**1. NAME AND TITLE**

VCS: Coupled Discrete Ordinates-Adjoint Monte Carlo Calculation of Radiation Protection Factors in Vehicles.

**AUXILIARY ROUTINES**

VISA: Coupling Surface Flux Generator.

DRC: Detector Response Calculator.

DOT III: Air Transport Calculator.

MORSE-CG: A General Purpose Monte Carlo Multigroup Neutron and Gamma-Ray Transport Code with Combinatorial Geometry. This includes the ALBERT routine.

**2. CONTRIBUTOR**

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

The Vehicle Code System (VCS) facilitates the calculation of radiation protection factors for a given vehicle; i.e., the ratio by which the free-field radiation is reduced due to the presence of the vehicle.

VCS was constructed by linking together a discrete-ordinates air-transport calculation and an adjoint Monte Carlo vehicle dose-importance calculation. A tactical nuclear weapon of low-kiloton yield is detonated within a kilometer of a vehicle. The air-transport calculation determines the neutron and photon flux as a function of energy on a coupling surface surrounding the vehicle. The dose-importance calculation determines the effectiveness of particles at the coupling surface in contributing to dose at a detector position within the vehicle.

**5. METHOD OF SOLUTION**

VCS calculates protection factors for armored military vehicles by coupling a discrete ordinates calculation with an adjoint Monte Carlo calculation. The discrete ordinates calculation determines the flux on a coupling surface surrounding the vehicle. The Monte Carlo calculation calculates the effectiveness of flux at the surface in causing response in a detector adjacent to the crew members, i.e., the "dose importance." A coupling code folds the flux together with the dose importance, giving the dose response. The coupling code can also rotate the vehicle, move it to different distances from the source, and perturb the energy response of the detector.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

The DOT section of VCS requires about 2 hours of CPU time on the IBM 195. Each new vehicle configuration or source position requires about 25 minutes. Each new range or detector response spectrum or vehicle orientation costs a fraction of a minute. RSIC did not complete the running of the packaged sample problem because of long running time.

**8. COMPUTER HARDWARE REQUIREMENTS**

VCS was designed for the IBM 360/370 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler and IBM OS/VS Assembler are required.

**10. REFERENCES**

**a. Included in package:**

W. Rhoades, M. B. Emmett, G. W. Morrison, J. V. Pace, III, and L. M. Petrie, "Vehicle Code System (VCS) User's Manual," ORNL-TM-4648 (August 1974).

**b. Background information:**

W. A. Rhoades, "Development of a Code System for Determining Radiation Protection of Armored Vehicles (The VCS Code)," ORNL-TM-4664 (October 1974).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the source code and sample problem input.

**12. DATE OF ABSTRACT**

September 1975; updated February 1983, April 1984.

**KEYWORDS: ** NEUTRON; GAMMA-RAY; COUPLED; DISCRETE ORDINATES;
ADJOINT; MONTE CARLO; COMPLEX GEOMETRY; AIR-GROUND
INTERFACE; WEAPONS RADIATION; AIR-TRANSPORT