222Rn In Air Research Articles

Attachment of Membrane Separator for Removal of Radon to Ionization Chamber Installed for Tritium Stack Monitor

The effect of background counts induced by α-particles mainly from Rn in air was removed by the attachment of a water-permselective membrane separator to a tritium stack monitor equipped previously. Water vapor, after permeating the membrane selectively, was carried by N2 gas into an ionization chamber where the activity of tritium was measured. The consumption of N2 gas for carrier was reduced by recycling the gas through dehumidification processes; (1) condensation by pressure, (2) condensation by refrigeration and (3) adsorption (by adsorbents), so that there is no added daily work arising from the attachment for maintenance of the tritium monitor.

Attachment of membrane separator for removal of radon to ionization chamber installed for tritium stack monitor.

The effect of background counts induced by α-particles mainly from Rn in air was removed by the attachment of a water-permselective membrane separator to a tritium stack monitor equipped previously. Water vapor, after permeating the membrane selectively, was carried by N2 gas into an ionization chamber where the activity of tritium was measured. The consumption of N2 gas for carrier was reduced by recycling the gas through dehumidification processes; (1) condensation by pressure, (2) condensation by refrigeration and (3) adsorption (by adsorbents), so that there is no added daily work arising from the attachment for maintenance of the tritium monitor.

Radiation Doses at the Radenci Health Resort

At the Radenci Health Resort in Slovenia, Yugoslavia, 226Ra in water and 222Rn in air were measured by the alpha scintillation technique, and the intake of radium and radon activity and the radiation doses received by personnel and patients were estimated. During a typical two-week stay at the resort a patient receives a bronchial dose of 1.35 mSv by breathing radon-rich air, while this dose would amount to 400 mSv for permanent personnel over 2000 yearly hours. By drinking radium-rich water a patient receives the following committed dose equivalents: 0.28 µSv for gonads, 1.8 µSv for red bone marrow, and 20 µSv for bone surface.

A Bayesian analysis or scientific judgment of uncertainties in estimating risk due to 222Rn in U.S. public drinking water supplies.

The elements which contribute to the range of values or uncertainties for the lifetime risk and dose equivalent due to 222Rn in U.S. public drinking water supplies are estimated and discussed here. From imperfect scientific knowledge, reasonable upper and lower bounds are placed on these estimates through the use of a semiquantitative Bayesian approach to uncertainty analysis. The factors considered are: occurrence of 222Rn in drinking water, indoor air 222Rn concentrations as a function of drinking water concentration, equilibrium state of the progeny, fraction of daughter products attached to aerosol particles, anatomical and dosimetric variables, epidemiological studies and choice of latency period, plateau period and effects of age. For Rn in U.S. public drinking water supplies, it is estimated that the best estimate for the lifetime lung cancer risk factor is 5 X 10(-9) excess cases of lung cancer per becquerel of Rn per m3 of water (2 X 10(-7) excess cases of lung cancer per picocurie of Rn per liter of water), with an estimated range between 2 X 10(-9) and 2 X 10(-8) excess cases per becquerel of Rn per m3 of water (5 X 10(-8) and 7 X 10(-7) excess cases per picocurie of Rn per liter). The best estimate of the lifetime population risk due to 222Rn in U.S. public drinking water supplies is estimated to be 6,000 excess lung cancers, with a reasonable range of 1,000 to 30,000.

Measurement of Rn in Air by Liquid Scintillation Techniques Using Cooling Sampling Method

Measurement of Rn in Air by Liquid Scintillation Techniques Using Cooling Sampling Method

αバックグラウンド除去によるトリチウムガスモニタの高感度化

A cancellation circuit was designed and constructed in order to eliminate signals, induced by α-particles from Rn in air, from output signals of a flow-through ion chamber used in a tritium gas monitor. This cancellation treatments can cause a high sensitivity in tritium gas monitoring.The circuit consists of a differentiating circuit, discrimator, adding circuit, peak-hold circuit, sample-hold circuit and differential amplifier. Pulsed α-signals are separated from tritium β-signals by the differentiating circuit and discriminator. After the shaping of α-signals are formed in the peak-hold circuit with the same decay time constant as that of the initlal α-signals, the α-signals are subtracted from initial signals in the differential amplifier.The test for the system showed that the cancellation cireuit eliminated successfully the effect of α-signals. The cancellation circuit functioned very well not only for isolated α-signals, but also for successive α-signals coming within their pulse widths. The long term stability of the system was obtained by combining the cancellation circuit with a temperature-controlled small-current amplifier. The system can offer the means to detect the tritium-gas concentration below the maximum permissible concentration for exhaust gas.

活性炭を用いた気中ラドンの測定法 実用上の基礎的検討

A method for sampling of Rn in air was experimentally studied. Radon gases flowing at 5l/min are adsorbed on activated charcoal (5g) in a column which is set in a coolant with dry ice and ethanol. The adsorbed Rn is transferred to an ionization chamber by heating the charcoal trap. The activity of Rn is then determined by the currents. The gross collection efficiency of this system was evaluated to be 0.88±0.05 in the region of 50-1, 200pCi/m3. An example of measurements obtained by this method is presented. The air concentration of Rn in a closed room is found to be 4, 000-5, 000pCi/m3.

通気式電離箱による横坑内のラドン濃度の測定, およびその濃度変化と地震発生の関係

The concentration of 222Rn in air in the gallery at Mikawa. Crustal Movement Observatory (Toyohashi City, central Japan) has been continuously measured with a flow-type ionization chamber since April, 1977 for the investigation of pre-earthquake anomalies. The observed 222Rn concentration shows remarkable increase after rainfall. It seems that 222Rn rich air is squeezed in the gallery by the contractile force caused by rainfalls from faults with elevated 226Ra content. The variation of 222Rn concentration in the gallery has been calculated from the rainfall data from June, 1977 to December, 1979. Sometimes remarkable disagreements between the observed and calculated values of the 222Rn concentration are seen before and after the occurrence of nearby earthquakes. Such a disagreement might be a precursor of nearby earthquake. The concentration of 222Rn is also influenced by the changes in atomospheric pressure; it increases as the pressure drops and decreases as the pressure rises. Seasonal variations are recognized, too. Continuous observation of 222Rn has also been started in June, 1980 at Kikugawa Crustal Movement Observational Station (Shizuoka Prefecture, central Japan).

Determination of environmental or occupational 222Rn in air and water and 226Ra in water with feasible and rapid methods of sampling and measurement.

Determination of environmental or occupational 222Rn in air and water and 226Ra in water with feasible and rapid methods of sampling and measurement.

Experimental Study on the Measurement of Rn in Air by Liquid Scintillator

Experimental Study on the Measurement of Rn in Air by Liquid Scintillator