Development of Gamma-ray Visualization Detector for NPP Decommission

Min Chul Kim,Gi Lim Kim,Young Il Na,Ji Hwan Yu,Hye Jin Jung,Hyu Chang Choi,Byong Sop Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Prevention of radiation hazards to workers and the environment in the event of decommissioning nuclear power plants is a top priority. To this end, it is essential to continuously perform radiation characterization before and during decommissioning. In operating nuclear power plants, various detectors are used depending on the purpose of measurement. Portable detectors used in power plants have excellent portability, but there is a limit to the use of a single measuring device alone to quantify radioactive contamination, nuclide analysis, and ensure representation of measurement results. In foreign countries, gamma-ray visualization detectors are being actively used for operating and decommissioning nuclear power plants. KHNP is also conducting research on the development of gamma-ray visualization detectors for multipurpose field measurement at decommissioning nuclear power plants. It aims to develop detectors capable of visualizing radioactive contamination, analyzing nuclides, estimating radioactivity, and estimating dose rates. To this end, we are developing related software according to the development process by purchasing sensors from H3D, which account for more than 75% of the US gamma-ray visualization detector market. In addition, field tests are planned in the order of Wolsong Unit 1 and Kori Unit 1 with Research reactor in Gongneung-dong in accordance with the progress of development. The detector will be optimized by analyzing the test results according to various gamma radiation field environments. The development detector will be used for various measurement purposes for Kori unit 1 and Wolsong

임상 ; 당뇨병 산모에서 출생한 신생아의 선천성 기형 진단에서의 산전 정밀 초음파 검사의 역할

김영아 ( Young A Kim ),임진아 ( Gin A Lim ),이병섭 ( Byong Sop Lee ),심재윤 ( Jae Yoon Shim ),원혜성 ( Hye Sung Won ),김애란 ( Ai Rhan Kim ),김기수 ( Ki Soo Kim ),이필량 ( Pil Ryang Lee ),김암 ( Ahm Kim ),피수영 ( Soo Young Pi ) 대한주산의학회 2010 Perinatology Vol.21 No.3

목적: 당뇨병 산모아는 비당뇨병 산모아에 비해 선천성 기형의 빈도가 높다. 연구자들은 당뇨병 산모에서 산전정밀 초음파의 태아 기형 선별 검사로서의 유용성을 확인하고 신생아에 대한 출생 후 진단적 검사의 필요성에 대하여 조사하였다. 방법: 2004년 1월부터 2009년 2월까지 서울아산병원에서 임신성 또는 임신전성 당뇨로 진단받고 태아 기형의 검사 목적으로 정밀 초음파가 시행 된 218명과 이들에서 출생한 226명의 신생아를 대상으로 하여 의무기록을 후향적으로 검토하였다. 산전 진단 소견과 출생 후 진찰 및 초음파 검사 결과와의 차이점을 비교하였다. 결과: 산전 정밀초음파 검사 및 산후 진찰 및 초음파 검사 상 각각 32명(14.2%) 및 35명(15.5%)에서 이상소견이 발견되었다. 산전 진단에서 정상이었던 194명의 신생아 중 7례(3.6%)에서만 산후에 선천성 기형이 발견되었으며 이들은 모두 신생아기 진찰로 진단되거나 의심할 수 있었다. 임신 24-28주경 공복 혈당이 120 mg/dL이상인 경우와 인슐린 치료를 받은 경우 선천성 기형의 발생이 의미 있게 증가하였다. 결론: 숙련된 산과의사에 의하여 시행된 산전의 정밀 초음파 검사는 당뇨병 산모아의 선천성 기형의 발견 및 신생아기 치료방침 결정에 유용하였다. 당뇨 산모아에서 산전 정밀 초음파 상 이상이 없었던 경우 신생아기의 추가적인 진단적 초음파 검사는 필요하지 않을 것으로 생각된다. Objective: Infants of diabetic mothers have higher incidence of congenital malformations compared with those of non-diabetic mothers. We investigated the usefulness of prenatal level II or “targeted” ultrasonography (TUS) as a diagnostic tool to identify congenital abnormalities in infants of diabetic mothers. Methods: We retrospectively reviewed the medical records of 218 mothers diagnosed as pregestational or gestational diabetes in whom prenatal TUS was performed in Asan Medical Center between 2004 and 2009. The prenatal TUS findings were compared with the congenital abnormalities found in the infants (n=226) of the diabetic mothers by physical examination and ultrasonography (including echocardiography). Maternal risk factors associated with congenital anomalies were also investigated. Results: The incidence of congenital anomalies was 14.2% (n=32) in prenatal TUS and 15.5% (n=35) postnatally, respectively. Only 7 cases (3.6%) out of the 194 infants with normal prenatal TUS findings were found to have congenital abnormalities diagnosed postnatally. All of the abnormalities in these 7 infants could be detected or suspected by physical examination after birth. Maternal fasting glucose level >120 mg/dL and insulin therapy were significant risk factors for predicting congenital abnormalities in infants of diabetic mothers. Conclusion: Prenatal TUS performed by experienced obstetricians had a good reliability in the diagnosis of congenital anomalies in infants of diabetic mothers. Need for universal screening of ultrasound or echocardiography in these infants should be questioned especially in the cases in which prenatal TUS was performed.

