In theory, let's say you wanted to make the smallest ultra clean 'tactical nuke' using Ripple or Golden TIS type technology - how small can you make it?

The limiting factor is obviously the primary and the smaller you make them - the less efficient they are typically. Would it be possible to make one say 5-10 kt or would the primary be too dirty to get 99% fusion like on the Ripple devices using only 8 kt primary for 10 MT yield?

Slightly off topic - does any other design get over 99% fusion yield like Ripple?

Just a fun topic to think about or could be used in future for say an Europa mission even - ultra clean small nuke to allow us to explore the ocean underneath through the thick ice and minimize contamination.