The operator of a regional disposal facility shall purchase the maximum amount of commercially available third-party nuclear liability insurance, pay the necessary periodic premiums at all times, and make an annual payment to the extended care and long-term liability account for such amount as the department of natural resources reasonably determines is necessary. The department of natural resources may make expenditures from this account, upon appropriation, for the purposes authorized in section 260.710. In the event of expenditures from the account as a result of radioactive releases from a regional disposal facility, the department shall to the maximum extent possible seek to obtain moneys from such insurance prior to using moneys from the extended care and long-term liability account.