SL-1 Reactor Accident Timeline

SL-1 Shut Down for Planned Maintenance

Work on the Reactor Core is Completed, and the Accident Occurs

Request for the Plant to be Built made by the AEC

Construction was Started by the Fegles Construction Company

Design and Proposed Operation of the Reactor were Reviewed

Initial Critical Operation Takes Place

Test Operations Terminate After 500 Hour run

CEI "Part-Time Project Manager" Writes letter to the AEC Contracting Officer's Representative Requesting that Shift Supervisors not be Required for Routine Supervision of Plant Operation During Night Shifts

Complete technical review of the reactor and its proposed operation was made

SL-1 Achieved its full power rating of electricity and space heat

40-Hour Xenon run was Made

Strips of Cadmium were Inserted in two of the T-rod Control Shrouds due to Reduced shut-down margin resulting from the boron loss

Army Reactors Branch Stated that the Procedures and Manuals Turned over to CEI by ANL were not Satisfactory for use by CEI

Test Operation by CEI for the Windsor Nuclear Safety Committee takes place

Cold Critical Experiments begin

SL-1 turned over to CEI for Operation

1000 Hour Sustained Power Run was concluded

Fuel Elements first Removed from the Core and Inspected by CEI and ANL Personnel

Initial Discovery of Bowing of Boron Strips

Large amounts of the boron strips were missing from some fuel elements and the fuel elements in the center of the core were extremely difficult to remove by hand. (Large loss of Boron attributed to larger rate of gain of reactivity)

It was Noted During the Second Periodic Inspection, that Central Fuel Elements were Difficult to Remove

It Appeared that the Core was Gaining Reactivity Faster that Predicted

Plant Superintendent orders shifts to perform complete rod travel exercise 4 hours into the start of their shift.

Operation Supervisor orders complete rod travel exercise on the graveyard and subsequent shifts

Plant Superintendent Orders not to perform control rod exercises during 2.56 MW power run

Two Remaining Bodies and Equipment and Records Recovered

Argonne National Laboratory Works on Designing, Testing, and Initial Operation of the Reactor Plant

Combustion Engineering, Inc. gets a Contract to run the Facility

The Reactor is Operated at a Power level of 3MW

Plant Shut Down for Maintenance, Modification, and Inspection