NEUTRON AND GAMMA INTERROGATION OF DRUMS OF RADIOACTIVE WASTE MAY BE USED TO DETERMINE ACTINIDE CONTENT. A LINAC, WITH APPROPRIATE TARGETS, PROVIDES POWERFUL GAMMA AND NEUTRON SOURCES YIELDING THE POTENTIAL FOR A VERY SENSITIVE TECHNIQUE FOR ACTINIDE DETERMINATION.
THE OBJECTIVE OF THE WORK IS TO PROVIDE INFORMATION WHICH WILL ENABLE AND INTEGRATED ASSAY FACILITY, INCORPORATING A NUMBER OF EXAMINATION TECHNIQUES, TO BE DESIGNED. THE PRESENT PROGRAMME IS DIRECTED AT RESEARCH TO DETERMINE THE FEASIBILITY AND SENSITIVITY OF A LINEAC DRIVE INTERROGATION SYSTEM IN THE ASSAY OF THE CONTENTS OF 500 LITRE DRUMS OF CEMENTED WASTES AND THE DEVELOPMENT OF METHODS BY WHICH SIGNALS GENERATED IN THE EXPERIMENTS MAY BE PROCESSED.
THE PROGRAMME IS LED BY TWC SUPPORTED BY THE HARWELL LABORATORY, PLESSEY CONTROLS LTD. (FORMERLY FISHER CONTROLS LTD) AND RAY TECHNOLOGY.
The development of a radioactive waste package assay facility, for cemented 500 litre intermediate level waste (ILW) drums was investigated.
The practical problems associated with the use of the various techniques in an integrated assay facility were identified and the key parameters defined.
Theoretical and experimental work was carried out at Harwell on active neutron and active gamma interrogation of 500 litre cemented ILW drums. Good correlations were established between the quantities of uranium-235, natural uranium and deuterium contained in the drums and the neutron signals. Clusters of small helium-3 proportional counters were found to be much superior for fast neutron detection than larger diameter counters.
Work on the data processing aspects of an integrated waste assay facility was also carried out.
STAGE 1 (FEASIBILITY STUDY) :
1.1. INVESTIGATE SUITABILITY OF LINAC AND NEUTRON TARGET FOR ACTIVE NEUTRON INTERROGATION.
1.2. DETERMINE AND EVALUATE THE PERFORMANCE AND LIMITATIONS OF COMBINED ACTIVE NEUTRON AND ACTIVE GAMMA INTERROGATION CHAMBER, AND COMPARE WITH SEPARATE CHAMBERS. CONSIDER COMPATIBILITY OF CHAMBER WITH PASSIVE NEUTRON EXAMINATION.
1.3. ESTABLISH DATA PROCESSING MODEL AND TEST AGAINST AVAILABLE CALCULATED AND EXPERIMENTAL INFORMATION.
STAGE 2 (MAIN EXPERIMENTAL PROGRAMME)
2.1. PROVIDE SUITABLE COMPONENTS FOR AN EXPERIMENTAL ASSAY SYSTEM.
2.2. COMMISSION EXPERIMENTAL SYSTEM.
2.3. OPERATE SYSTEM IN NEUTRON AND GAMMA INTERROGATION MODES AND MEASURE INITIAL RESPONSES.
2.4. MAKEPRELIMINARY EVALUATION OF SYSTEM AND MODIFY ACCORDINGLY.
2.5. OPERATE SYSTEM IN NEUTRON AND GAMMA INTERROGATION MODES AND MEASURE RESPONSES UNDER DIFFERENT CONDITIONS.
2.6. EVALUATE CHARACTERISTICS OF COMMON NEUTRON AND GAMMA INTERROGATION SYSTEM AND IDENTIFY DEVELOPMENT NEEDED FOR USE IN AN INTEGRATED ASSAY FACILITY.
2.7. DEVELOP DATA PROCESSING MODEL AND CHECK AGIANAST TEST RESULTS.
STAGE 3 (APPLICATION TO PRACTICAL ASSAY FACILITY)
3.1. EVALUATE PERFORMANCE OF INTEGRATED ASSAY FACILITY
3.2. CONSIDER ENGINEERING AND SYSTEMS DEVELOPMENTS REQUIRED FOR AN INTEGRATED ASSAY FACILITY.