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目的比较在不同管电压情况下,用3种方法计算X、γ射线探伤作业控制区和监督区边界大小可用性,以期估算出更为合理的辐射防护距离,尽最大可能减少辐射伤害。方法应用半值层法、什值层法(合称层值法)和图表法分别计算确定控制区和监督区的最佳边界距离。结果在主出束方向,当管电压<250 kV时,采用3种计算模式结果相差不大(管电压分别在150、200、250、300、350、400 kV时,考虑探伤材料自身的防护,则相应的防护控制距为0.6、0.76、1.28 m,监督距为1.48、1.86、3.15 m);当管电压≥250 kV时,层值法的计算结果较图表法大(考虑探伤材料自身的防护,则相应的防护控制距为41~44 m、94~104 m,监督距为102~106 m、232~254 m)。在散射线方向(非主出束方向),同样宜采用层值法计算模式(考虑探伤材料自身的防护,则相应的防护控制距为[(1.94~2.12)×10~(-4) m、(0.35~1.09)×10~(-2) m、0.35~1.18 m、2.85~2.98 m、6.64~7.09 m,监督距为0.71~0.84 m、4.64~5.11 m、6.51~18.28 m、3.49~33.0 m、61~65 m)];在漏射线方向(非主出束方向),3种方法的计算结果近似。结论在主出束方向,当管电压<250 kV时,可选用任何一种方法制定控制区及监督区边界;当管电压≥250 kV时,以层值法计算更为安全。在非主出束的散射线方向,宜采用层值法计算模式;在非主出束的漏射线方向,3种计算方法均可。
OBJECTIVE To compare the availability of X and Gamma ray flaw detection control areas and the size of the border area under different tube voltages with three methods in order to estimate a more reasonable radiation protection distance and minimize the radiation damage. Methods The optimal boundary distance between the control area and the supervised area was calculated by using the method of half value layer, the value layer method (called layer value method) and the chart method respectively. Results In the direction of the main beam, when the tube voltage is less than 250 kV, there is little difference between the three calculation modes (when the tube voltages are 150, 200, 250, 300, 350 and 400 kV respectively, The corresponding control distance is 0.6, 0.76, 1.28 m, and the monitoring distance is 1.48, 1.86, 3.15 m). When the tube voltage is greater than or equal to 250 kV, the calculation result of layer method is larger than that of the chart method , The corresponding protective control distance is 41 ~ 44 m, 94 ~ 104 m, monitoring distance is 102 ~ 106 m, 232 ~ 254 m). In the direction of scattered ray (non-main beam direction), the layer value method should also be adopted. Considering the protection of testing materials, the corresponding control distance is [(1.94 ~ 2.12) × 10 ~ (-4) m, (0.35 ~ 1.09) × 10 ~ (-2) m, 0.35 ~ 1.18 m, 2.85 ~ 2.98 m and 6.64 ~ 7.09 m respectively. The monitoring distance ranged from 0.71 to 0.84 m, from 4.64 to 5.11 m, from 6.51 to 18.28 m, from 3.49 to 33.0 m, 61-65 m)]. The calculation results of the three methods are approximate in the direction of the leak radiation (non-main beam-out direction). Conclusion In the main beam direction, when the tube voltage is less than 250 kV, either method can be used to set the boundary between the control area and the monitoring area. When the tube voltage is more than 250 kV, it is safer to calculate by the layer value method. In the non-main beam direction of the scattered line, should be calculated by the layer value method; non-beam main beam direction, three kinds of calculation methods can be.