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Implications of the new National Energy Basic Plan for nuclear waste management in Korea
ARTICLE IN PRESS Energy Policy 37 (2009) 3484–3488
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Implications of the new National Energy Basic Plan for nuclear waste management in Korea Won Il Ko 1, Eun-ha Kwon Korea Atomic Energy Research Institute, 150-1 Deokjin-dong, Youseong-gu, Daejeon 305-353, Republic of Korea
a r t i c l e in f o
a b s t r a c t
Article history: Received 2 March 2009 Accepted 21 May 2009 Available online 21 June 2009
The Korean National Energy Committee has recently adopted a new National Energy Basic Plan according to which the electricity generated by nuclear power plants is to increase from the current 35.5% of total electricity production to 59% by 2030. This large increase in nuclear power will inevitably accelerate the accumulation of spent fuel; if the direct disposal option is pursued, spent fuel arisings in Korea are expected to exceed 100,000 tHM in 2100. It is estimated that the country will require between 10–22 disposal sites, each with an area equal to the Gyeongju low- and intermediate-level radioactive waste (LILW) disposal site, to accommodate this amount of spent fuel. However, considering Korea’s geographic profile, securing this number of sites will be almost impossible, and will ultimately create a serious problem for the sustainability of nuclear energy in the country. In view of this dilemma, this paper recommends that the volume of Korean nuclear waste for disposal be significantly reduced, and offers sodium fast reactor (SFR)-based recycling as a potentially viable solution. & 2009 Elsevier Ltd. All rights reserved.
Keywords: Nuclear policy Spent fuel Underground repository
1. Introduction Around the world, the 21st century has witnessed a renewed interest in nuclear energy; many countries – both industrialised and developing – believe that nuclear power is the most reliable future energy source capable of meeting their increasing energy demands. They are also confident that nuclear energy can be used safely and economically with the guarantee of long-term supply and without adverse environmental impacts. For these reasons, numerous countries, particularly those in Asia, are considering or have already decided on the construction of nuclear power plants (NPPs) to augment their energy mix. Countries with established nuclear power programmes are also seeking to increase their generation capacity. In view of this global trend, the Korean National Energy Committee (NEC), the top energy policy-making body in Korea, has recently adopted a new National Energy Basic Plan (NEBP) which proposes that electricity generated by NPPs be increased from the current 35.5% of total electricity production to 59% by 2030 (Korean MKE, 2008). However, this huge increase in nuclear power will inevitably accelerate the accumulation of spent fuel in Korea; if the country pursues the direct disposal option for the existing pressurised water reactor (PWR) and pressurised heavy
Corresponding author. Tel.: +82 42 868 4731; fax: +82 42 868 8679.
E-mail addresses: [email protected] (W.I. Ko), [email protected] (E.-h. Kwon). 1 Tel.: +82 42 868 2040; fax: +82 42 868 8679. 0301-4215/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2009.05.068
water reactor (PHWR) systems, spent fuel arisings in Korea are expected to exceed 100,000 tHM by 2100. This implies that the effectiveness of spent fuel management will be key in determining the sustainability of nuclear energy in Korea. This paper examines the impact of the NEBP on spent fuel management in Korea, with a special emphasis placed on the permanent disposal option. The paper first considers the NEBP and several scenarios relating to nuclear power development in the country. The paper then estimates spent fuel arisings and determines the area required to house an underground repository for accommodating large amounts of spent fuel. The time period considered in this paper runs up to 2100.
2. Current status of nuclear energy in Korea Korea is a poor country in terms of energy resources. It is not endowed with significant fossil fuel reserves such as oil and gas. However, the country’s energy consumption has steadily grown, mainly owing to its rapid demographic and economic growth. This has rendered Korea exceedingly dependent on foreign energy resources, which predictably instigated two disastrous oil crises in the country in the 1970s. Having undergone several hardships during the crises, Korea considers nuclear power to be the most reliable energy source that is capable of meeting the increased energy requirements of continuing economic development. Consequently, Korea has chosen nuclear power as a major source of future energy. Since the first commercial operation of Kori Unit 1 in 1978, the country’s nuclear energy programme has
ARTICLE IN PRESS W.I. Ko, E.-h. Kwon / Energy Policy 37 (2009) 3484–3488
steadily expanded. As of April 2009, a total of 20 NPPs are in operation. The total generation capacity is about 17,700 MWe, which constitutes about 36% of the total electricity produced in Korea. According to the third Basic Plan for Electricity Supply and Demand (BPESD) (Korean MOCIE, 2006), eight new NPPs are to be constructed by 2020, taking the total number of units to 28. The total generation capacity of these units is expected to reach 27,320 MWe, which will correspond to about 43% of total electricity production. However, such an active nuclear energy programme will inevitably result in the production of significant quantities of spent fuel. By the end of 2007, the spent fuel generated in Korea was about 9500 MtHM, and this amount is expected to increase to about 27,000 MtHM by 2030. At present, the spent fuel is stored in temporary storage pools at plant sites, while a portion of the CANDU spent fuel is dry stored in concrete canisters. All the storage pools currently in operation are expected to be filled to capacity within the next decade. While the Korean government has adopted a ‘wait and see’ attitude and has not initiated steps to find ways to improve the management of spent fuel, the Korea Atomic Energy Research Institute (KAERI) has been developing a strategy for implementing an sodium fast reactor (SFR) fuel cycle that involves the use of pyroprocessing. The institute is also vigorously conducting research activities to support the initiative. In the SFR fuel cycle, the spent PWR fuel is converted into a metal fuel and resupplied to the SFRs. The uranium extracted from the spent PWR fuel is reused in SFRs and/or CANDU reactors. The spent SFR fuel is pyroprocessed and resupplied to the SFRs, while Cs- and Srcontaining high-level radioactive wastes (HLW) are managed separately (KAERI Newsletter, 2008). Proliferation resistant technology has been one of the most important requirements in the development program.
