Preparation And Study Of Nuclear Radiation Shielding Composites Based On Rubber

The boom in nuclear science and technology has led to the rapid development of nuclear power plants,nuclear medicine and diagnostics,and nuclear industrial flaw detection.However,while nuclear science and technology bring convenience to people,there is also the ever-present risk of radiation leakage.Traditional radiation protection composites are usually lead-containing materials,including reinforced concrete,iron sheets and lead plates.These radiation protection materials are only suitable for specific work scenarios and have many problems such as large space occupation and difficulty in moving.Since the 1970s,lead-rubber protective clothing prepared with a rubber matrix and lead and lead oxides as fillers has the outstanding feature of being flexible and wearable.However,lead itself is toxic and there is a weak absorption zone at 40 ke V to88 ke V,so there are health risks and risks of irradiation from specific rays from long-term use of protective clothing containing lead rubber.In order to achieve flexible and lead-free radiation protection composites,and to compensate for the weak absorption zone of traditional lead-containing radiation protection composites,the present study was first based on relevant radiation protection theories.In this study,different types of functional components containing heavy metal elements and rare earth oxides were selected as new lead-free shielding functional components based on relevant radiation protection theories and simulations to systematically investigate the differences in mechanical properties and X/γ-ray shielding performance of radiation protection composites with single fillers containing heavy metal elements and rare earth oxides.Secondly,based on the simulation results of the combined functional components,the performance differences of the single filler radiation protection composites and the actual filler cost control,the radiation protection composites containing 30wt%and 50wt%rare earth oxides were designed and prepared.In the end,the radiation protection composites containing combined fillers were successfully lead-free and flexible,achieving a comprehensive and balanced shielding of broad spectrum radiation and remedying the major problems such as the weak absorption zone of traditional radiation protection materials containing lead.The main research steps and results are as follows:（1）Simulations were carried out using Win XCom software to compare the single functional component containing heavy metals and the single functional component containing rare earth oxides,respectively.Based on the simulation results of the single functional component and the actual cost perspective,the combined functional component was designed.The differences between the single and combined functional components were simulated by Win XCom.The results show that at 60 ke V to 90 ke V,Ta,W and WC can exactly compensate for the weak absorption region of Pb in this energy band.At 50 ke V～60 ke V,the different types of rare earth oxides each have a high mass attenuation coefficient.The mass attenuation coefficients of Bi are even higher for other ray energies below 100 ke V.After comparing the relative errors of the experimental and simulated values,the simulated values of Win XCom are very informative in the range of20%relative error and can roughly assess the mass attenuation coefficient ofγ-rays for radiation protection composites.（2）Radiation protection composites containing heavy metal elements and single filler containing rare earth oxides were prepared using natural rubber as the matrix.The microscopic morphology,thermal stability,vulcanisation properties,mechanical properties and X/γ-ray radiation shielding properties of the radiation protection composite sections were investigated.The results show that there is local aggregation of fillers in the radiation protection composites containing heavy metal elements,but the aggregation of fillers has no significant effect on the mechanical properties and X/γ-ray radiation shielding properties of the radiation protection composites.The thermal stability of the composites with heavy metal elements improved with the addition of fillers.The vulcanisation properties of the heavy metal element radiation protection composites are similar to those of natural rubber NR.Due to the increased maximum torque MH of the heavy metal element radiation protection composites,the hardness of the composites increases,but the tensile strength and elongation at break decrease.For X-ray radiation protection properties,the highest shielding rate of W/NR is achieved at 100 k V in composites containing 100 phr fillers containing heavy metal elements.Bi/NR has the highest shielding rate at all X-ray energies except 100 k V.At 40 k V,Bi/NR achieves X-ray shielding rates of up to 94.2%and 89.5%at 1.4 mm±0.095 mm and 0.9 mm±0.108mm respectively.Forγ-ray shielding,Bi/NR and W/NR have good shielding effect at 59ke V and 81 ke V respectively,and W/NR has betterγ-ray shielding effect at 81 ke V,withγ-ray shielding rate up to 52.3%and 37.1%at 1.4mm±0.095mm and 0.9mm±0.108mm respectively.For X-ray shielding,the shielding effect of Dy₂O₃/NR is much higher than that of composites containing heavy metal elements,with X-ray shielding rates of 52.7%and 41.5%at 80 k V for 1.4 mm±0.095 mm and 0.9 mm±0.108 mm.Forγ-ray shielding,theγ-ray shielding effect of Dy₂O₃ is better at 59 ke V,withγ-ray shielding rates of up to67.1%and 52.5%at 1.4mm±0.095mm and 0.9mm±0.108mm.（3）Radiation protection composites containing 50wt%and 30wt%of combined rare earth oxide fillers were prepared with natural rubber as the matrix,and the mechanical properties and X/γ-ray shielding properties of the radiation protection composites were mainly studied and analysed.The results show that the radiation composite with 1.4mm±0.095mm is more prone to premature fracture during tension due to the large number of fillers and the formation of defects by filler agglomeration.The composites containing50 wt%and 30 wt%rare earth oxides show a decrease in tensile strength and elongation at break with the addition of fillers,but an increase in hardness,although both meet the basic requirements for flexible protective clothing.For X-ray shielding,（50wt%Sm₂O₃+30wt%W+20wt%Bi）/NR at 1.4mm±0.095mm and 0.9mm±0.108mm at80 k V gave X-ray shielding rates of 44.3%and 29.8%respectively.The X-ray shielding rates are between those of composites containing heavy metal elements for radiation protection and those of composites containing rare earth oxides.At 80 k V,the X-ray shielding rate of（15wt%Ce O₂+15wt%Sm₂O₃+40wt%W+30wt%Bi）/NR is higher than that of the heavy metal element radiation shielding composites at 1.4mm±0.095mm and0.9mm±0.108mm.However,they are lower than those of composites containing rare earth oxides.Forγ-ray shielding,at 59 ke V,（50wt%Sm₂O₃+50wt%Bi）/NR containing50wt%rare earth oxide radiation protection composites have a higherγ-ray shielding rate than W/NR and Bi/NR heavy metal element containing radiation protection composites and lower than Dy₂O₃ rare earth element oxide containing radiation protection composites.Therefore,the radiation protection composites with combined fillers achieve a comprehensive and balanced shielding of X/γ-rays under broad spectrum conditions and compensate for the weak absorption zone when containing a single filler.