Economic Assessment of Thorium-Based Fuels in a

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(AECL), and now Canadian Nuclear Laboratories (CNL) have evaluated various thorium-based fuel concepts for use in once- through thorium (OTT) fuel cycles ...
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Economic Assessment of Thorium-Based Fuels in a Pressure Tube Heavy Water Reactor (PT-HWR) A. Mendoza, M. Moore, A.V. Colton and B. P. Bromley Canadian Nuclear Laboratories Chalk River, Canada [email protected] To expand upon the initial assessments in [4], the estimated levelized fuel cycle costs (in $/MWe-hr) for various thorium-based fuel concepts are reported in this paper. The fuel concepts and reactor characteristics are provided in Section II. In Section III, the fuel cycle cost equations and results are discussed. Section V discusses the significance of the results, while Section VI provides a summary of the results.

Abstract—The levelized fuel cycle costs of various thorium-based fuels and uranium-based fuels augmented by small amounts of thorium in a pressure tube heavy water reactor (PT-HWR) are assessed, building upon previous studies. The results suggests that fuel concepts using slightly enriched uranium augmented by thorium, and thorium mixed with low enriched uranium can be cost competitive and have the greatest potential for near-term implementation in PT-HWRs. Thorium-based fuels that contain small amounts of recycled plutonium or U-233 will require more effort to identify and develop technologies to reduce the costs of reprocessing, and fabrication for these fuels. However, as an alternative nuclear fuel for reliable and sustainable low-carbon electricity generation, all thorium-based fuels are competitive for both short-term and long-term implementation.

II. FUEL CONCEPT AND REACTOR CHARACTERTISTICS Fuel bundle concepts and reactor characteristics, which are described in this section, are similar to those of a 37-element NU fuel bundle used currently in 700-MWe-class PT-HWRs [4], [5].

Index Terms—Fuel Cycle Cost, Nuclear Power Generation, Thorium.

A. Fuel Concept Characteristics The fuel concepts studied consist of modifications to fuel composition, central element materials, and the addition of thorium dioxide [4]. Three types of fuel bundle concepts were assessed in calculating fuel cycle costs: BUNDLE-37 (B37), BUNDLE-37-mod (B37mod), and BUNDLE-35 (B35), which are described in more detail in [4], [6]-[8]. Each fuel bundle is associated with different lattice concepts, which are described in Table I.

I. INTRODUCTION Over the last several decades, research and development institutions such as Atomic Energy of Canada Limited (AECL), and now Canadian Nuclear Laboratories (CNL) have evaluated various thorium-based fuel concepts for use in oncethrough thorium (OTT) fuel cycles that could be costcompetitive with the once-through natural uranium (NU) fuel cycle in a pressure tube heavy water reactor (PT-HWR) [1]-[3]. The work on OTT fuel cycles has continued and evolved with recent studies by Colton, Bromley, Wojtaszek and Dugal [4], which considered the safety, fuel performance, and economics of various fuel concepts with small amounts of thorium added to uranium-based fuels, in comparison to the NU fuel concept that is used currently in operating PT-HWRs. An important result from their preliminary study was that a slightly enriched uranium (SEU) fuel concept with small amounts of thorium added could have lower front-end fuel costs than NU.

Each lattice concept in Table I had varying amounts of uranium (U), recovered uranium (RU), (which is treated as 0.95 wt% 235U/U), SEU (1.2 wt% 235U/U), low enriched uranium (LEU), (which is treated as 5.0 wt% 235U/U), thorium (Th), plutonium (Pu), and 233U, with the balance of heavy metal being thorium. All the fuel was in oxide form. The earlier study [4] evaluated the fuel bundle concepts LC-01, LC-02, LC-04b, and LC-05b, which were uraniumbased fuels augmented by small amounts of thorium mixed into the end regions and also used in the central fuel pin. The fuel concepts LC-04b and LC-05b in Table I are slightly different than those characterized in [4], which assumed the

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2017 IEEE-Canada Electric Power and Energy Conference (EPEC-2017) October 22-24, 2017, Saskatoon, Saskatchewan mass equivalent of 0.5-cm long thorium end pellets. Lattice concept LC-03 is a pure thorium fuel bundle used in other studies as a blanket fuel for breeding 233U, but it is not considered in this set of economic assessments.

