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ST 4.3 –
Gestión de residuos radiactivos
CONSIDERATIONS ON THE DISPOSAL OF DISUSED SEALED
RADIOACTIVE SOURCES
Schenato, Flavia*; A. Aguiar, Laís
Comissão Nacional de Energia Nuclear (CNEN). Brasil.
* Responsible author, email: fschenato@cnen.gov.br
Disused sealed radioactive sources (DSRS) represent one of the largest waste problems from
non-power applications, particularly due to the long lived radionuclides such as 226Ra and
241Am. Despite their predominantly small physical size, many sources contain very high
activities with typical levels in the megabecquerel (106 Bq) to petabequerel (1015 Bq) range.
They are, for all practical purposes, another type of radioactive waste that needs to be disposed
of safely. Proven long term storage technologies are available for DSRS. However, numerous
factors may severely disrupt storage records and storage systems and final disposal of DSRS is
a way to avoid this risk. Many countries have existing or proposed near-surface radioactive
waste disposal facilities for low and intermediate level waste. However, the specific activity of
many sources exceeds the waste acceptance criteria for such facilities since the source
constitutes a localized high concentration levels and could give rise to unacceptable radiation
doses. Moreover, some DSRS are not subject to the repatriation clauses and a large number of
sources end up being stored for long time. Storage can be considered as an adequate final
management option for sources containing short lived radionuclides. However, most other
sources remain in storage pending a suitable disposal option becoming available. For the IAEA,
most countries have adequate regulatory infrastructures to keep national or institutional records
of DSRS and capabilities to ensure the safety and security of their sources. Nevertheless, a
strategy to safe management of radioactive waste will need to define the disposal routes for the
different types of waste and the actions required to implement a disposal plan. Considering the
large volume of DSRS generated in Brazil, this paper aims to discuss the available safety
guidelines for long term disposal of DSRS and the acceptability of disposal methods.