A FOREGOING RESEARCH CONTRACT (DE-B-004-D), AIMED AT THE INVESTIGATION OF THE COMPOSITION OF CONTAMINATION LAYERS AND OF THE EFFECTIVENESS OF POSSIBLE DECONTAMINATION PROCEDURES OF PRIMARY CIRCUIT STEAM LINES, WAS CONCLUDED BY FOLLOWING MAIN RESULTS:
- THE SURFACE CONTAMINATION IS TO AN EXTENT OF 99% OF OXIDE COMPOSITION, THE REMAINDER IS LOCATED AT A PENETRATION DEPTH OF UP TO 90 MICROMETERS IN THE BASE MATERIAL. FOR A SUCCESSFUL DECONTAMINATION, IT IS NECESSARY TO DISSOLVE, BESIDES THE OXIDE LAYER DEPOSITED ON THE SURFACE, ALSO A SMALL LAYER OF THE BASE MATERIAL;
- THE BEST WAY OF DECONTAMINATION (USING SOLUTIONS WITH LESS THAN 2% CONCENTRATION) IS TO STRIP THE DEPOSITED OXIDE LAYER BY A LOMI REACTIVE AND A PART OF THE BASE MATERIAL BY A MIXTURE OF HYDROCHLORIC AND NITRIC ACID.
THESE RESULTS HAVE BEEN OBTAINED BY LABORATORY-SCALE TESTS ON REPRESENTATIVE SAMPLES.
THE OBJECTIVE OF THIS RESEARCH CONTRACT IS TO DEMONSTRATE THAT THE ABOVE DECONTAMINATION PROCEDURE IS ALSO APPROPRIATE FOR A LARGE-SCALE APPLICATION TO A STEAM LINE OF THE LINGEN NUCLEAR POWER STATION.

1. MANUFACTURING OF THE DECONTAMINATION RIG COMPRISING THE SAMPLE STEAM PIPE AND ALL NEEDED COMPONENTS FOR DECONTAMINATION.
2. PRELIMINARY LABORATORY DECONTAMINATION TESTS OF REPRESENTATIVE SAMPLES INCLUDING DETERMINATION OF THE COMPOSITION AND ACTIVITY LEVEL OF THE CONTAMINATED LAYER.
3. MAIN TEST PROGRAMME USING THE DECONTAMINATION RIG.
4. ASSESSMENT ON OPTIMAL TREATMENT OF THE GENERATED RADIOACTIVE SECONDARY WASTE.
5. EVALUATION OF EXPERIMENTAL RESULTS WITH RESPECT TO MAN-DOSE, QUANTITIES OF SECONDARY WASTE AND COST ANALYSES, WITH EXTRAPOLATION TO A 1200 MWE BWR.