• 터널과지하공간
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• 제11권2호
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• pp.132-145
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• 2001

핵변환 후 영구 처분될 가압경수로 및 중수로용 사용후 핵연료에 대한 인간 생태계에 대한 영향을, 직접 처분하는 경우와 비교해 보았다. 심지층 처분된 용기에 저장된 사용후 핵연료로부터 유출된 방사성 핵종들이 공학적 방벽을거쳐 결정질 기반암 내 균열대를 통해 지하수의 흐름을 따라 이동하면서, 다양한 지질 및 암종을 거쳐 생태 환경으로 도달한다는 핵종 유출 시나리오 중 가장 보수적인 시나리오인 우물 시나리오에 대한 위해도를 평가하여 상대인 환경친화성을 정량적으로 제시하였다. 현재 국내에 가속기와 미임계형 원자로를 함께 사용하는 핵변환 시스템과 임계형 원자로와 같은 핵변환시스템이 개념적인 수준에서 개발되고 있어, 이 연구를 통해 향후 핵변환시스템 연구에서 요구되는 항목들도 기술적 개선, 경제성 제고, 환경 친화성, 그리고 수용성 측면에서 제시해 보았다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.117-121
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• 2016

Background: Definition and grouping of initiating events (IEs) are important basics for probabilistic safety assessment (PSA). An IE in a spent fuel reprocessing plant (SFRP) is an event that probably leads to the release of dangerous material to jeopardize workers, public and environment. The main difference between SFRPs and nuclear power plants (NPPs) is that hazard materials spread diffusely in a SFRP and radioactive material is just one kind of hazard material. Materials and Methods: Since the research on IEs for NPPs is in-depth around the world, there are several general methods to identify IEs: reference of lists in existence, review of experience feedback, qualitative analysis method, and deductive analysis method. While failure mode and effect analysis (FMEA) is an important qualitative analysis method, master logic diagram (MLD) method is the deductive analysis method. IE identification in SFRPs should be consulted with the experience of NPPs, however the differences between SFRPs and NPPs should be considered seriously. Results and Discussion: The plutonium uranium reduction extraction (Purex) process is adopted by the technics in a model reprocessing plant. The first extraction cycle (FEC) is the pivotal process in the Purex process. Whether the FEC can function safely and steadily would directly influence the production process of the whole plant-production quality. Important facilities of the FEC are installed in the equipment cells (ECs). In this work, IEs in the FEC process were identified and categorized by FMEA and MLD two methods, based on the fact that ECs are containments in the plant. Conclusion: The results show that only two ECs in the FEC do not need to be concerned particularly with safety problems, and criticality, fire and red oil explosion are IEs which should be emphatically analyzed. The results are accordant with the references.

• 대한두경부종양학회지
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• 제32권1호
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• pp.13-19
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• 2016

Background : The 2015 American thyroid association (ATA) guidelines greatly expanded section on risk stratification of thyroid cancer. Definition of "Low risk of recurrence" has expanded, by inclusion of small volume lymph node involvement, such as less than 5 lymph node metastases each smaller than 2mm in central compartment. Purpose : We evaluated the number of positive nodes, Positive node ratio (PNR), recurrence, and radioablation therapy. Also, evaluated the safety of omitting strategy of radioablation after total thyroidectomy with PTC, especially on low-PNR N1a patients compared with high-PNR N1a patients. Methods : Consecutive 147 N1a and 216 N0 patients who underwent total thyroidectomy with central neck dissection between 2003 and 2004 were enrolled. We divided 147 N1a patients into two groups, such as 96 high-PNR versus 51 low-PNR group according to 50% of PNR, and compared these two groups with N0 group. Results: 7.2% (26/363) recurrences were occurred, and 21/147 (14.3 %) recurrences were on N1a patients, and 5/216 (2.3 %) were on N0 patients. Of these 21 recurrences in N1a stage patients, 20 (95.2 %) recurrences were occurred in high-PNR N1a group and only 1 (4.8 %) recurrence was in low-PNR N1a group. The recurrence of low-PNR N1a group was significantly lower than high-PNR N1a group (Log-rank p value = 0.003), but significantly not different from N0 group (Log-rank p value = 0.889). Although this study was a retrospective non-randomized trial with small number of patients, the 10-year recurrence of omitting RAI in low-PNR N1a patients with less than 50% of PNR were shown to be comparable with 216 N0 low risk patients. Conclusion : Positive node ratio could be a useful predictor of recurrence and useful guidance postoperative management -rather than absolute number of positive node.