A REVIEW IS REQUIRED OF THE IMPURITY CONCENTRATIONS AND THE RESULTANT LONG-LIVED RADIOACTIVITIES, IN MATERIALS TO BE CONSIGNED TO LOW AND MEDIUM ACTIVE DISPOSAL FACILITIES. SAMPLING METHODS ARE TO BE DEVELOPED WHICH ARE APPLIED ALONG WITH ANALYSIS METHODS CURRENTLY AVAILABLE, TO DEMONSTRATE SUFFICIENTLY DETAILED KNOWLEDGE OF BETA, X-RAY AND GAMMA RADIOACTIVITIES FROM WASTE.
DEVELOPMENT OF CALCULATION METHODS, AND DEMONSTRATION OF THEIR VALIDITY FOR ASSAY OF RADIOACTIVITIES IN WASTE MATERIAL IN SEVERAL GEOMETRIES, IS REQUIRED AS PART OF A DECOMMISSIONING DEMONSTRATION PROJECT.
THE FINAL OBJECTIVE OF THE PROGRAMME IS TO PROVIDE AN EASILY USED AND ACCEPTABLE METHOD OF ASSAY WHICH WILL HAVE WIDE APPLICATION.
The radioactive waste inventories for the Windscale advanced gas cooled reactor (WAGR) have been assessed and demonstrated. Methods for assay, and codes to calculate the inventory of weak emitters following measurement of dominant gamma-emissions, have been developed.
This report covers:
methods for the cost effective sampling of steel, and for the assay of cobalt, nickel, niobium, silver and europium therein;
investigations on activities present in WAGR graphite;
preliminary work on activities in WAGR concrete;
development of calculation codes for the estimation of radioactive waste total activity, given a measure of the dominant gamma-radiation emissions from cobalt-60, which are applicable especially to steel radioactive waste.
The study showed that adequate sampling and assay methods for characterising steel radioactive waste can be defined, and that provision can be made for these during dismantling.
B.1. ANALYSIS OF CO, NI, NB AND LOW-LEVEL TRACE IMPURITIES IN REPRESENTATIVE WAGR MATERIAL SAMPLES.
B.2. DEVELOPMENT OF SUITABLE SAMPLING METHODS.
B.3. REVIEW OF PRESENT ANALYSIS DATA.
B.4. DESIGN AND TEST OF THE FINAL SAMPLING/ANALYSIS SCHEME.
B.5. SUPPLY OF SAMPLES.
B.6. DESIGN TEST OF CODES FOR CURIE ASSAY.
B.7. TESTS USING SOURCE ARRAY OF CO-60 SIMULATING TUBE, PLATE OR MIXED WASTE GEOMETRIES.
B.8. REVISION OF THE CODES USING TESTS RESULTS.