1. NAME AND TITLE

MYRA: Calculation of Shipping Costs and Cask Designs for Irradiated Fuel Elements.

MYRA has been distributed by RSIC 23 times between 19641979.

2. CONTRIBUTOR

Chemical Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN; CDC 1604 and IBM 7090; compatible with IBM 360/370 systems.

4. NATURE OF PROBLEM SOLVED

MYRA performs the calculation of the costs incurred in shipping irradiated uranium-containing fuel elements. Spent fuel elements removed from nuclear reactors must be shipped in heavily shielded casks because of high gamma-ray activity. The code is used to design the casks and to estimate the total shipping cost.

5. METHOD OF SOLUTION

PHEOBE, which is incorporated in MYRA as a subroutine, provides source strength and heat-generation-rates. The code designs the cask, using various numbers of elements per cask, starting at one and doubling successively until the allowable weight limitation is exceeded. Interpolation is then used to converge to the allowable weight. Shipping costs are then calculated using economic parameters supplied as input.

To design the cask two major calculations are coded: the determination of shielding thickness and the verification that heat removal is adequate without exceeding allowable temperatures. In the shielding calculation, the gamma-ray flux at the dose point is calculated by integrating the flux due to each element of volume of the homogenized cylindrical source for each of 12 energy groups. Self-shielding and buildup are taken into account. Heat transfer calculations are made to determine the maximum temperature of the fuel element cladding.

6. RESTRICTIONS OR LIMITATIONS

The following limits apply:

12 energy groups.

99 power points (for reactor operation at variable power).

7. TYPICAL RUNNING TIME

A problem calling for 36 different cask designs was run on the CDC-1604A in 2 minutes, 7 seconds.

8. COMPUTER HARDWARE REQUIREMENTS

The code was designed for a 32 K computer; is operable on the CDC 1604 and the IBM 7090; is compatible with IBM 360/370 systems.

9. COMPUTER SOFTWARE REQUIREMENTS

The code is available for the CDC FORTRAN-63 COOP and the IBM FORTRAN II monitor systems. Only standard systems and I-O tape assignments are made.

10. REFERENCES

R. Salmon, "A Computer Code (CDC 1604A or IBM 7090) for Calculating the Cost of Shipping Spent Reactor Fuels as a Function of Burnup, Specific Power, Cooling Time, Fuel Composition, and Other Variables," ORNL-3648 (August 1964).

E. D. Arnold, "PHOEBE A Code for Calculating Beta- and Gamma-Ray Activity and Spectra for ²³⁵U Fission Products," ORNL-3931 (July 1966).

11. CONTENTS OF CODE PACKAGE

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

12. DATE OF ABSTRACT

July 1967; updated July 1981.