Neutronic evaluation of two proposed fuel lattice pitches for ET-RR-1 reactor

The present fuel element of the ET-RR1 research reactor has a 1.75 cm lattice pitch. The neutronic studies were proved that, this lattice pitch is over moderated and not the suitable one from the fuel economic point of view. Two fuel lattice pitches are proposed, one has 1.4 cm lattice pitch with 10% U235 enrichment and the other has 1.75 cm lattice pitch with 15% U235 enrichment. The comparative neutronic study was done between these two pro- posed fuel lattice pitches against the present one in two cases, one for the complete core con- ®guration of the ET-RR-1 which includes 52 fuel elements and the other for one of the actual core con®guration load contains 47 fuel elements. This study is included the calculations of di€erent neutronic parameters as the in®nite and e€ective multiplication factor, the multi- group neutron ¯ux along the reactor core, and the power peaking factor. The above factors were calculated by using the WIMSD4 code for lattice cell calculation, and the DIXY2 code for di€usion calculations. The results are represented in some tables and ®gures.