3. Scenarios for increasing nuclear power Presently, there are 20 NPPs, 16 PWRs, and 4 PHWRs in operation in Korea. In addition, six NPPs are under construction, and two more NPPs, employing Korean Advanced Pressurised Reactors (APR1400), have been planned. Thus, a total of 28 NPPs will be operational by 2016. In 2007, the contribution of nuclear power to total electricity generated was approximately 36%. This overall plan is a part of the third BPESD. In addition, the Korean NEC announced the NEBP on August 27, 2008. According to the plan, the electricity generated from NPPs
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should be increased from the current 35.5% to 59% in 2030, and the addition of 10 NPPs with a 1400 MWe capacity is required to facilitate this increase. This plan does not quantify the amount of electricity that should be generated by NPPs in 2030; however, the addition of 10 NPPs with 1400 MWe capacity is equivalent to 59% of the electricity generation expected in 2030 and from this, the amount of electricity generated in 2030 can be estimated. The nuclear electricity that will be generated in 2030 is estimated to be 336.34 TWh, assuming the average capacity factor of the NPPs to be 85% and the total electricity generation to be 570 TWh. To forecast the amount of nuclear electricity that will be generated in the period 2030–2100, it is assumed that nuclear energy will continue to be a major source of electricity. Four plausible scenarios are considered, as shown in Table 1: High, Reference, Low, and Very Low scenarios. As shown in table, in three of the scenarios (High, Reference, and Low), nuclear electricity’s share (59% in 2030) of total electricity generated is constant up to 2100. In these scenarios, the requirement of additional NPPs after 2030 depends on the total electricity generated at that time. In the Reference scenario, the average annual increase in electricity demand up to 2050 is assumed to be 0.95% per year, which is equivalent to the value of the average annual increase from 2020 to 2030 on the basis of BPESD and NEBP. The annual increase in electricity demand is assumed to gradually decrease after 2050 and to finally reach zero in 2100. On the other hand, the annual increase in electricity demands up to 2050 for the High and Low scenarios are assumed to be 1.2 and 0.8 times the values in the Reference scenario, respectively. For the Very Low scenario, total nuclear capacity in 2030 is assumed to be maintained up to 2100. It means that there is no further increase in nuclear electricity from 2030 to 2100. Existing NPPs can be replaced by new ones when they become obsolete. Using the assumptions above, nuclear electricity generation in 2100 is estimated at about 336, 472, 513, and 558 TWh for the Very Low, Low, Reference, and High scenarios, respectively. Given that the capacity factor of NPPs is 85%, nuclear capacity in 2100 will be 45.0, 63.4, 68.9, and 75.0 GWe, respectively, for these scenarios. These results are described in Fig. 1. To deploy 75.0 GWe NPPs in Korea for the High scenario, assuming that each NPP site employs six NPPs with 1400 MWe – as the current Korean NPP site does – a total of nine sites are required. This implies that five more NPP sites are needed by 2100. In reality, it will not be easy to secure five sites in Korea. In the light of past experience, however, acquisition of NPP sites is easier than that of HLW repository sites.
