According to acceptance of radioactive waste, homogeneous waste such as concentrated liquid waste and spent resin must be solidified to reduce radiological hazards and protect public health and the ecology. However, when using a High Integrity Containers (HIC), it is stated that homogeneous waste can be disposed of without applying the solidification test requirements. PCHIC, developed in korea, is composed of polyethylene (PE, interior), polymer concrete (PC, filler), and steel (external reinforcement). Currently, PC-HIC will be used as a packaging container for low-level liquid waste and spent resin waste. PE has a lower shielding efficiency compared to PC, but it offers the economic advantage of lower production costs. Therefore, cost savings can be expected if very low-level waste is packaged and disposed of HIC made only of PE materials (PEHIC). Despite the economical advantage of PE-HIC, PE-HIC has not been used domestically since NRC (Nuclear Regulatory Commission) reported that PE-HIC couldn’t meet the mechanical integrity criteria for radiation exsure. However, according to IAEA (International Atomic Energy Agency) research, it has been reported that mechanical integrity of PE-HIC is not affected when the absorbed dose is below 50 kGy. Therefore, in this study, Radiological impact of VLLW packaged into PE-HIC is evaluated to confirm that the absorbed dose is below 50 kGy, which then be used to assess feasibility of PE-HIC to be used as packaging and disposal container for radioactive waste. Radiological impact of VLLW packaged into PE-HIC is evaluated to confirm that the absorbed dose is below 50 kGy, which then be used to assess feasibility of PE-HIC to be used as packaging and disposal container for radioactive waste. The feasibility of using PE-HIC as packaging-disposal containers for radioactive waste will be reviewed. In this study, the radiation effects of only waste packaged in PE-HIC were considered, and additional assumptions are as follows. - Nuclides subject to radioactivity evaluation: Co-60, Cs-137 - Radioactivity concentration: very low-level radioactive wastel concentration limit - Target waste: waste resin - PE-HIC dimensions: outer diameter: 1,194 mm, height: 1,290 mm, and thickness 88 mm (PCHIC internal PE shape) Considering the above assumption, the exposure rate was evaluated using the MicroShield program. Since the density of PE-HIC in the MicroShield program was assumed as the density of air. The absorbed dose was recalculated through density correction of the derived exposure rate. As a result, it was confirmed that absorbed dose was about 2-3 mGy over 300 years. As a result of dose evaluation by MicroShield, it is judged that the mechanical integrity of PEHIC as an packaging of VLLW can be proved by confirming that the absorption dose irradiated to PE-HIC by internal waste is less than 50 kGy.

Licensing for the application of the Polymer Concrete High Integrity Container (PC-HIC) to nuclear power plants has been completed or is in progress. Approval for the expanded application to all domestic nuclear power plants has been completed to utilize the 860 L PC-HICs for the 2nd stage surface repository, and the regulatory body is reviewing the license application to use the 510 L PCHICs for the 1st stage underground repository in the representative nuclear power plants. The 860 L PC-HICs, which have been licensed for all domestic nuclear power plants, will be used for safe storage management and disposal of low-dose dried concentrate waste and spent resin, and a total of 100 units is expected to be supplied to representative nuclear power plants that have been licensed first. The 510 L PC-HICs are planned to be used for underground disposal of high-dose spent resin and dried concentrate waste. Prior to the application of PC-HICs to nuclear power plants and disposal to the repository, it is necessary to establish realistic and reasonable requirements through close consultations between waste generator and disposal operators to ensure the suitability for disposal of PC-HIC packages and to carry out disposal delivery and acceptance work. Since the Polymer Concrete High Integrity Container (PC-HIC) has long-term integrity of more than 300 years and the barrier does not temporarily collapse, spent resin and dried concentrate waste, which are radioactive wastes to be solidified, can be disposed of much more safely in PC-HIC packages than solidified types. Acceptance criteria for the PC-HIC packages should be prepared fully reflecting the advantages of PC-HIC, and quality assurance methods for physical/chemical/radiological characterization results based on the Waste Certification Program (WCP) should be supported. In addition, infrastructure should be secured for safe transportation, handling, and storage of the PC-HIC packages. In this paper, we have tried to find a reasonable acceptance criteria, quality assurance method, and infrastructure level according to the dose and disposal conditions of PC-HIC packages.

Domestic NPPs had produced the paraffin-solidifying concentrate waste (PSCW) for nearly 20 years. At that time radioactive waste management policy of KHNP was to reduce the volume and to store safely in site. The PSCW has been identified not to meet the leaching index after introducing the treatment system. PSCW has to be treated to meet current waste acceptance criteria (WAC) for permanent disposal. PSCW consists of dried concentrate 75% and paraffin 25% of volume. When PSCW is separated into a dried concentrate and a paraffin by solubility, total volume separated is increased twice. Final disposal volume of dried concentrate can reach to several times when solidifying by cement even considering exemption. Application of polymer solidification technology is difficult because dried concentrate is hard to make form to pellet. When PSCW is packaged in High Integrity Container (HIC), volume of PSCW is equal to the volume before package. The packaging process of HIC is simple and is no necessary of large equipment. It is important to recognize that HIC was developed to replace solidification of waste. HIC has as design goal a minimum lifetime of 300 years under disposal environment. The HIC is designed to maintain its structural integrity over this period, to consider the corrosive and chemical effects of both the waste contents and the disposal environment, to have sufficient mechanical strength to withstand loads on the container and to be capable of meeting the requirements for a Type A transport Package. The Final waste form is required for facilitating handling and providing protection of personnel in relation to solidification, explosive decomposition, toxic gases, hazardous material, etc. Structural stability of final waste form is required also. Structural stability of the waste can be provided by the waste itself, solidifying or placing in HIC. Final waste form ensure that the waste does not structurally degrade and affect overall stability of the disposal site. The HIC package contained PSCW was reviewed from several points of view such as physicochemical, radiological and structural safety according to domestic WAC. The result of reviewing shows that it has not found any violation of WCP established for silo type disposal facility in Gyeongju city.

