One nuclear accident would result in global perceptions that would collapse our food exports and drastically reduce tourism.
Would it? I wonder how those industries have held up in Japan after Fukushima. According to these figures, although there was a dip in 2011 - the year of the earthquake itself - visitor numbers recovered again the following year and is still increasing. My Google-fu has not turned up any charts for beef exports, but I don't see Kobe beef going for a $4/kg at the Mad Butcher yet.
I think it would.
Put it this way: How any people would buy milk or beef from from Chernobyl?
The world sees NZ as a village. I suspect people won't get that it's a regional problem and the rest of the country is safe.