Table 1 Long-term scenarios for nuclear power generation. Scenarios Electricity generation
2030
2031–2050
Reference Total
The 3rd Basic Plan of Electricity Supply and Demand (2006) National Energy Basic Plan (2008)
Annual rate of increase will be Annual rate of increase will gradually decrease 0.95% per year and reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100
Nuclear High
Total Nuclear
Low
Total Nuclear
Very Low Nuclear
2051–2100
Annual rate of increase will be Annual rate of increase will gradually decrease 1.15% per year and reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100 Annual rate of increase will be Annual rate of increase will gradually decrease 0.76% per year and finally reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100 Total nuclear capacity in 2030 remains constant up to 2100
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4. Long-term spent nuclear fuel arisings
5. Underground repository area
In this section, accumulated total spent fuel arisings up to 2100 are estimated. It is assumed that a direct once-through cycle and PWRs and CANDU are employed. It is further assumed that the spent fuel from NPPs is not reprocessed and that it is directly transferred to an interim storage facility and subsequently relocated to the final repository. The annual spent fuel arisings can be calculated by assuming values for the fuel burn-up and some reactor parameters
In this section, the size of the underground repository required to accommodate all the spent fuel generated up to 2100 is estimated. The estimation begins with the Korean Reference Spent Fuel Disposal System (KRS), which was developed by the KAERI (Lee et al., 2007). The KRS has been designed at a location that is 500 m deep and is surrounded by granitic rocks. The capacity of the repository is 36,000 tHM (20,000 tHM for the PWR spent fuel and 16,000 tHM for the CANDU spent fuel). It is well known that the location of an underground repository is selected primarily on the basis of the decay heat of the waste. It is necessary for the peak temperature of the buffer material to be lower than 100 1C to assure the long-term integrity of the repository. Fig. 2 shows the layout of the KRS. The distances between bore holes and the disposal tunnel were calculated on the basis of the assumption that the heat generated by the PWR canister is 1540 W and that by the CANDU canister is 760 W; the heat generation values were obtained by considering the decay heat for spent fuel cooling times of 40 and 30 years, respectively. The distance between the parallel tunnels is 40 m, and the minimum distance between two deposition holes for the PWR canisters is 6 m (Lee et al., 2007). The total underground area is 4.62 km2 (2.2 2.1 km2); in this area, the disposal areas for the PWR spent fuel and the CANDU spent fuel are 4.07 and 0.55 km2, respectively. The resulting disposal densities are 4.91 and 29.09 kg/m2, respectively. It is noted that the disposal density of the CANDU spent fuel is about six times larger than that of the PWR spent fuel because of differences in the decay heat of the spent fuel.
Annual fuel arisings ¼
P 365 C BU
(1)
where P, C, e, and BU denote electric power (MWe), capacity factor (%), efficiency (%), and burn-up (MWd/tHM), respectively. In this paper, the burn-up of PWR fuels and CANDU fuels is assumed to range up to 50,000 and 7500 MWd/tU, respectively. The capacity factors are assumed to be 85% for a PWR and 90% for CANDU, and thermal efficiency is assumed to be 34% for a PWR and 33% for CANDU. In addition, it is assumed that no additional CANDU reactors are introduced and that the existing four units are maintained for their lifetime, which is assumed to be 50 years. Table 2 shows the projections for spent fuel accumulated under the four NPP scenarios on the basis of the above-mentioned assumptions. As shown in Table 2, the spent fuel arisings up to 2100 are forecast to be about 111,000 tHM for the Reference scenario, 115,000 tHM for the High scenario, 106,000 tHM for the Low scenario, and 92,000 tHM for the Very Low scenario.
Nuclear Electricity Generation (TWh)
650 High
550
Reference Low
450 Very Low
350 250 150 50 2008
2018
2028
2038
2048
2058 Year
2068
2078
2088
2098
Fig. 1. Forecast for long-term nuclear power generation.
Table 2 Projections for spent fuel accumulation. Year
2007 2020 2030 2040 2050 2060 2070 2080 2090 2100
Reference (1000 tHM)
High (1000 tHM)
Low (1000 tHM)
Very Low (1000 tHM)
PWR
CANDU
Total
PWR
CANDU
Total
PWR
CANDU
Total
PWR
CANDU
Total
4.328 9.266 16.197 24.478 33.766 44.229 55.495 67.399 79.740 92.293
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 41.022 52.260 62.723 73.989 85.893 98.234 110.787
4.328 9.266 16.197 24.571 34.143 45.115 57.104 69.911 83.283 96.931
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 41.114 52.637 63.609 75.598 88.405 101.777 115.425
4.328 9.266 16.197 24.387 33.397 43.374 53.960 65.024 76.412 87.956
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 40.930 51.891 61.868 72.455 83.518 94.906 106.450
4.328 9.266 16.197 24.033 32.008 40.252 48.496 56.740 64.983 73.227
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 40.576 50.503 58.746 66.990 75.234 83.477 91.721
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Fig. 2. Layout of the Korean reference spent fuel disposal system.
Table 3 Underground areas under different scenarios (ideal case). Underground area (km2)
Area for PWR SF Area for CANDU SF Total
Reference
High
Low
Very Low
18.78 0.55 19.33
19.73 0.55 20.28
17.90 0.55 18.45
14.90 0.55 15.45
It is important to note that the KRS concept was developed without site-specific data. In a real situation, there might be a fracture zone that cannot be used as a disposal rock. In this study, the KRS concept is referred to as the ideal case, with the real situation termed the real case. The disposal areas for the spent fuel accumulated up to 2100 are calculated as shown in Table 3. It is observed that the disposal area required for the Reference scenario is about 18 km2, while that necessary for the Very Low scenario is about 15 km2. Given that the Gyeongju low- and intermediate-level waste (LILW) site has an area of only about 2.1 km2, the spent fuel disposal area of 18 km2 might be too large to secure in a small country such as Korea. To estimate the disposal area required for the real case, we refer to the Swedish repository example; the repository rock and disposal system of the repository are very similar to those of the KRS. The Swedish Nuclear Fuel and Waste Management Co. (SKB) designed the disposal system in the 1980s and recently completed the characterisation of two candidate disposal sites, namely, Forsmark and Laxemar. The site-descriptive models were developed using various site data, including borehole data, before the repository layouts were designed for the potential repository sites (Hedin, 2006). The repository is located at a depth of 400 m in
Fig. 3. Repository layouts showing deposition areas.
