• Nuclear Engineering and Technology
• /
• 제54권9호
• /
• pp.3235-3241
• /
• 2022

The Korea Atomic Energy Research Institute (KAERI) is planning the construction of the KIJANG Research Reactor (KJRR) for stable supply of ⁹⁹Mo. The Fission ⁹⁹Mo Production Process (FMPP) of KJRR produces solid waste such as spent uranium cake and alumina cake, and liquid waste in the form of intermediate level liquid waste (ILLW) and low level liquid waste (LLLW). This study thus established the operating range and optimum operating conditions for the cementation of ILLW from FMPP. It also evaluated whether cement waste form samples produced under optimum operational conditions satisfy the waste acceptance criteria (WAC) of a disposal facility in Korea (Korea radioactive waste agency, KORAD). Considering economic feasibility and safety, optimum operational conditions were achieved at a w/c ratio of 0.55, and the corresponding salt content was 5.71 wt%. The cement waste form samples prepared under optimum operational conditions were found to satisfy KORAD's WAC when tested for structural stability and leachability. The results indicate that the proposed cementation conditions for the disposal of ILLW from FMMP can be effectively applied to KJRR's disposal facility.

• 한국세라믹학회지
• /
• 제25권5호
• /
• pp.455-464
• /
• 1988

Concrete used for radwaste container should have excellent properties such as mechanical strength, water-tightness, durability, etc. In order to improve such properties of ordinary portland cement concrete, superplasticizer, steel fiber, and/or epoxy resin were added to ordinary portland cement concrete respectively. Various concrete specimens were prepared and the physical properties of each concrete specimen were tested. From the experimental results, the properties of steel fiber and epoxy resin reinforced concrete were proved to be better qualified than others for low-and intermediate-level radwaste container.

• Journal of Radiation Protection and Research
• /
• 제48권2호
• /
• pp.77-83
• /
• 2023

Background: The purpose of this study is to purify uranium (U[VI])-contaminated soil-flushing effluent using the precipitation-distillation process for clearance. Precipitation and distillation are commonly used techniques for water treatment. We propose using a combination of these methods for the simple and effective removal of U(VI) ions from soil-flushing effluents. In addition, the U concentration (Bq/g) of solid waste generated in the proposed treatment process was analyzed to confirm whether it satisfies the clearance level. Materials and Methods: Uranium-contaminated soil was decontaminated by soil-flushing using 0.5 M sulfuric acid. The soil-flushing effluent was treated with sodium hydroxide powder to precipitate U(VI) ions, and the remaining U(VI) ions were removed by phosphate addition. The effluent from which U(VI) ions were removed was distilled for reuse as a soil-flushing eluent. Results and Discussion: The purification method using the precipitation-distillation process proposed in this study effectively removes U(VI) ions from U-contaminated soil-flushing effluent. In addition, most of the solid waste generated in the purification process satisfied the clearance level. Conclusion: The proposed purification process is considered to have potential as a soil-flushing effluent treatment method to reduce the amount of radioactive waste generated.

• Nuclear Engineering and Technology
• /
• 제55권7호
• /
• pp.2489-2497
• /
• 2023

Co and Eu impurities in the SSCs are nuclides that dominantly influence the neutron-induced radioactive inventory in metal and concrete radwastes (radioactive wastes) during NPP decommission. The impurity concentrations provided by NUREG/CR-3474 were used for the practical range of Co and Eu impurity concentrations to be applied to the code calculations. Metal structures near the core were evaluated to be ILW (intermediate-level waste) for the whole range of Co impurity concentration, so the boundary line between ILW and LLW (low-level waste) has no change for the whole concentration range provided by NUREG/CR-3474. Also, the boundary line between VLLW (very low-level waste) and CW (clearance waste) in the concrete shield could alter a little depending on the Eu impurity concentration within the range provided by NUREG/CR-3474. From this work, it is found that the concentration of material impurities of SSCs gives no critical impact on determining radwaste levels.

• 방사성폐기물학회지
• /
• 제10권2호
• /
• pp.117-123
• /
• 2012

한국원자력연구원 내 저장중인 중 저준위방사성폐기물의 안전한 영구처분을 위하여 방사성폐기물처리시설에서는 이들 저장폐기물의 핵종재고량 평가를 위한 드럼핵종분석장치의 도입을 기획하고 있으며, 이 장치를 운영하고 유지보수하기 위한 전용의 평가시설 구축을 추진하고 있다. 이 평가시설 외부에는 제1방사성폐기물저장시설이 인접하여 있으며 내부에는 평가대상드럼들과 드럼핵종분석장치의 밀도보정용 선원 등이 존재함으로 이들이 방사선원항으로 작용하여 평가시설 내 외부의 선량률에 영향을 미치게 된다. 따라서 방사선원항 주변의 콘크리트 구조물에 대한 방사선차폐 영향을 평가하여야 한다. 본 연구에서는 MCNP 코드를 이용하여 해당 방사선원항으로부터 평가시설 내부 방사선관리구역을 둘러싸고 있는 콘크리트 구조물에 대한 방사선 안전성을 평가하였다. 평가결과 현재 고려되고 있는 콘크리트 구조물의 약 30 cm 두께는 해당 방사선원항으로부터의 방사선을 차폐하기에 충분한 것으로 확인되었다.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2003년도 가을 학술논문집
• /
• pp.632-635
• /
• 2003

