CCC-0079 ISOSHLD.

1. NAME OR DESIGNATION OF PROGRAM:  ISOSHLD.

3. NATURE OF PHYSICAL PROBLEM SOLVED

ISOSHLD calculates the decay gamma-ray and bremsstrahlung dose at the exterior of a shielded radiation source. The source may be one of a number of common geometric shapes. If the radiation source originated as one or a group of fission products produced under known irradiation condition then the strength of the source is also calculated. The programme calculates shield region mass attenuation coefficients, buildup factors, and other basic data necessary to solve the specific problem.

4. METHOD OF SOLUTION

ISOSHLD performs kernel integration for common geometric shapes. The 'standard' point attenuation kernel (buildup factor x exponential attenuation / geometry factor) is numerically integrated over the source volume for 25 source energy groups.

Buildup is considered characteristic of the last shield region (or a different specified region) but dependent on the total number  of mean free paths from source to dose point, and is obtained by interpolation on effective atomic number from a table of point isotopic buildup factor data.

Mixed mass attenuation coefficients are obtained from a library of basic data using programme input material density specifications. The source strength may be specified 1) as the emissions from a selection of fission products irradiated under specific conditions,  2) the curies of particular fission and/or activation products, or 3) a number of photons per second of energy e specified by input.

An exponential source distribution may be specified for those source geometries which are applicable. If the source originates in a combination of fission products and their daughters, these are calculated by a fission product inventory procedure which runs through transmutation (decay chain) calculations for each fission product and daughter. The latest modification (ISOSHLD to ISOSHLD II) adds the capability for calculating shielded dose rates from bremsstrahlung sources. The addition consists of routines for calculating the bremsstrahlung source spectra from the beta decay properties of the isotope(s) of interest. Bremsstrahlung photons per group for 25 energy groups (9 groups below 0.1 Mev have been added)  are obtained by interpolation from tables of resolved spectra. This  spectral mesh, for internal and external bremsstrahlung, is tabulated as a function of the following parameters: beta-emitting and stopping nuclides with atomic numbers of 10, 30, 50, 70, and 90; ratios of photon energyto beta and point energy for 25 intervals from 0.00375 to 1.0; beta and point energies at the intervals 0.1, 0.2, 0.5, 1, 2, and 4 Mev. Buildup factors for photon energies less  than 0.1 Mev are interpolated from a table which contains data for 5 values of initial photon energy in the range 0.01 to 0.2 Mev, seven  values of shield thickness in the range 1 to 20 mfp, and 6 atomic numbers in the range 13 to 92.

The entire shielding problem is solved for most types of isotope shielding applications without reference to shielding handbooks for  basic data.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

     5 source cooling times
   500 radioactive isotopes
     5 shield regions including source region
    25 energy groups
    20 materials in each shield region
     choice of 11 source geometries.

6. TYPICAL RUNNING TIME

Dose from cylindrical volume source - 20 integration increments in each direction, fission product inventory  calculations with 5 decay times, 25 energy groups, 4 shield layers,  5 materials homogenized into each shield layer and the source volume --- 6 minutes UNIVAC 1107. (most other source geometries require less computation time).

NEA-DB executed the test case on IBm 3081K in 8.8 sec.

7. UNUSUAL FEATURES: UNUSUAL FEATURES OF THE PROGRAM

8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS

10. REFERENCES

- R.O. Gumprecht:
  'RIBD-Radioisotope Buildup and Decay'
  unpublished data.
- H.H. van Tuyl:
  'BREMRAD - A Computer Code for External and Internal Bremsstrahlung Calculations
  HW-83784 (September 1964) (packaged in CCC-31 only).

- R.L. Engel et al.:
  ISOSHLD - A Computer Code for General Purpose Isotope Shielding
  Analysis.  BNWL-236  (June 1966)
- G.L. Simmons et al.:
  ISOSHLD-2 : Code Data Revision to Include Calculation of
  Dose Rate from Shielded Bremsstrahlung Sources.
  BNWL-236 SUP1  (March 1967)
- C.A. Mansius:
  A Revised Photon Probability Library for Use with ISOSHLD-3.
  BNWL-236 SUP2  (April 1969)
- L.D. O'Dell and W.L. Bunch:
  Revised Fast Reactor Library for Use with RIBD.
  BNWL-962  (April 1969)
- R.O. Gumprecht:
  Mathematical Basis of Computer Code RIBD.  DUN-4136  (June 1968)
- J.L. Rash:
  Use of Computer Code RIBD for Fission Product Analysis.
  RL-NRD-610  (November 1965)
- D.T. Ingersoll and J.K. Ingersoll:
  Proceedings on the Topical Conference on Theory and
  Practices in Radiation Protection and Shielding
  Knoxville, Tennessee, April 22-24, 1987 (pages 18-27)
- R.L. Engel et al.:
  ISOSHLD - A Computer Code for General Purpose Isotope Shielding
  Analysis.  BNWL-236  (June 1966)
- G.L. Simmons et al.:
  ISOSHLD-2 : Code Data Revision to Include Calculation of
  Dose Rate from Shielded Bremsstrahlung Sources.
  BNWL-236 SUP1  (March 1967)
- C.A. Mansius:
  A Revised Photon Probability Library for Use with ISOSHLD-3.
  BNWL-236 SUP2  (April 1969)
- L.D. O'Dell and W.L. Bunch:
  Revised Fast Reactor Library for Use with RIBD.
  BNWL-962  (April 1969)
- R.O. Gumprecht:
  Mathematical Basis of Computer Code RIBD.  DUN-4136  (June 1968)
- J.L. Rash:
  Use of Computer Code RIBD for Fission Product Analysis.
  RL-NRD-610  (November 1965)
- D.T. Ingersoll and J.K. Ingersoll:
  Proceedings on the Topical Conference on Theory and
  Practices in Radiation Protection and Shielding
  Knoxville, Tennessee, April 22-24, 1987 (pages 18-27)

11. MACHINE REQUIREMENTS

The programmes were originally designed for the 65k UNIVAC 1107. They have been modified by RSIC to run on the IBM 7090 (I) and the 360 (II).

Main storage requirements on IBM 3081K are 232K bytes.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

The programmes were originally designed for the UNIVAC 1107 EXEC II  monitor system.
ISOSHLD I is available as an overlay job on the IBM FORTRAN IV IBJOB monitor within the IBSYS operating system. The ALTIO package is used.
ISOSHLD II is available for the IBM 360 computer and has been run on the model 50 on the level H compiler.
A library of data is packaged for each version.

The test case was run on IBM 3081K under MVS-SP.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

       Battelle Memorial Institute
       Pacific Northwest Laboratories
       Richland, Washington, U.S.A.

File name	File description	Records
CCC0079_04.001	INFORMATION + JCL	26
CCC0079_04.002	SOURCE WITH JCL	1793
CCC0079_04.003	LIBRARY	1087
CCC0079_04.004	INPUT DATA FOR SAMPLE PROBLEM	72
CCC0079_04.005	OUTPUT UNIT 6	3510
CCC0079_04.006	OUTPUT UNIT 3	902

File name	File description	Records
CCC0079_06.003	ISOSHLD-2 INFORMATION FILE	63
CCC0079_06.004	ISOSHLD-2 SOURCE (FORTRAN-4)	2416
CCC0079_06.005	DIVID SOURCE (ASSEMBLER)	64
CCC0079_06.006	ISOSHLD-2 JCL	75
CCC0079_06.007	ISOSHLD-2 INPUT DATA FOR TEST CASE	2355
CCC0079_06.008	ISOSHLD-2 OUTPUT OF TEST CASE	580