In the second quarter of calendar year 1996, 16 days of combust- boiler tests were performed, including 2 days of tests on a parallel DOE sponsored project on sulfur retention in a slagging combustor. Between tests, modifications and improvements that were indicated by these tests were implemented. This brings the total number of test days to the end of June in the task 5 effort to 28, increased to 36 as of the date of this Report, 8/18/96. This compares with a total of 63 test days needed to complete the task 5 test effort. It is important to note that the only major modification to the Williamsport combustor has been the addition of a new downstream section, which lengthens the combustor and improves the combustor-boiler interface. The original combustor section, which includes the fuel, air, and cooling water delivery systems remained basically unchanged. Only the refractory liner was completely replaced, a task which occurs on an annual basis in all commercial slagging utility combustors. Therefore, this combustor has been operated since 1988 without replacement. The tests in the present reporting period are of major significance in that beginning with the first test on March 31st, for the first time slagging opening conditions were achieved in the upgraded combustor. The first results showed that the present 20 MMBtu/hr combustor design is far superior to the previous one tested since 1988 in Williamsport, PA. The most important change is that over 95% of the slag was drained from the slag tap in the combustor. This compares with an range of one-third to one-half in Williamsport. In the latter, the balance of the slag flowed out of the exit nozzle into the boiler floor. In addition, the overall system performance, including the combustor, boiler, and stack equipment, ranged from good to excellent. Those areas requiring improvement were of a nature that could be corrected with some work. but in no case were the problems encountered of a barrier type.