RSICC CODE PACKAGE CCC-692

1. NAME AND TITLE

TOXRISK: Code System for Toxic Gas Accident Analysis.

2. CONTRIBUTORS

Sandia National Laboratories, Albuquerque, New Mexico, through the Energy, Science and Technology Software Center, Oak Ridge, Tennessee, and the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.

3. CODING LANGUAGE AND COMPUTER

Fortran 5; CDC Cyber 170/85 and Fortran 77; Cray (C00692CDCMF00).

4. NATURE OF PROBLEM SOLVED

TOXRISK is an interactive program developed to aid in the evaluation of nuclear power plant control room habitability in the event of a nearby toxic material release. The program uses a model which is consistent with the approach described in the NRC Regulatory Guide 1.78. Release of the gas is treated as an initial puff followed by a continuous plume. The relative proportions of these as well as the plume release rate are supplied by the user. Transport of the gas is modeled as a Gaussian distribution and occurs through the action of a constant velocity, constant direction wind. Dispersion or diffusion of the gas during transport is described by modified Pasquill-Gifford dispersion coefficients. Great flexibility is afforded the user in specifying the release description, meteorological conditions, relative geometry of the accident and plant, and the plant ventilation system characteristics. Two types of simulation can be performed: multiple case (parametric) studies and probabilistic analyses.

5. METHOD OF SOLUTION

Upon execution, TOXRISK presents a menu, and the user chooses between the Data Base Manager, the Multiple Case program, and the Probabilistic Study program. The Data Base Manager provides a convenient means of storing, retrieving, and modifying blocks of data required by the analysis programs. The Multiple Case program calculates resultant gas concentrations inside the control room and presents a summary of information that describes the event for each set of conditions given. Optimally, a time history profile of inside and outside concentrations can also be produced. The Probabilistic Study program provides a means for estimating the annual probability of operator incapacitation due to toxic gas accidents on surrounding transportation routes and storage sites. A skeleton database, which contains weather data for 29 cities, is included along with two auxiliary programs which convert the database from card-image to random-access format for use by TOXRISK and vice versa. Substantial effort would be required for conversion of the program to a non-CDC computer due to the strong dependence of the Data Base Manager on the CDC mass storage file system.

6. RESTRICTIONS OR LIMITATIONS

None to report.

7. TYPICAL RUNNING TIME

Problem dependent.

8. COMPUTER HARDWARE REQUIREMENTS

CDC CYBER 170/855 and Cray XMP.

9. COMPUTER SOFTWARE REQUIREMENTS

The TOXRISK, ESTDATA, and PUNDATA programs were developed on a CDC Cyber 170 under NOS. The NEA Data Bank converted them to run on a Cray XMS under UNICOS 6.1 with CFT777 5.0.1.0 compiler. Source files are included for both computers. Test case input and output from Cray are also included. No changes were made to the package when it was transferred to RSICC and released in September 2001. The TOXRISK source file is dated May 13, 1983. These codes run on mainframe computers. They are transmitted in self-extracting file for convenience, and the codes do not run on PC.

10. REFERENCES

a) included in documentation:

D. I. Chanin, A. W. Shiver, and D. E. Bennett, "Toxic Gas Accident Analysis Code User's Manual," NUREG/CR-3685; SAND84-0367 (August 1984).

b) background reference:

U. S. Nuclear Regulatory Commission, Office of Standards Development, Regulatory Guide 1.78, "Assumptions for Evaluating the Habitability of a Nuclear Power Plant Control Room During a Postulated Hazardous Chemical Release" (June 1974).

11. CONTENTS OF CODE PACKAGE

Included are the reference document in 10.a and one DS/HD diskette which includes the CDC and Cray source files and test case.

12. DATE OF ABSTRACT

September 2001.

KEYWORDS: AIRBORNE; CONTROL ROOM HABITABILITY; REACTOR SAFETY