Considerations on the Linkage Between Decommissioning Cost Items and Items in the ISDC

Hyung-Woo Seo,Chan-Geun Park,Byong-Sop Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

In the case of decommissioning nuclear facilities in Korea, the dismantling activities will be initiated after obtaining approval from the regulatory agency for the Final Decommissioning Plan (FDP). The contents to be described in the FDP are presented in the notice of the Nuclear Safety and Security Commission, and among them, it is suggested to estimate and provide the basis for the decommissioning cost. The Work Breakdown Structure (WBS) is used for schedule management for the project, and the performance activities can be used as a cost management structure as well as schedule management. In order to easily manage the process and cost, the WBS structure can be normally used, and at this time, there might be a connection with ISDC if necessary. Therefore, this study aims to examine the link between activities from the WBS structure to ISDC in the decommissioning project. In general, the activities assumed as a WBS structure in this study in carrying out the decommissioning project were derived at the Level 1 and Level 2. Activities at Level 1 can be classified into project management costs, controlled area dismantling, conventional area dismantling, site remediation, waste treatment facility, construction/service, R&D, waste treatment and disposal, and characterization. For Level 2 activities, a cost activities embodied in Level 1 was derived. ISDC was developed by the OECD Nuclear Energy Agency (NEA) decommissioning cost estimation group, which improves ambiguous cost systems and presents common cost items for direct comparison between international decommissioning projects. The ISDC consists of Level 1, Level 2, and Level 3, where Level 1 represents the principal activity, Level 2 represents the activity group, and Level 3 represents the typical activity. The cost categories for typical activity at Level 3 consist of labour, investment, expenses, and contingency. In this study, the connection between WBS and ISDC was shown, and a comparison was made at Level 2. Directly, one-on-one matches have difficulties, and as much as possible, they were organized into similar items. We arranged the Level 2 linked to ISDC based on WBS. If there is a difficulty in one-on-one matches, it seems that the accurate cost calculation of ISDC items should consider the impact of additional cost distribution. Therefore, in order to calculate ISDC costs, it seems necessary to organize cost items of WBS in consideration of the ISDC.

Considerations to be Taken Into Account in the Industrial Risk Assessment Process for Dismantling Activities

Hyung-Woo Seo,Hyun-Min Kim,Byong-Sop Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

For licensees who face the decommissioning project for the first time, even if they can utilize their experience in operation, they should be well prepared and assessed for the risks of dismantling activities reflecting the characteristics of decommissioning. This can be included in the risk management of the decommissioning project, but what we want to discuss in this study is the evaluation of the industrial risk of the actual work before the dismantling work is carried out. We would like to focus more on the review of dismantling activities subject to industrial risk assessment and a series of processes for risk assessment. The dismantling work plan will need to obtain approval from the supervisory department before work on the Systems, Structures, and Components (SSCs) can be carried out. At this time, risk assessment may be included among many safety-related required documents, which are divided into radiological and non-radiological risks. The target activities at Level 1 level can include preparation for dismantling and maintenance of facilities, dismantling big components, removing the contamination of concrete structures, managing radioactive waste, etc. In addition, it can be composed of preparation work, removal of connections, lifting/installation, cutting, radiation/radioactivity measurement, and withdrawal as detailed work stages of each item’s activities. For domestic nuclear decommissioning projects, two major performance organizations, licensees and contractors, must be considered. Regarding risk assessment, the licensee will have a supervisory department controlling decommissioning activities and an HSE department at the site, and a process will need to be established in consideration of the contractor’s work organization. Therefore, activities in the risk assessment process may be established. In this study, risk assessment was reviewed as safety-related matters to be considered when carrying out the dismantling work. Safety-related risk assessment is a necessary procedure for performing practical dismantling activities, and this should be considered well in advance. Therefore, work activities and criteria were established for risk assessment, and the performance process was assumed to apply them. In terms of the performance organization and the responsibilities and roles of the processes to be performed by each organization were constructed, and this can be referred to in the process of preparing for the decommissioning project.