B. Reactor Characteristics A number of general operational characteristics for 700MWe-class PT-HWRs are specified in Table II [5], [9]. Other operational and performance characteristics, such as reactor thermal power level and exit burnup associated with specific fuel concepts are shown in Table III.

The updated study is more conservative in that slightly more thorium (the mass equivalent of a 1-cm length of ThO2 at each end of the fuel bundle) is used in the fuels (with the exception of lattice concepts LC-01 and LC-02) as shown in Table I – see discussion in [4] for further details. The slightly larger ThO2 content will lead to higher neutron capture and lower fuel reactivity, leading to slightly lower exit fuel burnup, and an expected higher fuel cost per unit of energy generated. TABLE I.

Lattice Concept

Bundle Type

Fuel Content

235

B37

0.71 wt%

U/U

NU

None

LC-02

B37

0.71wt% 235U/U

NU

0.5

LC-03

B37

ThO2

ThO2

N/A

LC-04b

B37mod

0.95 wt% 235U/U

Thorium

1.0

LC-05b

B37mod

1.2 wt% 235U/U

Thorium

1.0

LC-06b

B35

Graphite

1.0

LC-07b*

B35

Graphite

1.0

LC-08b

B35

Graphite

1.0

LC-09b*

B35

Graphite

1.0

B35

LC-11b*

B35

LC-12b

B35

LC-13b*

B35

LC-14b

B35

LC-15b*

B35

3.5 wt% PuO2 *** 96.5 wt% ThO2 3.5 wt% PuO2 96.5 wt% ThO2 4.5 wt% PuO2 95.5 wt% ThO2 4.5 wt% PuO2 95.5 wt% ThO2 40 wt% LEUO2 *** 60 wt% ThO2 40 wt% LEUO2 60 wt% ThO2 50 wt% LEUO2 50 wt% ThO2 50 wt% LEUO2 50 wt% ThO2 1.8 wt% 233UO2 **** 98.2 wt% ThO2 1.8 wt% 233UO2 **** 98.2 wt% ThO2

PT-HWR CHARACTERISTICS

Variable Nominal Reactor Thermal Power Gross Electrical Power Net Electrical Power Net Thermal-to-Electrical Efficiency Number of Fuel Channels Number of Bundles per Channel Capacity Factor Operating Life

Equivalent End Pellet Length** (cm)

LC-01

LC-10b

TABLE II.

LATTICE CONCEPTS DESCRIPTION

Central Pin Material

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TABLE III.

REACTOR CORE CONCEPTS, POWER AND BURNUP

Core / Lattice Concepts

Thermal Power Level (MWth)

1.0

Graphite

1.0

Graphite

1.0

Graphite

1.0

Graphite

1.0

Graphite

Exit Burnup (MWd/kg)

Cores using Uranium-Based Fuel Augmented by Thorium CC-00/LC-01

1,958

7.56

CC-00/LC-02

1,752

5.00

CC-03/LC-04b

2,061

10.69

2,061

18.27

CC-04/LC-05b

Graphite

Value, Units 2,061 MWth 690 to 730 MWe 660 to 680 MWe 32% to 32.8% 380 12 ~90% ~30 years

Cores using (Pu,Th)O2 Fuel CC-05/LC-06b

1,958

23.59

CC-05D/LC-07b

1,958

23.74

CC-06/LC-08b

1,752

36.38

CC-06D/LC-09b

1,752

36.66

Cores using (LEU, Th)O2 Fuel CC-07/LC-10b

2,061

23.96

CC-07D/LC-11b

2,061

26.34

CC-08/LC-12b

2,061

39.56

1,855

39.61

CC-08D/LC-13b Cores using (

1.0

* Duplex heterogeneous fuel pellets inside fuel elements. Pure ThO2 is used for inner cylindrical pellets (~50% to 60% of fuel pellet volume), and it is surrounded by an outer annular pellet made of mixed oxide (Pu,Th)O2, (233U,Th)O2, or pure LEUO2.

