reactors constructed later. It was permanently shut down in February 1968. Current status The United States Department of Energy has administered the site since 1977 and offers public tours on set dates during the spring, summer, and fall of the year, as well as special tours for visiting officials. six of the nine production reactors at Hanford were considered to be in "interim safe storage" status, and two more were to receive similar treatment. The exception was the B Reactor, which was given special status for its historical significance. In a process called cocooning or entombment, the reactor buildings are demolished up to the concrete shield around the reactor core. Any openings are sealed and a new roof is built. Most auxiliary buildings at the first three reactors have been demolished, as well. The C reactor was put into operation in 1952 and was shut down in 1969. It was cocooned as of 1998. The D reactor operated from 1944 to June 1967, and was cocooned in 2004. The DR Reactor went online in October 1950, and was shut down in 1964. It was cocooned in 2002. The F reactor was shut down in June 1965 and cocooned in 2003. The H Reactor became operational as of October 1949 and was shut down as of April 1965. It was cocooned as of 2005. Cocooning of the N-Reactor, which operated from 1963 to 1987, was completed as of June 14, 2012. The decommissioned reactors are inspected every five years by the Department of Energy. The K East and K West reactors were built in the 1950s and went into use in 1955. They were shut down in 1970 and 1971, but reused temporarily for storage later. Preliminary plans for interim stabilizing of the K-East and K-West reactors were underway as of January 30, 2018. The B Reactor was added to the National Register of Historic Places (#) on April 3, 1992. A Record of Decision (ROD) was issued in 1999, and an EPA Action Memorandum in 2001 authorized hazards mitigation in the reactor with the intention of allowing public tours of the reactor. It was named a National Historic Landmark on August 19, 2008. In December 2014, passage of the 2015 National Defense Authorization Act (NDAA) made the B reactor part of the Manhattan Project National Historical Park, which also includes historic sites at Oak Ridge, Tennessee and Los Alamos, New