Scenarios with replacement heat generation 1. Introduction

Research work was performed on possible future development of nuclear energy generation in Ukraine. The study was implemented under Task 2 of the IAEA SYNERGIES project, including research on the possibility

of wide deployment of nuclear reactors for non-electricity use (heat production) and assessment of nuclear energy development based on Generation IV reactors. Proposals were made for international cooperation in the development of NESs in the medium and long term using Generation III+ and IV reactors. Neither of these scenarios were considered during the GAINS collaborative project (see Appendix III). The complete case study can be found in Annex XXII on the CD-ROM accompanying this publication.

3.1.9.2. Objective and problem formulation

The future deployment of nuclear power in Ukraine has to take into consideration the high cost of nuclear fuel cycle options and the low cost of non-nuclear electricity generation. Current power generation is largely based on coal and gas consumption, which produces CO₂ emissions. Economic development of Ukraine is likely to increase overall CO₂ emissions. In this context, Ukraine is considering wide deployment of nuclear power as a means to limit CO₂ emissions as well as to strengthen the security of energy supply and decrease the costs of national electricity generation.

Nuclear infrastructure in Ukraine is based on open fuel cycle options, which produce a significant amount of spent nuclear fuel. Reprocessing facilities are not widely in use, and their high cost suggests there will be no such facilities in Ukraine for the foreseeable future. Moreover, the high capital cost of nuclear power generation is largely responsible for decreasing development of nuclear reactors based on Generation III and III+ technologies.

The significant improvement of the technical and economical parameters of innovative nuclear reactors shall be considered as a means to enhance the economic attractiveness of electricity production by nuclear generation in Ukraine.

3.1.9.3. Assumptions, methods, codes and input data used

(a) General assumptions

The energy system of Ukraine is modelled by generation forms independent of specific power units and regional features. Nuclear generation, however, is represented by different reactor types: LWRs installed, advanced LWRs, and small modular reactors (SMRs) for Scenario 1; and LWRs installed, advanced LWRs and SCWRs for Scenario 2. Economic parameters (e.g. price for resources and capital construction) are given in short term prices (overnight cost).

The modelling of non-nuclear-generated energy is performed using the following boundary conditions:

— Solar power plants and bioenergy have a small contribution to electricity production.

— Coal reserves are enough to cover energy needs in full scope and thus are considered to be unlimited. The mining rate is also unlimited.

— Gas for energy generation is imported, therefore its reserves are assumed to be unlimited.

— Electric power losses in the grids are decreased in accordance with the updated Energy Strategy until 2030¹⁰, and then they remain unchanged until 2050.

— The modelling period projects until 2100.

— Total capacity of boiler plants was 117 800 GCal/year at the end of 2012.

— The commissioning of new cogeneration plants is not more than 600 MW per year.

— The commissioning of new boiler plants is not more than 200 MW per year.

The modelling of the NES is performed using the following boundary conditions and assumptions:

— Nuclear generation is represented absolutely, as a basic component of the energy system of Ukraine.

— SMRs can be deployed after 2030.

— The Centralized Dry Storage Facility will be commissioned in 2018.

— The nuclear share of the energy mix of Ukraine will be limited to 50%.

10 See http://mpe.kmu.gov.ua/minugol/control/uk/doccatalog/list?currDir=50358

— One third of heat consumed by the population and communal domestic households may be generated by nuclear power plants.

— The commissioning of new SMRs will not be more than one unit per year (325 MW).

(b) Assumptions for the nuclear fuel cycle analysis

Assumptions for the nuclear fuel cycle analysis included the following:

— Five LWRs (two LWRs installed and three advanced LWRs) with UOX fuel will be commissioned by 2030.¹¹

— There is a possibility to commission annually no more than one reactor of any type after 2030.

(c) Code and methods

The modelling of the energy system is performed with the MESSAGE software [3.36]. Input data for both scenarios is presented in Annex XXII.

3.1.9.4. Summary presentation and analysis of the results

The study considers two scenarios: replacement heat generation by small nuclear units; and wide deployment of the SCWRs.

(a) General assumptions of Scenario 1: Replacement heat generation by small nuclear units

According to the 2013 updated energy strategy for Ukraine, total heat consumption is in the range of 216–244 million GCal per year. Domestic household (44%) and industry (35%) were the main consumers. Other sectors of the economy consumed about 21%. The 2013 strategy predicts an increase of heat consumption up to 290 million GCal (at 25%) by 2030.

