Bolboschoenus planiculmis has been acknowledged as a key species in whooper swans (Cygnus cygnus) habitat by providing food for this migratory waterfowl. B. planiculmis wetlands are being degraded by water shortages and salinization caused by anthropogenic activities and climate changes. In 2004, the distribution of B. planiculmis in the tidal flats of the Nakdong Estuary was 2,475,568 m2, and in 2021, the distribution area was 798,731 m2, which decreased by 32.3%. In order to restore the degraded B. planiculmis wetlands, shoot transplantation and seed sowing were tentatively used in three places with different salinity and water levels. The average density per unit area in September at the optimal growth period after planting were A (fresh water level 50 cm) 58±15.65 m-2, B (brackish water level 0~5 cm) 188±63.83 m-2, C (brackish water level 0 cm or less) 188±45.13 m-2. The tubers were observed as A 0 g dw m-2, B 25.32±2.94 g dw m-2, and C 13.39±0.91 g dw m-2. Tubers were distributed in the soil, with only 3.0% at the 10~20 cm depth but 97.0% at the 0~10 cm depth. In contrast, the germination rate of B. planiculmis seeds was observed to be 0%. Results of this study provide technical support for the restoration of B. planiculmis wetland and the improvement in the quality of whooper swans habitat.

낙동강하굿둑의 건설로 원활한 용수 공급이 이루어졌으나, 하구 수생태계의 종적 연결성을 단절시켰다. 이에 낙동강 하굿둑 개방에 대한 사회적 요구가 지속적으로 제기되어 왔으며, 2017년부터 낙동강하구역 기수생태계 복원을 위한 노력이 본격화되었다. 낙동강 하구에는 다양한 어종이 서식해 왔으며, 이들의 서식·이동 특성은 상이하므로 이를 고려한 수문운영은 기수생태계 복원에 필수적이다. 이에 본 연구에서는 낙동강하구에 서식·이동하는 어류를 모니터링을 통해 확인하였으며, 방류 시 수문운영 형태별, 개도별 평균 유속을 산출하여, 어종에 따른 원활한 소상 가능성을 분석하였다. 또한 대상어종을 선정하고, 주 분포 수심에 따른 수문운영 형태를 제시하는 등 낙동강 하구역의 기수생태계 복원을 적극적으로 수행하기 위한 수문운영 방안을 제시하였다.

본 연구는 낙동강하굿둑 개방으로 인한 하구 인근의 식생 변화를 모니터링하기 위해서 현재 식생에 대해서 조사하고, 하구수변식생평가지수를 통해서 식생의 건강성을 평가하였다. 장기모니터링의 첫 번째 조사로 낙동강하구 인근의 6개 구역에 대해서 2021년 7월과 10월 2차례 수행하였으며, 식생모니터링 및 수생식물, 수변식물, 육상식물의 종조성, 분포밀도 조사를 진행하였다. 조사구역 내에서 확인된 관속식물은 82과 192속 230종 1아종 28변종 3품종 262분류군으 로 파악되었다. KREVI를 통한 식생건강성 평가 결과는 1, 6번 구역이 두 차례 조사에서 모두 ‘매우 좋음’ 등급이었고, 2, 4번 구역은 ‘매우 좋음’에서 ‘좋음’으로 2차 조사결과가 낮게 산정되었으며, 3, 5번 구역은 1차 조사에 비해 2차 조사결과가 1등급 상향되었다. 조사구역 대부분의 건강성 등급이 대체로 높게 평가되었다. 기수역 조성을 위한 수문개 방 후 잠재자연식생의 대부분은 갈대군락으로 이루어질 것으로 예상되며, 수역과 인접한 버드나무군락의 경우 다소 면적이 좁아질 수 있으나 군락 형태를 유지하고, 염분농도가 매우 낮은 내륙지역 담수역의 경우 갈대가 대부분을 차지하며, 일부 물억새, 부들 등의 군락이 분포할 것으로 사료된다. 장기모니터링을 통해 이런 예상되는 변화를 관찰하 며, 건강한 기수역이 조성될 수 있도록 하굿둑 개방 운영방안 등 대책이 수립되어야 할 것으로 판단된다.

