The licensing process of Cernavoda interim spent fuel dry storage

For Cernavoda Nuclear Power plant, finding sufficient capacity of storage for spent fuel is essential, if the plant is to be allowed to continue to operate. After the intense initial radioactivity has decayed, the reactor operator would has faced a choice: the fuel can be stored in an extension of the pool (or some other pool) for a longer period, it can be placed in one of several forms of dry storage, or it can be sent to a geologic repository for disposal. Currently, geological disposal is only an objective within the framework of the radioactive waste management policy. Also, maintaining and operating a spent fuel storage pool involves significant operational costs and some modest generation of radioactive wastes. Thus, for spent fuel that is to be stored for a substantial period, the plant operator turned to dry storage. Interim dry storage offers a safe, flexible and cost-effective approach to spent fuel management. Both experience in countries around the world and a number of regulatory reviews reinforce the conclusion that dry storage is safe. The basic safety goals that must be met are to ensure that: (a) sufficient shielding is provided so that workers at the facility are not exposed to hazardous levels of radiation, and (b) the fuel is contained so that any release of radioactive material to the surrounding environment is reliably prevented. To ensure that dry storage provide adequate shielding and containment, the system design was considered to meet the following regulatory requirements: fuel cladding must maintain its integrity while in storage; high temperature that could cause fuel degradation must be avoided; accidental chain reactions (criticality) must be prevented; effective radiation shielding must be provided; radioactive releases must be avoided; and fuel retrievability must be ensured. During the autumn of 2000, SNN proceeded with an international tendering process for the supply of a dry storage system to be implemented at the Cernavoda station to store the spent fuel from Unit 1 and from Unit 2 for a minimum period of 50 years. The bidding process resulted in early 2001 in the selection of a technology that uses the best features of dry storage systems in use at similar CANDU 6 reactors in Canada. The Cernavoda storage site will contain MACSTOR storage modules identical to the ones in use at the Gentilly 2 reactor in Canada. The storage site is provided with a physical security system adapted to the storage of spent nuclear fuel that integrates with the station's security system. The facility is designed to meet the stringent Safeguards requirements imposed by the International Atomic Energy Agency (IAEA) for the control of nuclear fissile materials. The storage module has proved to provide: an excellent shielding of radiation; an excellent structural integrity provided by its massive reinforced concrete construction; an excellent fuel cooling providing safe low fuel temperatures; and a double confinement envelope to the fuel bundles, a configuration believed to offer the best overall protection in the industry. All these features assure a very good behavior of the spent fuel and its integrity in dry storage conditions. During normal operation and following postulated accidents, the proposed system will limit occupational and public doses well within values permitted by the most stringent international standards. The minimum design life of the dry storage facility is 50 years. The licensing processes of Cernavoda interim dry storage was implemented according to the requirements of Romanian Authorities. Romania does not have specific regulatory requirements and criteria governing nuclear licensing of spent fuel dry storage. For this reason the Regulatory Body imposed the observance of the following American guidance: - 10 CFR Part 72 - Licensing requirements for the storage of spent fuel and high level waste; NRC Regulatory Guide 3.48 Standard format and content for the safety analysis report; ANSI/ANS 57.9-1992 Design criteria for an independent spent fuel storage installation. The main difficulties experienced in the licensing process are related to: - lack of specific Romanian regulations for this type of facilities; - application of NRC guidance to the vault type storage installation; - meeting some requirements of the environmental authorities