**1. NAME AND TITLE**

HYACINTH: Fast Heavy Isotope Point Burnup and Decay Code System - Analytical
Solution.

**DATA LIBRARY**

HLD: Seventy-four isotopes from stable ^{206}Pb up to ^{253}Es are included.

**2. CONTRIBUTOR**

Central Electricity Generating Board, Berkeley Nuclear Laboratory, United Kingdom.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

HYACINTH replaces NUC-022/HYLAS for predicting the heavy isotope content of reactor
fuel during and after irradiation for any reactor design and any irradiation history. Seventy-four
isotopes, from the stable ^{206}Pb up to ^{253}Es, are included which allow comprehensive studies of the
re-irradiation of wastes and their decay on geological time scales. New mathematical methods used
in solving the set of seventy-four coupled differential equations which describe the system have led
to improved execution times in dealing with irradiation periods, and an analytical solution may be
used to obtain results for cooling periods ranging from a fraction of a second to millions of years.
Output consists of isotope number densities, activities and spontaneous fission rates, the hazard
associated with each isotope, total and energy release rate, and a 15-group spectrum.

**5. METHOD OF SOLUTION**

The system of burnup equations is said to be stiff, that is, it involves a wide range of time
constant values. Straight-forward methods of solution require a large number of small time steps
for accuracy. To avoid long execution times, the method of Chambers was adapted. This method
uses an implicit trapezoidal rule for integration and Aitken's formula to accelerate the convergence.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running time for HYACINTH.

**8. COMPUTER HARDWARE REQUIREMENTS**

HYACINTH is operable on the IBM 360/370 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required.

**10. REFERENCES**

G. A. Harte, "A Heavy Isotope Point Burnup and Decay Code," RD/B/N3564 (February 1976).

G. A. Harte, "The Numerical Integration of a Stiff System of Linear Differential Equations,"
RD/B/N3693 (June 1976).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

January 1984, updated August 1991.

**KEYWORDS: ** WASTE MANAGEMENT; ISOTOPE INVENTORY