**1. NAME AND TITLE**

DCHAIN2: A Code System for Calculation of Transmutation of Nuclides.

**AUXILIARY ROUTINE**

LIBCON: Library Conversion Code.

**2. CONTRIBUTOR**

Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki-ken, Japan, through the OECD Nuclear Energy Data Bank, Issy-les-Moulineaux, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77, PC 386, PC 486 (C00370/PC486/00).

**4. NATURE OF PROBLEM SOLVED**

DCHAIN2 is a one-point depletion code which solves the coupled equations of radioactive growth and decay for a large number of nuclides. It can treat any type of transmutation through decays of neutron-induced reactions. Unknown decay energy in the nuclear data library can be estimated. Cyclic chains can be treated by an approximation and the calculation can be performed even if two nuclides with equal decay constants exist in a chain. Power, neutron flux, neutron spectrum, fission ratio, and fission energy of each fissile nuclide can be varied for each time step.

**5. METHOD OF SOLUTION**

DCHAIN superseded the FP-S code and enabled it to linearize any type of decay schemes in the code. DCHAIN2 constructs the decay scheme of each nuclide and breaks it into linear chains. Accumulation of the nuclide by each linear chain is calculated analytically by the Bateman method and the total accumulation is obtained as the summation of solutions for linear chains. The Bateman method differs from the matrix exponential method in computational accuracies and in saving computer storage for the code.

**6. RESTRICTIONS OR LIMITATIONS**

The core memory size for the variable dimensions is limited to 100 K and the total necessary core memory size is 128 K for the accumulation calculation.

**7. TYPICAL RUNNING TIME**

Running time was 180 seconds for calculating accumulations of 1170 fission products for 1 irradiation-history time step and 32 output times on the IBM 3033 computer.

Running time is approximately proportional to the number of nuclides, irradiation time steps, and output times. It depends also upon the complexity of the decay scheme. The running time was tripled when consideration of neutron capture transformations in fission products was included. The four test cases plus the creation of the binary library took about 5 minutes on a PC 486 (33 megahertz) under DOS 5.0. A math co-processor was used.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code is operable on the PC 386 or PC 486 computers with a math co-processor.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The Microsoft Fortran 5.0 compiler was used on the PC 386 or PC 486 (C00370/PC486/00) to create the executable included in the package.

**10. REFERENCE**

Kanji Tasaka, "DCHAIN2: A Computer Code for Calculation of Transmutation of Nuclides," JAERI-M-8727 (March 1980).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document, the source codes and sample problem input, plus output from the sample problem on one DS/HD 5.25 inch diskette (1.2 MB).

**12. DATE OF ABSTRACT**

February 1982; revised September 1983; March 1987; and June 1992, July 1995.

**KEYWORDS:** FISSION PRODUCTS; FISSION PRODUCT INVENTORY;
BURNUP; ISOTOPE INVENTORY; MICROCOMPUTER;
POINT DEPLETION; RADIONUCLIDES