Forsmark and 500 m in Laxemar. On the basis of the site characterisation, underground layouts were prepared for the two sites, as shown in Fig. 3. The disposal tunnel layout of the Swedish repository is quite different from that of the KRS. This is mainly due to the
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Table 4 Underground areas under different scenarios (real case).
Area for PWR SF Area for PHWR SF Total No. of Gyeongju LILW sites
Real area calculated considering Forsmak disposal density (km2)
Real area calculated considering Laxemar disposal density (km2)
Reference
High
Low
Very Low
Reference
High
Low
Very Low
26.15 0.77 26.92 13.0
27.46 0.77 28.23 13.0
24.92 0.77 25.69 12.0
20.75 0.77 21.51 10.0
42.30 1.24 43.54 21.0
44.43 1.24 45.67 22.0
40.31 1.24 41.55 20.0
33.56 1.24 34.80 17.0
consideration of host rock deformation and the fracture zone in the design. Forsmark is less flexible than Laxemar in terms of the space available for deposition. On the basis of the footprint of the SKB concept, the disposal densities of Forsmark and Laxemar are calculated to be about 3.53 and 2.18 kg/m2, respectively. These values are about 30% and 56% less than those of the KRS. It is important to note that both the SKB and KRS concepts are based on granitic rock and have the same borehole pitch (6 m) and tunnel pitch (40 m). Therefore, an approximate value for the real underground area of the KRS can be obtained by referring to the disposal density of the SKB concepts. Table 4 shows the results. It is observed that the disposal area required in the Reference scenario is about 26–44 km2, while that required for the Very Low scenario is about 21–34 km2. It is interesting to compare these areas with the Gyeongju LILW site area; the Reference scenario and the Very Low scenario require sites equivalent to about 13–21 and 10–17 times the Gyeongju area, respectively. If it were possible to secure facilities larger than the Gyeongju LILW disposal site – not an easy task in Korea – fewer facilities would be required.
6. Discussions and conclusion The use of nuclear power to accommodate future energy needs has been an unavoidable choice in Korea, one of the poorest countries in the world in terms of natural resource reserves. This policy direction was once again clearly expressed when the Korean NEC announced the new NEBP which proposes that electricity generated by NPPs is to be increased from the current 35.5% of total electricity production to 59% by 2030. If realised, more than 100,000 tHM of spent fuel is expected to accumulate in Korea by 2100, which implies that the effectiveness of spent fuel management will be the key for determining the sustainability of nuclear energy in Korea, as has been the case in other countries.
Examining the impact of the NEBP on spent fuel management in Korea, it was estimated that the country requires somewhere between 10–22 disposal sites, each with an area equal to the Gyeongju LILW disposal site, to accommodate the projected amounts of spent fuel. Considering its geographic profile, however, securing such a large number of sites will be almost impossible in Korea. It is clearly evident that if Korea pursues the once-through cycle for PWRs up to 2100, the absence of a viable solution for the disposal of accumulated spent fuel will ultimately create a serious problem for the sustainability of nuclear energy in the country. Hence, it is recommended that the volume of nuclear waste for disposal in Korea be significantly reduced. It is suggested that sodium fast reactor-based recycling offers a viable solution in this regard, as it transmutes the high-toxicity isotopes and separately manages high heat-emitting isotopes. According to Wigeland et al. (2006) if 99.9% of TRU and Cs and Sr are recovered during the process, the disposal loading area in the Yucca Mountains will increase 225-fold. Of course, it is important to note that there are still many pitfalls in SFR-based recycling, namely, technical, economic, political, and proliferation concerns. Future R&D on SFR-based recycling should focus on reducing these pitfalls to facilitate the social realisation of the technology. References Hedin, A., 2006. Initial state report for the safety assessment, SR-Can Technical Report, TR-06-21 SKB, Swedish Nuclear Fuel and Waste Management Co. KAERI, 2008. Advanced Nuclear Fuel Cycle, KAERI Newsletter, Volume 01/Winter 2008. Lee, J., et al., 2007. Concept of a Korean reference disposal system for spent fuels. Journal of Nuclear Science and Technology 44, 1565–1573. MKE, National Energy Basic Plan, 2008. Korean Ministry of Knowledge Economy, Press Release, August 28, 2008. MOCIE, The 3rd Basic Plan of Electricity Demand and Supply (BPEDS), 2006. Korean Ministry of Commerce, Industry, and Energy (MOICE), Seoul. Wigeland, R.A., et al., 2006. Separations and transmutation criteria to improve utilization of a geological repository. Nuclear Technology 154, 95.
