Their SNM license was for “up to 93.5% enriched”[1] and their decommissioning plan describes them as MTR-type Al-clad plates. So I’d take a reasonable guess that these are at 93% nominal enrichment, like ATR and HFIR fuel plates.

[1] https://www.nrc.gov/docs/ML0900/ML090080661.pdf

[2] https://www.nrc.gov/docs/ml0816/ML081690374.pdf