Comparative assessment of collaborative fuel cycle options for Indonesia 1. Introduction

The introduction of nuclear energy in Indonesia is not considered only to reach an optimum energy mix with regard to costs and the environment, but also to relieve the pressure arising from the increasing domestic demand for oil and gas (as oil and gas resources can be used for export and feed stocks). Thus, the role of nuclear power in Indonesia is to stabilize the supply of electricity, conserve strategic oil and gas resources, and protect the environment from harmful pollutants resulting from the use of fossil fuels.

Considering the projected energy generation for the CO₂ limitation scenario and the role of nuclear in the energy mix as calculated by the Model for Energy Supply Strategy Alternatives and their General Environmental Impacts (MESSAGE) low carbon scenario, nuclear power will enter into the energy mix in 2024 with an installed capacity of 2000 MW(e), and is anticipated to grow up to 36 000 MW(e) by 2050. The inclusion of nuclear energy in the energy mix sets the ground for the need of sustainable planning of the country’s nuclear power plant programme into the future. In order to support the long term sustainability of nuclear power plant development in Indonesia, this study analyses a range of fuel cycle options from the perspective of their effect on the utilization of natural uranium resources and the radioactive waste generated (i.e. spent fuels).

This study is associated with the objective of INPRO SYNERGIES Task 1, on the evaluation of synergistic collaborative scenarios of fuel cycle infrastructure development. The complete case study can be found in Annex II on the CD-ROM accompanying this publication.

3.1.6.2. Objective and problem formulation

The objectives of this study are to assess the most viable option of fuel cycle strategies to support the sustainability of nuclear power plant implementation in Indonesia, based on the potential of national, regional and international arrangements for fuel cycle. The assessment results could be used to support the preparation of nuclear fuel cycle policy, to develop awareness of long term issues surrounding the nuclear power programme, and to support strategic planning and decision making for the development and deployment of a nuclear power plant programme in a sustainable manner.

Five options of nuclear fuel cycles were evaluated in order to support the sustainability of nuclear power in Indonesia:

(1) Once through fuel cycle. This reference fuel cycle assumes the electricity production of 1000 MW(e)·year of PWRs with conventional UO₂ fuel, and the direct disposal of spent nuclear fuel in a geological repository.

(2) Plutonium mono-recycling with MOX fuel in PWRs. This fuel cycle incorporates conventional reprocessing of LWR fuel (e.g. the one used in some countries in Europe and Asia). The recycle scheme for plutonium is based on the use of 1000 MW(e) PWRs using UO₂ fuel. The spent UO₂ fuel is processed using the conventional PUREX process. The separated plutonium is recycled in the form of uranium–plutonium MOX fuel in PWRs. This fuel cycle provides for disposal of the HLW resulting from the PUREX process and direct disposal of MOX spent fuel in a geological repository.

(3) Direct use of spent PWR fuel in CANDU reactors (DUPIC). This fuel cycle is based upon dry thermal and mechanical processes to directly fabricate CANDU (Canada deuterium–uranium) fuel from spent PWR fuel material without separating the fissile material and fission products. This concept was proposed and termed the DUPIC fuel cycle in a joint development programme involving the Korea Atomic Energy Research Institute (KAERI), Atomic Energy of Canada Limited (AECL) and the United States Department of State FIG. 3.31. Transuranic in-pile amounts (high demand). FIG. 3.32. Transuranic out-of-pile (and out-of-repository)

amounts (high demand).

FIG. 3.33. High level waste amounts (high demand). FIG. 3.34. Total amounts of transuranic in disposal (high demand).

FIG. 3.35. Cumulative natural uranium used (high demand). FIG. 3.36. Annual enrichment needs (high demand).

in 1991. Since then, KAERI, AECL and the United States, with the participation of the IAEA, have been engaged in a practical exercise to verify the concept.

(4) Synergistic fuel cycle of LWR–fast reactor. This is a ‘classical’ synergy assuming fast reactor fuel is based on reprocessed fuel of LWR containing uranium and transuranics, which fast reactor could effectively burn owing to its high neutron flux and good neutron economy. Being started like that, fast reactors could then operate in closed fuel cycle, recycling its own discharges, among other things. The non-consumed uranium from LWR spent fuel could then be disposed, presumably, in a more simple way compared to direct disposal of spent fuel. This case is basic in emerging fast reactor programmes of nearly all interested countries [3.24].

