Based on the safety assessment framework and site-specific characteristic
investigations in northwest China, an approach to deriving the specific
activity limit of 239Pu is applied to establish a proposed value. Our
analyses, in conjunction with the results of other previous studies, allow
for the following conclusions: (1) As an intrusion scenario with a feature
of minimal site-dependence and pervasive applicability, the drilling
scenario can be used as the limiting scenario for the post-closure period;
(2) Given a dose limit of 5 mSv per year, a derived specific activity of 287
Bqg-1 (at a disposal depth shallower than 5 m) for 239Pu is obtained
through the formulation of models and subsequent calculations. It is
suggested that both our approaches to deriving the limit and the results
can be effectively applied to establish acceptance criteria of long-lived
transuranic nuclides, for the particular disposal facility; and (3) From the
standpoint of exploring the approach for limit derivation, the intrusion
scenario and the corresponding exposure evaluation can be the focus of
concern in the study area. It is implied that, in arid regions, a leaching
scenario may lead to a more complex evaluation, with unnecessary effort,
and can be virtually excluded.
Simulation and estimation of future precipitation changes in arid regions: a case study of Xinjiang, Northwest China
