Radon Concentration Dependence of Alpha Radioactivity Measurement Using Ionized Air Transportation

Nakahara

Sano

et al. 2007

ICONE

Section: Introductionmentioning

confidence: 99%

“…Both of the above are closely related and require precise knowledge about the relation between the radioactivity and the resultant ion currents. And the information about this relation has been pursued both from experimental and theoretical aspects (Sakai, et al, 2005;Naito, et al, 2005b).…”

Section: Introductionmentioning

confidence: 99%

Icone15-10426 Innovative Alpha Radioactivity Monitor for Clearance Level Inspection Based on Ionized Air Transport Technology (Ii) : CFD-Simulated and Experimental Ion Transport Efficiencies for Uranium-Attached Pipes

Nakahara

Sano

et al. 2007

ICONE

“…It has been discussed that such a clearance level that the wastes are allowed to be treated as non-radioactive wastes should be set. [1][2][3] Thus, the radiation levels have to be accurately measured. The existent measurement system of alpha radioactivity is inefficient and hence, cannot meet a rapid accumulation of waste materials.…”

Section: Introductionmentioning

confidence: 99%

“…In order to solve this issue, a new alpha radioactivity measurement system has been being developed. [1][2][3] In the system, the radioactive waste is fixed in a flow of air. The air is ionized by -ray from the waste and the generated ions form ion clusters.…”

Section: Introductionmentioning

confidence: 99%

Particle Modeling of Transport of α-Ray Generated Ion Clusters in Air

Tong¹,

Nanbu²,

et al. 2006

Jpn. J. Appl. Phys.

A particle model is developed using the test-particle Monte Carlo method to study the transport properties of α-ray generated ion clusters in a flow of air. An efficient ion–molecule collision model is proposed to simulate the collisions between ion and air molecule. The simulations are performed for a steady state of ion transport in a circular pipe. In the steady state, generation of ions is balanced with such losses of ions as absorption on the measuring sensor or pipe wall and disappearance by positive–negative ion recombination. The calculated ion current to the measuring sensor agrees well with the previous measured data.

“…Both of the above are closely interrelated and require precise knowledge about the relation between the radioactivity and the resultant ion currents. And the information about this relation has been pursued both from experimental and theoretical aspects (4) (8) .…”

mentioning

confidence: 99%

Innovative Alpha Radioactivity Monitor for Clearance Level Inspection Based on Ionized Air Transport Technology CFD-Simulated and Experimental Ion Transport Efficiencies for Uranium-Attached Pipes

Nakahara

Sano

et al. 2008

JPES

An innovative alpha radioactivity monitor for clearance level inspection has been developed. This apparatus measures an ion current resulting from air ionization by alpha particles. Ions generated in a measurement chamber of about 1 m 3 in volume are transported by airflow to a sensor and measured. This paper presents computational estimation of the ion transport efficiencies for two pipes with different lengths, the inner surfaces of which were covered with a thin layer of uranium. These ion transport efficiencies were compared with those experimentally obtained for the purpose of validating our model. Good agreement was observed between transport efficiencies from simulations and those experimentally estimated. Dependence of the transport efficiencies on the region of uranium coverage was also examined, based on which such characteristics of ion currents as anticipated errors arising from unknown contaminated positions are also discussed to clarify the effective operation conditions of this monitor.