(5) Once through thorium–uranium fuel in PWRs. The very attractive neutronic characteristics in thermal spectrum of LWRs of ²³³U–thorium fuel is on account of the favourable fission to capture cross-section ratio.

Such fuel is thus sometimes being considered as an alternative fuel for present day PWRs, where it could help improve burnup characteristics and plant economy. The use of ²³³U–thorium fuel could also contribute to a decreased long term radiotoxicity of spent fuel owing to smaller minor actinide generation rate inherent to the uranium–thorium fuel cycle [3.12].

3.1.6.3. Assumptions, methods, codes and input data used

The comparison of different nuclear fuel cycle options has become an integral element to any analysis of the future prospects for nuclear energy in Indonesia. The evaluation metrics used to evaluate and compare include:

resource utilization, waste production, proliferation risk and fuel cycle cost. Resources utilization is measured as the mass of natural uranium (or thorium) required per unit energy generated. Waste production is measured using two metrics: the mass of transuranics and the mass of fission products discharged per unit energy generated. The proliferation risk posed any given fuel cycle is difficult to quantify, therefore to avoid these difficulties, the study continued the inventories of plutonium and transuranics per unit energy generated. A fuel cycle cost metric was used to capture the impact of advanced fuel cycles on the costs of fuel alone.

Mass flow calculations were performed based on data publicly available [3.9, 3.25, 3.26]. For simplicity, only equilibrium conditions were considered. The current once through cycle of medium burnup (51 GW·d/t HM) was used as a baseline in the study; and all mass flow calculations were represented for the production of 1 GW(e)·year of electricity. The analysis was only restricted to the equilibrium state of the fuel cycle schemes. The data used in the study regarding processes and material flows for each fuel cycle scheme considered are drawn from published literature. For fuel cost analysis, a simplicity model of a Massachusetts Institute of Technology study was used [3.27]. The main input data used is summarized in Table 3.17.

3.1.6.4. Summary presentation and analysis of the results

A summary is presented in Fig. 3.37 and Table 3.18.

(a) Resource utilization

Resource utilization is strictly linked to the environmental component of sustainable development.

A nuclear system should be able to generate energy while making efficient use of fissile/fertile material and other non-renewable materials and without giving rise to a substantial degradation of these resources. Hence long term availability, and efficient use, of resources are a key component of sustainability.

The analysis results indicate that PWRs on the once through UOX fuel cycle utilize uranium resources inefficiently, while the once through thorium–uranium fuel cycle consumes uranium resources at an even higher rate. In comparison, the synergistic fuel cycle with PWRs and fast reactors utilizes uranium resources more efficiently, but the gains in uranium utilization are not significant.

Among the pure thermal reactor strategies, the DUPIC fuel cycle — which utilizes CANDU reactors with better neutron economy compared to PWR reactors – is the only strategy which offers significant savings in uranium demand. Both the DUPIC and PWR–fast reactor cycle are still under development and not yet available in the commercial market.

Uranium resources are sufficient to support the moderate growth of nuclear power plant capacity until the mid 21st century (according to the GAINS study). The significant reduction of natural uranium demand could be

TABLE 3.17. MAIN INPUT DATA

Item Condition

Fuel discharge burnup PWR (UOX, MOX): 51 GW d/t HM CANDU (DUPIC): 14 GW d/t HM

PWR (MOX): 8.1% Pu, 91.9% depleted U [Pu mono-recycle in PWR]

Fast reactor: 66.84% U, 33.16% TRU [metallic fuel] Seed assembly of Th–U fuel: UOX, 20% ²³⁵U

Blanket assembly of Th–U cycle: [U,Th]O₂, 87% ThO₂, 13% UO₂ [10% ²³⁵U]

Spent fuel composition PWR (once through cycle): 1.197% Pu, 0.51% MA, 5.264% FP, 93.439% U PWR (MOX) [Pu mono-recycle]: 5.52% Pu, 0.54% MA, 5.15% FP DUPIC: 0.8379% Pu, 0.12% MA, 6.7091% FP, 0.9233% U Fast reactor: 59.94% U, 26.46% TRU, 14.1% FP

Seed assembly of Th–U fuel: 1.97% TRU, 1.56% Pu, 14.5% FP Blanket assembly of Th–U fuel: 0.51% TRU, 0.45% Pu, 8.8% FP Fuel cost data: front end Natural uranium: US $80/kg HM

