Real-Time Monitoring of Gross Beta Radioactivity in Tap Water and Committed Effective Dose.

To achieve real-time monitoring of gross beta radioactivity in drinking water, a scintillating fiber array system was developed. Using this system, the gross beta radioactivity in tap water at Tsinghua University campus in Beijing was monitored, and the same water samples were measured using the evaporation concentration method as a comparison experiment. Finally, the annual committed effective doses to children and adults who drank the tap water for a long time were estimated. The results showed that the gross beta radioactivity in tap water was 0.09 ± 0.03 Bq L using the scintillating fiber array system and 0.076 ± 0.009 Bq L using the evaporation concentration method. The annual committed effective dose values were less than the dose reference level of 0.1 mSv y, as suggested by the World Health Organization. The scintillating fiber array system can be used for measuring gross beta radioactivity in drinking water and protecting public health.

Gross beta determination in drinking water using scintillating fiber array detector.

A scintillating fiber array detector for measuring gross beta counting is developed to monitor the real-time radioactivity in drinking water. The detector, placed in a stainless-steel tank, consists of 1096 scintillating fibers, both sides of which are connected to a photomultiplier tube. The detector parameters, including working voltage, background counting rate and stability, are tested, and the detection efficiency is calibrated using standard potassium chloride solution. Water samples are measured with the detector and the results are compared with those by evaporation method. The results show consistency with those by evaporation method. The background counting rate of the detector is 38.131 ±â€¯0.005 cps, and the detection efficiency for ß particles is 0.37 ±â€¯0.01 cps/(Bq/l). The MDAC of this system can be less than 1.0 Bq/l for ß particles in 120 min without pre-concentration.

Design of cosmic veto shielding for HPGe-detector spectrometer.

A Monte Carlo simulation to optimize the shielding design of a cosmic-veto HPGe spectrometer is described. The incident sources were simulated using the CRY code and the effect on the integral background count rate of different shielding structures was evaluated using the simulation code GEANT4 with application of veto mechanics during simulation. This procedure has been validated by experimental results, and another optimized cosmic veto shielding for an HPGe-detector has been illustrated.

New correction method for dynamic error in on-line gamma ray thickness detection.

In this paper, we present a new method to correct dynamic error (DE) in on-line gamma ray thickness measurement, which significantly improves measurement precision over traditional method, in most cases, by one order of magnitude. Theoretical analysis of DE is presented and the correction method is proposed. In order to further prove our theory, Monte Carlo simulation is taken and the performance improvement is given. The method has been successfully applied to our thickness measurement system and brought dramatic improvement to its dynamic precision.