RASCAL: Radiological Assessment System for Consequence AnaLysis
The Radiological Assessment System for Consequence AnaLysis (RASCAL) code is a tool used by the Protective Measures Team in the U.S. Nuclear Regulatory Commission's (NRC's) Operations Center for making independent dose and consequence projections during radiological incidents and emergencies. RASCAL was developed by NRC over 25 years ago to provide a tool for the rapid assessment of an incident or accident at an NRC-licensed facility and aid decision-making such as whether the public should evacuate or shelter in place. RASCAL evaluates atmospheric releases from nuclear power plants, spent fuel storage pools and casks, fuel cycle facilities, and radioactive material handling facilities. Its data is not the only criterion used by the local authorities during an accident, but certainly an important one.
RASCAL has been continually upgraded and improved upon to include updated source term models, atmospheric transport models, nuclear power plant site-specific data and updated computer calculation methods. RASCAL version 4.2, which was issued in March 2012, provided for large and small updates and fixes to the RASCAL 4.0 code. Some of these include updates to the dose conversion factors (DCFs), Source Term to Dose (STDose) models and the Field Measurement to Dose (FMDose) models and the addition of approved facility power-uprates to the facility database.
What’s new — RASCAL 4.3
RASCAL 4.3 incorporates the Near Term Task Force's lessons learned on the Fukushima Daiichi nuclear power plant accident in Japan. RASCAL 4.3 incorporates several new features that were not available in previous versions of the code including:
RASCAL 4.3 Welcome Splash Screen
RASCAL 4.3 Main Screen
- Create Inventory Base File option which allows users to enter information about how a reactor has been operated so as to develop a more realistic and accurate reactor core inventory for use in the STDose model calculations.
- Source Term Merge/Export option which allows users to combine source terms for two or more reactors on a single site into a common source term. Allowing the user to assess the consequences from a multi-reactor event.
- Configure Met Download option allows users to setup an automated meteorological data acquisition module to gather and retrieve meteorological data from the National Weather Service.
- Changes to the STDose model to include:
- Long Term Station Blackout (SOARCA) option for accident progression as described in NUREG-1935, “State-of-the-Art Reactor Consequence Analyses (SOARCA)”
- LOCA (NUREG-1465) option (previously named Time Core Is Uncovered in RASCAL 4.2) which incorporates a change in the containment pressure/hole-size method of estimating release rates
- Coolant Release Accidents option (previously named Specified Core Damage Endpoint in RASCAL 4.2) which is now associated with a specific accident that results in core damage and updated coolant source terms consistent with the Gale codes (NUREG-0016 and NUREG-0017)
- Use of Custom Reactor Inventory option which allows the user to model realistic source terms based upon fuel management practices of the site using the Create Inventory Base File option.
- Spent Fuel Source Term calculations have not changed significantly in RASCAL 4.3; however, the calculation details require a more complete description of the fuel pools contents and the determination of the nuclide inventory at risk.
- The changes to the transport, dispersion and dose calculation adds a fourth Cartesian computational grid which increases the RASCAL 4.3 domain from a 50 mile radius to a 100 mile radius with the associated surface roughness data files for all grids. The calculation of the child thyroid dose has been added to allow for administration of potassium iodide (KI) and ingestion DCFs from Federal Guidance Reports 11 and 13 are included in the radionuclide database.
- Creation of activity balance file which allows the user to track the activity for selected nuclides and nuclide groups from the reactor core and coolant systems through various pathways to the environment.
- Addition of an importance model utility, which allows the user to process the total nuclide activity released to the environment in the course of an event by evaluating the relative importance of the nuclides to four dose measures and ranking the nuclides in order of importance.
- The ability to export and import a time dependent source term file describing the release of radionuclides to the atmosphere and surface concentration in the STDose model in either a XML or CSV format.
How to Obtain the Computer Code and Documentation
The RASCAL 4.3 computer code is available, for free, from the Radiation Safety Information Computational Center (RSICC).
The draft documentation for RASCAL 4.3 can be obtained from the links below:
We encourage you to contact us, if you are aware of any problems or errors associated with the RASCAL computer code. In addition, we are accepting comments on the draft documents until January 15, 2014. Please send questions, comments, or programming errors (bugs) to RASCAL_Help@nrc.gov.
See Frequently Asked Questions (FAQs) on how to download and install RASCAL 4.3.