I'm not an expert in this topic but I've been working on a book in a related area and had to learn a lot. Here's what I can figure.
Unfortunately radiation medicine is pretty complicated and the report gives us very little info, presumably mostly because they don't have very much info. It will take some time and effort to establish more.
What we do know is that they measured 300 CPM at the person's hair, which was probably where they expected the highest count due to absorbed water (likely clothing was already stripped at this point). CPM is a tricky unit because it is something like the "raw" value from the instrument, the literal number of counts from the tube, and determining more absolute metrics like activity and dose requires knowing the calibration of the meter. The annoying thing here is that radiation protection professionals will still sometimes just write CPM because for a lot of applications there's only one or a handful of instruments approved and they tend to figure the reader knows which instrument they have. Frustrating. Still, for the common LND7311 tube and Cs137, 300CPM is a little below 1 uSv/hr. That wouldn't equate to any meaningful risk (a common rule of thumb is that a couple mSv is typical annual background exposure). However, for a less sensitive detector, the dose could be much higher (LND7311 is often used in pancake probes for frisking because it is very sensitive and just background is often hundreds of CPM). Someone who knows NRC practices better might know what detector would be used here.
That said the field dose here is really not the concern, committed dose from ingesting the water is. Ingesting radioactive material is extremely dangerous because, depending on the specific isotopes involved, it can persist in the body for a very long time and accumulate in specific organs. Unfortunately it is also difficult to assess. This person will likely go to a hospital with a specialty center equipped with a full body counter, and counts will also be taken on blood samples. These are ways of estimating the amount of radioactive isotopes in the body. In some cases tissue samples of specific organs may be taken.
I believe that the cavity pool water would be "clean" other than induced radioactivity (activation products from being bombarded by radiation). Because water shields so well the pool should not be that "hot" from this process. Most of those products have short half-lives which, on the one hand, means that they deliver a higher dose over a shorter period of time---but also means they will not longer forever and are less likely to be a chronic problem if they are not an acute one.
I suspect this will get some press coverage and we will perhaps learn more about the patient's state.
Another way we can get at this question is by the bureaucracy of the notification. An 8-hour notification as done here is required in relatively minor cases. Usually for a "big deal emergency" a one-hour notification is required. The definition of such an emergency depends on the site emergency plan but I think acute radiation exposure to a worker would generally qualify.
Unfortunately radiation medicine is pretty complicated and the report gives us very little info, presumably mostly because they don't have very much info. It will take some time and effort to establish more.
What we do know is that they measured 300 CPM at the person's hair, which was probably where they expected the highest count due to absorbed water (likely clothing was already stripped at this point). CPM is a tricky unit because it is something like the "raw" value from the instrument, the literal number of counts from the tube, and determining more absolute metrics like activity and dose requires knowing the calibration of the meter. The annoying thing here is that radiation protection professionals will still sometimes just write CPM because for a lot of applications there's only one or a handful of instruments approved and they tend to figure the reader knows which instrument they have. Frustrating. Still, for the common LND7311 tube and Cs137, 300CPM is a little below 1 uSv/hr. That wouldn't equate to any meaningful risk (a common rule of thumb is that a couple mSv is typical annual background exposure). However, for a less sensitive detector, the dose could be much higher (LND7311 is often used in pancake probes for frisking because it is very sensitive and just background is often hundreds of CPM). Someone who knows NRC practices better might know what detector would be used here.
That said the field dose here is really not the concern, committed dose from ingesting the water is. Ingesting radioactive material is extremely dangerous because, depending on the specific isotopes involved, it can persist in the body for a very long time and accumulate in specific organs. Unfortunately it is also difficult to assess. This person will likely go to a hospital with a specialty center equipped with a full body counter, and counts will also be taken on blood samples. These are ways of estimating the amount of radioactive isotopes in the body. In some cases tissue samples of specific organs may be taken.
I believe that the cavity pool water would be "clean" other than induced radioactivity (activation products from being bombarded by radiation). Because water shields so well the pool should not be that "hot" from this process. Most of those products have short half-lives which, on the one hand, means that they deliver a higher dose over a shorter period of time---but also means they will not longer forever and are less likely to be a chronic problem if they are not an acute one.
I suspect this will get some press coverage and we will perhaps learn more about the patient's state.
Another way we can get at this question is by the bureaucracy of the notification. An 8-hour notification as done here is required in relatively minor cases. Usually for a "big deal emergency" a one-hour notification is required. The definition of such an emergency depends on the site emergency plan but I think acute radiation exposure to a worker would generally qualify.