Contents lists available at ScienceDirect
Energy Policy journal homepage: www.elsevier.com/locate/enpol
Viewpoint
Implications of the new National Energy Basic Plan for nuclear waste management in Korea Won Il Ko 1, Eun-ha Kwon Korea Atomic Energy Research Institute, 150-1 Deokjin-dong, Youseong-gu, Daejeon 305-353, Republic of Korea
a r t i c l e in f o
a b s t r a c t
Article history: Received 2 March 2009 Accepted 21 May 2009 Available online 21 June 2009
The Korean National Energy Committee has recently adopted a new National Energy Basic Plan according to which the electricity generated by nuclear power plants is to increase from the current 35.5% of total electricity production to 59% by 2030. This large increase in nuclear power will inevitably accelerate the accumulation of spent fuel; if the direct disposal option is pursued, spent fuel arisings in Korea are expected to exceed 100,000 tHM in 2100. It is estimated that the country will require between 10–22 disposal sites, each with an area equal to the Gyeongju low- and intermediate-level radioactive waste (LILW) disposal site, to accommodate this amount of spent fuel. However, considering Korea’s geographic profile, securing this number of sites will be almost impossible, and will ultimately create a serious problem for the sustainability of nuclear energy in the country. In view of this dilemma, this paper recommends that the volume of Korean nuclear waste for disposal be significantly reduced, and offers sodium fast reactor (SFR)-based recycling as a potentially viable solution. & 2009 Elsevier Ltd. All rights reserved.
Keywords: Nuclear policy Spent fuel Underground repository
1. Introduction Around the world, the 21st century has witnessed a renewed interest in nuclear energy; many countries – both industrialised and developing – believe that nuclear power is the most reliable future energy source capable of meeting their increasing energy demands. They are also confident that nuclear energy can be used safely and economically with the guarantee of long-term supply and without adverse environmental impacts. For these reasons, numerous countries, particularly those in Asia, are considering or have already decided on the construction of nuclear power plants (NPPs) to augment their energy mix. Countries with established nuclear power programmes are also seeking to increase their generation capacity. In view of this global trend, the Korean National Energy Committee (NEC), the top energy policy-making body in Korea, has recently adopted a new National Energy Basic Plan (NEBP) which proposes that electricity generated by NPPs be increased from the current 35.5% of total electricity production to 59% by 2030 (Korean MKE, 2008). However, this huge increase in nuclear power will inevitably accelerate the accumulation of spent fuel in Korea; if the country pursues the direct disposal option for the existing pressurised water reactor (PWR) and pressurised heavy
Corresponding author. Tel.: +82 42 868 4731; fax: +82 42 868 8679.
E-mail addresses: [email protected] (W.I. Ko), [email protected] (E.-h. Kwon). 1 Tel.: +82 42 868 2040; fax: +82 42 868 8679. 0301-4215/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.enpol.2009.05.068
water reactor (PHWR) systems, spent fuel arisings in Korea are expected to exceed 100,000 tHM by 2100. This implies that the effectiveness of spent fuel management will be key in determining the sustainability of nuclear energy in Korea. This paper examines the impact of the NEBP on spent fuel management in Korea, with a special emphasis placed on the permanent disposal option. The paper first considers the NEBP and several scenarios relating to nuclear power development in the country. The paper then estimates spent fuel arisings and determines the area required to house an underground repository for accommodating large amounts of spent fuel. The time period considered in this paper runs up to 2100.
2. Current status of nuclear energy in Korea Korea is a poor country in terms of energy resources. It is not endowed with significant fossil fuel reserves such as oil and gas. However, the country’s energy consumption has steadily grown, mainly owing to its rapid demographic and economic growth. This has rendered Korea exceedingly dependent on foreign energy resources, which predictably instigated two disastrous oil crises in the country in the 1970s. Having undergone several hardships during the crises, Korea considers nuclear power to be the most reliable energy source that is capable of meeting the increased energy requirements of continuing economic development. Consequently, Korea has chosen nuclear power as a major source of future energy. Since the first commercial operation of Kori Unit 1 in 1978, the country’s nuclear energy programme has
ARTICLE IN PRESS W.I. Ko, E.-h. Kwon / Energy Policy 37 (2009) 3484–3488
steadily expanded. As of April 2009, a total of 20 NPPs are in operation. The total generation capacity is about 17,700 MWe, which constitutes about 36% of the total electricity produced in Korea. According to the third Basic Plan for Electricity Supply and Demand (BPESD) (Korean MOCIE, 2006), eight new NPPs are to be constructed by 2020, taking the total number of units to 28. The total generation capacity of these units is expected to reach 27,320 MWe, which will correspond to about 43% of total electricity production. However, such an active nuclear energy programme will inevitably result in the production of significant quantities of spent fuel. By the end of 2007, the spent fuel generated in Korea was about 9500 MtHM, and this amount is expected to increase to about 27,000 MtHM by 2030. At present, the spent fuel is stored in temporary storage pools at plant sites, while a portion of the CANDU spent fuel is dry stored in concrete canisters. All the storage pools currently in operation are expected to be filled to capacity within the next decade. While the Korean government has adopted a ‘wait and see’ attitude and has not initiated steps to find ways to improve the management of spent fuel, the Korea Atomic Energy Research Institute (KAERI) has been developing a strategy for implementing an sodium fast reactor (SFR) fuel cycle that involves the use of pyroprocessing. The institute is also vigorously conducting research activities to support the initiative. In the SFR fuel cycle, the spent PWR fuel is converted into a metal fuel and resupplied to the SFRs. The uranium extracted from the spent PWR fuel is reused in SFRs and/or CANDU reactors. The spent SFR fuel is pyroprocessed and resupplied to the SFRs, while Cs- and Srcontaining high-level radioactive wastes (HLW) are managed separately (KAERI Newsletter, 2008). Proliferation resistant technology has been one of the most important requirements in the development program.