233

U,Th)O2 Fuel

CC-09/LC-14b

2,061

17.11

CC-09D/LC-15b

2,061

18.69

III. LEVELIZED FUEL CYCLE COSTS This section presents fuel cycle costs, which consists of front-end and back-end fuel costs, for the 14 different fuel bundle concepts presented in Section II.

** Equivalent fuel pellet length of pure ThO2 used to down blend the fissile content in the last 2 to 4 cm of fuel at each end of the fuel bundle, to help reduce axial power peaking. *** Pu is reactor grade plutonium, with ~ 67 wt% Pu-fissile/Pu and would be obtained from the reprocessing of stockpiles of partially used fuel from light water reactors (LWR). LEU is 5 wt% 235/U, obtained from an enrichment facility.

A. Formula The cost calculations are based on the levelizing of fuel cycle costs (measured in $/MWh) formula:

**** The fissile isotope 233U would be obtained from a stockpile of previously irradiated ThO2, either from a thermal or fast spectrum reactor system.

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2017 IEEE-Canada Electric Power and Energy Conference (EPEC-2017) October 22-24, 2017, Saskatoon, Saskatchewan 

LFCC = ∑ (cj ∙× qj) / (P × 30 years)



reference case LC-01/CC-00 (NU). Although the back-end fuel cycle costs (shown in Fig. 2) were higher, the front-end fuel cycle costs (shown in Fig. 3) were sufficiently lower than the reference case to enable improved economics.

where 30 represents the expected number of years of electricity generation, P the electrical energy generation per year (MWe-hr/year), cj the unit cost associated with the j-th fuel cycle activity (for example, the price of mining NU), and qj is the amount of an input used for the j-th fuel cycle activity (for example, uranium mined). The electricity generated is calculated by the equation 

P = Pth × ε × cf × 365 days/year× 24 hr/day

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

where 24 represents the number of hours in a day, ε is the net thermal-to-electricity conversion efficiency, Pth is the reactor thermal power level, and cf is the capacity factor. B. Results Fuel cycle cost results are illustrated in Fig. 1 (total), Fig. 2 (back-end), Fig. 3 (front-end), Fig. 4 (front-end components), and Fig. 5 (back-end components). Lattice/core concept LC-01/CC-00, which uses NU in a PT-HWR, is considered the nominal or reference case for comparison, with a total fuel cost of $11.59/MWe-hr. The most cost-competitive fuel concepts (shown in Fig. 1) are those based on the use of uranium-based fuels augmented by small amounts of thorium (LC-04b/CC-03, LC-05b/CC-04), and the LEU/Th fuels (LC-10b/CC-07, LC-11b/CC-07D, LC-12b/CC-08, and LC-13b/CC-08D), which have total costs ranging from $10.14/MWe-hr to $12.20/MWe-hr.

Figure 2. Back-End Fuel Cost

Figure 1. Total Fuel Cost

The fuel concepts LC-05b/CC-04 (SEU+Th), LC-11b/CC-07D (LEU/Th), LC-12b/CC-08 (LEU/Th), and LC-13b/CC-08D (LEU/Th) have lower costs than the 3

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lower. The UNF disposal costs were lower since the volume of high level waste were lower than for NU fuel, which is in part attributable to the higher required fuel consumption. Thus, the net result is that the total back-end fuel costs for the SEU+Th and LEU/Th fuel concepts are only slightly higher than that for NU.

