[en] The technology for fabricating fuel simulators, based on the use of boron nitride (BN) preforms, was demonstrated by the production of 92 acceptable simulators for future test needs. Two single-rod tests were conducted, using prototype fuel simulators produced in this development effort, to demonstrate satisfactory performance. The results of the tests are reported. Results are reported of further analyses performed to characterize the B-1 temperature distribution and to assess the importance of the effect of shroud temperature on bundle deformation. The results indicate a relatively minor effect on localized deformation. Posttest examination and analysis of the B-2 test data were completed, and the results are reported and compared with B-1 results. The results are in very good agreement. The B-3 test was performed, and quick-look results and some data analyses are reported. Deformation was greater and more extensive than that observed in the B-1 and B-2 tests, presumably due to more uniform temperature and the lower heating rate (strain rate) employed in the test. The bundle is being sectioned to obtain strain data. Test equipment and components are being fabricated in preparation for the B-4 test