I know MIT is in the process of converting. Still, the info I found stated very clearly 93% enriched uranium. MIT is one of two research reactors in the country that still use highly enriched uranium, if facts on the internet are to be believed.

http://www.rertr.anl.gov/RERTR33/pdfs/S8-P1_Newton.pdf
http://dels.nas.edu/resources/static...tonNAS-RAS.pdf

I think using HEU in research reactors was more common in the past, along with higher enrichment values.