Nuclear Energy and Technology 6(3): 195–201 DOI 10.3897/nucet.6.58969 Research Article Providing rationale for the possibility of decommissioning Bilibino nuclear cogeneration plant based on the onsite disposal option* Igor A. Engovatov1, Rinat Kh. Adiyatullin2 1 National Research University Moscow State University of Civil Engineering (NRU MSUCE), 26 Yaroslavskoye shosse, Moscow, 129337, Russia 2 Startech Co. Ltd., 84 Metallurgov St., room 26, Yekaterinburg, 620131, Russia Corresponding author: Lyudmila M. Danilenko ([email protected]) Academic editor: Georgy Tikhomirov ♦ Received 24 January 2020 ♦ Accepted 25 August 2020 ♦ Published 6 November 2020 Citation: Engovatov IA, Adiyatullin RK (2020) Providing rationale for the possibility of decommissioning Bilibino nuclear cogeneration plant based on the onsite disposal option. Nuclear Energy and Technology 6(3): 195–201. https://doi.org/10.3897/ nucet.6.58969 Abstract The problem of the NPP decommissioning after the end of the specified or extended life has reached the practical solution stage for countries possessing a nuclear power industry. The major decommissioning options, both in Russia and abroad, include immediate dismantling and deferred dismantling. At the same time, there are NPP units for which, for a number of reasons, none of the two options are acceptable in terms of ensuring the safety of the personnel, the public and the environment. Disposal, the third and a more rare option, shall be used for decommissioning in this case. The purpose of the work is to provide rationale for the possibility of decommissioning Bilibino Nuclear Cogeneration Plant based on the Onsite Disposal option by covering the main building with an inert material with the formation of a mound. The option has been selected considering the results of an integrated analysis taking into account the geographical, operational, radiological, and socioeconomic factors, as well as based on a limited experience of de- commissioning commercial uranium-graphite reactors both within and outside Russia. In accordance with Russian law, the decommissioning stage will start after spent nuclear fuel is withdrawn from the unit and removed. Emphasis is placed on the proposed option preparation and implementation issues. Dates and sequences for the performance of operations to dismantle the components and civil works of buildings and structures, as well as the onsite protective mound formation structure and composition are discussed. The geometrical dimensions, as well as the quantities and types of the mound-forming materials have been estimated. The key mound-forming materials will be fragments of the components, the biological shielding, and the civil works, as well as local materials. Keywords Decommissioning, NPP unit, decommissioning option, onsite disposal, radiation safety, radioactive waste, dismantling of components, buildings and structures * Russian text published: Izvestiya vuzov. Yadernaya Energetika (ISSN 0204-3327), 2020, n. 2, pp. 73–84. Copyright Engovatov IA, Adiyatullin RK. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 196 Engovatov IA, Adiyatullin RK: Decommissioning Bilibino nuclear cogeneration plant Introduction • ensuring the radiation safety of the personnel, the public, and the environment; Presently, there are over one hundred reactor plants wor- • minimizing the radioactivity release and the radio- ldwide which are in the process of being or prepared to be active waste (RW) quantities; decommissioned, including NPP units, research reactors, • achieving a high technical and economic and social production reactors, etc. Decommissioning options depend efficiency. on the national context, the prospects for the nuclear power In accordance with Russian regulations, the decom- evolution in the given country, as well as social, technoeco- missioning stage starts after spent nuclear fuel is removed nomic, technological and many other factors (Laraia 2012, from the NPP unit (Decommissioning of Facilities 2014). Decommissioning Strategies 2007, Engovatov et al. 2005, Since the paper deals exactly with decommissioning, no Selecting Strategies 2006). The base options in all leading SNF handling, interim storage, and removal issues are countries with nuclear power are immediate or deferred re- considered here. (The potential BiNCP SNF solution is actor plant dismantling. At the same time, there are plants discussed in (Baryshnikov et al. 2012)). the preferred option for which (Russia), with regard for To provide the rationale for the pre-selection of the their designs and operating histories, will be onsite disposal BiNCP decommissioning option, such indicators were or entombment (in Western terms) (Engovatov et al. 2005, analyzed as geography, location and climate (permafrost, Bolshov et al. 2015, Linge and Abramov 2017). This op- rock); structural and space-planning solutions for the main tion suggests that radioactively contaminated components and auxiliary buildings; the performance history for the (including the reactor vessel) are confined or localized by entire period of the plant operation; radioactive contami- being accommodated inside of the containment or barriers nation of buildings, structures, materials and steelworks; of concrete or other protective materials preventing unau- integrity of structures in historical mounds; remoteness thorized access and ensuring radiation safety of the person- from RW burial sites; and experience in decommissioning nel, the public and the environment throughout the time of uranium-graphite reactors (PUGR). period until exempted from regulatory control. Such de- Based on the analysis results, a conclusion has been commissioning option is the one used to the smallest extent made that onsite disposal using mound technology com- in practice. In Russia, such approach is taken largely for ponents should be regarded as the rational, safe and production reactors (PUGR) [7, 8]. In the USA, this stra- cost-effective BiNCP decommissioning option (Korovkin tegy has been implemented only for three nuclear power and Tutunina 2012, IAEATECDOC-1124 1999). reactors out of more than forty decommissioned or under decommissioning. However, there is a growing global in- terest in the strategy in question as applied to reactor plants Characteristics of BiNCP’s of generation I (Laraia 2012, Linge and Abramov 2017). buildings and structures Bilibino Nuclear Cogeneration Plant (BiNCP) stands out among all of the NPPs in Russia. BiNCP is the pioneer of nuclear power in the Russian Trans-Polar region built on The BiNCP site plan, along with the main buildings and permafrost, and a unique life-support facility at the center structures, is shown in Fig. 1. of Chukotka (town of Bilibino) for the local ore and gold The NCP’s main building includes four power units mining enterprises (800 km to the south of Pevek, 2000 km with EGP-6 reactors. to the north of Magadan, and 12000 km off Moscow) (Bi- The building’s footprint is 108.8 ´ 78.0 m2. The eleva- libino NPP). The climatic conditions in Bilibino are nearly tions are in a range of – 8.80 to 22.50 m. extreme. Winter lasts for more than 10 months a year with The plant has the following compartments: an indoor winter temperatures being occasionally as low as –55 °C. switchgear (ISG) compartment, a turbine compartment, a The town is surrounded by mountains and by hundreds ki- deaerator and control room compartment, a reactor com- lometers of lakes and swamps due to which it is accessible partment, and a combined auxiliary building (CAB). by air from Pevek and Magadan or by road (in winter). The plant’s key components are the EGP-6 reactor The plant consists of four single-type power units of and the primary circuit consisting of two loops. The- the total electric power 48 MW with EGP-6 water-cooled re are loops provided for each reactor, each loop com- water-moderated heterogeneous pressure-tube reactors. prising two drum separators and four reactor coolant Following the connection of Akademik Lomonosov, the pumps (RCP) with pipelines and distributor group hea- world’s first floating nuclear cogeneration plant (FNPC), ders the water from which is distributed among process to Chukotka’s power grid, BiNCP that has had its speci- channels. There is one turbine installed in the reactor fied and extended life expired is to be decommissioned. unit. The turbine is capable to extract auxiliary heat Any NPP decommissioning option is known to be ba- as well as heat for the residential area and other users. sed on results of a multifactor analysis including political, The reactors and the primary circuit components are in- organizational and technical, socioeconomic, technologi- stalled in separate buildings. The reactor compartment cal and operational factors. The key points of the decom- also accommodates auxiliary systems: a blowdown wa- missioning strategy implementation (Selecting Strategies ter cleaning facility, an air purification and radioactive 2006, Bylkin and Engovatov 2014, Decommissioning of gas and aerosol suppression system, repair services, Facilities 2014) are and others. Nuclear Energy and Technology 6(3): 195–201 197 Figure 1. A 3D model of Bilibino NCP. The turbine compartment is shared by the four power cus (on the engineering and radiological components) units. It accommodates four turbines with generators and