username etc

The only mildly strange thing about it is that such a check should take like 10 seconds and this article was apparently written after the capsule was found, but before the result of the check was announced.

But the serial number check itself is an obvious thing to do and it doesn't necessarily imply they believe there are more of the capsules missing.

It's going to take a bit longer than 10 secobds to safely get close enough to such a strong radiation source as to take a clear picture or read a number.

It's not that strong of a source. You wouldn't want to go about your day with it in your pocket, but last I read a 1m exposure for an hour was a few x-rays worth of radiation. Take out your phone and zoom in.

And since they knew they were looking for radioactive material, I would hazard a guess that they already have necessary protection.

The article was updated to say the serial number was confirmed, it took about three hours after the news first broke. Seems fair, probably took that long for the Australian Defense Force to get to the capsule.