The salt worked well to contain the waste. The issue they wound up having was a barrel burst from pressure (Los Alamos National Laboratory incorrectly used organic kitty litter as an absorbent material). The radioactive contamination leaked slightly because the ventilation system failed to close fully when the radiation monitors triggered. Turns out the salt had deposited in the ventilation shaft and blocked the vents from closing.
The US also tested burying nuclear waste in a salt mine with the Waste Isolation Pilot Plant (WIPP), though with less success.
The salt worked well to contain the waste. The issue they wound up having was a barrel burst from pressure (Los Alamos National Laboratory incorrectly used organic kitty litter as an absorbent material). The radioactive contamination leaked slightly because the ventilation system failed to close fully when the radiation monitors triggered. Turns out the salt had deposited in the ventilation shaft and blocked the vents from closing.