Figure 3. Front-End Fuel Cost

The fuel concepts LC-05b/CC-04, LC-11b/CC-07D, and LC-12b/CC-08 operated at slightly higher electrical power levels (~2,061 MWth) than the reference case (~1,958 MWth). The lower power level for the reference case (and a number of other core concepts) was due to the requirement of slight derating, to avoid exceeding bundle and channel power limits, based on computational reactor physics modeling results. However, it is known and recognized that a more realistic core model would include the use and explicit modeling of various reactivity devices that would help flatten the axial and radial power distributions, to enable the reactor to operate at full power (2,061 MWth). The thorium-based fuel concepts involving the use of recycled fuel (either Pu, or 233U) had significantly higher total fuel costs, ranging from ~$59/MWe-hr to $78/MWe-hr. As will be discussed below, these significantly higher costs are attributed to the front-end costs. C. Front-End Fuel Cost Components The components of the front-end fuel costs are shown in Fig. 4. The main conclusion from these results is that all the fuel concepts LC-05b/CC-04, LC-11b/CC-07D, LC-12b/CC-08, and LC-13b/CC-08D have lower fuel fabrication costs than the reference case (LC-01/CC-00). This result is attributable to each of these fuel concepts having a higher burnup than the reference case, since a higher burnup consumes less fuel annually. However, higher burnup does not always guarantee lower front-end fuel costs, as is the case with the (Pu,Th)O2 fuels (LC-06b, LC-07b, LC-08b, LC-09b), and the (233U,Th)O2 fuels (LC-14b, and LC-15b). In such cases, the Pu or U-233 require reprocessing of stockpiles of irradiated uranium-based or thorium-based fuels, prior to fabricating either (Pu,Th)O2 or (233U,Th)O2 fuel types. The added cost of reprocessing and fabrication is found to be significantly larger than the costsavings achieved through higher fuel burnups and the avoidance of the use of mined uranium.

Figure 4. Front-End Component Fuel Cost

Fuel fabrication costs for either (Pu,Th)O2 or (233U,Th)O2 fuel types are higher than fabricating natural uranium, primarily because fabrication and reprocessing facilities for either (Pu,Th)O2 or (233U,Th)O2 use remote methods of handling fuel due to radioactivity of the elements in the fuel [10]. Historically, fabrication and some reprocessing facilities had a relatively small throughput capacity [11]-[13] in addition to using remote-handled methods. In addition, existing reprocessing facilities have been used typically at low capacity [14]-[16]. D. Back-End Fuel Cost Components The components of the back-end fuel costs are shown in Fig. 5. The main reason for the higher back-end costs for the fuel/core concepts LC-05b/CC-04, LC-11b/CC-07D, LC-12b/CC-08, and LC-13b/CC-08D relative to the reference case (NU) is the larger requirements for dry storage. However, the waste conditioning and UNF disposal costs are

Figure 5. Back-End Component Fuel Cost

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value of $5.60/MWe-hr (or 5.6 mills/kWh) for the front-end fuel costs for NU fuel, which is very comparable to that of the enriched fuel used in a PWR, as discussed in [23].

IV. IMPLICATIONS AND OPTIONS FOR RECYCLED FUELS Unless the cost of mined natural uranium increases significantly (for example, $200-300/kg range [17]), it will be necessary to develop improved technologies and processes that can significantly reduce the costs of reprocessing and fabrication for (Pu,Th)O2 and (233U,Th)O2 fuels, which make use of recycled Pu or 233U. Suggested areas for further investigation include the following: 1. reliability (and design) of plants [14]-[16]; 2. alternative methods of processing such as the Direct Use of spent PWR Fuel in Candu (DUPIC) [18]; 3. alternative fuels that eliminate an aspect of the front-end fuel cost such as recovered uranium fuel, which eliminates reenrichment [19]; 4. different fuel management strategies [20]; 5. different technologies for incorporating in the design of a plant, such as an “α-cavern concept rather than glove boxes” [21].

B. Fuel Costs Relative to Total Energy Costs and Comparison with Other Low-Carbon Power Sources Although alternative thorium-based nuclear fuels such as (Pu,Th)O2 or (233U,Th)O2 may have larger fuel costs than NU, it may still be economically feasible to use such fuels in the near-term to produce electricity, given that the fuel costs is a fraction of the total electrical energy costs. In addition, the use of (Pu,Th)O2 or (233U,Th)O2 fuels in a PT-HWR may be more economically attractive than alternative sources of lowcarbon electricity. Based on Ontario Power Generation’s (OPG’s) most recent nuclear performance benchmarking results [24], fuel costs as a percent of the total electricity generating cost for a PT-HWR are approximately 8.4% to 13.6%. Based on the data shown above in Fig. 1, the fuel costs for (Pu,Th)O2 fuel could be a factor of ~ 6.7 = 77.5/11.6 larger than that for NU. If a factor of 6.7 is assumed and that fuel costs are 13.6% of total unit electrical energy costs, then the use of a plutoniumbased fuel with thorium may lead to an increase of ~77% in total unit cost of generating electricity by using NU. Although such an increase in cost would be less competitive in the shortterm than using NU or SEU+Th, or LEU/Th fuels, it might be competitive with alternative forms of low-carbon power generation.

