1. NAME AND TITLE

CRAC2: Code System for Calculating Reactor Accident Consequences.

DATA LIBRARIES

DC: Dose Conversion (Health) Data.

MD-NYC: Meteorological Data for New York City.

IPS: Indian Point Site Data.

2. CONTRIBUTORS

Sandia National Laboratories, Albuquerque, New Mexico.

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran 77 and Assembler language (A), Fortran IV (B); IBM 3033 (A), CDC (B).

4. NATURE OF PROBLEM SOLVED

The CRAC code system was developed in support of the Reactor Safety Study (WASH-1400) to access the risk from potential accidents at nuclear power plants. CRAC2 was developed to satisfy the need for more realistic consequence estimation techniques to be used for such purposes as site evaluation, emergency planning and response, and general risk assessment and to correct errors which existed in the original CRAC code system. CRAC2 includes modification of the atmospheric dispersion model and introduction of a new meteorological sampling technique, a new evacuation model, and new output capabilities.

5. METHOD OF SOLUTION

The assessment of accident risk entails the coupling of a series of mathematical and statistical models. CRAC2 requires as input an inventory of radioisotopes released from the reactor containment to the environment and a description of the accident conditions. It (1) models the meteorological dispersion of the cloud of radioactive material; (2) determines the health effects of the material upon the surrounding population; and (3) estimates the costs to the public from the accident. CRAC2 samples specific meteorological conditions from a set of representative reactor locations and probabilistically combines the results to form frequency distributions of consequence from a reactor accident. It requires detailed meteorological, population, economic, and health data. In addition, CRAC2 models emergency planning procedures, such as evacuation. Detailed parametric and sensitivity studies can be simply accomplished in one computer run.

Data utilized by some of the models have been upgraded: (1) latent cancer fatality risk factors have been changed to reflect the lifetime risk of latent cancer from radiation exposure and (2) economic data have been upgraded to reflect 1980 economic statistics for the United States.

6. RESTRICTIONS OR LIMITATIONS

The IBM version of CRAC2 may generate incorrect results when temporary modifications are stacked in a single run. Users are advised to avoid running stacked cases with temporary modifications using the IBM Fortran 77 version of CRAC2 which was originally released in December 1985.

7. TYPICAL RUNNING TIME

On the IBM 3033, sample problems 1, 2, 3 took about 30 seconds; sample problems 1, 2, 4 took about 2 minutes and 40 seconds; sample problems 1, 2, and 5 required 3 minutes and 34 seconds.

8. COMPUTER HARDWARE REQUIREMENTS

CRAC2 is operable on the IBM 3033 (A) or CDC (B) computers.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required for the CDC version and a Fortran 77 compiler for the IBM version. Version A also requires an assembler for function RANF.

10. REFERENCES

L. T. Ritchie, J. D. Johnson, R. M. Blond, "Calculations of Reactor Accident Consequences Version 2 CRAC2: Computer Code User's Guide," NUREG/CR-2326, SAND81-1994 (February 1983).

L. T. Ritchie, D. J. Alpert, R. P. Burke, J. D. Johnson, R. M. Ostmeyer, D. C. Aldrich, R M. Blond, "CRAC2 Model Description," NUREG/CR-2552, SAND82-0342 (March 1984).

Brief explanation of IBM assembler function RANF.

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and sample problem input and output.

12. DATE OF ABSTRACT

October 1982; revised September 1983, January 1986, October 1986, and September 1989.