WIMS Library Update Project

The newly developed library has an increased number of isotopes, much more resonance nuclides and exists in two versions: with 69 and 172 library groups. The standard WIMSD code in all its versions, including the last one WIMSD5B, has been developed for a library with maximum number of 69 groups. Although the number of library groups used in WIMSD calculations is read from that library, there exists a set of auxiliary arrays in the code with dimensions established assuming usage of 69-group library. There exist also arrays with dimensions depending on the number of fast, resonance and thermal groups which also had to be revised. A similar situation existed with the total number of isotopes, the number of resonance nuclides, the number of fissionable isotopes and the number of fission products which are also read from the library. All of them, although formally taking the library values, are used in the particular subroutines in an indirect way.

The main updates developed on the frame of WLUP to overcome the problems mentioned above were:

1. Extension of number of resonance isotopes that can be managed in one WIMSD5 run. This update is required for the 69 and the 172 group libraries, because both libraries contain more resonance isotopes than the original WIMSD libraries. Now up to 30 resonance isotopes can be treated in one material.

2. Updating the WIMSD5B code to allow the use of the 172 group library. It required the extension of the number of groups, as well as the number of resonance groups. These values are set to 200 and 55 groups respectively. The use of the 172 energy groups implies that the higher energy limit is set now about 20 MeV.

3. Due to the new libraries contain more isotopes and more materials that undergo burnup the number of burnable nuclides that can be treated was increased up to 300 and the number of burnable MATERIALs that can be specified in a WIMSD input was set to 60.

4. Modification to treat WIMSD libraries with extended format that includes multiple product-nuclei reactions, in spite of that the WLUP libraries do not use this extended format.

5. Some constants built into the code were updated as the Avogadro number and the default tolerance amongs others.

A detailed description of each update is given in the documentation and the file wimsd5b.upd contains the updates in the format required by the upd code.