Jaeryong Yoo

Effective dose evaluation of NORM-added consumer products using Monte Carlo simulations and the ICRP computational human phantoms

The aim of this study is to evaluate the potential hazard of naturally occurring radioactive material (NORM) added consumer products. Using the Monte Carlo method, the radioactive products were simulated with ICRP reference phantom and the organ doses were calculated with the usage scenario. Finally, the annual effective doses were evaluated as lower than the public dose limit of 1mSv y(-1) for 44 products. It was demonstrated that NORM-added consumer products could be quantitatively assessed for the safety regulation.

Radiobioassay performance evaluation of urine and faeces samples for radiation emergency preparedness

ABSTRACT In the event of a radiation emergency, it is necessary to assess intake and radiation dose for the internally contaminated casualties. This paper provides relatively rapid and simple procedures of bioassay. Faeces samples were ashed to improve sample homogeneity. Gamma spectrometry was used for radioactivity measurement. The measured results, including activity of the biosamples and associated uncertainty, were evaluated for traceability based on ANSI N42.22 and bias and precision based on ANIS/HPS N13.30. For all urine customary exercise samples, measurement results of 60Co and 137Cs were in good agreement with NIST values within 5% and satisfied ANSI N42.22 and ANIS/HPS N13.30 acceptance criteria. In contrast, the uncertainty of 57Co was quite large and the activity differed from the NIST value by 18%. For the urine emergency preparedness exercise, all measured results agreed well with NIST values, with less than 10% difference. Synthetic faeces samples included 54Mn, 60Co, and 134Cs. The activity of 60Co was different from the NIST value by 9%, whereas the results for 54Mn and 134Cs were within 3.2%. The measurement procedures given in this study can be applied to assess intake of radionuclides and resulting radiation dose to casualties.

Screening of alpha- and beta-emitting radionuclides using liquid scintillation counting and monitoring procedures in radiation emergencies.

Abstract Urine gross alpha and beta activity analysis was conducted, and an internal contamination screening method was adopted to monitor visitors to Japan after the Fukushima accident. In particular, spot urine samples were used to evaluate internal contamination for 16 mo, and a total of 90 people participated in gross alpha and beta emitter screening. An ultra-low-background liquid scintillation counter was used for measurement, and optimal pulse shape analysis values were determined by measuring alpha- and beta-emitting certified reference materials. Moreover, linearity and reproducibility were assessed to validate the adopted methods, and international intercomparison was conducted using synthetic urine samples by measuring alpha- and beta-emitting radionuclides in multi-contaminated samples. Here, the measurement results of visitors to Japan are discussed, and a screening procedure is established for gross alpha and beta activity analysis during radiation emergencies.

Radioactive contamination monitoring for the Korean public following Fukushima nuclear accident

On March 11, 2011, as a result of the Great East Japan Earthquake, severe damage to the Fukushima nuclear power plant caused the release of radioactive materials. We conducted radioactive contamination monitoring for Korean residents in Japan and Korean travelers to East Japan after the accident. More than 800 members of the Korean public were surveyed for personal monitoring. Measured levels of external and internal contamination were within the screening levels for each monitoring method.

Evaluation of sodium activation distribution in the PMMA water phantom after fast neutron irradiation.

(24)Na produced by the neutron activation of stable sodium in the body is commonly used to assess neutron doses after criticality accidents. However, the (24)Na distribution is not uniform owing to the interaction with the human body. In this study, we experimentally evaluated the (24)Na distribution in a PMMA water phantom and 60 polyethylene vials. The vials were analyzed to evaluate the sodium activation distribution in the PMMA water phantom by employing a correction factor.

32P measurement and dose conversion factor evaluation of activated human hair by criticality accident.

In order to conduct dose assessment of victims in criticality accidents, a method of fast neutron capture-activated (32)P measurement of hair in which samples are treated by a chemical and analytical procedure that takes 9 h and measurement is conducted by liquid scintillation counting is presented. To validate this measurement method, hair samples spiked with a (32)P reference source were measured and the results analysed and the optimal sample mass and detection efficiency were determined. To verify the correlation between (32)P-specific activity and absorbed dose for spectra with two neutron mean energies, samples collected from three normal individuals were irradiated at various neutron energies and irradiation times using the MC50 Cyclotron of the Korea Institute of Radiological and Medical Sciences. The (32)P-specific activity trend of the irradiated hair agreed well with the absorbed doses. Based on the results, dose conversion factors, which were 0.67 ± 0.15 and 0.59 ± 0.06 Gy (Bq g(-1))(-1) at neutron mean energies of 2.33 and 5.36 MeV, respectively, were calculated as a guide for medical treatment of criticality accident victims.