Moreover, even 1/2 or 1/4 or 1/8 of the original amount can be dangerous depending on how much there was to begin with.
Many people seem to assume that a half-life is how long it takes for a radioactive substance to become safe. That's understandable, since the half-life is usually the only time scale that scientists mention when they're talking about radioactivity.
Maybe we should stop mentioning half-lives in public communication and instead emphasize exactly how long something will take to decay to a safe level (either to a level specified by relevant regulations, or to the average background level).
Whoever put those notes in a lead box and is responsible for granting access knows exactly how much radiation is coming off of them, and how its amount and composition change every year.
Once you have that data, it shouldn't be too difficult for someone with relevant expertise to figure out roughly how much of each radioactive substance is in there and how they will decay over time.
Even that's not straightforward though. She lived to 66 in a house filled with all manner of radioactive material. I suspect someone could safely spend significant time going through her notebooks without being in much danger assuming they didn't ingest any radioactive particles.
The dose rate on contact (assuming someone is handling it) or at the location in which that person would be working is easily measured. Radiation workers have an annual dose limit, and it is trivial to determine how long they can work somewhere before exceeding that limit.
Surface contamination is a separate concern, getting radioactive stuff on (or in) you is not my --or presumably anyone's-- idea of a good time.
Why wouldn't someone elect to look at pictures of the notebooks? Is there more scientific value in holding them? Or would this be like "Oh I just got a government grant, let me spend it on travel to go view the documents?"
Many people seem to assume that a half-life is how long it takes for a radioactive substance to become safe. That's understandable, since the half-life is usually the only time scale that scientists mention when they're talking about radioactivity.
Maybe we should stop mentioning half-lives in public communication and instead emphasize exactly how long something will take to decay to a safe level (either to a level specified by relevant regulations, or to the average background level).