Lt. General Nathan Twining prepared a report, entitled "Air Accident Report on 'Flying Disc' Aircraft Stored at White Sands Proving Ground, New Mexico", dated 16 July 1947.  It contains his findings resulting from a Presidential Directive to investigate the UFO incident.  The data furnished in this report was provided by his Air Material Command engineering staff and scientific personnel from the Jet Propulsion Laboratory, CIT, and the Army Air Forces Scientific Advisory Group.   This report states: "Upon examination of the interior of the craft, a compartment exhibiting a possible atomic engine was discovered.  At least this is the opinion of Dr. Robert Oppenheimer and Dr. Theodore von Karman.  A possibility exists that part of the craft itself comprises the propulsion system, thus allowing the reactor to function as a heat exchanger and permitting the storage of energy into a substance for later use.  This may allow the converting of mass into energy, unlike the release of energy of our atomic bombs.  The description of the power room is as follows:   There was a doughnut shaped tube approximately thirty-five feet in diameter, made of what appears to be a plastic material, surrounding a central core.  This tube was translucient, approximately one inch thick.  The tube appeared to be filled with a clear substance, possibly a heavy water.  A large rod, counterwise inside the tube, was wrapped in a coil, of which appears to be of copper material, ran through the circumfurance of the tube.  This may be the reactor.  The activation of an electrical potential is believed to be the primary power to the reactor, though it is only a theory at present.  Just how a heavy water reactor function in this environment is unknown.   On the deck of the power room there are what resembles typewriter keys, possibly reactor/powerplant controls.  There were no conventional electronics nor wiring to be seen connecting these controls to the propulsion turret.
Another report was written on the subject, "Mission Assessment of Recovered Lenticular Aerodyne".  In Part II of that report, entitled "Technical Evaluation (Preliminary)", it states, "The power plant (severely damaged) appears to be a neutronic engine.  Heavy water and deuterial (light hydrogen) elements appear to be the primary ignitor.  A series of coils and heavy magnets connected to the neutronic engine via an oddly arranged grids of electrodes (metal not yet identified) appears to be the motive force.  The atomic motor was examined.  It is encased in a pure aluminum capsule directly underneath the main crew compartment.  There is a small exhaust aperture attached that has what can be only described as an nelicold mechanism... The auxilliary motor may be articulated.   The following elements were analyzed and found to exist in the small neutronic power plant that was found inside ULAT-1: UFO in metallic form, hydrogen-fluoride gas, water and uranium tetraflueride, powdered magnesium and potassium chlorate, metal similar to lead with a chocolate brown color, U-235 in metallic form, plastic-like material similar to NE 102, Baryllium, pure aluminium, Therium isatope material, and plutonium powder..   Scientists from Los Alamos and Sandia base were alarmed that the power plant could possibly function as a bomb if the elements described above were processed in similar fashion as was done for the lens and shotgun detenators.  This originally was the first conclusion.  After further evaluation, it was determined that since no recognizable firing circuits were identified, the threat of detonation did not exist.   The only evidence of circuitry found on the motor was thin plastic-like sheets fashioned like platters encased on the exterior of the spherically-shaped casing coated by a thin film of pure silver.  Under high power magnification it was observed a series of fine grid-like lines intersecting groups of dots arranged in circular patterns.