plant accidents compared torisk of natural disasters); risk of plutonium ship-
ments (Hall et al. 1977); risk of natural and man-caused radioactivity (Turnage 1976); the
relevance of nuclide migration at Oklo (Walton and Cowan 1975); underground testing of
nuclear devices (Teller et al. 1968); direct impact of disruptive events (Starr 1970); and
risk comparisons to alternative energy resources (Grahn 1976, pp. 371-387; Straker and Grady
1977; Cottrell 1976; Blot et al 1.977; Starr et al. 1972; Petrikova 1970; McBride et al.
1977).
The various hazard indices attempt to incorporate additional considerations (such as
the concentration of the waste material and the pathways for the nuclear material to enter
the biosphere) into the comparison between nuclear waste and naturally occuring radioactive
materials. As can be seen in Table H.0.1, the total quantity of radioactive material (Q),
the maximum permissible concentration (MPC), and the maximum permissible intake (MPI) give
measures of the toxicity of the waste material. A better index of the toxicity of the mate-
rial is the hazard measure (HM) (Walton and Cowan 1975), which is the quantity of water
required to dilute the material to its acceptable maximum permissible (non-toxic) concentra-
tion. Thus, the HM is a number that is proportional to the toxicity of the waste material.
The "first modified hazard measure" (HM1) (Walsh et al. 1977) compares the anticipated expo-
sure (or dose) to an allowable limit. It was introduced to evaluate the effect of environ-
mental pathways on hazards from a variety of environmental pollutants including nuclear
wastes. The second modified hazard measure (HM2) (McGrath 1974) is a measure of the poten-
tial hazard of radioisotope releases in air and water. It is a number proportional to such
hazard. The third modified hazard measure (HM3) (Petrikova 1970) is a quantity to assess
the radioactive risk to future generations from future releases of radioisotopes. It is the