Conversion: US $10/kg HM U enrichment: US $120/kg SWU UOX fuel fabrication: US $275/kg HM MOX fuel fabrication: US $1500/kg HM DUPIC fabrication: US $850/kg HM

Fast reactor fuel fabrication: US $2500/kg HM Th–U fuel fabrication: US $275/kg HM Fuel cost data: back end PWR (UO₂, MOX) SFDS: US $250/kg HM

PWR (UO₂) SF reprocessing: US $1000/kg HM HLW storage and disposal: US $200/kg HM DUPIC SFDS: US $250/kg HM

Advance PUREX: US $1000/kg HM

Reprocessing losses of 0.1% are assumed for all fuel type reprocessing methods Fuel service: lead time Natural U purchase: 24 months

Conversion service: 20 months Enrichment service: 18 months Fuel fabrication: 12 months

SF reprocessing (PUREX): 24 months DUPIC fuel fabrication: 24 months Fuel service: lag time SFDS: 5 years

Others ²³⁵U in natural uranium: 0.007 114

Tail assay in enrichment service: 0.3

No material losses in uranium conversion and fuel fabrication SF cooling time prior to reprocessing: >5 years

Note: CANDU — Canada deuterium–uranium; DUPIC — direct use of spent PWR fuel in CANDU reactors; FP — fission product;

HM — heavy metal; HLW — high level waste; MA — minor actinide; MOX — mixed oxide; PHWR — pressurized heavy water reactor; PUREX — plutonium and uranium recovery by extraction; PWR — pressurized water reactor; SF — spent fuel;

SFDS — spent fuel dry storage; SWU — separative work unit; TRU — transuranic; UOX — uranium oxide.

TABLE 3.17. MAIN INPUT DATA

Item Condition

Fuel discharge burnup PWR (UOX, MOX): 51 GW d/t HM CANDU (DUPIC): 14 GW d/t HM Fast reactor: 140 GW d/t HM Reactor thermal efficiency PWR: 34%

PHWR: 33%

Fast reactor: 40%

Fresh fuel composition PWR: UO₂, 4.3% ²³⁵U [PWR]

CANDU (DUPIC): UOX from PWR SF

PWR (MOX): 8.1% Pu, 91.9% depleted U [Pu mono-recycle in PWR]

Fast reactor: 66.84% U, 33.16% TRU [metallic fuel]

Seed assembly of Th–U fuel: UOX, 20% ²³⁵U

Blanket assembly of Th–U cycle: [U,Th]O₂, 87% ThO₂, 13% UO₂ [10% ²³⁵U]

Spent fuel composition PWR (once through cycle): 1.197% Pu, 0.51% MA, 5.264% FP, 93.439% U PWR (MOX) [Pu mono-recycle]: 5.52% Pu, 0.54% MA, 5.15% FP DUPIC: 0.8379% Pu, 0.12% MA, 6.7091% FP, 0.9233% U Fast reactor: 59.94% U, 26.46% TRU, 14.1% FP

Seed assembly of Th–U fuel: 1.97% TRU, 1.56% Pu, 14.5% FP Blanket assembly of Th–U fuel: 0.51% TRU, 0.45% Pu, 8.8% FP Fuel cost data: front end Natural uranium: US $80/kg HM

Conversion: US $10/kg HM U enrichment: US $120/kg SWU UOX fuel fabrication: US $275/kg HM MOX fuel fabrication: US $1500/kg HM DUPIC fabrication: US $850/kg HM

Fast reactor fuel fabrication: US $2500/kg HM Th–U fuel fabrication: US $275/kg HM Fuel cost data: back end PWR (UO₂, MOX) SFDS: US $250/kg HM

PWR (UO₂) SF reprocessing: US $1000/kg HM HLW storage and disposal: US $200/kg HM DUPIC SFDS: US $250/kg HM

Advance PUREX: US $1000/kg HM

Reprocessing losses of 0.1% are assumed for all fuel type reprocessing methods Fuel service: lead time Natural U purchase: 24 months

Conversion service: 20 months Enrichment service: 18 months Fuel fabrication: 12 months

SF reprocessing (PUREX): 24 months DUPIC fuel fabrication: 24 months Fuel service: lag time SFDS: 5 years

Others ²³⁵U in natural uranium: 0.007 114

Tail assay in enrichment service: 0.3

No material losses in uranium conversion and fuel fabrication SF cooling time prior to reprocessing: >5 years

Note: CANDU — Canada deuterium–uranium; DUPIC — direct use of spent PWR fuel in CANDU reactors; FP — fission product;

HM — heavy metal; HLW — high level waste; MA — minor actinide; MOX — mixed oxide; PHWR — pressurized heavy water reactor; PUREX — plutonium and uranium recovery by extraction; PWR — pressurized water reactor; SF — spent fuel;

SFDS — spent fuel dry storage; SWU — separative work unit; TRU — transuranic; UOX — uranium oxide.

