Decontamination and disposition of Hallam and Piqua reactors

The Hallam Nuclear Power Facility, a sodium cooled, graphite moderated, 256 Mw(t) power reactor, went critical in 1962, was shut down as a result of moderator problems in 1964, and was decommissioned in 1969. The Piqua Nuclear Power Facility, an organic cooled, 45 Mw(t) power reactor went critical in 1963, was shut down in 1966 because of coolant problems, and was decommissioned in 1969. Fuel, coolant, and support systems of both reactors were removed from the site. The reactor vessels are entombed at their sites. Remaining systems at Hallam were sealed in the underground vaults and were then covered with six feet of earth. The Piqua vessel is sealed in the concrete reactor containment building. The state of Nebraska is responsible for monitoring 3 x 105 curies in 1969. The Piqua site was purchased by the U. S. Government and then leased to the City of Piqua. The remaining radioactivity at Piqua was 2.6 x 105 curies