ANALYSIS OF NUCLEAR POWER DEVELOPMENT SCENARIOS
IN TERMS OF NUCLEAR FUEL CYCLE SERVICE REQUIREMENTS
T. Akbaş1 M. Ceyhan2 C. Kocar1
Turkish Atomic Energy Authority Ankara/TURKEY, international Atomic Energy Agency Vienna/AUSTRIA
ABSTRACT
The role of nuclear power in future sustainable energy supply gets an increasing focus in several studies in the world. Various roadmap exercises have been undertaken to look essentially to the technical solutions for nuclear energy to fulfill such a role. This study describes the analysis of different nuclear power development scenarios, in terms of nuclear fuel cycle aspects such as natural uranium and enrichment requirements, spent fuel arising, etc.
Calculations are done using the Nuclear Fuel Cycle Simulation System that has been developed by the International Atomic Energy Agency (IAEA). Nuclear Fuel Cycle Simulation System is a scenario based computer model for the estimation of fuel cycle service requirements. The model uses simplified approaches to calculate the fuel cycle requirements. These simplified approaches make the code capable to estimate the long term fuel cycle service requirements for both open and closed cycle fuel cycle strategy. Nuclear Fuel Cycle Simulation System takes strategy parameters, fuel parameters, control parameters as input and gives main front- end and back-end fuel cycle service requirements and spent fuel and plutonium arisings. Results of the calculations for the different nuclear power development scenarios and conclusions regarding the impact of the different fuel cycle options are presented in this paper.
1. INTRODUCTION
The role of nuclear power in future sustainable energy systems gets an increasing focus in several studies in the world. Various exercises have been undertaken to look essentially to the technical solutions for nuclear energy to fulfill such a role [1, 2, 3]. Nuclear reactor technologies and fuel cycle are the main aspects of a typical roadmap for the nuclear power development.
Fuel cycles have always key strategic importance to the nuclear industry. Keen interest in the nuclear fuel cycles that improve uranium utilization was originally driven by a belief that uranium resources would not support the requirements of a growing nuclear power demand. Nowadays, interest in effective uranium utilization is motivated by considerations, such as environmental concerns for the front- and back- end of the fuel cycle, and national policies to secure the maximum benefit from nuclear energy resources, or to increase energy self reliance. Reprocessing and recycling uranium and plutonium in spent fuel back into nuclear power reactors, is a means of increasing the energy derived from the original mined uranium [4].
This study is focused on the analysis of a typical nuclear power development based on two reactor technologies (pressurized light water reactor and pressurized heavy water reactor) and fuel cycle options, regarding especially front-end and back-end nuclear fuel cycle services.
2. METHODOLOGY
A nuclear power development scenario based on installation of a nuclear capacity within the specified period is established. Nuclear power reactor technologies and fuel cycle options are main parameters in the scenario. Fuel cycle service requirements to produce the specified amount of electricity using the specified reactor and fuel cycle options are analyzed with Nuclear Fuel Cycle Simulation System that has been developed by the IAEA. Nuclear Fuel Cycle Simulation System (VISTA) is a scenario based computer model for the estimation of fuel cycle service requirements. VISTA code takes strategy parameters, fuel parameters, control parameters as input and gives some fuel cycle service requirements and spent fuel arisings, plutonium arisings as result.
Input parameters are categorized into three groups:
■ Strategy Parameters: nuclear capacity variants, reprocessing-recycling strategies, reactor type mixtures and
■ Fuel Parameters: discharge burnup, initial enrichment, tail assay on an annual basis and for each reactor type.
■ Control Parameters: share of MOX fuel in reactor fuel, lead and lag times for different processes and the
number of spent fuel reprocessing cycles. Outputs are:
■ Natural uranium, conversion and enrichment service requirements.
■ Fresh fuel requirements and spent fuel arisings.
■ Total plutonium arisings and separated plutonium utilization.
■ Reprocessing and MOX fuel fabrication service requirements.
Detailed information on the VISTA can be found at IAEA website [5].
3. NUCLEAR POWER DEVELOPMENT SCENARIOS
This study is based on nuclear power generation scenario given in Figure 1. It is assumed that a total capacity of 15,000 MWe is installed, based on addition of a 1,500 MWe nuclear power capacity every two years. Since the timing of the fuel cycle services is not important for the aims of this study, lead and lag times for the nuclear fuel cycle services are not taken into account.
Installed Capacity Generated Electricity 16.500 15.000 13.500 12.000 10.500 9.000 7.500 6.000 4.500 3,000 1.500 0 140.000 120.000 100,000 80,000 60,000 40.000 20.000 0 10 20 30 40 Years 50 60 70 80 0
Figure 1. Nuclear capacity and electricity generation
The attributes of the reactors and fuels used in this study are given in Table 1. Two different nuclear power technologies, namely pressurized water reactor (PWR) and pressurized heavy water reactor (PHWR) technologies and two fuel types for each reactor technology are taken into account for this study. Characteristics of CANDU reactors are used to represent PWHRs. UOX fuel and MOX fuel are technologically matured fuels for light water reactors (LWRs). UOX fuel fabricated from natural Uranium is common in current PWHRs.
Table 1. Reactor and Fuel Cycle Parametersx
Reactor Technology PWR PHWR (CANDU)
Fuel Type UOX MOX (with depleted U) UOX UOX
Enrichment (%) 5.0 (Fissile Pu Content) 6.5 (Natural U) 0.71 1.2
Burnup (GWD/ton HM) 60.0 60.0 7.0 20.0
Capacity Factor (%) 90.0 90.0 90.0 90.0
Thermal Efficiency (%) 33.0 33.0 33.0 33.0
U Tail (%) 0.2 - - 0.2
Plant Life (years) 60.0 60.0 60.0 60.0
4. RESULTS
Results of the analysis done using VISTA for the four scenarios are presented in Figure 2 - Figure 5 for the front- end fuel cycle characteristics. Cumulative natural U requirement (Figure 2) is the highest for the PWR that uses UOX fuel; PHWR fuelled with natural U is very close to the PWR-UOX case. Since it is assumed that depleted U is used in MOX fuel, no natural U is necessary for the PWR-MOX case.
