27 1961 Stationary Low-Power Reactor The darkest hour in the history of NRTS was the January 1961 accident at Stationary Low-Power Reactor number one, which killed three men. SL-1 was the first of several prototype reactors designed for the U.S. Army to develop a low-power, boiling water reactor plant to be used in geographically remote locations. It came online Aug. 11, 1958. On Jan. 3, 1961, a night crew arrived to complete maintenance and startup activities after the Christmas break. Investigators concluded that the accident happened after one of them manually withdrew the central control rod, which had a history of sticking, in an attempt to reconnect it to its drive mechanism.The AEC immediately surveyed the nation’s 47 licensed reactors to assure shutdown procedures and operating parameters fell within safe specifications. “ After SL-1 … it turned into a totally new way of doing business with reactors. Procedural documents that originally had been two pages long were expanded into thick books, and all activity became rigidly prescribed.” — Joe Henscheid, ETR Critical Facility supervisor