3. Scenarios for increasing nuclear power Presently, there are 20 NPPs, 16 PWRs, and 4 PHWRs in operation in Korea. In addition, six NPPs are under construction, and two more NPPs, employing Korean Advanced Pressurised Reactors (APR1400), have been planned. Thus, a total of 28 NPPs will be operational by 2016. In 2007, the contribution of nuclear power to total electricity generated was approximately 36%. This overall plan is a part of the third BPESD. In addition, the Korean NEC announced the NEBP on August 27, 2008. According to the plan, the electricity generated from NPPs
3485
should be increased from the current 35.5% to 59% in 2030, and the addition of 10 NPPs with a 1400 MWe capacity is required to facilitate this increase. This plan does not quantify the amount of electricity that should be generated by NPPs in 2030; however, the addition of 10 NPPs with 1400 MWe capacity is equivalent to 59% of the electricity generation expected in 2030 and from this, the amount of electricity generated in 2030 can be estimated. The nuclear electricity that will be generated in 2030 is estimated to be 336.34 TWh, assuming the average capacity factor of the NPPs to be 85% and the total electricity generation to be 570 TWh. To forecast the amount of nuclear electricity that will be generated in the period 2030–2100, it is assumed that nuclear energy will continue to be a major source of electricity. Four plausible scenarios are considered, as shown in Table 1: High, Reference, Low, and Very Low scenarios. As shown in table, in three of the scenarios (High, Reference, and Low), nuclear electricity’s share (59% in 2030) of total electricity generated is constant up to 2100. In these scenarios, the requirement of additional NPPs after 2030 depends on the total electricity generated at that time. In the Reference scenario, the average annual increase in electricity demand up to 2050 is assumed to be 0.95% per year, which is equivalent to the value of the average annual increase from 2020 to 2030 on the basis of BPESD and NEBP. The annual increase in electricity demand is assumed to gradually decrease after 2050 and to finally reach zero in 2100. On the other hand, the annual increase in electricity demands up to 2050 for the High and Low scenarios are assumed to be 1.2 and 0.8 times the values in the Reference scenario, respectively. For the Very Low scenario, total nuclear capacity in 2030 is assumed to be maintained up to 2100. It means that there is no further increase in nuclear electricity from 2030 to 2100. Existing NPPs can be replaced by new ones when they become obsolete. Using the assumptions above, nuclear electricity generation in 2100 is estimated at about 336, 472, 513, and 558 TWh for the Very Low, Low, Reference, and High scenarios, respectively. Given that the capacity factor of NPPs is 85%, nuclear capacity in 2100 will be 45.0, 63.4, 68.9, and 75.0 GWe, respectively, for these scenarios. These results are described in Fig. 1. To deploy 75.0 GWe NPPs in Korea for the High scenario, assuming that each NPP site employs six NPPs with 1400 MWe – as the current Korean NPP site does – a total of nine sites are required. This implies that five more NPP sites are needed by 2100. In reality, it will not be easy to secure five sites in Korea. In the light of past experience, however, acquisition of NPP sites is easier than that of HLW repository sites.