Sampling Design of SSCs for Characterization at Shut-Down Power Plant

Hyu Chang Choi,Jong Sun Hwang,Hye Jin Jung,Byong Sop Lim,Jong Hyuk Hong,Yo Gyeong Yun,Yoon Seok Kim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

The radiological characterization of SSCs (Structure, Systems and Components) plays one of the most important role for the decommissioning of KORI Unit-1 during the preparation periods. Generally, a regulatory body and laws relating to the decommissioning focus on the separation and appropriate disposal or storage of radiological waste including ILW (intermediate level waste), LLW (low level waste), VLLW (very low level waste) and CW (clearance waste), aligned with their contamination characteristics. The result of the preliminary radiological characterization of KORI Unit-1 indicated that, apart from neutron activated the RV (reactor vessel), RVI (reactor vessel internals), and BS (biological shielding concrete), the majorities of contamination were sorted to be less than LLW. Radiological contamination can be evaluated into two methods. Due to the difficulties of directly measuring contamination on the interior surfaces of the pipe, called CRUD, the assessment was implemented by modeling method, that is measuring contamination on the exterior surfaces of the pipes and calculating relative factors such as thickness and size. This indirect method may be affected by the surrounding radiation distribution, and only a few gamma nuclides can be measured. Therefore, it has limitation in terms of providing detailed nuclide information. Especially, α and β nuclides can only be estimated roughly by scaling factors, comparing their relative ratios with the existing gamma results. To overcome the limitation of indirect measurement, a destructive sampling method has been employed to assess the contamination of the systems and component. Samples are physically taken some parts of the systems or components and subsequently analyzed in the laboratory to evaluate detailed nuclides and total contamination. For the characterization of KORI Unit-1, we conducted the radiation measurement on the exterior surfaces of components using portable instruments (Eberline E-600 SPA3, Thermo G20-10, Thermo G10, Thermo FH40TG) at BR (boron recycle system) and SP (containment spray system) in primary system. Based on these results, the ProUCL program was employed to determine the destructive sample collection quantities based on statistical approach. The total of 5 and 8 destructive sample quantities were decided by program and successfully collected from the BR and SP systems, respectively. Samples were moved to laboratory and analyzed for the detail nuclide characteristics. The outcomes of this study are expected to serve as valuable information for estimating the types and quantities of radiological waste generated by decommissioning of KORI Unit-1.

Review on ASME Standard Guide for Preparing Characterization Plans for Decommissioning Nuclear Facilities

Hye Jin Jung,Kwang Ho Jo,Hyu Chang Choi,Byong Sop Lim,Jin Won Son 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

As an initial part of Kori-1 & Wolsung-1 Unit decommissioning planning, a characterization plan is developed to define the nature, extent and location of contaminants, determine sampling locations and protocols, determine quality assurance objectives for characterization, and define documentation requirements. The actual characterization of a facility is an iterative process that involves initial sampling according to the characterization plan, field management (such as labeling, packaging, storing, and transport) of the samples, laboratory analysis, conformance to the data quality objectives (DQOs), and then identifying any additional sampling required, refining the DQOs, and modifying the characterization plan accordingly. The final product of the facility characterization is a document that describes the type, amount, and location of contaminants that will require consideration and removal during the decommissioning operations sufficient to prepare a decommissioning plan. In this study, implementing a characterization plan, developed in accordance with this standard, will result in obtaining or deriving the above information.

Review on Influencing Factors for the Selection of the Waste Routes in a Decommissioning Project

Hye Jin Jung,Hyu Chang Choi,Kwang Ho Jo,Byong Sop Lim,Jin Won Son 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

Kori Nuclear Power Plant Unit 1, which began operating in 1978, is Korea’s oldest commercial nuclear reactor. The reactor was permanently shut down in June 2017, and now the decommissioning process has begun. The decommissioning process will generate a significant amount of waste that requires appropriate management to minimize the impact on the environment and human health. And the waste routing, i.e. the activities and logistics for managing the material generated, is a key point in a decommissioning project. It determines the routes from the material inventory to the envisaged material end states. In this study, we review on several factors for the selection of the waste routes in a decommissioning project. In terms of sustainability, the ‘waste hierarchy’ should be applied to routing materials from nuclear facilities. According to the waste hierarchy, the preferred end state is reuse or recycling of the waste as material or, more preferably, the avoidance of waste generation. In addition, treatments (such as decontamination and thermal treatment) that can reduce the volumes requiring disposal as radioactive waste should be considered. Another important parameter is the need to secure availability and capacity of waste routes. Short-term bottlenecks or any delay in the removal of the waste from the site often has an impact on other site activities. If possible, at least two alternative waste routes should be identified for the main categories of waste and kept available throughout the decommissioning project. All routes should be direct to the material end state if possible, but it is more important that waste is removed from the site so that other site operations are not impeded.

