VALIDATION & TESTING OF THE VAM2D COMPUTER CODE

SEVERAL STATES ARE CURRENTLY SEEKING MUCH-NEEDED NEW LOW-LEVEL RADIOACTIVE DISPOSAL SITES IN ACCORDANCE WITH THE LOW-LEVEL RADIOACTIVE WASTE POLICY ACT OF 1980. ANY NEW COMMERCIALREQUIREMENT THAT A SITE BE CAPABLE OF BEING MODELED AND THATITS PERFORMANCE BE ASSURED FOR 500 YEARS. FOR MOST SITES, THE HYDROGEOLOGICAL AND RADIONUCLIDE TRANSPORT CHARACTERIS- TICS OF THE UNSATURATED ZONE ARE MAJOR FACTORS IN ASSESSING SITE PERFORMANCE AND THEREFORE MUST BE PROPERLY MODELED. CURRENT UNSATURATED ZONE MODELS CANNOT ACCONNODATE MANY PRO-CESSES OR CHARACTERISTICS THAT MAY BE IMPORTANT, SUCH AS HYSTERESIS, HIGHLY VARIABLE SPATIAL/TEMPORAL CONDITIONS, MACROPORES AND FRACTURES, NON-LINEAR SORPTION, AND MULTI- PHASE FLUIED FLOW. THE PROPOSED RESEARCH PROJECT IS AIMED DEVELOPING THE KEY MODEL ENHANCEMENTS NEEDED TO ENABLE MODELING REQUIREMENTS AT POTENTIAL SITES TO BE SATISFIED. PHASE I WILL INVOLVE DEVELOPMENT OF THE NUMERICAL APPROACHESTO AND ALGORITHMS FOR EACH OF THE PROCESSES AND A DETAILED OUTLINE OF THE OVERALL INTEGRATED MODEL. PHASE II WILL IN- VOLVE CODING, TESTING, AND MODEL VERIFICATION.