1. NAME AND TITLE

ACDOS3-Version 2: Calculation of Activities and Dose Rates Produced by Neutron Activation.

DATA LIBRARIES

ACTLMFE: Evaluation neutron activation library.

LEVDEC: Subset of LLNL evaluated nuclear structure radioisotope decay library.

ACDOS3 is an improved version of the neutron dose rate code ACDOS2 which was based on ACDOS1. All three codes were developed at Lawrence Berkeley Laboratory.

In ACDOS3-Version 1, the decay processes which were considered for purposes of the dose rate calculation were beta-minus, beta-plus (including the effect of annihilation radiation), and gamma deexcitation. In Version 2, all of the foregoing are considered plus electron-capture decays.

2. CONTRIBUTOR

Lawrence Berkeley Laboratory, Berkeley, California.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; CDC 7600 (C00442C760000)

4. NATURE OF PROBLEM SOLVED

ACDOS3 is designed to calculate the activities and dose rates produced by neutron activation in a variety of simple geometries. Neutron fluxes, in up to 50 groups and with energies up to 20 MeV, must be supplied as part of the input data. The neutron-source strength must also be supplied or, alternately, the code will compute it from neutral-beam operating parameters in the case where the source is a fusion-reactor injector.

The chief approximations used in ACDOS3 are that the gamma-ray dose rate is computed on the basis of analytic formulae. The latter often involve approximations and sometimes contain functions which have to be further approximated. This is particularly true for the coefficients used in buildup factors. In calculating the energy absorption in irradiated materials, ACDOS3 assumes that charged-particle reaction products are entirely absorbed and that gamma-ray reaction products can be treated by an average-chord method.

5. METHOD OF SOLUTION

ACDOS3 first uses the group fluxes to calculate radioactive products and radioactive daughters of radioactive products, which are produced by single-or multiple-pulse neutron irradiation. Irradiated materials may take the form of solid or hollow spheres and cylinders or cylindrical shells. ACDOS3 next calculates the dose rate at an exterior point except in the case of a hollow sphere where an interior point may also be selected. The latter choice simulates the dose rate due to activation of a shielding cell. An option provides for a choice of self-absorption or no self-absorption of gamma rays in the materials irradiated. ACDOS3 also provides an option to compute the energy absorption in the irradiated materials due to the neutron reaction products.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

Running time for the ACDOS3 sample problem was 9.45 seconds from the compiled source.

8. COMPUTER HARDWARE REQUIREMENTS

Storage for the sample problem was approximately 61400 octal words to load and 47000 octal words to execute.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required.

10. REFERENCES

C. S. Martin, "ACDOS3: A Further Improved Neutron Dose Rate Code," LBL-14547 (July 1982).

J. C. Lagache, "ACDOS2: An Improved Neutron-Induced Dose Rate Code," LBL-12711 (June 1981).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one DS/HD diskette which contains the source code, sample problem input and data libraries written in EBCDIC card images, plus output from the sample problem.

12. DATE OF ABSTRACT

March 1983, update April 1986.