Corresponding author: Andrey A. Andrianov (andreyandrianov@yandex.ru)

Academic editor: G. Tikhomirov

The article presents a description and some illustrative results of the application of two optimization models for a two-component nuclear energy system consisting of thermal and fast reactors in a closed nuclear fuel cycle. These models correspond to two possible options of developing Russian nuclear energy system, which are discussed in the expert community: (1) thermal and fast reactors utilizing uranium and mixed oxide fuel, (2) thermal reactors utilizing uranium oxide fuel and fast reactors utilizing mixed nitride uranium-plutonium fuel. The optimization models elaborated using the IAEA MESSAGE energy planning tool make it possible not only to optimize the nuclear energy system structure according to the economic criterion, taking into account resource and infrastructural constraints, but also to be used as a basis for developing multi-objective, stochastic and robust optimization models of a two-component nuclear energy system. These models were elaborated in full compliance with the recommendations of the IAEA’s PESS and

Currently, of all possible options for the national nuclear energy development, two alternatives are most actively discussed: they are denoted by the common term, i.e., two-component nuclear energy system (

One of the options (hereafter Option 1) assumes that the thermal and fast reactors will run on pellet oxide fuel; at the same time, thermal reactors can use both uranium oxide and mixed uranium-plutonium (

In the second option (hereinafter Option 2), thermal reactors will continue to use uranium oxide fuel as long as there are resources of natural uranium available at an affordable cost, and fast reactors (with or without fuel breeding) will use mixed nitride uranium-plutonium (MNUP) fuel, plutonium for which can be extracted from

Both of these options have their own characteristics, advantages and disadvantages as well as certain similarities and differences that are discussed in the above publications. However, there are currently no studies in which a comparative analysis of both concepts is carried out at the system level, on a unified methodological and calculation basis, proceeding from common scenario and model assumptions. This article is partly aimed at filling this gap, focusing on identifying the characteristic structural features of the above concepts using optimization models of a two-component

In analytical and foresight studies conducted to justify the development priorities of nuclear technologies, system models imitating the

The optimization tools compensate for this drawback of the simulation instruments, but remain a less popular tool for modeling the two-component

The MESSAGE energy planning software was used as the main calculation tool (developed by the International Institute for Applied Systems Analysis (

The aim of this study is to demonstrate the added value which can be provided by applying an optimization approach to the problem of searching and rationale for the most efficient structures of a two-component

The existing thermal reactors were combined into two groups: RBMK and VVER. In the future, the following reactor types are considered for introduction into the

The main structural elements of the two-component

All values used in the calculations are annual average ones, i.e., they correspond to the steady-state reactor operating characteristics, the initial fuel loads and the last

The following assumptions were adopted for the growth of

The models developed in accordance with the recommendations (

The optimal structures of a two-component

Taking into account the accepted conservative assumptions regarding the cost data, the levelized unit energy costs of thermal reactors turn out to be less than as compared to fast reactors. At the same time, since the reserves of natural uranium are not enough to ensure the given increase in the

This deferred (but more intense in the future) option for introducing fast reactors into the system entails a significant increase in the requirements for

Accounting for the infrastructural constraints on the capacities of

Examples of typical optimal

For the assumptions made in both options, several BN-1200 units with a total installed capacity of about 2.4 GW are introduced into the system in 2030. In Option 1, the total installed capacities of BN-1200 reach 7.2 GW in 2040 and remains at this level until 2060; after which, intensive BN-1200 commissioning begins. In Option 2, in 2040, alongside with the BN-1200 units (4 GW), the BR-1200 units are introduced into the system, their installed capacity becomes equal to 9.8 GW in 2056 and remains at this level until 2085. At this time, the BN-1200 units are intensively commissioned; their total installed capacity reaches 44 GW by 2085 and is fixed at this level. Since 2085, the BR-1200 units are actively introduced into the system.

The initial stage of commissioning fast reactors is characterized by the utilization of separated plutonium and mainly by the reprocessing of fast reactor

To ensure the required

The annual natural uranium consumption and requirements for its conversion, enrichment and fuel fabrication for thermal reactors are determined by the program of their commissioning, and the peak for both options falls on the beginning of the 2060s. By 2100, about 90% of the available natural uranium for Option 1 and 86% for Option 2 will be consumed. The remaining part of the natural uranium will be consumed after 2100 to provide fuel for thermal reactors which have not exhausted their plant life by the end of the prognosis interval.

For Options 1 and 2:

– the maximum conversion requirements will be 8.2 and 7.6 thousand t per year;

– the maximum uranium enrichment requirements will be ~ 7 and 6.5 million kg SWU per year;

– the requirements for thermal reactors fuel fabrication will not exceed 1,200 and 1,100 t HM per year.

The average annual requirements for manufacturing

The fast reactor fuel fabrication involves the stored separated plutonium (initially) and plutonium extracted during the reprocessing of

The maximum amount of

In the considered base case of the cost data under the assumptions made, the difference between the options in the total discounted costs for the entire development program is less than 1%. Considering significant uncertainties in the cost data on

The performed calculations of the optimal

The spread in

Due to the limited scope of the study, the results of this analysis obviously cannot form the basis for management decisions, but they are quite sufficient to demonstrate the usefulness of using an optimization approach for the purposes of the scenario analysis of national nuclear energy development. Given the assumptions on the costs of

To ensure the given growth rate of

On the contrary, in the long term, the technological diversity of the fast reactor component in the two-component

The results of the analysis of the two-component

The analysis indicated the economic feasibility of technological diversification of the fast reactor component in the two-component

* Russian text published: Izvestiya vuzov. Yadernaya Energetika (ISSN 0204-3327), 2018, n. 3, pp. 100–112.