Statement of Problem: To exercise
its authority to set radiation protection standards in Sweden and to
evaluate whether such standards are implemented properly, the Swedish
Radiation Protection Institute (SSI), located in Stockholm, needed a
computer-based set of tools to evaluate alternatives, test basic
concepts, and train its staff. The computer code known as “SSI Tool
Box,” which simulates a geologic repository system in an integrated
manner, was developed by CNWRA® to meet this need.
Approach and Accomplishments: CNWRA assembled a team of subject matter specialists and programmers to
accomplish the task. As a first step, a software requirements document (SRD)
was prepared describing the specific needs the tool box must
satisfy. The SRD identified the system components and related processes
that must be simulated, specified the user interface, described
post processing needs, and identified the hardware on which the code
must operate. After the client approved the SRD, a basic design for the
software was developed. To minimize costs, existing codes (e.g., CAP88
and ISOSHLD for shielding calculations) or existing codes with
modifications (e.g., TRAM for calculation of transportation risks) were
identified and used as modules of the Tool Box wherever possible. New
codes (e.g., FRAC_SSI for flow and transport in a fractured medium and
SOSIM for diffusive release from the engineered barrier subsystem) were
developed where needed. A new code also was developed to ensure proper
interface and exchange of data between these different modules to create
an overall flexible and integrated model. A Monte Carlo algorithm was
incorporated into the code so uncertainties in model parameters
could be addressed quantitatively.
The user interface was designed to be
friendly so nontechnical people could use the code also. Input
could be entered interactively through well-designed computer screens. A
post-processor was built to provide output in both tabular and graphical
form. The code was delivered to the client with a user’s manual, and
training was provided to SSI staff.
Client Benefits: The Tool Box is
being extensively used by the SSI for repository simulations in Sweden.
In addition, the SSI is using the Tool Box in Russia and other Eastern
European countries as a training tool.