The economic damage caused by Chernobyl in 30 years is estimated in 235 Billion of dollars.
Source Belarus Foreign Ministry: http://chernobyl.undp.org/russian/docs/belarus_23_anniversar...
This includes destroying trust in Ukrainian agriculture for 30 years and removing also a good chunk of lands suitable for agriculture in a country previously called "The Breadbasket of Europe (and soviet countries)".
I would expect also huge maintenance bills for a long time. The cost of the new sarcophagous and auxiliary buildings is estimated in 2.3 Billion dollars extra.
Plus increase of health services and cancer surveillance checks in nations affected by the disaster (like Ukranie, Belarus or Russia, but also Polland or Germany). Belarus registered a x40 increase in children's thyroid cancers since the accident.
Ukraine and Belarus still need to spend more than 5% of its annual budget in benefit payments to compensate 7 million people for the accident. In whole, Belarus pays around $1 million at day for Chernobyl
Plus the cost of vigillance of the restricted area to avoid garbage collectors (if not, mafias could load trucks with free metal scraps and sell it in Moscow, Berlin or Paris for example), or keeping unauthorized adventurers from doing stupid things.
Plus the cost of the damaged nuclear central itself that lose a quarter of its planned energy production for 15 years and is not producing any energy since the year 2000; only debts.
Taking all of this in mind, As thematic park and bussiness, Chernobyl is a ruinous one. Is a nice continental nature park, the first in the world, but apart of that is a ruinous adventure.