TABLE 3.18. SUMMARY OF ANALYSED RESULTS (COMPARATIVE TABLE)

Fuel cycle metrics Once through Pu mono-recycle DUPIC PWR–FR Th–U

Resources utilization (t HM/GW(e)·year)

Natural U consumption 204.66 178.34 162.71 126.17 247.74

High level waste (kg HM/GW(e)·year) TRU discharge

FP discharge 273.01

1108.05 182.61

1104.97 159.99

1120.56 0.83

1035.5 117.95 1078.0 Proliferation (kg HM/GW(e)·year)

Pu discharge Separated Pu TRU discharge

Reprocessing rate (t HM/GW(e)·year)

251.96 273.01—

—

149.65 219.27 182.61 18.34

139.95 159.99— (16.73)

NC— 15.480.83

95.33 117.95—

— Economic (US $mil/kW·h)

Fuel cost of NPP park 6.347 8.481 6.648 7.699 8.054

Note: DUPIC — direct use of spent PWR fuel in CANDU reactors; FP — fission product; FR — fast reactor; HM — heavy metal;

NC — not calculated; NPP — nuclear power plant; SF — spent fuel; SFDS — spent fuel dry storage; SWU — separative work unit; TRU — transuranic.

(a) Once through (b) Plutonium mono-recycle

(c) DUPIC

(e) Thorium–uranium

(d) ) Light water reactor–fast reactor

FIG. 3.37. Mass flow analysis results for fuel cycle considered (all quantities are per GW(e)·year).

performed by incorporating fast reactors into the reactor mix; the reduction would correspond approximately to the percentage of fast reactors in the mix. Considering the current size of the depleted uranium stock, any fast reactors which could be constructed in this century would not depend on the availability of natural uranium.

(b) Waste production

Reference [3.28] points to problems in evaluating the adverse impacts of radioactive waste on the environment. The mobility of radioactive isotopes is mentioned as an important factor defining the hazard, it is also noted that radiotoxicity of fission products in longer term is several orders of magnitude less compared to actinides. Nevertheless, according to Ref. [3.28] these are the fission products that difine radiological hazard of spent nuclear fuel repository in the first hundreds of thousands of years, just because their mobility is higher as compared to actinides.

From the waste production point of view, the synergistic PWR–fast reactor scenario is the best choice among the fuel cycles considered. This fuel cycle discharges transuranic elements and fission products at a much lower rate per unit energy generated (electricity). The DUPIC cycle is expected to discharge more transuranic elements and fission products per unit energy generated owing to extended burnup of UOX fuel in CANDU reactors. Although both the single pass plutonium recycling MOX fuel and once through cycle of uranium–thorium are expected to have modest discharges of transuranic elements and fission products per unit energy generated, there is no clear advantage for fission product transmutation (i.e. no fuel cycle is a clear champion in minimizing fission product discharge rates).

The rate of fission product discharge for synergistic PWR–fast reactor fuel cycle is somewhat lower than that of PWR once through fuel cycle. This is because of a contribution of fast reactors to increased thermal efficiency of the whole reactor fleet. However, the corresponding effect has its clear limit because increase in thermodynamic cycle efficiency is limited by around 50%. Which means the discharge rates could be at best reduced by 50%

compared to present day LWRs.

If commericial availability is to be considered, the synergistic PWR–fast reactor fuel cycle is the best option based on the rate of specific discharge of transuranic elements and fission products. This is also the best option if the selection process assigns high importance to uranium resources. However, if residual uranium is not considered as a resource for future fast reactors, its long term radiological impact has to be considered as an integral part of waste management, due to the fact that uranium decay products always dominate global radiotoxicity in the very long term.

TABLE 3.18. SUMMARY OF ANALYSED RESULTS (COMPARATIVE TABLE)

Fuel cycle metrics Once through Pu mono-recycle DUPIC PWR–FR Th–U

Resources utilization (t HM/GW(e)·year)

Natural U consumption 204.66 178.34 162.71 126.17 247.74

High level waste (kg HM/GW(e)·year)

Note: DUPIC — direct use of spent PWR fuel in CANDU reactors; FP — fission product; FR — fast reactor; HM — heavy metal;

NC — not calculated; NPP — nuclear power plant; SF — spent fuel; SFDS — spent fuel dry storage; SWU — separative work unit; TRU — transuranic.

