last modified: 01-OCT-1977 | catalog | categories | new | search |

CCC-0148 SPARES.

SPARES, Program System for Space Radiation Environment and Shielding System Evaluation

top ]
1. NAME OR DESIGNATION OF PROGRAM:  SPARES.
top ]
2. COMPUTERS
To submit a request, click below on the link of the version you wish to order. Only liaison officers are authorised to submit online requests. Rules for requesters are available here.
Program name Package id Status Status date
SPARES CCC-0148/01 Tested 01-OCT-1977

Machines used:

Package ID Orig. computer Test computer
CCC-0148/01 IBM 370 series IBM 370 series
top ]
3. DESCRIPTION OF PROBLEM OR FUNCTION

(A). The ELMC Code calculates the electron number, energy, and angular fluence resulting from the penetration of a specified initial spectrum on a multilayered one-dimensional shield.
(B). Data from the ELMC Electron Monte Carlo Code have been used in EPEN to formulate analytic expressions to describe electron  number penetration and the penetrating energy spectrum. Dose and spectral data are obtained for a set of initial energies, and the results are then weighted by the incident spectra of interest and summed for the final solution.
(C). The bremsstrahlung dose resulting from electrons incident on a shield is calculated. Either one-dimensional, multilayer slab geometrie or three-dimensional geometries can be treated.
(D). HEVPART calculates the penetrating energy spectrum, LET spectrum, and absorbed dose in multilayered slabs resulting from a fluence of protons, He, or heavy ions. Results for three-dimensional geometries can also be obtained to describe space vehicle structures.
(E). The penetrating proton energy spectrum and the resulting secondary protons, neutrons, and gamma rays are calculated in SECPRO for multilayered shields. Dose and LET spectral data are also given. The recoiling nuclei dose resulting from the penetrating proton and  neutron spectra are also given.
(F). TANDE was designed to calculate the Van Allen belt electron and proton fluxes and fluences, encountered in or near earth trajectories.
top ]
4. METHOD OF SOLUTION

(A). ELMC employs the Monte Carlo method with angular scattering treated by the method of Leiss, Penner, and Robinson. Energy loss is treated by the continuous slowing down approximation, and energy straggling is not treated. The energy dose and angular deflections are calculated in path length segments of delta x, where delta x can be adjusted by input data and made proportional to particle energy if desired.

(B). The EPEN code calculates the absorbed dose at a point of interest caused by electrons penetrating a shielding system. The penetrating electron energy spectrum is also calculated. Multilayer shields can be treated.

(C). The bremsstrahlung differential energy spectrum produced in a material is estimated by an expression given by Wyard.

The photon energy spectrum is then transported through the remaining shielding material by the use of ray theory plus buildup factors.

Two basic calculational modes are available. In the surface production option, the bremsstrahlung is all produced at the surface of the shield. In the volume production option, the attenuation of the electron spectrum is considered, and the bremsstrahlung source is volume distributed. (BREMS).

(D). The straight ahead approximation is used in HEVPART and nuclear interactions are neglected to provide a rapid solution of the heavy ion transport problem. The range-energy and stopping power tables of Barkas and Berger are used. Low energy correction factors  are employed to describe the changes in stopping power resulting from electron capture.

(E). The first collision approximation and the straight ahead approximation are employed in SECPRO to simplify the cascade transport problem. Neutron induced protons are also calculated to refine  the neutron dose estimate. The code employs the tabulated Barkas and Berger range energy data and the secondary particle production data  of Bertini for numerical integration of the primary and secondary particle fluxes.

(F). The user supplies to TANDE description of a vehicle trajectory and radiation-environment data. The program calculates electron or proton flux rate and time-integrated flux along the trajectory.

The general then compute radiation flux at these points.

Given a description of the orbit and the point of injection, subject trajectory points are calculated as a function of time, using orbital flight equations. The trajectory points are converted  to McIlwain's geomagnetic coordinates (B,L, and R, lamda).

Proton or electron flux at each point is determined by a table lookup and interpolation. Numerical integration (in conjunction with an interpolation scheme on B and L) gives a time-integrated flux for each point. A table lookup and interpolation on an array of spectral coefficients determines the spectral coefficients for the point. The flux at the point, dose-conversion factors, and the spectral coefficients are then used to determine dose rate and total dose at the point.

Angular distribution is determined for each trajectory point by solution of a pitch angle distribution function.

The code is designed so that new experimental data on the radiation environment and on the interaction of radiation with matter can be accepted.

    The following general methods are followed:

1. calculation of the spacecraft trajectory in B, L, and t coordinates,

2. devising a mathematical representation of the space-radiation environment, including geomagnetically trapped radiation (Van Allen belts), solar particle event radiation, and galactic cosmic radiation;

3. determination of the radiation flux and energy spectra encountered in a given space mission.
top ]
5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

(A). Validity of results in ELMC is dependent on the choice of delta x, and the number of histories.
(B). The basic accuracy of EPEN is determined by the Monte Carlo data. In addition, the analytic fits developed have ranges of validity.
(C). The volume source options in BREMS must be carefully chosen to match the electron energy and shield configuration.
(D). As secondary interactions are neglected in HEVPART, the shield should then be compared to the mean free path of the ion.
(E). In SECPRO secondary data is provided only for aluminum and H2O. The shield thickness must be smaller than a proton mean free path to remain within the valid range of the first collision appro-  ximation.
(F). The principle restriction in the use of TANDE is that the trajectories selected for analysis can only be evaluated at B,L points described by the flux maps.
top ]
6. TYPICAL RUNNING TIME

No statistics are available to determine typical running time. Estimated running time for the sample problems are tabulated below.