Radioactive source terms are important factor in design, licensing and operation of SMR (Small Modular Reactor). In this study, regulatory requirements and evaluation methodology for normal operation on NuScale SMR, which received standard design certification approval on September 11, 2020 from US NRC, are reviewed. The radioactive waste management system of nuclear power reactor should be designed to limit radionuclide concentration in effluents and keep radioactive effluents at restricted area boundary ALARA according to 10 CFR 20 and 10 CFR 50 Appendix I. Also, in general, the coolant source term to calculate the off-site radiological consequences for normal operation of SMR should be determined by using models and parameters that are consistent with regulatory guide 1.112, NUREG- 0017 and the guidance provided in ANSI/ANS-18.1-1999, and the result should be corrected by reflecting the design characteristics of SMR. The coolant source term of NuScale, unlike the case of large NPPs, cannot rely solely on empirical source term data, because the NuScale source term is based on first principle physics, operational experience from recent industry, and lessons learned from large PWR operation. Fission products in reactor coolant are conservatively calculated using first principle physics in SCALE Code assuming 60 GWD/MTU. The release of fission products from fuel to primary coolant based on industry operational experience is determined as fuel failure fraction of 0.0066% for normal operation source term and 0.066% for design basis source term while coolant source term of large NPP is calculated by using ANSI/ANS-18.1 for normal operation and fuel failure fraction of 1% for design basis source term. Water activation products in reactor coolant are calculated from first principles physics and corrosion activation products are calculated by utilizing current large PWR operating data (ANSI/ANS 18.1- 1999) and adjusted to NuScale plant parameters. Also, because ANSI/ANS 18.1-1999 is not based on first principle physics models for CRUD generation, buildup, transport, plate-out, or solubility, NuScale has incorporated lessons learned by using ERPI’s primary water chemistry and steam generator guidelines to ensure source term is conservative and design of materials used cobalt reduction philosophy to help ensure the coolant source term are conservative. Based on the coolant source term calculated according to the above-described method, the annual releases of radioactive materials in gaseous and liquid effluents from NuScale reactor are evaluated. Currently, Small Modular Reactors such as ARA, SMART 100 are under review for licensing in Korea. This study will be helpful to understand how the reactor coolant system source terms are defined and evaluated for SMR.

In Korea, the NUREG-0017 methodology based on realistic model for reactor coolant concentrations are used to estimate the annual radioactive effluent releases for normal operation of nuclear power plant. The realistic model to estimate the radionuclide concentrations in reactor coolant is formulated as a standard, ANSI/ANS-18.1. This standard has provided a set of the reference radionuclide concentrations and adjustment factors for estimating the radioactivity in the principal fluid systems of target plant. Since ANSI/ANS-18.1 was first published in 1976, it was revised in 1984, 1999, 2016, and most recently in 2020. Therefore, this study analyzed revision history of assessment methodology of radioactive source term of light water reactors, which is ANSI/ANS-18.1. Assessment methodology of radioactive source term given ANSI/ANS-18.1 is by using radionuclide concentrations for reactor coolant and steam generator fluid of the reference plant and adjustment factors, which is modifying radioactive source term according to differences in design parameters between reference plant and target plant. There are three type of reference plant: PWR with u-tube steam generator, PWR with once-through steam generator, and BWR. This study analyzed for PWR with u-tube steam generator. Although the standard was revised, evaluation methodology and formula of adjustment factor have been retained, but some of items have been revised. First revision item is reduction of the number of radionuclides and decrease of radioactive concentration in reactor coolant. In the 1976 version of the standard, there were 71 target radionuclides, but the target nuclides have reduced to 57 in 1984 and 56 after 1999. In the case of radioactive concentration in reactor coolant, as the version of standard was updated, the radioactive concentration of 18 nuclides in 1984, 14 nuclides in 1999, and 25 radionuclides in 2016 was decreased. Most of the radionuclides with decrease radioactivity concentration were fission product, it is resulted from improvement of nuclear fuel performance. Second revision item is change of adjustment factors. After the revision in 2016, the adjustment factors for zinc addition plants using natural or depleted zinc are changed. This study analyzed revision history of evaluation methodology of radioactive source term of light water reactors. Furthermore, result of this study will be contributed to the improvement of understanding of assessment methodology and revision history for the radioactive source term.

목적: 안경사 직무를 분석하여 국가시험 교과목과의 연계성을 확인하고 대학의 시험과목 비율과 교육과정 개발에 기초자료를 제공한다. 방법 : 안경사 872명과 안경광학과 교수 99명을 대상으로 5개의 직무영역과 18개의 일로 구성된 설문을 조사하여 분석하였다. 결과 : 안경사 직무분석에서 작업의 중요도와 필요도가 모두 높은 영역에서 필요능력인 지식과 기술을 도출하여 안경조제가공(39.1%), 시력검사(27.5%) 및 콘택트렌즈(14.8%), 기타(18.6%)의 비중을 통해 안경사 1차 직무 분석(2000년)과 비교해 검안안경사 분야로 안경사의 직무가 이동된 것으로 나타났다. 결론: 안경사 직무에서의 변화는 안경사 국가시험과 대학의 교육과정에 적절히 반영되어야 할 것으로 생각된다.