[2] BONUS was a prototype whose objective was to assess the economic and technical feasibility of the integral boiling superheating advanced reactor concept.

[3] The disadvantage of superheating is that higher temperatures can lead to more corrosion and fuel element failures, making the reactor more complex.

During decommissioning, all special nuclear materials (fuel) and certain highly activated components (e.g., control rods and shims) were removed from the island to the US mainland, all piping systems were flushed, the reactor vessel and associated internal components within the biological shield were entombed in concrete and grout, and systems external to the entombment were decontaminated.

Many contaminated and activated materials were placed in the main circulation pump room beneath the pressure vessel and entombed in concrete.

During subsequent years, more radioactive contamination was identified in portions of the building, and additional clean-up and shielding activities were conducted in the 1990s and early 2000s.