원자력 발전소에서 배출되고 있는 방사성 폐기물의 운반 및 처분과 관련하여 규제가 예상되는 대상 핵종을 선정하고, 특히 방사능 계측기로 직접 측정이 불가능한 드럼 내 방출핵종에${\alpha}{\cdot}{\beta}$ 대한 농도 예측과 검증방법에 관한 연구가 진행되고 있다. 본 연구에서는 $\beta$방출 핵종이면서 반감기가 매우 긴 $^129I(t_{1/2}=1.57{\times}10^7)$의 정량을 위하여 모의 폐기물 중에 함유되어 있는 요오드의 분리 및 회수율을 측정하였다. 모의 폐기물중 가용성 및 난용성 시료의 전처리 방법으로 혼합산 분해법과 알칼리 용융방법을 각각 이용하였으며 두 방법에 대한 요오드의 회수율을 비교하였다. 요오드의 측정방법으로 이온 크로마토그라피를 이용하였으며 매질의 음이온성분에 의한 영향은 없었다. 두 방법의 전체 공정에서 혼합산분해에 의한 요오드의 회수율은 76.7 (RSD 1.7%)이고 알칼리용융에 의한 방법에서 모직물의 경우에는 74.3(RSD 2.2%)이고 Resin의 경우 56.5(5.6%)로 각각 나타났다.

• 시스템엔지니어링학술지
• /
• 제17권1호
• /
• pp.65-75
• /
• 2021

When the decommissioning of South Korea nuclear power plants is promoted in earnest with the permanent shutdown of Kori Unit 1 in 2017, a large amount of various types of radioactive waste will be generated. For minimal generation and safe management of decommissioning waste, the waste should be made by appropriate classification of the dismantling waste characteristics in accordance with physical, chemical and radiological characteristics to meet the acceptance criteria of disposal facilities. Replacing the preliminary inspection at the site for the compliance of the waste acceptance criteria (WAC) of medium and low-level radioactive waste with the generator's own radioactive waste certification program (WCP), from the perspective of disposal, the optimization of waste management at the national level contributes to the efficient availability of disposal, such as the processing of non-conforming radioactive wastes at the site. To this end, it is important to evaluate radioactivity in each system and area such as nuclear reactors before decommissioning is carried out in earnest, and the prior removal of harmful wastes is important. From waste collection to waste disposal, decommissioning waste should be managed at each stage in consideration of the acceptance criteria of disposal facilities to minimize the generation of non-conforming waste.

• Nuclear Engineering and Technology
• /
• 제54권7호
• /
• pp.2418-2426
• /
• 2022

The grouping analysis is a method guided by the Korea Radioactive Waste Agency for efficient analysis of radioactive waste for disposal. In this study, experiments to verify the adequacy of grouping analysis were conducted with radioactive soil, concrete, and dry active waste in similar environments. First, analysis results of the major radionuclide concentrations in individual waste samples were reviewed to evaluate whether wastes from similar environments correspond to a single waste stream. As a result, the soil and concrete waste were identified as a single waste stream because the distribution range of radionuclide concentrations was "within a factor of 10", the range that meet the criterion of the U.S. Nuclear Regulatory Commission for a single waste stream. On the other hand, the dry active waste was judged to correspond to distinct waste streams. Second, after analyzing the composite samples prepared by grouping the individual samples, the population means of the values of "composite sample analysis results/individual sample analysis results" were estimated at a 95% confidence level. The results showed that all evaluation values for soil and concrete waste were within the set reference values (0.1-10) when five-package and ten-package grouping analyses were conducted, verifying the adequacy of the grouping analysis.

• 분석과학
• /
• 제9권1호
• /
• pp.20-25
• /
• 1996

암석 및 토양 등의 지질시료에 미량으로 존재하는 우라늄과 토륨을 파장분산형 X-선 형광분석법을 사용하여 정량하였다. X-선관의 target 물질로 사용되는 Rh의 산란선을 내부 표준물질로 사용하였다. 토륨의 경우는 50초, 그리고 우라늄의 경우는 400초 동안 측정하였을 때, 우라늄과 토륨의 X-선 형광분석결과는 중성자방사화분석 및 유도결합플라즈마 원자방출분광분석의 결과와 큰 차이를 보이지 않았으며 10% 이내의 정밀도와 15% 이내의 정확도를 보여 주었다.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1995년도 추계학술발표회논문집(2)
• /
• pp.879-884
• /
• 1995

The results of performance assessment analyses have shown that the long-lived radionuclides such as I-129 control the potential individual dose impact to the public. I-129 is difficult-to-measure(DTM) in low-level waste because it is non-gamma emitting radionuclides and exists at extremely low concentrations in radioactive waste generated by nuclear reactors. In this study, computer modeling technique to predict release rate of I-129 is developed to provide another tools far performance assessment of land disposal facilities and characteristics of radwaste. Model suggested in this study will give conservative values of I-129 release rate far determination of radwaste characteristics. More detailed approach is implemented to account for release conditions of fuel source-nuclides. 1-131 concentration measured from reactor coolant and released fraction from tramp fuel have dominant roles in calculating release rate of I-129 with fuel defect conditions.