Currently, Japan is undertaking a nationwide project to measure and map radioactive contamination around Fukushima, as part of the efforts to restore normalcy following the nuclear accident. The Japan Atomic Energy Agency (JAEA) manages the Fukushima Environmental Safety Center, located approximately 20 km north of the Fukushima Daiichi nuclear power plant in Minamisōma City, Fukushima Prefecture. In collaboration with the JAEA, this study involved conducting comparison experiments and analyses with radiation detectors in high radiation environments, a challenging task in Korean environments. Environmental radiation surveys were conducted using three types of detectors: CZT, NaI(Tl), and LaBr3(Ce), across two contaminated areas. Dose rate values were converted using dose rate conversion factors for each detector type, and dose rate maps were subsequently created and compared. The detectors yielded similar results, demonstrating their feasibility and reliability in high radiation environments. The findings of this study are expected to be a crucial reference for enhancing the verification and supplementation of procedures and methods in future radiation measurements and mobile surveys in high-radiation environments, using these three types of radiation instruments.

Concerning the apprehensions about naturally occurring radioactive materials (NORM) residues, the International Atomic Energy Agency (IAEA) and its member nations have acknowledged the imperative to ensure the radiation safety of NORM industries. Residues with elevated radioactivity concentrations are predominantly produced during NORM processing, in the form of scale and sludge, referred to as technically enhanced NORM (TENORM). Substantial quantities of TENORM residues have been released externally due to the dismantling of NORM processing factories. These residues become concentrated and fixed in scale inside scrap pipes. To assess the radioactivity of scales in pipes of various shapes, a Monte Carlo simulation was employed to determine dose rates corresponding to the action level in TENORM regulations for different pipe diameters and thicknesses. Onsite gamma spectrometry was conducted on a scrap iron pipe from the titanium dioxide manufacturing factory. The measured dose rate on the pipe enabled the estimation of NORM concentration in the pipe scale onsite. The derived action level in dose rate can be applied in the NORM regulation procedure for on-site judgments.

Gamma spectrometry is one of the main analysis methods used to obtain information about unknown radioactive materials. In gamma-ray energy spectrometry, even for the same gamma-ray spectrum, the analysis results may be slightly different depending on the skill of the analyst. Therefore, it is important to increase the proficiency of the analyst in order to derive accurate analysis results. This paper describes the development of the virtual spectrum simulator program for gamma spectrometry training. This simulator program consists of an instructor module and trainee module program based on an integrated server, in which the instructor transmits a virtual spectrum of arbitrarily specified measurement conditions to the students, allowing each student to submit analysis results. It can reproduce a virtual gamma-ray energy spectrum based on virtual reality and augmented reality technique and includes analysis function for the spectrum, allowing users to experience realistic measurement and analysis online. The virtual gamma-ray energy spectrum DB program manages a database including theoretical data obtained by Monte Carlo simulation and actual measured data, which are the basis for creating a virtual spectrum. The currently developed database contains data on HPGe laboratory measurement as well as in-situ measurements (ground surface, decommissioned facility wall, radiowaste drum) of portable HPGe detectors, LaBr3(Ce) detector and NaI detector. The analysis function can be applied not only to the virtual spectrum, but also to the input measured spectrum. The parameters of the peak analysis algorithm are customizable so that even low-resolution spectra can be properly analyzed. The validity of the database and analysis algorithm was verified by comparing with the results derived by the existing analysis programs. In the future, the application of various in-situ gamma spectrometers will be implemented to improve the profiling of the depth distribution of deposited nuclides through dose rate assessment, and the applicability of the completed simulator in actual in-situ gamma spectrometry will be verified.

“Radiation measurement situation virtual reality program” is a three-dimensional modeling program. It is a program that virtually implements the measurement situation by applying visualization techniques such as animation effect charts, and effectively delivers gamma radiation energy spectrum data. This program was developed to respond to various measurement situations by visualizing major analysis objects such as radiation detectors, radioactive waste drums, radioactive building structures, and the ground surface as a 3D model. User-friendliness was secured by supporting various control functions such as distance, size, and angle while checking the three-dimensionally produced detector and analysis target in a virtual space. By using high-resolution photos obtained through 360-degree shooting, a virtual space was implemented to approximate the actual situation, such as the ground surface measurement. In addition, data communication safety was secured so that a large number of users could use it through a local area network in consideration of the actual operating environment.