In the case that fossil fuel generation is replaced by nuclear generation for heat production in domestic households, nuclear reactors would not be located far from large consumers (i.e. in large cities and industrial centres). However, it will not be possible to replace all fossil fuel generation; conservatively, it can be expected that one third of heat consumed by the population and communal domestic households could be generated by nuclear power plants. In the long term, heat consumption in domestic households is proposed to be a constant 100 million GCal per year — constant because energy consumption will decline and energy efficiency will grow.

Thus, the substitution level of fossil fuel generation to nuclear generation could be 33 million GCal.

The following constraints are used:

— Nuclear power application for district heating is possible after 2030.

— Commissioning of one reactor per year.

Small sized reactors can be operated in a cogeneration mode. For such a case in Ukraine, the generation structure and share are presented in Figs 3.66 and 3.67. In this, the nuclear power plant share increases, and by 2050 would make up 50% of total generation (cogeneration of heat and electricity). Total installed capacities of large sized reactors are maintained at the level of 15 GW in the long term (see Fig. 3.68). The dynamic of ALWR and SMR commissioning are presented in Fig. 3.69. Spent nuclear fuel accumulation is presented in Fig. 3.70.

Results obtained for the case of SMR exploitation for the electricity and heat cogeneration are presented in Figs 3.71 and 3.72. Results are obtained assuming conditions with no limitation for the heat cogeneration by small sized reactors. The total installed nuclear capacity and schedule of new capacities commissioning are presented in Figs 3.73 and 3.74. Spent nuclear fuel accumulation is presented in Fig. 3.75.

11 Ibid.

FIG. 3.66. Electricity generation structure. FIG. 3.67. Generation share.

FIG. 3.68. Total installed capacities. FIG. 3.69. Schedule of new capacities commissioning.

FIG. 3.70. Spent nuclear fuel accumulation.

FIG. 3.66. Electricity generation structure. FIG. 3.67. Generation share.

FIG. 3.68. Total installed capacities. FIG. 3.69. Schedule of new capacities commissioning.

FIG. 3.70. Spent nuclear fuel accumulation.

FIG. 3.71. Electricity generation structure. FIG. 3.72. Generation share.

FIG. 3.73. Total installed capacities. FIG. 3.74. Schedule of new capacities commissioning.

FIG. 3.75. Spent nuclear fuel accumulation.

(b) General assumptions of Scenario 2: Wide deployment of supercritical water cooled reactors

The electricity generation structure and generation share for a scenario in which SCWRs are widely deployed in the energy system of Ukraine are shown in Figs 3.76 and 3.77. The commissioning of SCWRs is not expected before 2030. The total installed capacities and schedule of new commissioning capacities are shown in Figs 3.78 and 3.79. Spent nuclear fuel accumulation is presented in Fig. 3.80.

(c) Analysis of the results under Scenario 1

In the case of SMR implementation in the energy system for heat generation, the generation structure and share of the nuclear power plant increases and by 2050 will have a share of up to 50% from the total generation.

Total installed capacities of large sized reactors are maintained at the level of 15 GW in the long term. The rate of construction for new nuclear power units should be high enough to maintain a 50% nuclear share in electricity generation. In 2020–2030, 4 GW of large sized reactors would be commissioned and 6 GW of large sized reactors would be commissioned from 2030 to 2040, plus an additional 3 GW of small sized reactors.

In the case that considers heat generation by boiler plants (i.e. combined heat and power plants and small sized reactors which operate in the mode of electricity and heat cogeneration), the modelling results demonstrate the viability of nuclear power application for electricity and heat cogeneration (district heating) purposes. The scenario considers the replacement of some fossil fuelled power plants by nuclear power plants. Total installed capacity of nuclear power plants would increase up to 20–21 GW. In 2020–2030, 4 GW of large reactors would be commissioned, while 5–6 GW would be commissioned during 2040–2050, 3 GW of 300 MW small sized reactors would be commissioned from 2030 to 2040, and 2 GW of small sized reactors would be commissioned annually from 2050 to 2060. The commissioning of a considerable amount of new nuclear capacities corresponds to the large amount of acting nuclear reactors to be decommissioned in the indicated period. The amount of accumulated spent nuclear fuel will make up about 30 000 t until 2100.

The analysed scenario demonstrates the viability of nuclear power application for district heating. The obtained results should be considered as optimistic because:

— The rate of commissioning nuclear power units is relatively high.

— Although the potential of using nuclear reactors for district heating has been demonstrated, it is not always possible to construct nuclear power plants near large consumers.