Table 1 Long-term scenarios for nuclear power generation. Scenarios Electricity generation
2030
2031–2050
Reference Total
The 3rd Basic Plan of Electricity Supply and Demand (2006) National Energy Basic Plan (2008)
Annual rate of increase will be Annual rate of increase will gradually decrease 0.95% per year and reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100
Nuclear High
Total Nuclear
Low
Total Nuclear
Very Low Nuclear
2051–2100
Annual rate of increase will be Annual rate of increase will gradually decrease 1.15% per year and reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100 Annual rate of increase will be Annual rate of increase will gradually decrease 0.76% per year and finally reach zero in 2100 Share of nuclear electricity (59%) in the total electricity generated in 2030 remains constant up to 2100 Total nuclear capacity in 2030 remains constant up to 2100
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4. Long-term spent nuclear fuel arisings
5. Underground repository area
In this section, accumulated total spent fuel arisings up to 2100 are estimated. It is assumed that a direct once-through cycle and PWRs and CANDU are employed. It is further assumed that the spent fuel from NPPs is not reprocessed and that it is directly transferred to an interim storage facility and subsequently relocated to the final repository. The annual spent fuel arisings can be calculated by assuming values for the fuel burn-up and some reactor parameters
In this section, the size of the underground repository required to accommodate all the spent fuel generated up to 2100 is estimated. The estimation begins with the Korean Reference Spent Fuel Disposal System (KRS), which was developed by the KAERI (Lee et al., 2007). The KRS has been designed at a location that is 500 m deep and is surrounded by granitic rocks. The capacity of the repository is 36,000 tHM (20,000 tHM for the PWR spent fuel and 16,000 tHM for the CANDU spent fuel). It is well known that the location of an underground repository is selected primarily on the basis of the decay heat of the waste. It is necessary for the peak temperature of the buffer material to be lower than 100 1C to assure the long-term integrity of the repository. Fig. 2 shows the layout of the KRS. The distances between bore holes and the disposal tunnel were calculated on the basis of the assumption that the heat generated by the PWR canister is 1540 W and that by the CANDU canister is 760 W; the heat generation values were obtained by considering the decay heat for spent fuel cooling times of 40 and 30 years, respectively. The distance between the parallel tunnels is 40 m, and the minimum distance between two deposition holes for the PWR canisters is 6 m (Lee et al., 2007). The total underground area is 4.62 km2 (2.2 2.1 km2); in this area, the disposal areas for the PWR spent fuel and the CANDU spent fuel are 4.07 and 0.55 km2, respectively. The resulting disposal densities are 4.91 and 29.09 kg/m2, respectively. It is noted that the disposal density of the CANDU spent fuel is about six times larger than that of the PWR spent fuel because of differences in the decay heat of the spent fuel.
Annual fuel arisings ¼
P 365 C BU
(1)
where P, C, e, and BU denote electric power (MWe), capacity factor (%), efficiency (%), and burn-up (MWd/tHM), respectively. In this paper, the burn-up of PWR fuels and CANDU fuels is assumed to range up to 50,000 and 7500 MWd/tU, respectively. The capacity factors are assumed to be 85% for a PWR and 90% for CANDU, and thermal efficiency is assumed to be 34% for a PWR and 33% for CANDU. In addition, it is assumed that no additional CANDU reactors are introduced and that the existing four units are maintained for their lifetime, which is assumed to be 50 years. Table 2 shows the projections for spent fuel accumulated under the four NPP scenarios on the basis of the above-mentioned assumptions. As shown in Table 2, the spent fuel arisings up to 2100 are forecast to be about 111,000 tHM for the Reference scenario, 115,000 tHM for the High scenario, 106,000 tHM for the Low scenario, and 92,000 tHM for the Very Low scenario.
Nuclear Electricity Generation (TWh)
650 High
550
Reference Low
450 Very Low
350 250 150 50 2008
2018
2028
2038
2048
2058 Year
2068
2078
2088
2098
Fig. 1. Forecast for long-term nuclear power generation.
Table 2 Projections for spent fuel accumulation. Year
2007 2020 2030 2040 2050 2060 2070 2080 2090 2100
Reference (1000 tHM)
High (1000 tHM)
Low (1000 tHM)
Very Low (1000 tHM)
PWR
CANDU
Total
PWR
CANDU
Total
PWR
CANDU
Total
PWR
CANDU
Total
4.328 9.266 16.197 24.478 33.766 44.229 55.495 67.399 79.740 92.293
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 41.022 52.260 62.723 73.989 85.893 98.234 110.787
4.328 9.266 16.197 24.571 34.143 45.115 57.104 69.911 83.283 96.931
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 41.114 52.637 63.609 75.598 88.405 101.777 115.425
4.328 9.266 16.197 24.387 33.397 43.374 53.960 65.024 76.412 87.956
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 40.930 51.891 61.868 72.455 83.518 94.906 106.450
4.328 9.266 16.197 24.033 32.008 40.252 48.496 56.740 64.983 73.227
5.092 9.887 13.576 16.543 18.494 18.494 18.494 18.494 18.494 18.494
9.420 19.153 29.773 40.576 50.503 58.746 66.990 75.234 83.477 91.721
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Fig. 2. Layout of the Korean reference spent fuel disposal system.
Table 3 Underground areas under different scenarios (ideal case). Underground area (km2)
Area for PWR SF Area for CANDU SF Total
Reference
High
Low
Very Low
18.78 0.55 19.33
19.73 0.55 20.28
17.90 0.55 18.45
14.90 0.55 15.45
It is important to note that the KRS concept was developed without site-specific data. In a real situation, there might be a fracture zone that cannot be used as a disposal rock. In this study, the KRS concept is referred to as the ideal case, with the real situation termed the real case. The disposal areas for the spent fuel accumulated up to 2100 are calculated as shown in Table 3. It is observed that the disposal area required for the Reference scenario is about 18 km2, while that necessary for the Very Low scenario is about 15 km2. Given that the Gyeongju low- and intermediate-level waste (LILW) site has an area of only about 2.1 km2, the spent fuel disposal area of 18 km2 might be too large to secure in a small country such as Korea. To estimate the disposal area required for the real case, we refer to the Swedish repository example; the repository rock and disposal system of the repository are very similar to those of the KRS. The Swedish Nuclear Fuel and Waste Management Co. (SKB) designed the disposal system in the 1980s and recently completed the characterisation of two candidate disposal sites, namely, Forsmark and Laxemar. The site-descriptive models were developed using various site data, including borehole data, before the repository layouts were designed for the potential repository sites (Hedin, 2006). The repository is located at a depth of 400 m in
Fig. 3. Repository layouts showing deposition areas.