To obtain the gamma-ray energy spectrum of artificial radionuclides which is difficult to obtain practically, virtual gamma-ray energy spectrum simulator program was developed. It can be applied for the predetermined measurement condition for which the database was developed through computational simulation and actual measurement of background radiation. For gamma spectrometry training for KHNP HPGe detectors using this program, the database for KNPG HPGe detectors was developed. First, the geometry of the detector in the simulation was adjusted to resemble the real structure by comparing the actually measured net counts rate at the main gamma peak with the value simulated by MCNP6. The Certified Reference material (CRM) of 137Cs and 60Co were used for verification. The comparison was made with respect to the situation where CRM was attached to the top and side of the detection part of the considered detector. The geometry structures of detectors were simulated by reflecting the design drawing of the products, and the simulation was performed for several thicknesses of the Ge/Li dead layer in consideration of the change in the thickness over time. As the results, the simulation geometry was tuned so that the results for 137Cs showed a difference within 10% for all detectors. At this time, in some detectors, the result for 60Co shows a 10% higher error, which is estimated to be due to the random summing. It was not considered in tuning the simulation geometry, but it was found that improvements were needed to reflect the coincidence summing when construction the virtual spectrum in the future. The determined simulation geometry was applied to generate theoretical gamma-ray energy spectra of representative artificial radionuclides. In order to create a virtual spectrum similar to the real one, the background spectrum was measured for each detector without a source, and the simulation results were calculated in the form of having the same energy channel as the background spectrum. The background spectrum and theoretical spectra of artificial radionuclides for each detector were databased so that virtual spectra could be generated under desired conditions. The virtual spectrum was generated by adding a background spectrum and a spectrum obtained by multiplying the spectrum of the desired nuclide by the concentration of the nuclide. The validity of generated virtual spectra was verified using the pre-developed gamma spectrometry program. As a results of gamma spectrometry of virtual spectra, the virtual spectra was verified by showing a difference within 20% from the radioactivity value input when generating the virtual spectra.

Capsicum annuum ‘Bukang’ is a resistant variety to Cucumber mosaic virus isolate-P0 (CMV-P0), CMV-P1 can overcome the CMV resistance of ‘Bukang’ due to mutations in Helicase (Hel) domain of CMV RNA1. To identify host factors involved in CMV-P1 infection, a yeast two-hybrid system derived from C. annuum ‘Bukang’ cDNA library was used. A total of 156 potential clones interacting with the CMV-P1 RNA helicase domain were isolated. These clones were confirmed by β-galactosidase filter lift assay, PCR screening and sequence analysis. Then, we narrowed the ten candidate host genes which are related to virus infection, replication or virus movement. To elucidate functions of these candidate genes, each gene was silenced by virus induced gene silencing in Nicotiana benthamiana. The silenced plants were then inoculated with green fluorescent protein (GFP) tagged CMV-P1. Virus accumulations in silenced plants were assessed by monitoring GFP fluorescence and enzyme-linked immunosorbent assay (ELISA). Among ten genes, silencing of formate dehydrogenase (FDH) or calreticulin-3 (CRT3) resulted in weak GFP signals of CMV-P1 in the inoculated or upper leaves. These results suggested that FDH and CRT3 are essential for CMV infection in plants. The importance of FDH and CRT3 in CMV-P1 accumulation was also validated by the accumulation level of CMV coat protein confirmed by ELISA. Altogether, these results demonstrate that FDH and CRT3 are required for CMV-P1 infection in plants.

Cucumber mosaic virus (CMV), which has the broadest host range among plant viruses, is a very destructive pathogen in pepper production. Various resistance sources against CMV have been identified by plant breeders. One of them is Capsicum annuum ‘Bukang’, which contains a single dominant resistance gene, Cmr1. C. annuum ‘Bukang’ is resistant to CMV-P0 strains (CMV-Kor and CMV-Fny), but susceptible to CMV-P1. CMV-P1 is a new strain recently identified in South Korea. Previously we showed that CMV-P1 RNA1 helicase domain is responsible for overcoming Cmr1 and may be play a role in viral replication and systemic infection. To identify the plant host factors involved in CMV-P1 replication and movement, we utilized a yeast two-hybrid system derived from C. annuum ‘Bukang’ cDNA library as a prey. A total of 78 potential host genes interacting with the CMV-P1 RNA1 helicase domain were isolated in the first screening, and PCR confirmation and sequencing analysis narrowed the candidates to ten genes. The candidate genes have found to be encoding acireductone dioxygenase, ADP-glucose pyrophosphorylase, ADP-ribosylation factor 1, ADP-ribosylation factor, calreticulin-3 precursor, cysteine synthase, formate dehydrogenase, histone-H3, phosphomannomutase and polyubiqutin 6PU11. Previous studies showed that these genes were involved in virus infection, replication or virus movement. To elucidate the function of these genes, VIGS and coimmumo precipitation assay is being done.