**1. NAME AND TITLE**

PLUMEX: A Computer Program to Evaluate External Exposures to a Gaussian Plume by Point Kernel Integration.

A similar code, STDOSE, was developed at Japan Atomic Energy Research Institute. PLUMEX can be regarded as an extension of STDOSE, but the program is completely new.

**2. CONTRIBUTOR**

Tokai Works, Power Reactor and Nuclear Fuel Development Corporation, Tokai-mura, Ibaraki-ken, Japan.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

PLUMEX evaluates external exposures caused by photons emitted from a radioactive plume. The exposure can be calculated at any point in a half-space above the ground surface. The gaseous radioactive effluent released into the atmosphere is assumed to have a concentration distribution represented by a Gaussian plume which is, in turn, considered to be the source of the photons in the dose calculation. Bremsstrahlung radiation produced in the air is ignored. An inversion layer may be present at any height above the ground. The radioactive decay during cloud passage is taken into account by the inclusion of an exponential decay term. The range of photon energy considered is from 0.01 to 5.0 MeV.

**5. METHOD OF SOLUTION**

The point attenuation/buildup kernel for photons is integrated over the space concerned. The spatial three-dimensional integration is performed numerically using Gaussian quadratures, trapezoidal rule and Romberg's extrapolation method. Spherical, cylindrical, and Gaussian-plume coordinate systems are employed.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

Running time largely depends upon the choice of input parameters, primarily the selection of the orders of quadratures, maximum subdivision numbers for the integration interval, the presence of an inversion layer, etc.

The sample problem runs in 6 seconds on the IBM 360/91.

**8. COMPUTER HARDWARE REQUIREMENTS**

PLUMEX is operable on the IBM 360/370 computers. 90 K bytes of storage are required.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran H compiler is required. The code uses standard I/O.

**10. REFERENCE**

Yoshihisa Kitahara, Yoichiro Kishimoto, Osamu Narita, Kunihiko Shinohara,
Kiyoshi Tatsukuchi, *PLUMEX A Computer Program to Evaluate External Exposures to
a Gaussian Plume by Point Kernel Integration*, PNCT 843-79-16 (September 1979).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and a reel of magnetic tape which contains the source codes and sample problem input written in EBCDIC card images, plus output from the sample problem; total records 2028.

**12. DATE OF ABSTRACT**

January 1982.

**KEYWORDS: ** KERNEL; GAUSSIAN PLUME MODEL; GAMMA-RAY;
NUMERICAL INTEGRATION; ENVIRONMENTAL DOSE;
RADIONUCLIDES