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MELTING/REFINING OF CONTAMINATED STEEL SCRAP FROM DECOMMISSIONING

Objective

THIS IS A RESEARCH INTO THE MELTING AND REFINING OF CONTAMINATED STEEL SCRAP ARISING IN THE DISMANTLING OF NUCLEAR INSTALLATIONS.THE GENERAL AIM OF THE RESEARCH IS TO OPTIMIZE THE MANAGEMENT OF THESE METAL WASTES SO AS WITH MINIMUM RADIOLOGICAL IMPACT TO IMMOBILIZE THE VARIOUS RADIOACTIVITIES IN METAL AND SECONDARY PRODUCTS OF MINIMUM VOLUME FOR STORAGE.ALTERNATIVELY FROM SOME STARTING CONTAMINATION OR ACTIVATION LEVEL TO BE DETERMINED,TO RECYCLE THE METAL PRODUCT EITHER FOR UNLIMITED RELEASE OR FOR SPECIFIC SHIELD OR STORAGE CONTAINERS FOR MORE HIGHLY RADIOACTIVE MATERIALS.THE FIRST RESEARCH PROGRAMME 1979-83 YIELDED A CONSIDERABLE BODY OF KNOWLEDGE,WITH RADIOACTIVITY BEHAVIOUR IN SEVERAL TYPES OF MELTING RECOGNIZED.
THE PRESENT WORK IS A CONTINUATION STUDY WITH THESE AND OTHER FURNACE SYSTEMS AND WITH EXAMINATION OF BEHAVIOUR OF SOME SMALLER PRESENCE RADIOACTIVITIES.RADIOLOGICAL SAFETY FACTORS AND UPDATED COST BENEFIT FOR RECYCLING AND DISPOSAL WILL ALSO BE EVALUATED.
IN A SUPPLEMENTARY AGREEMENT CONCLUDED IN 1988, THE INITIAL WORK PROGRAMME WAS EXTENDED TO THE DEVELOPMENT OF A SYSTEM FOR MONITORING OF THE RADIOACTIVE SCRAP AT ARRIVAL AND DURING STORAGE AND TREATMENT AT THE MELTING FACILITY, SEE ADDITIONAL WORKING PACKAGE B.8.
The first part of this work is concerned with the steelmaking behaviour of various radioisotopes encountered in steel from the decommissioning of nuclear installations. Cobalt-60, caesium-134 and europium-154 have been used in various steelmaking experiments. It is evident that, under a wide range of conditions, cobalt is largely absorbed by the steel and europium is absorbed by the slag. Caesium may be largely volatilised or largely absorbed by the slag, but experience suggests that it cannot be reliably confined to either route alone.
The second part of the work concerns the detection of radioactive materials in steel scrap. Work has been completed on the development of detectors which would indicate the presence of radioactivity in the scrap. Experiments have shown that a gamma-ray detector of large volume could provide useful sensitivity of detection. A detector has been developed, and is being tested to examine incoming scrap for radioactivity.
B.1. TESTS ON THE 5T ELECTRIC ARC FURNACE WITH APPROPRIATE NUCLEAR SCRAP AND SIMULATED CONTAMINATION.
B.2. INVESTIGATION OF CAESIUM RETENTION IN 10T INDUCTION FURNACES USING NORMAL ACID SLAG AND LOW LEVEL RADIOTRACER.
B.3. MELTING OF ACTIVATED/CONTAMINATED STEEL WASTE IN A 6T EXPERIMENTATAL BASIC OXYGEN FURNACE (BOF) IN ORDER TO EXAMINE THE CO-RETENTION IN SLAG WHEN CO IS PRESENT AS SURFACE CONTAMINANT.
B.4. PRE-FURNACE ASSESSMENT OF THE CONTAMINATION OF STEEL WASTE BY MONITORING.
B.5. INVESTIGATION OF THE SLAG/METAL CHEMISTRY TO IDENTIFY SPECIFIC RADIONUCLIDES (NB-94,NI-63,SR-90,SB-124,EU-154 AND AM-241).
B.6. INVESTIGATION OF THE TRANSFER OF RADIOACTIVITIES TO FURNACE AND REFRACTORIES WITH PARTICULAR VIEW TO THE CONCENTRATION EFFECT OF THE NUCLIDES.
B.7. EVALUATION OF RADIATION EXPOSURE (INDIVIDUAL AND COLLECTIVE) OF INVOLVED PERSONS AND OF RADIOACTIVE EMISSIONS TO THE ENVIRONMENT FOR LONG-TERM OPERATIONS; COST/BENEFIT OPTIMIZATION FOR RE-CYCLING AND DISPOSAL BASED ON RESULTS OBTAINED.
B.8. CONCEPTION OF A SYSTEM FOR DETECTION OF RADIOACTIVE SOURCES IN STEEL PLANT SCRAP MATERIALS.
B.8.1. EXAMINATION OF DETECTION STRATEGIES BY COMPUTER MODELLING.
B.8.2. DEFINITION OF RADIOACTIVITY LEVELS TO BE DETECTED, ACCOUNT BEING TAKEN OF POTENTIAL HEALTH HAZARDS, AND CALCULATION OF THE CONDITIONS REQUIRED TO DETECT THESE LEVELS.
B.8.3. ASSESSMENT OF VARIOUS DETECTION STRATEGIES.
B.8.4. COST ESTIMATION.

Funding Scheme

CSC - Cost-sharing contracts
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Coordinator

Swinden Technological Centre
Address
Moorgate
S60 3AR Rotherham
United Kingdom