Research On Long Rang Alpha Contamination Instrument

In the nuclear facility retirement and the nuclear radiation examination domain, needs to examine the pipe internal surface alpha pollution,to understood the alpha pollution in the pipe,makes the corresponding processing measures,this is one kind of monitor measure adopted by people for their own health,safety and the environment avoids radionuclide pollution.Because alpha particle have very short range and extremely weak penetration in the air,it is difficult for the detectors to get close to the surface pollution of irregular geometric shapes,such as small diameter long pipe.When its inner surface is monitored,it is very difficult to achieve results through hand-held probe methods or to use polished methods.Regarding the heteromorphous object surface's nuclear radiation pollution monitor,the long range alpha detection(LRAD)technology has provided one new method.The LRAD technology basis's foundation is the ion which the alpha ionization produces compound requires several seconds time in the air,if the air current can effectively transport the pollution place ion to the distant place receive pole plate in this time,can the long pipe internal surface pollution activity carry on the survey.Based on the LRAD technology's principle,we have developed the new long rang alpha contamination instrument.The measuring instrument is based on the SCM development,the hardware system is mainly composed of fan driving unit,ionization chamber,current -voltage converter,the signal acquisition and processing system taken the SCM as the core,LCD display,power(Li-ion battery and DC-DC)and chargers,and so on.After nearly a year of development work,the results are:1.Has designed the current ionization chamber,which can survey the fA level weak-current,the detection efficiency is high,stable property. 2.Take the SCM as the control core,has completed the data collection,memory, and analysis process.3.System's man-machine interface has used the lattice type liquid-crystal display and the small keyboard,the interface demonstrated in the Chinese character that the interface is friendly.4.Has developed power circuit and the lithium battery charging circuit for this system.Has designed the board and the cabinet,and assembled the instrument.5.Selected the standard radioactive source,carried on the instrument's duplication and stability test,the test result had indicated that this instrument performance was good.Use show that the measuring instrument stable performance,can detect the pipe internal surface contamination which the traditional alpha surface contamination instrument detector can't detect.When monitoring the small diameter long pipe internal surface activity,does not need to conduct prejudicial to deal with the measured channels,but also can real-time,highly effective,carry on the activity monitor safely to it.