It is unclear what the enrichment level will be. Although the French are consultants, Brazil is apparently designing the reactor and the level might be up to 20% as compared to France’s 5-7%. Anything under 20% is still LEU. Sealed reactors need HEU so it is unlikely Brazil could obtain HEU without undertaking a HEU production program.One of the biggest concerns if fuel rods "rusting" and contaminating the primary coolant circuit. The UK is acting proactively on that, and typical its observed by monitoring coolant, you don't always have to walk into a reactor to monitor it.
Many of these proliferation issues are similar to issue bought up by Brazils SSN program. It is far safer to offer a sealed reactor unit, than every country developing its own HEU enrichment facility. Which would output tons of HEU all the time. NPT is more about proliferation of technologies that can make HEU.