Although it is not regarded as any danger to have a large nuclear powered ship visiting Oslo, precautions for any unforeseen accident have planned for months in advance of the arrival of USS Gerald R. Ford:
In the scenario considered the vessel is assumed moored at Festningkaia (near Aker Brygge):
When USS Iwo Jima visited Oslo in 2018 she was moored at Festningskaia in downtown Oslo:
Back in the day, when the U.S. still had a couple diesel carriers operational like the America and the Kennedy, those were the carriers allowed to anchor in New York harbor for Fleet Week. As I recall, none of the Nimitz class carriers were able to participate. I could be completely wrong on this though.
FORD probably moored out because the shore power was insufficient for the ship. There’s only one pier at Norfolk navy base she can use. It would surprise me if the Norway ports had compatible shore power.
Since shore power was not an option, she had the reactors up to power the ship. When reactors are critical, Navy nuke ships limit their time pier side.
FORD has 13.8KV electric plant, compared to the 4160 V NIMITZ plant. I don’t know what cruise ships have. When I was on TRUMAN, we rarely tied to a foreign pier. We didn’t always tie to pier in the US. At Key West we were ~5 miles out, while cruise ships pulled in. I’m not sure if it was the draft or the power plant, possibly both.
AFAIK, the only places FORD can connect shore power is NOB Norfolk and Newport News Shipbuilding.
For 3 or 4 days, we’d shut down. Many times a CVN will go out for 2 weeks, come in for 24-36 hours and go back out for 2 weeks. Allows for change out contractors, test personnel, etc. Plus the Navy doesn’t have shell out the Lack of Nookie pay. I can’t remember if we shut down on short inports or not. It’s been a long time.
Shut downs are no big deal. Start-ups can be a PITA.