(a) Once through (b) Plutonium mono-recycle

(c) DUPIC

(e) Thorium–uranium

(d) ) Light water reactor–fast reactor

FIG. 3.37. Mass flow analysis results for fuel cycle considered (all quantities are per GW(e)·year).

(c) Non-proliferation

No nuclear fuel cycle is free from the risk of proliferation, but separation of plutonium from spent nuclear fuel is traditionally viewed as one of the most dangerous activities within commercial nuclear fuel cycles from a proliferation risk perspective. Working inventory of around 219.27 kg/year is required at any given time for a signle recycle of plutonium. To put in perspective, a 1000 MW(e) PWR would produce aquantity of plutonium sufficient to make about 22 nuclear weapons.

The plutonium present in the repository is also of proliferation concern. A PWR operating in a once through nuclear fuel cycle ‘delivers’ 251.96 kg/GW(e)·year of plutonium to the repository. This quantity is huge compared to the 10 kg plutonium needed for a nuclear weapon.

Limited (single) recycle of spent fuel or even a once through uranium–thorium cycle in LWRs (Radkowsky thorium fuel) cannot reduce the content of plutonium in spent fuel even by one order of magnitude and therefore the advantage offered by them with respect to proliferation risk reduction cannot be rated as significant. In general, high burnup fuel contains the plutonium that is less attractive for nuclear weapon progammes owing to higher content of ²³⁸Pu, a neutron and alpha emitted with huge decay heat.

When multiple recycling of spent nuclear fuel is performed (e.g. in a PWR–fast reactor NES), only traces of plutonium are likely to come to the repository (<1 kg/GW(e)·year of transuranics). In this case, both the low content of the plutonium and a high degree of its dilution in HLW offer a meaningful barrier to proliferation [3.28].

(d) Economics of the fuel cycle

The fuel cost contribution to the total cost of nuclear electricity generation is known to be small. Fuel cycle costs are in the range of 10–20% of the total, with waste management accounting for only 1–5 % of the total. While waste management costs vary significantly among strategies, their contribution to total generation costs is small enough to prevent it from being a major driving factor in decision making.

With regard to the costs of specific fuel cycle options, they are known to be lowest for once through fuel cycles with conventional thermal spectrum reactors. A fuel cycle with only physical processing of spent fuel, such as DUPIC, is also expected to result in low cost, being cheaper compared to closed fuel cycles with chemical reprocessing. With respect to the latter, the uranium price is a factor affecting competitiveness, but its impact is known to be moderate when compared to the cost of the processes and facilities of a closed fuel cycle. According to Ref. [3.28]:

“the lower spent fuel and plutonium discharge rates and degraded plutonium isotopics afforded by this concept are not rewarded under the current system of nuclear waste management. Thus there is no incentive for nuclear plant operators to incur the expenses associated with developing thorium fuels and refitting LWR cores to accommodate seed and blanket assemblies.

“...the benefits from these fuel cycles...are insufficient to change the prospects for nuclear energy considerably.”

3.1.6.5. Conclusions

Considering uranium utilization, it can be concluded that until the mid 21st century, a once through UOX fuel cycle with PWRs is the most viable option to support the nuclear power programme in Indonesia in a sustainable manner. If available uranium becomes scarce (or there are problems with spent fuel management), the implementation of a limited recycle option with a single recycle of MOX fuel could be considered. Proven technology to recycle plutonium from used UOX fuel exists in the commercial market now and may become much cheaper in the future.

The single pass MOX fuel recycling offers some uranium resource saving. In addition, the waste production per unit energy generated is lower than waste production in a once through UOX fuel cycle. However, this fuel cycle poses a larger proliferation risk owing to substantial working inventory of separated plutonium. Coupled with fast reactors (PWR–fast reactor strategy), this fuel cycle could become more attractive in the future.

The single pass MOX fuel recycling offers some uranium resource saving. In addition, the waste production per unit energy generated is lower than waste production in a once through UOX fuel cycle. However, this fuel cycle poses a larger proliferation risk owing to substantial working inventory of separated plutonium. Coupled with fast reactors (PWR–fast reactor strategy), this fuel cycle could become more attractive in the future.

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