γ射线高度计在模拟航天器回收舱着陆的静态实验中剂量分布的测量及其评价

Measurement and Evaluation of Radiation Dose Distribution of γ-ray Altimeter in Static Test for Recovery Capsule during Simulated Landing.

γ射线高度计用于航天器回收舱回收着陆过程中的近地高度测量。其内装有活度为２．９６×１０１０Ｂｑ的１３７Ｃｓγ放射源。为了解仪表舱附近，特别是回收舱内有效载荷所在处的γ剂量分布，利用ＦＪ－３１７Ｃ＿γ剂量率仪和ＡＨＰИ－０１－０２γ剂量率仪对单机试验现场的γ剂量场进行了测量。结果表明，当高度计下降到距地面０．１６ｍ时，地面上距γ源５ｍ处的吸收剂量率低于辐射防护限值。随着回收舱高度的增加，地面对γ射线的反射作用将下降。因此，回收舱内有效载荷处的γ剂量率水平将满足安全飞行的要求。

The γ-ray altimeter, containing a γ-radioactive source 137 Cs with activity of 2.96 ×10 10 Bq,was used to detect the height of the spacecraft recovery capsule during landing.To measure the γ-dose distribution near to the guidance section, especially at position where the useful load is located in recovery capsule,γ-dose field at the test-site for one machine test was measured by means of a γ-dose rate meter FJ-317C and a γ-dose meter AHPИ-01-02. The result showed that the absorbed dose rate at 5 meters from γ-source on the ground is as low as the radiation protection limit when the altimeter is down to 0.16 m from the ground.The ground reflection effect for γ-ray decreases as height of the recovery capsule increases. Therefore, the γ-dose level at useful load in the recovery capsule will meet the requirements of flight safety.