When a loss of coolant accident which causes a partial or a full drainage in the SFP would happen, Zircaloy-4 spent fuel cladding begin to react with high temperature air, and the heat generates by exothermic reaction between Zircaloy-4 cladding and surrounding air. Due to the heat, the ignition may occur in the surface of Zircaloy-4 cladding. If the Zr-fire phenomenon occurs during the accident in a SFP, the spent fuel cladding and pellets would be severely fragmented and powdered and it may bring about a massive release of radioactive source terms. Therefore, it is crucial to prevent the zirconium fire phenomenon for the spent fuel pool safety. However, a main cause to trigger the zirconium fire was not identified. In order to identify a possible mechanism of the Zr-fire phenomenon, OECD-NEA SFP Project I, II was initiated. In this paper, we reviewed the Zr-fire phenomenon which may occur in the spent fuel pool for complete loss of coolant accident scenario. The Spent Fuel Pool Project (hereinafter SFP project) is the experimental program to investigate the phenomena of spent fuel pool complete loss of coolant accident using a 17×17 PWR fuel assembly. In this section, the zirconium fire phenomenon which was observed from the SFP project is briefly investigated. This paper presented the fuel assembly temperature (i.e. zirconium alloy cladding temperature) and oxygen concentration profile of the SFP project phase-1 ignition test. At around 12.7 hour, the temperature abruptly increased and the oxygen concentration also dramatically decreased. This abrupt temperature escalation is the zirconium fire phenomenon. In order to investigate the mechanism of this zirconium fire phenomenon, behaviors of both temperature and oxygen concentration were fully compared. This paper reviewed the results of OECD-NEA SFP project experiment and then a mechanism of Zr-fire phenomenon was dscussed. It seems that the Zr-fire phenomenon might be a consequence of thermal mismatch between heat generation and dissipation. A large amount of heat might be generated by the air oxidation of Zircaloy-4 spent cladding immediately after the kinetic transition which is a breakaway phenomenon. This paper discussed the relationship between the breakaway phenomenon and the Zr-fire phenomenon in case of air oxidation of Zircaloy-4 spent cladding. This paper presents preliminary findings on the Zr-fire phenomenon from the open experiment data of the prototypic spent fuel severe accident scenario. These findings would enhance the understanding of Zircaloy-4 spent cladding air oxidation and severe accident scenario progression in a SFP.

This paper attempted to analyze the correlation between the risk image of the evacuees in the tunnel and the variables that affect the evacuation behavior due to the closed feeling. As to whether there is a difference in the level of recognizing the tunnel risk image according to the distribution of jobs, the null hypothesis was rejected at the significance probability of 0.002, so it can be said that the level of recognition of the tunnel risk image varies depending on the job group. In the distribution difference between gender and tunnel risk image recognition level, the significance probability was 0.012, indicating that the null hypothesis was rejected, indicating that the tunnel risk recognition distribution according to gender was different. As a result of analyzing the distribution difference between the tunnel's closed feeling and the tunnel risk perception level, the significance probability was 0.001, and the null hypothesis was rejected, indicating that there was a difference in the tunnel risk image level.

Nuclear power plants decommissioning is planned to be started in middle of the 2020. It is necessary to develop safety evaluation and verification technology during decommissioning to ensure the safety of security monitoring measures and maintenance measures, appropriate emergency plans and preparations for decommissioning, and the use of proven engineering when establishing decommissioning plan. For this purpose, a nuclear power plant decommissioning plan is prepared in several stages before decommissioning. When a lifetime of a nuclear power plant has reached, it needs to be decommissioned and therefore operator company should submit decommissioning plans to the National Safety and Security Commission. And safety analysis should be included in this document and it is explained in chapter 6. According to the NSSC Notice No. 2021-10, it is largely divided into principles and standards, exposure scenarios, dose assessment, residual radioactivity, abnormal events, and risk analysis. When unexpected radiological accident is happened, both public and occupational dose analysis should be conducted. However, research on the former can be found easily on the other hands, research on the latter is not active. In this paper, method of choosing scenarios of accidents during the decommissioning the nuclear power plants is briefly introduced. Accidents during nuclear power plants decommissioning cases in USA is chosen and its risk is evaluated by using risk matrix and ranked by AHP method. During the decommissioning phases, varieties of radioactive waste is expected to be generated such as contaminated concrete and metal. On the other hand, Dry Active Waste (DAW) is generated and its amount is and its amount is 7,353 drums. Characteristic of DAW is highly flammable compared to concrete or metal. Moreover, depending on method of radioactive waste conditioning and type of radioactive nuclides, release rate of the nuclides varies. Thus this type of radioactive waste is critical to fire accidents and such accident can occur extra dose exposure which exceeds the guideline of the regulatory body to workers. Therefore, in this paper, occupational dose exposure during the fire accident is conducted.

The purpose of this study was to verify the relationship between fire fighter's musculoskeletal disorder related observable symptom and their absence from disease and accident. Online questionnaire was distributed with a total of 7,673 fire fighters, and statistical analysis was conducted to the collected data. The result shows that on a one year basis, patients with musculoskeletal disorder related observable symptom felt symptom in sequence of back, shoulder, neck, knee. The result verified that 12.9% of absence of disease and 5.9% of absence of accident experienced these symptoms. Both absence from disease and absence from accident showed body part symptoms related to neck and shoulder. This study ascertained the relationship between fire fighters' absence and their musculoskeletal disorder related observable symptom. The author hopes this study to be used as a basis of precautionary program for absence management.

The effect of parameters on the consequence of the flash fire accident by the release of heavy gas(in this study, xylene vapor) was analyzed. Simulation results showed that the distance with the lower flammable limit(XLFL) was increased with the increase of the release hole diameter. For the case of the elevated release, XLFL was increased with the increase of the wind speed and the release height, but XLFL was not affected by the wind speed for the release on the ground level. Therefore, the accident in the elevated release was more dangerous than the release on the ground level. In this condition, the release height had more effect on XLFL at the night time than the daytime and in the urban area than the rural area.

국내외적으로 “녹색성장”을 내세우지만 막상 산불로 인한 피해에 대하여는 간과하고 있는 것이 사실이다. 특히 산불로 인한 환경 피해는 치유도 어렵고 많은 시간이 소요된다는 점에서 산불예방과 신속한 진화의 필요성이 요구된다 할 수 있을 것이다. 인류가 산업화 사회에서 산불 발생을 원초적으로 방지하는 것은 불가능할 것이다. 따라서 적극적인 예방과 산불 발생시 신속한 초기 대응 및 진화체계 구축으로 피해발생을 최소화하여 산림자원을 보호하는 것이 우리의 사명이고 후세에 대한 의무일 것이다. 본 연구는 우리나라에서 발생하는 산불의 특성 및 대응방안과 제도적 측면을 검토하고, 산불의 원인 분석을 위하여 FTA분석을 실시하였고, 통계자료를 통해 연도별 극치자료의 빈도분석을 실시하였다. 산불을 더욱 효과적으로 예방하고, 대응할 수 있는 대책을 제시하였다.

Concrete structures known that relatively safe for the fire, but the fire damage at different depending on the materials used will be affected, depending on the strength of the concrete damage situation appears different. In this study compared to compressive strength properties acooding to different type of concrete strength fire damege through about concrete structure is utilized as a basis for maintenance.