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        검색결과 2

        1.
        2022.10 구독 인증기관·개인회원 무료
        For deep geological repository of the spent nuclear fuel, the fuel assemblies loaded in the storage cask are transferred to the disposal cask and the operation is performed in the fuel handling hot cell at the fuel re-packaging facility. As the fuel handling hot cell shielding is accomplished by the concrete wall and the viewing glass window, the required shielding thickness was evaluated for both materials. The ordinary concrete is applied to hot cell wall and two kinds of glasses, i.e., single layer of lead glass and double layer of lead glass and borosilicate glass, are considered for the viewing glass window. A bare spent PWR fuel assembly exposed to the environment in the hot cell was considered as the neutron and gamma radiation sources. The neutron and gamma transport calculations were performed using the MAVRIC program of the SCALE code system for the dose rate evaluation. The dose limit of 10 μSv/h is applied as the target dose to establish the required shielding thickness. The concrete wall of 94 cm thickness reduces the total dose rate to 6.9 μSv/h, which is the sum of neutron dose and gamma dose. Penetrating the concrete wall, both of the neutron dose and the gamma dose decrease constantly with shield thickness and the gamma dose is always dominant through whole penetrating distance. Single layer lead glass of 74 cm thickness reduces total dose rate to 6.2 μSv/h. Applying double layer shield glass combined of lead glass and borosilicate glass, the total dose rate reduces to 3.6 μSv/h at same shield thickness of 74 cm. Through the shield glass, gamma dose decreases rapidly and neutron dose decreases slowly compared with those for concrete wall. In result, neuron dose becomes dominant on the window glass shielding. The more efficient dose reduction of double layer glass is achieved by the borosilicate glass’s superior neutron shielding power. Thus, the use of double layer glass of lead glass and borosilicate glass is recommended for the viewing glass of the fuel handling hot cell. Finally, it is concluded that about 1 m thick concrete wall and 75 cm thick viewing glass window are sufficient for the radiation shielding of the hot cell at the spent fuel repackaging facility.
        2.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Reanalysis using the US Food and Drug Administration Hazard Analysis method was performed to evaluate the effectiveness of the current Critical Control Point (CCP) configuration for non-thermal processes such as meat packaging plants and butcher shops. During non-heat treatment processing without the process of removing or reducing contaminated microorganisms, it is necessary to set and control the incoming material inspection step with the CCP since this step is essential to prevent the inflow of contaminants through incoming materials. The temperature control of the final product storage refrigerated room can be managed by the prerequisite program. However, the CCP setting of the refrigerated room prior to shipment of the meat packaging plant in which the cold chain system should be maintained in the following distribution stage is recognized. It is not an effective method to install a metal detector and manage it with CCP for metal hazard control. Improving hygienic cleaning guidelines and enhancing hygiene training are proactive and effective measures against metal particle contamination.
        3,000원