Statistical Characterization of Damage of Different Surface P-Wave Velocity Sets under Dynamic Load and Study on Overall Radon Detection Consistency

On the basis of reviewing the existing research status of cumulative damage of the rock mass and summarizing the existing engineering application fields of radon, this paper attempts to apply radon detection technology to the research field of rock damage mechanics so as to monitor the evolution process of cumulative damage of the rock mass. Based on the above research purposes, a test device for detecting cumulative damage of radioactive rocks by surface radon gas was designed, and the test results were obtained by integrating the system to implement the test scheme. Due to the limitation of the nonmetallic ultrasonic detector, a single blasting damage value of 25 detection points appears after a single blasting measurement, which is a surface longitudinal wave velocity characterization damage set, while the surface radon exhalation rate in the subsequent analysis process is an overall characterization value; that is, the existence of damage directly affects the whole body radon exhalation rate of the test block, and the data dimensions of the two are different. In order to solve this problem, we try to introduce three data evaluation methods, the average weighting method, grey prediction method, and K-means clustering algorithm, and compare the feasibility of these three methods. It is proved that there is a certain linear relationship between the radon exhalation rate and the cumulative damage, which further verifies the feasibility of using radon to detect cumulative damage. The results show that the cumulative damage of loaded radioactive rock test blocks can be reflected by surface radon detection technology, and finally, the correlation between the cumulative damage characteristics and the continuous change of the body radon exhalation rate is obtained. Based on the correlation, the body radon exhalation rate is introduced into the field of fractured rock mass damage characterization, which is mutually improved with common monitoring methods such as acoustic emission and microseismic monitoring, supplementing and enriching the means of rock mass damage evolution characterization, providing a theoretical basis for finely describing the whole process of fracture closure and initiation, and finally accurately ensuring the stability of surrounding rock under the action of deep underground engineering excavation disturbance.

Assessment of Radon, Radium, and Uranium Concentrations in Decorative Materials (Used to walls) Samples in Iraqi Markets

In present study, natural alpha emitters (222Rn, 226Ra, and 238U) were tested in decorative materials used as walls collected from different Iraqi local markets by CR-39 detectors that it was purchased from TASTRAK Analysis System. Annual effective dose and radon exhalation rate were calculated. The results obtained showed that the range and average value of 222Rn concentrations in air container were 7.94 – 738.10 Bq/m3 and 252.38±37.63 Bq/m3, while 222Rn concentrations in in sample were 45.73– 4252.99 Bq/m3 and 1454.25±216.84 Bq/m3. The ranged of 226Ra and 238U concentrations were 0.010- 1.000 Bq/kg, with an average value 0.278±0.04 Bq/kg and 0.01- 1.24 ppm, with an average value 0.344±0.05 ppm, respectively. The results obtained showed that the range and average value of annual effective dose in mSv/y were 0.2 –18.62 and 6.29±0.95. Also, it is found that the mass exhalation rate as well as surface exhalation rate were 8.38±1.33 mBq/kg.day and 240.77±36.56 mBq/m2.day, respectively. The data of 222Rn concentration (in air container), and annual effective dose in some samples of the present study were higher than the global limit range (200-300 Bq/m3), and (3-10 mSv/y) according to ICRP. While, all results of 226Ra, and 238U concentrations as well as the mass with surface exhalation rate were within the permissible limits that suggested by UNSEAR, and ICRP. Then, it can be concluded that the most samples of decorative materials which used as walls according to radiation scope no causes health risk.

Radon emission fluctuation as a result of biochar application into the soil

The presented research was focused on the analysis of the impact of biochar application into the soil on the radon exhalation process as a new issue of radiation protection in agriculture. Field measurements of the radon exhalation rate utilizing two methods—active and passive as well as laboratory measurements of the radon emanation coefficient were performed. In laboratory a soil samples with sunflower husk biochar were analysed using the accumulation chamber technique. At the final step the assessment of the effective dose for humans coming from radon exhalation from soil depending on biochar dose applied were evaluated. The doses of biochar applied in the analysed experimental fields were 0, 20, 40, 60, 80, and 100 Mg ha−1. The results show that biochar application into the soil contribute to a decrease in the emanation coefficient from a value around 7% to less than 2% with a simultaneous decrease in the radon exhalation rate from 4.4 to 14.8 mBq m−2 s−1 when the biochar dose increase from 0 to 100 Mg ha−1.

Physical-mechanical Properties and Radon Exhalation of Fiber-reinforced Uranium Tailings Geopolymer Solidified Bodies

Uranium tailing ponds are a potential major source of radioactive pollution. Solidification treatment of uranium tailings can control the diffusion and migration of radioactive elements in uranium tailings to safeguard the surrounding ecological environment. Literature review and field investigation were conducted in this study prior to fabricating 11 solidified uranium tailings samples with different proportions with PVA fiber, basalt fiber, metakaolin, and fly ash. The samples’ pore structure, volume resistivity, compressive strength, and radon exhalation rate variations were analyzed. The pore size of the solidified samples is mainly between 1–50 nm, the pore volume is between 0.726–1.750 cm3/g, the volume resistivity is between 1411.33-1937.33 Ω·m, and the compressive strength is between 20.61–36.91 MPa. The radon exhalation rate is between 0.0397–0.0853 Bq·m2·s− 1, which is lower than the national standard. Based on a comprehensive analysis of the physical and mechanical properties and radon exhalation rate of the solidified samples, the basalt fiber is found to outperform PVA fiber overall. The solidification effect is optimal when the 0.6% basalt fiber is added.