3. DESCRIPTION OF PROGRAM OR FUNCTION
ORIP-XXI software suite was developed for the study of radioactive and stable isotope transmutation chains, i.e. networks with feedbacks. This system contains ChainSolver 2.34, ChainFinder and NKE. Using these programs, it is possible to estimate various quantitative characteristics of a transmutation chain both for nuclide irradiations in neutron fluxes and in case of pure radioactive decays. The main parts of ORIP_XXI are NKE, the electronic nuclide chart, ChainFinder, the program for finding transmutation chains, and ChainSolver, the program for simulating transmutation.
All programs use a common data file, which contains nuclear constants and decay data for more than 2800 nuclides with atomic weights from 1 up to 293 (nuclear charge from 1 up to 118) and characteristics of chemical elements. The file includes data on fission product yields for thermal and fast neutron induced fission of 22 heavy isotopes. Users may edit data as necessary for carrying out transmutation calculations. The transmutation calculation code ChainSolver allows users to take into account neutron flux depression and self-shielding factors, the latter using additional data from the resolved resonance parameters file. All data are taken from freely available public nuclear data libraries.
The ChainFinder program looks for nuclide transmutation chains possible under neutron irradiation (a search for pure decay chains is available). The ways for transmutations include radioactive decay, neutron capture, fast neutron induced threshold reactions, neutron induced nuclear fission. During the chain search decay "subbranchings" are considered also (the "subbranching", for example: at Zr-95 beta- decay the daughter nuclide Nb-95 is formed in both the ground and metastable states).
ChainSolver is designed for carrying out fast transmutation simulations of samples during irradiation in nuclear reactors. The code calculates a nuclide density time evolution with burnup, decay and buildup. The depression of thermal neutrons flux, resonance self-shielding of isotopes during an irradiation, and the irradiation schedule (the schedule of the reactor work and rearrangement of an irradiated target in various positions) are taken into account. Such calculations allow to define the chosen mode of an irradiation and to calculate the expected outputs for both products and inevitable impurities. The main approximation used at calculation of transmutations is the assumption that the influence of changes in the irradiated material structure on characteristics of a reactor as a neutron source is significant. Resonance self-shielding factors are calculated in Intermediate Resonance approximation. A minor bug was corrected in ChainSolver in the February release of the code.
The Nuclide Explorer (NKE) program is a tool for retrieving interactively detailed data on radionuclides properties. The data that can be retrieved are:
a) elements information (average mass, density, neutron cross sections);
b) nuclear ground/metastable states properties (half-life and decay channels percentage);
c) decay alpha, beta, gamma, electron, positron radiation information (spectra and lines);
d) fission products yields (for various fissionable target nuclides);
e) thermal neutron cross sections and resonance integrals (capture and fission);
f) fission spectrum average threshold neutron reactions cross sections for (n,p), (n,alpha), (n,2n), (n,n') and (n,gamma) reactions.
Fast neutron fission has been added. It contains data on more than 3000 nuclides (approximately 3700 ground and metastable states).