Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

INTERNAL RADIATION SAFETY 597
the United States. In the 1970s, three of these sites were closed because of leakage
of radioactivity into the groundwater. As a consequence, and to lessen the burden
on the remaining burial sites, the U.S. Congress passed the Low-Level Radioactive
Waste Policy Act of 1980. This act made each state responsible for the disposal of
waste generated within its borders. However, the states were authorized to form
compacts for the establishment and operation of regional facilities for the disposal
of LLRW generated within the compact states. As of the middle of 2006, the first
LLRW burial site under the provisions of this act had yet to be identified. Currently
(2007), there are three sites in the United States where LLRW is accepted for burial:
Barnwell, South Carolina; Hanford, Washington; and Clive, Utah.
When we deal with waste disposal, we mean that there is no expectation of ever
recovering it. However, the waste disposal site is not abandoned but is kept under
surveillance and governmental control for an appropriate period of time. The longterm
surveillance and stringent attention to long-term safety is in accordance with
the IAEA’s principle: “Radioactive waste shall be managed in such a way that will not
impose undue burdens on future generations.” The objective of shallow land burial
is to confine the radioactivity and prevent it from reaching the biosphere for a long
enough time that the radioactivity does not represent an unacceptable risk. The
fitness of a LLRW disposal site is therefore determined mainly by its hydrogeological
characteristics as they relate to the prevention of migration of radioactivity outside
of the site or the migration of radioactivity into the groundwater. Any activity that
does migrate beyond the limits of the site should be of such low level that it will do
no harm to humans or the environment.
Because of the wide range of activity in radioactive waste, ranging from very large
amounts from the nuclear fuel cycle (Table 11-6) to the very small amounts from
scientific laboratories that use tracer quantities of radioisotopes, several basically
TABLE 11-6. Radioactive Wastes from the Fuel Cycle
APPROXIMATE
RADIOACTIVITY LEVEL
TYPES OF WASTES AND
PRINCIPAL CONSTITUENTS Ci/ton U Bq/ton U
Mining and milling Gaseous: 222Rn, 218Po, 214Bi, 214Po 10−4 –10−3 4 × 106 –4 × 107 Liquid
Solid: U, 226Ra, 230Th, 210Pb 0.5–1 2 × 10 10 –4 × 10 10
Refining Liquid: 238U, 234Th, 234Pa, 226Ra 10−4 –10−3 4 × 106 –4 × 107 Fuel fabrication Liquid
Solid: U, Pu, Th 10−4 –10−3 4 × 106 –4 × 107 Reactor operation Gaseous: 13N, 41Ar, 89Kr, 87Kr, 138Xe, 135Xe 10–100a 4 × 1011 –4 × 1012 Liquid
Solid: 58Co, 60Co, 59Fe, 51Cr, 3H 50–100a 2 × 1012 –4×1012 Chemical processing Gaseous: 85Kr, 133Xe, 131I, 129I, 3H 7000b 26 × 1013 Liquid
Solid: Fission products, Pu, Am, Cm 6,6000,000b 22 × 1016 a At time of waste discharge or shipment based on fuel exposure of 20,000 Mwd/ton of U.
b Waste from fuel at 20,000 Mwd/ton, 120 days cooled.
Source: From ORNL Drawing 69–83 R2. Oak Ridge, TN: Oak Ridge National Laboratory; 1969.