**1. NAME AND TITLE**

PELSHIE3: General Purpose Kernel Integration Shielding Code SystemPoint and Extended Gamma-Ray Sources.

**AUXILIARY ROUTINE**

PELSHIE Data Generator.

**2. CONTRIBUTORS**

Atomic Energy Corporation of South Africa, LTD, Pretoria, Republic of South Africa.

Electricity Supply Commission, Johannesburg, Republic of South Africa.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370 (A) or CDC (B).

**4. NATURE OF PROBLEM SOLVED**

PELSHIE3 calculates dose rates from gamma-emitting sources with different source geometries and shielding configurations. Eight source geometries are provided and are called by means of geometry index numbers. Gamma-emission characteristics for 134 isotopes, attenuation coefficients for 57 elements or shielding materials and Berger build-up parameters for 17 shielding materials can be obtained from a direct access data library by specifying only the appropriate library numbers. A different option allows these data to be read from cards.

For extended sources, constant source strengths as well as exponential and Bessel function source strength distributions are allowed in most cases.

**5. METHOD OF SOLUTION**

A point kernel integration technique is applied to obtain dose rates for extended sources. Dose rates for the different photon energies are calculated separately and added. When too many energies are present, these are or can be grouped into 18 fixed groups.

Where integration cannot be done analytically, some known integral functions are used. In other cases, numerical integration techniques (applying Simpson's rule in the case of one variable function and a Monte Carlo sampling technique for two and three variable functions) are used.

**6. RESTRICTIONS OR LIMITATIONS**

Computing time is the major limitation but only when numerical integration is applied. This limitation can be overcome by accepting results with lower accuracies. The restriction is particularly relevant in the case of large sources where the dose contributions from large regions of the source are negligibly small or where the kernel function varies considerably over the integration region (that is near or inside volume sources).

The current versions in RSIC are CCC-202A/PELSHIE3, for IBM hardware, and CCC-202B/PELSHIE2, for CDC hardware. The latter was incorporated into RSIC in 1983 and does not have the later data sets available in PELSHIE3.

**7. TYPICAL RUNNING TIME**

Running times are given per photon energy and per iteration in the case of Simpson's rule or per 1000 samples in the case of Monte Carlo sampling. In the former case the times are proportional to the ``number-of-iterations'' power of 2 and in the latter case to the number of samples taken. Simpson's rule normally requires 5 to 10 iterations and the Monte Carlo sampling anything from 500 to 5000 samples depending on the circumstances described under 6 above.

**Geometry Time (seconds) **

Line source with constant strength 6

Line source with exponential strength distribution 8

Line source with cosine strength distribution 7

Disc source with exponential strength distribution 8

Disc source with Bessel function strength distribution 7

Spherical source with constant strength 18

Cylinder side source with constant strength 18

Cylinder side source with exponential strength distribution 19

Cylinder side source with cosine-Bessel function strength distribution 23

Cylinder end source with constant strength 9

Cylinder end source with exponential strength distribution 11

Cylinder end source with cosine-Bessel function strength distribution 16

Rectangular source with constant strength 10

Rectangular source with exponential strength distribution 12

Rectangular source with cosine strength distribution 14

**8. COMPUTER HARDWARE REQUIREMENTS**

PELSHIE3 is operable on the IBM 360/370 computers (version A) with standard I-O plus 2 direct access devices.

PELSHIE2 is also operable on the CDC computers (version B).

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required. PELSHIE3 was developed under the MVS/VS2 operating system of an IBM System/370.

The CDC version runs under NOS1 operating system.

**10. REFERENCES**

G. P. de Beer, D. E. Sartori, and T. J. van Rooyen, "PELSHIE3-A Third Edition of the PELSHIE General Purpose Shielding Program," PEL 290 (November 1986).

G. P. de Beer, A. E. Language, and J. I. Thompson, "PELSHIE2-A Revised Version of the PELSHIE General Purpose Shielding Program for Point and Extended Gamma-Ray Sources," PEL 258 (October 1979).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

October 1975; updated October 1983; December 1987.

**KEYWORDS: ** KERNEL; GAMMA-RAY