Alternatively, it may be useful to consider other fuel concepts and associated reactor systems that could reduce or circumvent the need for reprocessing and re-fabrication of recycled fuel. An example would be to take irradiated blanket fuel (made of fertile thorium and/or depleted uranium) from a fast-spectrum reactor system, with sufficiently high fissile content (2 wt% to 3 wt% fissile Pu or 233U) and use it directly in a PT-HWR without reprocessing or re-fabrication [22]. Of course, such an approach would have different technical issues to address, and economic assessments to be evaluated. V. UNCERTAINTIES AND TOTAL ENERGY COSTS In the analyses performed in this study, the nominal fuel cycle costs considered showed that SEU+Th and LEU/Th fuels are economically competitive with NU, and could be implemented in the short-term. In contrast, thorium-based fuels containing recycled Pu or 233U appear to have significantly larger front-fuel costs than NU, based on current technologies and industrial capacity for reprocessing and recycling. Thus, other factors would need to be considered to help justify the use of (Pu,Th)O2 or (233U,Th)O2 in the shortterm, until fuel costs can be brought down through technology innovation and economies of scale. Two key factors to consider are the total power generation costs (in addition to fuel), along with uncertainties in current cost estimates.

An Ontario Energy Board’s recent electricity price report [25] indicates that the total generation unit cost for nuclear energy is 6.8 cents/kWh ($68/MWe-hr) compared to 14.0 cents/kWh estimated for natural gas, 13.3 cents/kWh for wind, 48.1 cents/kWh for solar, and 13.0 cents/kWh for bio-energy. Thus, if a 77% increase is applied to nuclear power costs due to the use of (Pu,Th)O2 fuel, then the nuclear power costs will be ~ 12.1 cents/kWh, which is still lower cost than the alternatives, and also has the added benefit of being a reliable baseload source of power. While it is possible that various energy storage technologies could improve the effective capacity factors of intermittent low-carbon sources of energy (such as wind and solar/photovoltaics), it is expected that such energy storage technologies would drive up their respective total costs. Thus, a plutonium/thorium-based fuel (or even a 233 U/Th fuel) in a PT-HWR could lead to lower cost lowcarbon electrical energy than alternatives such wind, solar, or perhaps even natural gas or bio-energy.

A. Implications of Uncertainties Recently, the levelized fuel cycle costs for a once-through cycle in a pressurized water reactor was estimated to be “5.94 ± 0.67 mills/kWh” and for a thermal reactor recycle (using reprocessing and fabrication of mixed oxide fuel) was “6.13 ± 0.55 mills/kWh” [23]. Thus, fuel cycle costs of the recycled fuel is approximately 3% larger, with a 9% uncertainty. The results in [23] suggest that two options (enriched uranium vs. MOX) have comparable costs, with MOX being higher by 3% to 12%. The results may also imply that the costs estimates used in this study for reprocessing and recycling of Pu or 233U may be highly pessimistic or conservative. Thus further investigation may be required to obtain more accurate and realistic estimates for the costs of reprocessing and recycling Pu and 233U. By comparison, the studies reported here give a

Given worldwide concerns with the environmental consequences from generating electricity [12], it would seem prudent to continue considering both the short-term and longterm implementation of thorium-based fuels to complement the use of uranium-based fuels, especially when considered existing uncertainties in cost estimates, and taking into account relative costs compared to alternative sources of lowcarbon power generation. For example, recent estimates [26] suggest that a PT-HWR with either NU or thorium-based fuel would offer significant savings on the abatements costs for the production of carbon dioxide and other greenhouse gases, in 5

2017 IEEE-Canada Electric Power and Energy Conference (EPEC-2017) October 22-24, 2017, Saskatoon, Saskatchewan comparison to both coal-fired and natural-gas-fired electrical power generation.