Forsmark and 500 m in Laxemar. On the basis of the site characterisation, underground layouts were prepared for the two sites, as shown in Fig. 3. The disposal tunnel layout of the Swedish repository is quite different from that of the KRS. This is mainly due to the
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W.I. Ko, E.-h. Kwon / Energy Policy 37 (2009) 3484–3488
Table 4 Underground areas under different scenarios (real case).
Area for PWR SF Area for PHWR SF Total No. of Gyeongju LILW sites
Real area calculated considering Forsmak disposal density (km2)
Real area calculated considering Laxemar disposal density (km2)
Reference
High
Low
Very Low
Reference
High
Low
Very Low
26.15 0.77 26.92 13.0
27.46 0.77 28.23 13.0
24.92 0.77 25.69 12.0
20.75 0.77 21.51 10.0
42.30 1.24 43.54 21.0
44.43 1.24 45.67 22.0
40.31 1.24 41.55 20.0
33.56 1.24 34.80 17.0
consideration of host rock deformation and the fracture zone in the design. Forsmark is less flexible than Laxemar in terms of the space available for deposition. On the basis of the footprint of the SKB concept, the disposal densities of Forsmark and Laxemar are calculated to be about 3.53 and 2.18 kg/m2, respectively. These values are about 30% and 56% less than those of the KRS. It is important to note that both the SKB and KRS concepts are based on granitic rock and have the same borehole pitch (6 m) and tunnel pitch (40 m). Therefore, an approximate value for the real underground area of the KRS can be obtained by referring to the disposal density of the SKB concepts. Table 4 shows the results. It is observed that the disposal area required in the Reference scenario is about 26–44 km2, while that required for the Very Low scenario is about 21–34 km2. It is interesting to compare these areas with the Gyeongju LILW site area; the Reference scenario and the Very Low scenario require sites equivalent to about 13–21 and 10–17 times the Gyeongju area, respectively. If it were possible to secure facilities larger than the Gyeongju LILW disposal site – not an easy task in Korea – fewer facilities would be required.
6. Discussions and conclusion The use of nuclear power to accommodate future energy needs has been an unavoidable choice in Korea, one of the poorest countries in the world in terms of natural resource reserves. This policy direction was once again clearly expressed when the Korean NEC announced the new NEBP which proposes that electricity generated by NPPs is to be increased from the current 35.5% of total electricity production to 59% by 2030. If realised, more than 100,000 tHM of spent fuel is expected to accumulate in Korea by 2100, which implies that the effectiveness of spent fuel management will be the key for determining the sustainability of nuclear energy in Korea, as has been the case in other countries.
Examining the impact of the NEBP on spent fuel management in Korea, it was estimated that the country requires somewhere between 10–22 disposal sites, each with an area equal to the Gyeongju LILW disposal site, to accommodate the projected amounts of spent fuel. Considering its geographic profile, however, securing such a large number of sites will be almost impossible in Korea. It is clearly evident that if Korea pursues the once-through cycle for PWRs up to 2100, the absence of a viable solution for the disposal of accumulated spent fuel will ultimately create a serious problem for the sustainability of nuclear energy in the country. Hence, it is recommended that the volume of nuclear waste for disposal in Korea be significantly reduced. It is suggested that sodium fast reactor-based recycling offers a viable solution in this regard, as it transmutes the high-toxicity isotopes and separately manages high heat-emitting isotopes. According to Wigeland et al. (2006) if 99.9% of TRU and Cs and Sr are recovered during the process, the disposal loading area in the Yucca Mountains will increase 225-fold. Of course, it is important to note that there are still many pitfalls in SFR-based recycling, namely, technical, economic, political, and proliferation concerns. Future R&D on SFR-based recycling should focus on reducing these pitfalls to facilitate the social realisation of the technology. References Hedin, A., 2006. Initial state report for the safety assessment, SR-Can Technical Report, TR-06-21 SKB, Swedish Nuclear Fuel and Waste Management Co. KAERI, 2008. Advanced Nuclear Fuel Cycle, KAERI Newsletter, Volume 01/Winter 2008. Lee, J., et al., 2007. Concept of a Korean reference disposal system for spent fuels. Journal of Nuclear Science and Technology 44, 1565–1573. MKE, National Energy Basic Plan, 2008. Korean Ministry of Knowledge Economy, Press Release, August 28, 2008. MOCIE, The 3rd Basic Plan of Electricity Demand and Supply (BPEDS), 2006. Korean Ministry of Commerce, Industry, and Energy (MOICE), Seoul. Wigeland, R.A., et al., 2006. Separations and transmutation criteria to improve utilization of a geological repository. Nuclear Technology 154, 95.