United States Nuclear Regulatory Commission - Protecting People and the Environment

RASCAL 4.3: Description of Models and Methods (NUREG-1940, Supplement 1)

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Publication Information

Manuscript Completed: February 2015
Date Published: May 2015

Prepared by:
J. V. Ramsdell, Jr.1
G. F. Athey2
J. P. Rishel3

1Ramsdell Environmental Consulting
13106 184th Avenue, NE
Redmond, WA 98052-2103

2Athey Consulting
P.O. Box 178
Charles Town, WV 25414-0178

3Pacific Northwest National Laboratory
P.O. Box 999
Richland, WA 99352

John Tomon, RES Technical Monitor/Contracting Officer’s Representative
Anthony Huffert, RES Technical Monitor
Jeff Kowalczik, NSIR Technical Monitor

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

RASCAL 4.3 contains a number of new features and revision of several old features in response to the lessons learned by the U.S. Nuclear Regulatory Commission staff during its response to the events at the Fukushima Daiichi nuclear power plants following the March 11, 2011 earthquake off the coast of Japan and the tsunami that it triggered. This document is a supplement to NUREG-1940, “RASCAL 4: Description of Models and Methods,” which is the technical basis for the models and methods used in the RASCAL computer code versions 4.0, 4.1 and 4.2. This supplement contains the technical basis for changes and additions to RASCAL implemented in versions RASCAL 4.3 and 4.3.1. Additionally, Appendix A provides errata information for NUREG-1940.

RASCAL 4.3 adds a long-term station blackout source term (LTSBO) model based on the results of the State-of-the-Art Reactor Consequences Analyses (SOARCA) study. It extends the RASCAL domain to 100 miles, increases the allowed calculation duration to 96 hours, and it adds a child thyroid dose calculation. RASCAL 4.3 includes new features to acquire meteorological data from the Internet, to calculate custom radionuclide inventories for reactor cores and spent fuel, to display a radionuclide activity balance within the power plant components and atmosphere, and to sort and display the radionuclides released to the atmosphere by importance to dose pathways. RASCAL 4.3 also adds the capability to import, merge, and export source terms. Improvements include revision of the pressure-hole size method of calculating the leak rate from containment and revision of the calculation of spent fuel source terms.