[7]

[8]

VI. CONCLUSION The analyses documented in this paper compared 14 fuel concepts in terms of levelized fuel cycle costs. Fuel concepts using uranium-based fuels mixed with small amounts of thorium, or LEU mixed with significant amounts of thorium had LFCCs that were comparable or lower than that for NU. Thorium-based fuel concepts using recycled Pu or 233U had significantly larger LFCCs.

[9]

[10]

The fuel concepts with SEU+Th (LC-05b) and LEU/Th (LC-12b) had the lowest levelized fuel costs and were more economical than conventional NU fuel (LC-01), with total fuel costs that were 11% to 13% lower. These fuel bundles have the greatest potential for implementation in PT-HWRs in the near-term, and further refinements of the economic assessments should be carried out for these concepts.

[11]

[12]

[13]

It is apparent that greater effort will be required to identify and develop technologies to reduce the costs of recycling (Pu,Th)O2 and (233U,Th)O2 fuels. Further studies will be required to quantify more accurately the various fuel cost components, and to quantify potential non-fuel cost savings. However, even with larger fuel costs, it is apparent that (Pu,Th)O2 and (233U,Th)O2 could still be used to produce electricity at costs that are competitive with alternative lowcarbon energy sources, such as wind, solar/photovoltaics, and others.

[14]

[15]

[16] [17] [18]

ACKNOWLEDGMENT The authors gratefully acknowledge the assistance provided by S. Sell, J. Festarini, M. Leblanc, D. Hoover, T. Wright, S. Scott, R. Dennis, S. Gimson, A. Nava-Dominguez, H. Hanke, D. Wojtaszek, and G. W. R. Edwards.

[19]

REFERENCES [1]

[2]

[3]

[4]

[5] [6]

[20]

M. S. Milgram, “Thorium Fuel Cycles in CANDU Reactors: A Review,” Atomic Energy of Canada Limited, AECL-8326, January 1984. P. G. Boczar, P. S. W. Chan, G. R. Dyck, R. J. Ellis, R. T. Jones, J. D. Sullivan and P. Taylor, “Thorium fuel-cycle studies for CANDU reactors,” in Thorium fuel utilization: Options and Trends, Proceedings of three IAEA meetings held in Vienna in 1997, 1998 and 1999, pp. 2541, IAEA, Vienna, IAEA-TECDOC-1319, 2002. P. G. Boczar, G. R. Dyck, P. S. W. Chan, and D. B. Buss, “Recent advances in thorium fuel cycles for CANDU reactors,” in Thorium fuel utilization: Options and Trends, Proceedings of three IAEA meetings held in Vienna in 1997, 1998 and 1999, pp. 104-120, IAEA, Vienna, IAEA-TECDOC-1319, 2002. A. V. Colton, B. P. Bromley, D. Wojtaszek and C. Dugal, “Evaluation of Uranium Based Fuels Augmented by Low Levels of Thorium for Near-Term Implementation in Pressure Tube Heavy Water Reactors,” Nuclear Science and Engineering, in press. International Atomic Energy Agency (IAEA), “Heavy Water Reactors,” IAEA, Vienna, Technical Reports Series No. 407, 2002. B. P. Bromley, “Heterogeneous Seed-Blanket Cores in Pressure-Tube Heavy Water Reactors for Extracting the Energy Potential from Plutonium/Thorium Fuels,” CNL Nuclear Review, 2016.

[21]

[22]

[23]

[24] [25]

[26]