High Integrity Container (HIC) made of polymer concrete was developed for the efficient treatment and safe disposal of radioactive spent resin and concentrate waste in consideration of the disposal requirements of domestic disposal sites. Permission for application of Polymer Concrete High Integrity Container (PC-HIC) to the domestic nuclear power plants (NPPs) has been completed or is under examination by the regulatory agency. In the case of 860 L PC-HIC for very-low-level-waste (VLLW) or low low-level-waste (LLW), the application of four representative NPPs has been approved, and the license for extended application to the rest NPPs is also almost completed. A licensing review is also underway to apply 510 L PC-HIC for intermediate and low-level-waste (ILLW) to representative nuclear power plants. In order to handle and efficiently store and manage PC-HICs and high-dose PCHIC packages, a gripper device that can be remotely operated and has excellent safety is essential, and the introduction of NPPs is urgent. The conventional gripper device developed by the PC-HIC manufacturer for lifting test to evaluate the structural integrity of PC-HIC requires a rather wide storage interval due to its design features, and does not have a passive safety design to handle heavy materials safely. In addition, work convenience needs to be reinforced for safety management of high radiation work. Therefore, we developed a conceptual design for a gripper device with a new concept to minimize the work space by reflecting on-site opinions on the handling and storage management conditions of radioactive waste in NPPs, and to enhances work safety with the passive safety design by the weight of the package and the function of checking the normal seating of the device and the normal operation of the grip by the detector/indicator, and to greatly improves the work efficiency and convenience with the wireless power supply function by rechargeable battery and the remote control function by camera and wireless monitoring & control system. Through design review by experts in mechanical system, power supply and instrumentation & control fields and further investigations on the usage conditions of PC-HICs, it is planned to facilitate preparations for the application of PC-HIC to domestic NPPs by securing the technical basis for a gripper device that can be used safely and efficiently and seeking ways to introduce it in a timely manner.

HIC refers to a radwaste packaging container that can maintain integrity for more than 300 years in the general underground environment and disposal conditions in Korea. For HIC, the integrity of containers is verified according to the HIC regulation guideline for LLW and ILW disposal. Existing material tests include mechanical stability, permeability resistance, corrosion properties, chemical durability and biological resistance. In this study, a chemical durability test was conducted to prove the suitability of the HIC material by measuring the degree of chemical influence other than corrosion from the disposal environment. The chemical resistance evaluation method was used to simulate the disposal environment in the underground repository, and the amount of change in the physical properties of the degraded polymer concrete specimens according to the test time was confirmed. The technical standards considered leaching of material components, sulfation attack, acid attack, alkali, carbonate, and salt crystallization. The compressive strength and weight change of the specimens with time were checked by immersing them in a chemical solution that could leak major hazardous substances and wastes in the groundwater of the repository for several months. In addition, in order to evaluate the integrity in condition severe than the disposal environment, a flow was applied to a chemical solution having a concentration twice that of the basic chemical resistance test conditions, and the test period was extended twice to accelerate the deterioration of the specimen.

고밀도폴리 에틸렌 고건전성용기에 담은 폐수지의 운반을 위해 원전 폐수지의 방사능 분석결과를 사용하여 운반물 등급 분류방법을 도출하였다. 원전 폐수지의 방사능 분석결과로부터 폐수지 내 핵종 존재비를 구하였고, 폐수지의 표면선량률로 핵종재고량을 평가하기 위해 MCNP 코드로 방사능대선량 환산인자를 모사하였다. 이로부터 고밀도폴리에틸렌 고건전성용기에 담은 폐수지에 대한 A형 운반물과 B형 운반물의 경계값은 1.19 TBq 이고 이를 표면선량으로 환산한 결과는 124.2 mSv/h임을 알 수 있었다.

원전에서 발생하는 건조폐수지를 함유한 고건전성용기(HIC, high integrity container)를 운반하기 위한 HIC 운반용기는 내용물의 높은 방사능으로 인하여 원자력법 및 IAEA의 안전수송규정의 B형 운반용기의 요건을 따라야 하고 정상운반 및 운반사고조건에 대하여 구조적 건전성을 유지하여야 한다. 운반용기는 최대손상을 야기하는 위치에서 단단한 바닥면 위로 9 m 높이에서의 자유낙하충격 및 연강봉 위로의 1 m 높이에서의 낙하충격을 견디어야 한다. HIC 운반용기의 개념설계를 위하여 9 m 자유낙하 및 1 m 파열조건에 대하여 ABAQUS 전산코드를 이용한 3차원동적 구조해석을 수행하고 건전성을 평가하였다.