It is necessary to process (mining and milling) the ore in amount of roughly a hundred times these values to obtain required natural U. Conversion of U is another important services required for further processes such as enrichment.
Regarding U enrichment services (Figure 3), the case of PWR with UOX fuel requires the enrichment service of around 140 million SWU as cumulative. PHWR case with slightly enriched U fuel requires enrichment services of 35 million SWU. There is no enrichment need for PWR case with MOX and PHWR case with natural U fuel. Depleted U accumulation in stocks is proportional to the amount of enrichment activity (Figure 4). For the PWR with MOX case, a significant amount of depleted U (13.5 ton) is necessary.
In terms of fuel fabrication services (Figure 5), PHWR with natural U fuel requires nine times much more fuel fabrication then the PWR cases. A significant reduction in fuel fabrication requirements is achieved when the slightly enriched U fuel is used in PHWRs.
Figure 4. Depleted Uranium stock (depleted U need for Figure 5. Cumulative fuel fabrication requirements PWR-MOX case)
Spent fuel stock, Pu and minor actinides contained in spent fuel are important parameters regarding to spent fuel management. Spent fuel arising (Figure 6) is the same as the amount of fuel fabricated: the highest for the PHWR with natural U fuel and lowest for the PWR cases.
Pu accumulation is the highest for the PWR-MOX case as expected (Figure 7). Spent fuel from PHWR with natural U fuel contains the highest percentage of fissile Pu among the all cases, around 75% of Pu in spent fuel is fissile. Accumulation of minor actinide is higher for the PWR cases (Figure 8). PWR with MOX fuel has a minor actinide accumulation of twenty times higher than the PWHR with natural U fuel.
— — pwr-uox —o— pwr-mox-du —=— candu-nu —H— candu-seu pwr-uox —©— pwr-mox —=— candu-nu —H— candu-seu
Figure 8. Minor actinides accumulated in spent fuels
5. CONCLUSIONS
Figure 9 and 10 summaries the front-end and back-end characteristics of the scenarios. Table 2 compares the performances of the scenarios in terms of fuel cycle characteristics normalized to amount of electricity generation. In terms of natural sources utilization, recycling such as MOX fuel in PWRs is a good alternative to the current cases based on enriched or natural U. Since enrichment of U is not necessary, PHWR with natural U fuel has a great advantage on one hand, on the other hand it has the largest amount of spent fuel and Pu accumulation with lowest MAs.
Assessing the future of nuclear power as part of a sustainable energy mix is a multidisciplinary and multi dimensional issue. This study highlighted the differences between the PWR and PHWR cases in terms of major fuel cycle characteristics.
VISTA code developed by IAEA for the analysis of nuclear energy systems allows the user to simulate important aspects of a mix of reactor and fuel types. Major advantage of VISTA is that all the calculations are performed within one integrated code with an easy-to-use web-based interface. The short calculation time allows users to assess multiple options before embarking on more detailed studies on a roadmap for a nuclear power development program.
F ro n t-en d C h aracteristics
□ pwr uox □ pwr mox ■ candu nu □ candu seu
1.0E+ 1.0E+ 1.0E+ 1.0E+ 1.0E+ 1.0E+ 1.0E+
Natural U Enrichment Depleted U Pu Requirement Fuel Fabrication Requirement Requirement Slock/Requiremenl (ton) (lonHM)
(ton) (k SWU) (ton)
Figure 10. Back-end fuel cycle characteristics
Table 2. Summary of fuel cycle characteristics for scenarios
Reactor Technology PWR PHWR (CANDU)
Total Capacity (MWe) 15,000 15,000 15,000 15,000
Electricity Generation (GWh) 7,095,600 7,095,600 7,095,600 7,095,600
Fuel Type pwr-uox pwr-mox candu-nu candu-seu
Natural U Requirement (ton/TWh) 19.7675 0.0000 18.0374 12.3541
Enrichment Requirement (kSWU/TWh) 18.6259 0.0000 0.0000 4.4072
Dep. U Stock/Requirement (ton/TWh) 17.6628 1.9127 0.0000 6.0409
Pu Requirement (ton/TWh) 0.0000 0.1915 0.0000 0.0000
Fuel Fabrication (ton HM/TWh) 2.1047 2.1047 18.0374 6.3132
Spent Fuel (ton HM/TWh) 2.1047 2.1047 18.0374 6.3132
U in SF (ton/TWh) 1.9483 1.8567 17.8376 6.1448
Pu in SF (ton/TWh) 0.0228 0.1066 0.0692 0.0372
Fisile Pu in SF (ton/TWh) 0.0141 0.0563 0.0512 0.0219
MA in SF (ton/TWh) 0.0031 0.0110 0.0005 0.0009
6. REFERENCES
1. “From Gen-II to Gen-IV: A Systems View on Nuclear Energy Development Scenarios"; L.V.D. Durpel, D.
Wade, A. Yacout; ICAPP 2005, 15-19 May 2005.
2. “Multilateral Approaches to the Nuclear Fuel Cycle: Expert Group Report", IAEA, 2005.
3. “Projected Cost o f Generating Electricity, 2005 Update"', NEA/IEA; 2005.