— More intensive operation of nuclear reactors means more spent nuclear fuel accumulation. The scenarios assume a once through nuclear fuel cycle with spent nuclear fuel disposal, but the construction of storage facilities is not considered.

(d) Analysis of the results under Scenario 2

Taking into account for increased capital construction costs for Generation III and III+ reactors (over previous generation reactors) as a result of more complicated safety systems, increased time required for commissioning, construction delays and periodical changes in exchange rates, fossil fuelled power plants may be seen as more attractive from an economic perspective. However, increased costs and technical parameters have also increased capital construction costs for fossil fuel generation.

A possible solution is the construction and operation of SCWRs. The first commissioning of SCWRs is not expected before 2030, but as a result of the high technical specifications of SCWRs, the capacity of new SCWRs that could be commissioned in 2030–2040 could generate up to 10 GW. This would allow the share of nuclear power in all electricity generation to remain at 50% — in line with policy requirements for the energy system of Ukraine.

This fact is considered as an attractive feature of SCWRs in comparison with approaches involving generation of energy other than electricity. By 2100, the total installed capacity of ALWR and SCWR would be 20 GW.

With utilization of SCWRs, a total of 25 000 t HM of spent nuclear fuel will accumulate by 2100. This amount of spent nuclear fuel is much less in the option based on a once through nuclear fuel cycle (up to 30 000 t HM).

This is notable since reprocessing and infrastructure development for minor actinides and plutonium storage would not be required.

FIG. 3.71. Electricity generation structure. FIG. 3.72. Generation share.

FIG. 3.73. Total installed capacities. FIG. 3.74. Schedule of new capacities commissioning.

FIG. 3.75. Spent nuclear fuel accumulation.

FIG. 3.76. Electricity generation structure. FIG. 3.77. Generation share.

FIG. 3.78. Total installed capacities. FIG. 3.79. Schedule of new capacities commissioning.

FIG. 3.80. Spent nuclear fuel accumulation.

In consideration of better nuclear fuel utilization in the scenario based on SCWR, natural uranium reserves will be sufficient until 2100, an unfavorable result compared to scenarios based on a closed nuclear fuel cycle with unlimited recource.

3.1.9.5. Conclusions

(a) Scenario 1: Replacement heat generation by small nuclear units

Small reactors have a number of advantages that could be decisive when building an innovative system, including:

— Their small size allows for a significantly shorter construction period and hence reduced investment risks.

— Their capability for different applications in addition to electricity generation: production of industrial heat, sea-water desalination and cleaning, operating in cogeneration mode and central heating.

— Their compactness is advantageous where the construction of large sized units is not feasible (e.g. due to high population density or poor cooling water resources).

Small sized reactors are technically feasible for cogeneration of electricity and heat. If the price for hydrocarbon fuel is high, it could be attractive to use nuclear reactors intensively for heat generation needs (as per input data accepted and model built). However, the use of small sized reactors for base scale electricity generation is a less feasible solution for Ukraine due to high capital costs. Small sized reactors are more attractive if they are deployed for industrial and civil heat generation purposes, as a means to strengthen security of supply in the Ukrainian energy system. However, the system would accumulate a large amount of spent nuclear fuel (30 000 t) as compared to a basic power generation scenario based on the once through fuel cycle.

(b) Scenario 2: Wide deployment of supercritical water cooled reactors

SCWRs are considered to be feasible and attractive, can produce a significant share of electricity in the energy system as a result of their higher technical parameters (increased values of capacity factor, efficiency and fuel burnup rate). Taking into account the technical and economic characteristics applied in this study, the introduction of SCWRs would significantly increase the share of nuclear generation in Ukraine. The results show the economic attractiveness of deploying SCWRs after 2030 in comparison to advanced LWRs. SCWR application would allow for a decrease in spent nuclear fuel accumulation, and is the only feasible approach to maintain a 50% share of nuclear generation in the Ukrainian energy system.

Development of a SCWR fleet is a reasonable approach to consider as a component of a once through nuclear fuel cycle. In this case, international cooperation in the nuclear fuel cycle field will be required only for enrichment of uranium hexafluoride and fuel pellet sintering (until implemented at the domestic nuclear fuel fabrication plant).

As for the fuel cycle back end, it may be reasonable to address the capability of establishing a regional complex for long term spent fuel storage, so as to optimize economic expenditures and to minimize deployment of dry spent fuel storage facilities at each nuclear power plant.

3.2. SCENARIOS WITH THE INTRODUCTION OF A NUMBER OF FAST REACTORS TO SUPPORT