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B. P. Bromley and B. Hyland, “Heterogeneous Cores for Implementation of Thorium-Based Fuels in Heavy Water Reactors,” Nuclear Technology, Volume 186, Number 3, pp. 317-339, June 2014. A. V. Colton and B. P. Bromley, “Full-Core Evaluation of UraniumBased Fuels Augmented with Small Amounts of Thorium in Pressure Tube Heavy Water Reactors,” Nuclear Technology, Volume 196, Number 1, pp. 1–12, October 2016. International Atomic Energy Agency (IAEA), Country Statistics and Reactor Details, https://www.iaea.org/PRIS/CountryStatistics/CountryStatisticsLanding Page.aspx, website last accessed January 2017. D. E. Shropshire, K. A. Williams, J. D. Smith, B. W. Dixon, M. Dunzik-Gougar, R. D. Adams, D. Gombert, J. T. Carter, E. Schneider and D. Hebditch, “Advanced Fuel Cycle Cost Basis,” Idaho National Laboratory, INL/EXT-07-12107, Rev. 2, December 2009. K. Fukuda, J.-S. Choi, R. Shani, L. Van Den Durpel, E. Bertel and E. Sartori, “MOX fuel use as a back-end option: Trends, main issues and impacts on fuel cycle management,” in MOX Fuel Cycle Technologies for Medium and Long Term Deployment, IAEA, IAEA-CSP-3/P, 2000. J. P. Revol, M. Bourquin, Y. Kadi, E. Lillestol, J. C. de Mestral and K. Samec (Editors), Thorium Energy for the World. Cham, Switzerland: Springer International Publishing, 2016. International Nuclear Fuel Cycle Evaluation (INFCE) Working Group 4, “The Influence of Size of Plant upon Reprocessing Costs,” IAEA, INFCE/DEP/WG--4/80, October 1978. C. Bastin, “We Need to Reprocess Spent Nuclear Fuel, and Can Do It Safely, At Reasonable Cost,” 21st Century Science & Technology, 2008. C. Bastin, “Nuclear Technology: Need for New Vision,” in The Challenges to Nuclear Power in the Twenty-First Century, B. N. Kursunoglu, S. L. Mintz and A. Perlmutter (Editors). New York: Kluwer Academic Publishers, 2002. L. J. Carter, Nuclear Imperatives and Public Trust: Dealing with Radioactive Waste. New York: Routledge, 2016. J. B. Slater, “Economic Potential of Advanced Fuel Cycles in Candu,” Atomic Energy of Canada Limited, AECL-7753, July 1982. W. I. Ko, H. Choi and M. S. Yang, “Economic Analysis on Direct Use of Spent Pressurized Water Reactor Fuel in CANDU Reactors - IV: DUPIC Fuel Cycle Cost,” Nuclear Technology, Volume 134, Number 2, pp. 167-186, May 2001. P. G. Boczar, J. D. Sullivan, H. Hamilton, Y. O. Lee, C. J. Jeong, H. C. Suk and C. Mugnier, “Recovered Uranium in CANDU: A Strategic Opportunity,” in International Nuclear Congress Proceedings, October 3-6, 1993 Toronto, Ontario, Canada, Canadian Nuclear Association, 1993. A. Galperin, “Feasibility of the Once-Through Thorium Fuel Cycle for CANDU Reactors,” Nuclear Technology, Volume 73, Number 3, pp. 343-349, June 1986. E. O. Moeck, J. Griffiths, A. D. Lane and R. T. Jones, “Advanced Fuel Cycles for CANDU Reactors: The R&D Program and the Technologies Required to Support Them,” in Second International Conference on CANDU Fuel, October 1-5, 1989, Pembroke, Canada, I. J. Hastings (Editor), Canadian Nuclear Society, Toronto, 1989. B. P. Bromley, “Studies Of Pressure-Tube Blanket Lattices with Thorium-Based Fuels for a Hybrid Fusion-Fission Reactor,” Fusion Science and Technology, Volume 68, Number 3, pp. 546-560, October 2015. C. Zhou, X. Liu, Z. Gu, Y. Wang, “Economic analysis of two nuclear fuel cycle options,” Annals of Nuclear Energy, Volume 71, pp. 230– 236, September 2014. Ontario Power Generation, “Business Planning and Benchmarking Nuclear,” EB-2016-0152, 2016. Ontario Energy Board, “Regulated Price Plan Price Report May 1, 2016 to April 30, 2017,” April 2016. Accessed February 2017: http://www.ontarioenergyboard.ca/oeb/_Documents/EB-20040205/RPP_Price_Report_May2016.pdf. B. Graves, A. Wong, K. Mousavi, C. Canter and A. Kumar, “Technoeconomic assessment of thorium power in Canada,” Annals of Nuclear Energy, Volume 85, pp. 481-487, November 2015.