            CODE     CORE SIZE(GO STEP)  RUNNING TIME(Sec)
                                            IBM 360/91
            ----------------------------------------------
    (A).    ELMC       246K                 49.54
    (B).    EPEN       162K                  0.96
    (C).    BREMS      184K                  0.72
    (D).    HEVPART    186K                  0.82
    (E).    SECPRO     296K                  3.11
    (F).    TANDE      314K                  5.09
top ]
7. UNUSUAL FEATURES OF THE PROGRAM:
top ]
8. RELATED AND AUXILIARY PROGRAMS

       (A) ELMC:  Electron Monte Carlo Code.
       (B) EPEN:  Electron Penetration Code.
       (C) BREMS:  Bremsstrahlung Code.
       (D) HEVPART:  Heavy Particle Penetration Code.
       (E) SECPRO:  Secondary Proton Penetration Code.
       (F) TANDE:  Trajectory and Environment Code.
top ]
9. STATUS
Package ID Status date Status
CCC-0148/01 01-OCT-1977 Tested at NEADB
top ]
10. REFERENCES

- John A. Barton, B.W. Mar, G.L. Keister, W.R. Doherty, J.R.
  Benbrook, W.R. Sheldon, J.R. Thomas, K. Moriyasu, and M.C.
  Wilkinson:
  "Computer Code for Space Radiation Environment and Shielding"
  Volume I and II (August 1964).
CCC-0148/01, included references:
- Paul G. Hahn:
  "Space Radiation Environment and Shielding System"
  AS 2807 (1969).
top ]
11. MACHINE REQUIREMENTS

The codes were designed to run on the IBM 360 with standard I-O and a maximum of 3 tape units or direct access devices.
top ]
12. PROGRAMMING LANGUAGE(S) USED
Package ID Computer language
CCC-0148/01 FORTRAN+ASSEMBLER
top ]
13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

The code is operable on the IBM 360/75/91 Operating System using OS-360 FORTRAN  H Compiler.
A random number generator is required in ELMC and is included on the master tape.
top ]
14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:
top ]
15. NAME AND ESTABLISHMENT OF AUTHOR

Contributed by: Radiation Safety Information Computational Center
                Oak Ridge National Laboratory
                Oak Ridge, Tennessee, U. S. A.
Developed by:   Aerospace Group, The Boeing Company, Seattle, Washington, USA
top ]
16. MATERIAL AVAILABLE
CCC-0148/01
File name File description Records
CCC0148_01.002 ELMC SOURCE - F4 EBCDIC 1491
CCC0148_01.003 RANDM SUBROUTINE - F4 EBCDIC 39
CCC0148_01.004 ELMC JOB CONTROL 2
CCC0148_01.005 ELMC SAMPLE PROBLEM INPUT 195
CCC0148_01.006 ELMC SAMPLE PROBLEM OUTPUT 1462
CCC0148_01.007 EPEN SOURCE - F4 EBCDIC 1313
CCC0148_01.008 EPEN JOB CONTROL 4
CCC0148_01.009 EPEN SAMPLE PROBLEM INPUT 99
CCC0148_01.010 EPEN SAMPLE PROBLEM OUTPUT 140
CCC0148_01.011 BREMS SOURCE - F4 EBCDIC 1563
CCC0148_01.012 BREMS JOB CONTROL 4
CCC0148_01.013 BREMS SAMPLE PROBLEM INPUT 64
CCC0148_01.014 BREMS SAMPLE PROBLEM OUTPUT 83
CCC0148_01.015 HEVPART SOURCE - F4 EBCDIC 1375
CCC0148_01.016 HEVPART JOB CONTROL 4
CCC0148_01.017 HEVPART SAMPLE PROBLEM INPUT 80
CCC0148_01.018 HEVPART SAMPLE PROBLEM OUTPUT 178
CCC0148_01.019 SECPRO SOURCE - F4 EBCDIC 2005
CCC0148_01.020 SECPRO JOB CONTROL 4
CCC0148_01.021 SECPRO SAMPLE PROBLEM INPUT 353
CCC0148_01.022 SECPRO SAMPLE PROBLEM OUTPUT 762
CCC0148_01.023 TANDE SOURCE - F4 EBCDIC 3503
CCC0148_01.024 TANDE JOB CONTROL 5
CCC0148_01.025 TANDE SAMPLE PROBLEM INPUT 491
CCC0148_01.026 TANDE SAMPLE PROBLEM OUTPUT 407
top ]
17. CATEGORIES
  • J. Gamma Heating and Shield Design

Keywords: Monte Carlo method, electron spectra, electrons, shields.