long period of operation is about 0.2 TBq (5 Ci) per watt of power. Thus, the core of a 1000 MW(e) power reactor, say 3500 MW(t), would contain 7∙108 TBq (1.75∙1010 Ci), a very large quantity. From the point of view of safety, the characteristics of the radionuclides that are of most concern are: Chemical volatility, because volatility promotes release in accidents; A strong chemical affinity for the human body, because such nuclides are easily taken up and remain in the body; A high energy decay, because of the need to shield against such radiation; and/or A relatively long half-life, because of the persistence of contamination from such a nuclide. Thus, some of the radionuclides of particular interest include the gases, strontium-90, iodine-131, and caesium-137. Uncontrolled release of radioactive materials must be prevented or mitigated by confinement as as possible to their point of origin or their intended location. This is achieved by physical barriers that enclose radioactive materials. Confinement as a applies to those barriers that are in direct contact or very close to the radioactive material. In principle, these barriers must be passive. In a typical pressurized or boiling water reactor confinement is provided by: The fuel matrix (sintered uranium dioxide) which can retain solid fission products; The zirconium cladding of the fuel rods which retains fission gases and volatile fission products as long as its integrity is preserved; The reactor coolant pressure boundary (reactor pressure vessel, primary piping, steam generator tubes, pressurizer, reactor coolant pumps) which retains fission products that may have leaked through the cladding and dissolved activation products. In the spent fuel pit confinement is provided by: The fuel matrix; The zirconium cladding of the fuel rods; The spent fuel pit stainless steel cladding and the filtered cooling system. In the radioactive waste storage and repository confinement is provided by the: Waste form (usually it is solidified in some way); Container. Questions
Series 110, The Safety of Nuclear Installations, now superseded by Safety Fundamentals SF-1. These obligations are summarized in Table 5.1. Table 5.1: Obligations contained in Convention on Nuclear Safety. Legislation and regulation General safety considerations Safety of installations Legislation and regulatory framework Priority of safety Siting: effect of environment on the NPP Safety requirements and regulations Financing for safety Siting: effect of NPP on the environment System of licensing Competence of staff Siting: Regulatory inspection and assessment Human performance Design: defence in depth Enforcement Quality assurance Design: proven technology Regulator with authority Safety assessment Easily manageable operation Independent regulator Verification: analysis and survey Initial authorization and commissioning Operator’s responsibility Radiation protection Operational limits and conditions Emergency preparedness Emergency operating procedures Engineering and technical support Incident reporting Operating experience feedback Waste management Implementing measures Each Contracting Party must take, within the framework of its national law, the legislative, regulatory and administrative measures and other steps necessary for implementing its obligations under this Convention. Each Contracting Party must submit for review prior to each review meeting, a National Report on the measures it has taken to implement each of the obligations of the Convention. National Reports should, among other requirements, demonstrate that: A Regulatory Body entrusted with the implementation of the legislative and regulatory framework is established;