Dose Assessment Method for Heavy Water Reactor Decommission Workers

Min Chul Kim,Gang Woo Ryu,Young Il Na,Hyu Chang Choi,Hyun Jun Jo,Byong Sop Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.1

KHNP is carrying out international technical cooperation and joint research projects to decommission Wolsong unit 1 reactor. Construction data of the reactor structures, experience data on the pressure tube replacement projects, and the operation history were reviewed, and the amount of dismantled waste was calculated and waste was classified through activation analysis. By reviewing COG (CANDU owners Group) technical cooperation and experience in refurbishment projects, KHNP’s unique Wolsong unit 1 reactor decommissioning process was established, and basic design of a number of decommissioning equipment was carried out. Based on this, a study is being conducted to estimate the worker dose of dismantling workers. In order to evaluate the dose of external exposure of dismantling workers, detailed preparation and dismantling processes and radiation field evaluation of activated structures are required. The preparation process can be divided into dismantlement of existing facilities that interfere with the reactor dismantling work and construction of various facilities for the dismantlement process. Through process details, the work time, manpower, and location required for each process will be calculated. Radiation field evaluation takes into account changes in the shape of structures by process and calculates millions of areas by process, so integrated scripts are developed and utilized to integrate input text data. If the radiation field evaluation confirms that the radiation risk of workers is high, mutual feedback will be exchanged so that the process can be improved, such as the installation of temporary shields. The results of this study will be used as basic data for the final decommissioning plan for Wolsong unit 1. By reasonably estimating the dose of workers through computer analysis, safety will be the top priority when decommissioning.

A Study on the Decommissioning of Calandria in Wolsong Unit 1

Min Chul Kim,Gang Woo Ryu,Young Il Na,Hyun Min Kim,Hyu Chang Choi,Byong Sop Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2

KHNP is conducting research to decommission Wolsong Unit 1 Calandria. Establishment of preparation and dismantlement processes, conceptual design of equipment and temporary radiation protection facilities, and waste management are being established. In particular, the ALARA plan is to be established by performing exposure dose evaluation for workers. This study aims to deal with the methodology of evaluating exposure dose based on the calandria dismantling process. The preparation process consists of bringing in and installing tooling and devices, and removing interference facilities to secure work space. The main source term for the preparation process is the calandria structure itself and crud of feeders. In the case of the dismantlement process, a structure with a shape that changes according to the process was modeled as a radiation source. It is intended to estimate the exposure dose by selecting the number of workers, time, and location required for each process in the radiation field evaluated according to the preparation and dismantlement process. In addition, it is also conducting an evaluation of the impact on dust generated by cutting operations and the human impact of C-14, H-3, which are specialized nuclides for heavy water reactors. KHNP is conducting an exposure dose evaluation based on a process based on the preparation and dismantlement process for decommissioning Calandria through computation code analysis. If additional worker protection measures are deemed necessary through dose evaluation according to this methodology, the process is improved to prepare for the dismantling of worker safety priorities.

Evaluation of immunogenicity of the 2008-2009 seasonal influenza vaccines by microneutralization test

Kim, Seung Youn,Kim, Yun Kyung,Eun, Byung Wook,Kim, Nam Hee,Kang, Eun Kyeong,Lee, Byong Sop,Lim, Jung Sub,Lee, Jun Ah,Kim, Dong Ho The Korean Pediatric Society 2012 Clinical and Experimental Pediatrics (CEP) Vol.55 No.12

Purpose: For evaluating the immunogenicity of an influenza vaccine, the microneutralization (MN) test has a higher sensitivity and specificity as compared to the hemagglutination inhibition (HI) test. However, the MN test is more time consuming and is difficult to standardize. We performed the MN test to determine its usefulness as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines. Methods: We compared the MN test with the HI test using 50 paired samples taken from a previous clinical study (2008-2009) in Korean children under 18 years of age. Results: The linear correlation coefficients of the 2 tests for H3N2, H1N1, and influenza B were 0.69, 0.70, and 0.66, respectively. We identified a high index of coincidence between the 2 tests. For an influenza vaccine, the postvaccination seroprotection rates and seroconversion rates determined by the MN test were 78.0% and 96.0%, 90% and 42.0%, and 42.0% and 48.0% for H3N2, H1N1, and influenza B, respectively. Geometric mean titer fold increases of H3N2, H1N1, and influenza B were 2.89, 5.04, and 4.29, respectively, and were 2.5-fold higher. We obtained good results in the evaluation of the immunogenicity of the 2008-2009 seasonal influenza vaccines. Conclusion: We found that the MN test was as effective as the HI test. Therefore, we suggest that the MN test can be used as an alternative or complementary test to the HI test for evaluating the immunogenicity of influenza vaccines.