[en] The response to small dose rate variation is one of important performance for environmental γ radiation monitor. In this paper we presented a radioactive plume simulator that home made and the test result for its radiation field dose rate. The components of this device include radiation source and its transport system, source shielding, lead attenuator, controller. The air Kerma rate at 3 m from the radiation source and 1 m above ground was obtained by MC simulation and G(E) function method, and the difference between two method is within 5%. This device can provide the radiation field over the range of 10∼50 nGy/h, used to testing the performance of response to small dose rate variation for environmental γ radiation monitor. (authors)

[en] In this paper we presented performance test and it's result of response to small dose rate variation for environmental γ radiation monitor based on the radioactive plume simulator. Data process result indicated that good agreement between recorded dose rate of the environmental γ radiation monitor and the radiation dose rate from the radioactive plume simulator, and verified that the environmental γ radiation monitor which are most widely used in our country can correctly response to the small dose rate variation. (authors)

[en] According to the recommendations of ISO4037-1:1996, we have established the filtered x-ray reference radiation of low air kerma rate series (10 reference radiations), narrow spectrum series (13 reference radiations), wide spectrum series (7 reference radiations) and high air kerma rate series (8 reference radiations) in CIRP. The relevant calibration facilities, such as ISO water phantom, are also built for calibration practice. An Yxlon MG325 is used as x-ray generator. Totally 38 reference radiations are produced with tube voltage range from 15 kV to 300 kV. The characteristics, such as HVL (half value layer), for these reference radiations are investigated. They are well consistent with the recommendations of ISO and can be used for the calibration of dose and doserate meters for radiation protection purpose. (author)

[en] The method on temperature drift correction of energy spectrum measured by seawater in-situ γ-ray spectrometer composed of NaI(Tl) detector is studied. The method is based on the improvement of temperature compensation device powered by POE to design the experiment and explore the function relationship of measuring energy spectrum with temperature. Meanwhile the correction function about the peak shift with temperature is obtained utilizing curve fitting and used to correct the peak shift. The results show that the certain correspondence between the peak shift of the energy spectrum from γ spectrometer and the temperature variation is observed. The validity of the modified function is verified by the ⁶⁰Co and ¹⁵²Eu. Finally, this method provides a reference for the accurate measurement of seawater radionuclide recognition and nuclide activity. (authors)

[en] The response to small dose variation is an important performance indicator for environmental γ radiation monitor. This paper introduces a radioactive plume simulator and the test result for its radiation field dose rate. The components of this device include a ^l37CS source and its transport system, source shieldings, lead attenuators of different thickness, and a controller system. The air Kerma rate at 3 m from the radiation source and 1 m above ground was obtained by MC simulation and G(E) function method, and the difference between two method is within 5%. This device can provide a radiation field over the range of 10 nGy/h-50 nGy/h, when loading the MBq grade ¹³⁷CS radioactive source, can be used to testing the performance of response to small dose rate variation for environmental γ radiation monitor. (authors)

[en] Through radiation measurement of in-site system equipment in three types of reactors during overhauling, the typical types of radio-nuclides and the energy range of β ray existed in nuclear power plants (NPPs) were obtained. The surface activity responses to β rays with different energy of some common-used β surface contamination monitors were experimentally investigated. It is found that using the surface activity response of ⁹⁰Sr-⁹⁰Y plane source to calibrate these monitors would underestimate the real level of surface contamination. With respect to the energy range of β ray in NPPs, it is suggested that ²⁰⁴Tl or ³⁶Cl would be employed to calibrate the surface activity response of β surface contamination monitors. (authors)

[en] The efficiency of the underwater radioactivity monitor needs to be calibrated. KC1 powder was diluted into large volume water tank. The accurate efficiency calibration of the detector depends on correct determination of the solution radioactivity. This paper measured some spectra with hyper pure germanium detector. This study describes some methods, including mass abundance methods, extrapolation of measured detection efficiency, the combination of Monte Carlo method and experiment, semi-experimental formula method, to solve the problem. (authors)

[en] The technical requirements and methods for some verification items are adjusted along with the revision of verification regulation of personal dose equivalent H_p (10) monitors for X and y radiations. In order to analyze the effect of the new regulation on the original monitor, sixty active meters with different type and common detector (double silicon semiconductor detectors) are selected. All projects of the first verification are carried out. It is show that the statistical fluctuation and relative inherent error of all instruments still meet the requirements. Energy response and alarm threshold errors of some monitors are not up to standard. Most DMC2000S and all NRF 30 meters at 60 degrees angle response beyond the range of 29%. According to the results, the processing opinions of nonconforming are given after revision of verification. (authors)

[en] A HPGe spectrometer was used to measure the established filtered X ray reference radiation of low kerma series and narrow spectrum series. A monte carlo model of measurement system was developed with the responses matrix for 6 keV - 305 keV simulated by energy interval of 1 keV and the fluence spectra was calculated by unfolding method. To verify the measuring and unfolding method, the mean energy, the first second half-value layers and the energy resolution of the spectra were calculated from the fluence spectra and compared with the values given in GB/T 12162, the deviation was about less than 5%. The conversion coefficients from the air kerma to the ICRU operational quantities H_p(10), H_p (0.07), and H^* (10) were calculated using monoenergetic conversion coefficients at zero angle of incidence, which agreed well with the values given in GB/T 12162. (authors)

[en] The design of a new type of GM Tube radiation detector was introduced. The detector was designed according to the principle of Time-to-Count method. The hardware structure and program flow design of the radiation detector were presented. The test results showed that the linearity of Time-to-Count method is better than pulse counting method. Besides, the range upper limit based on Time-to-Count method extended two orders of magnitudes compared with the traditional pulse counting method. (authors)