AN IMPROVED RADIOGRAPHIC IMAGING TECHNIQUE FOR FREE LIQUID DETECTION IN CEMENT SOLIDIFIED DRUMS OF NUCLEAR WASTE

THE LONG-TERM STORAGE OF LOW LEVEL NUCLEAR WASTE IN CEMENT SOLIDIFIED DRUMS HAS GIVEN RISE TO A NEED FOR A NONDESTRUCTIVE EXAMINATION (NDE) TECHNIQUE THAT WILL DETERMINE THE PRESENCE OF FREE LIQUIDS. WE PROPOSE TO DEVELOP, EVALUATE, AND IMPLEMENT A NEW RADIOGRAPHIC NDE TECHNIQUE WITH EXCELLENT LOW CONTRAST AND DEPTH RESOLUTION FOR THIS PURPOSE. RECENT ADVANCES IN PROJECTION RADIOGRAPHYHAVE EXTENDED THE DYNAMIC RANGE FOR BOTH AREA AND LINE SCAN TECHNIQUES. THESE IMPROVEMENTS IN IMAGE CONTRAST MAY RESULTIN EASIER DETECTION OF LIQUIDS. IN ADDITION, NEW DEVELOPMENTS IN DIGITAL LAMINOGRAPHY AND PARTIAL- OR FULL-VIEW COMPUTED TOMOGRAPHY.(CT) HAVE YIELDED DEPTH MEASURING TECHNIQUES CAPABLE OF LAMINAR OR CROSS-SECTIONAL INSPECTION. THESE NEW IMAGING TECHNIQUES ELIMINATE THE SUPERPOSITIONING OF STRUCTURES INHERENT IN PROJECTION IMAGING. WE WILL INVESTIGATE NEW PROJECTION AND CROSS-SECTIONAL IMAGING TECHNIQUES TO INCREASE CONTRAST RESOLUTION AND ISOLATE THE FREE LIQUID LOCATION IN THREE DIMENSIONAL SPACE. DURING PHASE I, WE PROPOSE TO FABRICATE A NONRADIOACTIVE PHANTOM CONSISTING OF A DRUM CONTAINING CONCRETE WITH SALTWATER FILLED CAVITIES TO REALISTICALLY SIMULATE THE PRESENCE OF A TYPICAL FREE LIQUID. WE WILL IMAGE THIS PHANTOM ON A STATE-OF-THE-ART DIGITAL RADIOGRAPHY/COMPUTED TOMOGRAPHY INDUSTRIAL SCANNER CALLED ACTIS. ACTIS CAN INSPECT A VARIETY OF DIFFERENT OBJECT SIZES AT BOTH LOW AND HIGH ENERGIES. SYSTEMS ARE CURRENTLY INSTALLED AT NASA MARSHALL SPACE FLIGHT CENTER AND AT BOEING AEROSPACE. A DEMONSTRATION OF THE TECHNIQUE, AND THEDEVELOPMENT OF PERFORMANCE REQUIREMENTS WILL BE PRESENTED IN PHASE I. PHASE II WOULD CONSIST OF THE DESIGN AND DEVELOPMENT OF AN APPLICATION-SPECIFIC RADIOGRAPHIC SYSTEM FOR EXAMINING CEMENT SOLIDIFIED DRUMS.