Inside MIT's Nuclear Reactor - ANS Nuclear Cafe Friday Matinee

Historic Illustrations of the MIT Reactor, by Will Davis

The MIT reactor - known in the early letter identifier days as the "MITR" - was designed jointly by MIT itself and by the Nuclear Products / ERCO Division of ACF Industries.  ACF had made the move to enter nuclear power in the middle 1950's and for a time had on board Dr. Marshall Holloway who had previously been employed by the US AEC.

The November 1956 issue of the company magazine "ACF Horizons" included the following mention of the MIT reactor:  "ACF has a contract with the Massachusetts Institute of Technology to design, fabricate and erect a reactor with an associated building and facilities on a site near their main campus at Cambridge, Massachusetts."  The information was accompanied by the illustration reproduced below.

"Cutaway diagram shows nuclear reactor and associated facilities which ACF will design and build for the Massachusetts Institute of Technology." From November 1956 ACF Horizons magazine, Will Davis collection.

The reactor was originally constructed as a 2000 Kwt heavy water moderated tank-type reactor, using universal MTR-type fuel elements.  The reactor was surrounded by a graphite reflector.

"MTR type fuel" is a generic term applied to flat plate type nuclear fuel, typically roll bonded sandwich construction which is then mounted in a stacked form with multiple plates comprising one fuel element as seen here.  This is a standard 'off the shelf' MTR type fuel element manufactured by Sylvania-Corning Nuclear, whose trade name was SYLCOR or SYL-COR.  This is very similar to the fuel used originally in the MIT reactor, which was manufactured by Sylvania-Corning Nuclear.  In this illustration we are seeing the top or 'grapple' end of the fuel element.  The illustration is from original SYLCOR sales material in Will Davis' collection.

The construction of the MIT reactor and its facilities was fairly typical of those found at varied locations around the United States and, for that matter, around the world as being constructed by a number of concerns during the latter half of the 1950's when there was a large boom in the construction of pool and tank type training and research reactors.

Cutaway of the MITR facility from The Atomic Energy Deskbook, John F. Hogerton; Reinhold Publishing 1963.

The August 1958 ACF Horizons employee magazine featured the illustration below, and noted that "the first ACF-built test and research reactor to be completed will be operative at the Massachusetts Institute of Technology this year."

"Core tank of ACF-built research reactor at MIT is lowered into place as unit nears completion." ACF Horizons, August, 1958; in Will Davis collection.

Typical of test and research reactors of the day, the MIT reactor employed plate type fuel known in the industry as "MTR type" fuel as it had originally been developed for the AEC's Materials Test Reactor at the National Reactor Testing Station, Idaho.  The fuel for MIT's reactor was purchased from Sylvania-Corning Nuclear, who advertised itself as "the world's first nuclear fuel vendor."

This remarkable photo from Sylvania-Corning materials in Will Davis' collection shows the initial fuel loading of the MIT Reactor in 1958.

As a footnote to the successful construction of the MIT reactor, it might be noted that ACF Industries took the experience to heart and carried on with the type.  According to an ACF sales brochure (undated, in my collection) "The ACF Heavy Water Tank Type standard reactor is the direct result of the experience gained with the MIT reactor."  In that brochure, this type of reactor is shown as part of a standardized lineup with several other types.  The type was still offered after the mid-1959 buyout that saw Allis-Chalmers purchase and merge all of ACF's nuclear business and contracts into its own Atomic Energy Division.

Will Davis is a member of the Board of Directors for the N/S Savannah Association, Inc. He is a consultant to the Global America Business Institute, a contributing author for Fuel Cycle Week, and he writes his own popular blog Atomic Power Review. Davis is also a consultant and writer for the American Nuclear Society, and serves on the ANS Communications Committee and the Book Publishing Committee. He is a former U.S. Navy reactor operator and served on SSBN-641, USS Simon Bolivar.  His popular Twitter account, @atomicnews is mostly devoted to nuclear energy.