**1. NAME AND TITLE**

QAD: Kernel Integration Code System.

**AUXILIARY ROUTINES**

QAD-IV: General Purpose Radiation Transport Prototype.

QAD-P5: Expanded QAD-IV, Neutron Moments Interpolation.

QAD-B: Expanded QAD-P5, Simplified Input and Data Library.

QAD-BR: QAD-B with Special Treatment of Neutron Moments Data.

QAD-HD: Expanded QAD-IV, Propellant Heat and Dose Calculator.

QAD-P5A: QAD-P5, Data Library Built In.

QAD-V: Expanded QAD-IV, Volume Heating, and Two-dimensional Integration.

QAD-INT: Gamma-ray Heating Rate Calculator for Source Region.

QAD-5K: Utilizes Multiple Source Region Data.

**2. CONTRIBUTORS**

Los Alamos National Laboratory, N Division, Los Alamos, New Mexico developed QAD and made the initial contribution.

*Other contributions were made by: *

NASA/Lewis Research Center, Shielding Analysis Section, Cleveland Ohio;

Brown Engineering Company, Inc., Huntsville, Alabama;

NUS Corporation, Rockville, Maryland; and

the Institute of Nuclear Energy Research, Lung-Tan, Taiwan (ROC).

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370 and CDC 6600.

**4. NATURE OF PROBLEM SOLVED**

QAD is a point kernel code system designed to calculate fast neutron and gamma-ray penetration of various shield configurations. The QAD-IV program provides an estimate of uncollided gamma-ray flux, dose rate, and energy deposition at specified detector points. The fast neutron dose is also obtained using a modified Albert-Welton kernel.

Input data consists of a description of the source distribution and intensity by a number of point isotropic sources; a mathematical representation of the physical geometry with quadratic surfaces; and the tabulation of attenuation coefficients, buildup factors, and conversion factors.

The QAD-P5 code is an expansion of QAD-IV which incorporates a technique for interpolating the results of neutron calculations by the moments method solution to the Boltzmann equation, additional source description routines, and an increase of the options on output. Interpolated moments-method neutron fluxes, energy depositions and dose rates may be calculated.

QAD-HD is written to evaluate the heat deposition and temperature rise of the propellant and the dose to a crew during nuclear rocket reactor operation.

The QAD-P5A code is a version of QAD-P5 which includes a built-in library of gamma-ray attenuation coefficients, buildup factor coefficients, neutron removal cross sections and neutron moments method spectra coefficients.

QAD-INT is designed to calculate gamma-ray heating rates within a source region, or in a semi-infinite region surrounding the source zone. It also calculates direct beam and buildup fluxes and dose rates. Like all QAD codes, QAD-INT is a distributed source point kernel calculation and uses the energy buildup factors for water.

The QAD-V code is a version of QAD-IV written to permit heating calculations with a two-dimensional integration scheme.

QAD-B is an expanded version of QAD-P5 with a simplified input format and a more detailed
output format. This version also includes a data library of many of the required input parameters.

**5. METHOD OF SOLUTION**

In the gamma-ray calculation, the point kernel method used involves representing the gamma-ray source by a number of point isotropic sources and computing the line-of-sight distance from each of these source points to the detector point. From the distance through the shielding regions and the characteristics of the shielding materials the geometric attenuation and material attenuation are calculated. The energy transferred along the line-of-sight is then calculated based on this attenuation and the appropriate buildup factor to account for the scattered radiation. With a distributed source, the point kernel including the buildup factor are integrated over the source volume for each source energy considered.

The buildup factor applied to the uncollided flux to obtain the total response is determined from polynomial fits to buildup data.

The calculation for neutron penetration is made using a kernel obtained from the moments method solution to the Boltzmann equation. In this method, the neutron spectrum penetrating a shield is determined based on the equivalent length of a reference material between the source point and the receiver point. The equivalent length is calculated by weighting the penetration distance for each material in accordance with the material removal cross section. The neutron spectrum at this distance in the reference material as determined by the moments method solution to the Boltzmann equation for a point isotropic fission source, is equated to the neutron spectrum in the shield.

QAD calculates the neutron fluxes using moments data which have been fit by an exponential
expression. Provisions are also made in the code for computing an alternate neutron dose rate
based on the Albert-Welton kernel.

**6. RESTRICTIONS OR LIMITATIONS**

Limitations on size of individual input quantities are detailed in the referenced documents.

**7. TYPICAL RUNNING TIME**

No studies of typical running time have been made by RSIC.

**8. COMPUTER HARDWARE REQUIREMENTS**

The QAD system is operable on the IBM 360/370 and the CDC 6600.

**9. COMPUTER SOFTWARE REQUIREMENTS**

FORTRAN IV systems.

**10. REFERENCES**

ICOMPL Informal Notes.

R. E. Malenfant, "QAD: A Series of Point Kernel General-Purpose Shielding Programs," LA-3573 (April 1967).

J. R. Streetman, "The Program QAD-V for Calculation of Volume Heating," LA-3573 Supplement (April 1968).

Gerald P. Lahti, "QAD-HD Point Kernel Radiation Shielding Computer Code to Evaluate Propellant Heating and Dose to Crew," NASA TM-X-1397 (April 1967).

T. W. Smith and R. J. Knies, "QAD-5K Operating Manual," Brown Engineering Company, Inc., Huntsville, AL, Tech Note RL-251 (December 1967).

E. Solomito and J. Stockton, "Modifications of the Point-Kernel Code QAD-P5A: A Conversion to the IBM 360 Computer and Incorporation of Additional Geometry Routines," ORNL-4181 (July 1968).

Richard E. Malenfant, "QAD-BR," Informal Notes (October 1968).

**11. CONTENTS OF CODE PACKAGE**

The package contains the referenced documents and miscellaneous informal notes, one (1.2MB)
DOS diskette on which is written, in separate files, the source card decks for each hardware
version with input and output for a sample problem for each code.

**12. DATE OF ABSTRACT**

July 1967; updated July 1981, February 1985, October 1991.

**KEYWORDS: ** KERNEL; NEUTRON; GAMMA-RAY; COMPLEX GEOMETRY; POINT
SOURCE; HEATING