Republic of Korea: experience of radioactive waste (RAW) management and contaminated site clean-up

21 Republic of Korea: experience of radioactive waste (RAW) management and contaminated site clean-up J.-I. Y U N, Y. H. J E O N G and J. H. K I M, KAIST, Korea DOI: 10.1533/9780857097446.2.673 Abstract: Republic of Korea currently operates 21 nuclear units providing one-third of the nation’s electricity. Low and intermediate level radioactive materials emanating from these plants, medical facilities, research reactors, and industry need to be safely stored and managed. Disposal of spent nuclear fuel is also an important national issue. This chapter reviews the current state of affairs in Korea and examines the national policy, strategy, and direction for managing spent fuel and radioactive waste (RAW) materials. Decontamination of waste materials is also discussed. Key words: Republic of Korea, radioactive waste (RAW), spent nuclear fuel (SNF) storage, disposal, decommissioning, decontamination.

21.1

Introduction

The twenty-first century’s grand challenges are aptly characterized by energy, environment, and economy – the so-called tri-lemma of sustainability. These three Es are intricately interconnected, and balancing them is necessary for a healthy society. Many of this century’s issues are global in nature, such as global warming that cuts across national boundaries and requires global cooperation in energy, environment, and economy to solve them. We are all in the same boat and must work together to meet these formidable challenges. According to the International Energy Outlook 2011 reference scenario, the world’s energy consumption is expected to grow by 53% between 2008 and 2035. Global electricity generation will grow from 19.1 trillion kWh in 2008 to 35.2 trillion kWh in 2035, an increase of 84%. Likewise, nuclear generation is expected to increase from 2.6 trillion kWh in 2008 to 4.9 trillion kWh in 2035. As for Korea, energy is particularly crucial for its national growth planning, as Korea has virtually no natural resources.

21.1.1 The energy situation in Korea The energy situation in Korea is worse than in many countries, as Korea has no viable natural energy sources and must import primary energy. In 673 © Woodhead Publishing Limited, 2013

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2011, Korea imported approximately 97% of its primary energy. South Korea is the world’s No. 5 crude oil buyer and No. 2 liquefied natural gas importer and has boosted spending to acquire assets and develop oil and gas reserves, with a heavy focus so far on the Middle East and the Arctic. As a result, Korea is currently the ninth largest emitter of greenhouse gases in the world. Korea’s greenhouse gas emission rates are increasing at the fastest rate (2.8%) in the world. An important agenda in Korea’s energy development plan is to promote nuclear power as a strategic response in the post-fossil fuel era and as a pillar of energy security and independence. Korea mapped out its long-term energy development plan based on the 3Es – energy security, economic efficiency and environmental protection. Korea hopes to reach its long-term energy goals by • improving energy efficiency and reducing energy consumption, • promoting clean energy including nuclear and renewable energy to reduce dependence on fossil fuels, • boosting the green energy industry, and • making energy sources accessible and affordable to low-income households. Korea’s total installed electricity generation capacity, standing at 72,491 MWe as of 2008, is projected to grow to 95,115 MWe by 2020 and further to 105,195 MWe by 2030. According to the Carbon Dioxide Information Analysis Center (CDIAC), Korea is the ninth highest country in carbon dioxide emissions in the period 1950–2005. USA (25%), China (10%) and Russia (8%) are the top countries in carbon dioxide emission in 1950–2005. The Korean government is focusing its efforts on nuclear power as part of a national strategy to reduce greenhouse gas emissions and to achieve low carbon sustainable growth, Korea aspiring to become a green power country with low carbon, green growth. The national vision is to become the world’s seventh largest green power by 2020 and the fifth largest green power by 2050.

21.1.2 Nuclear power in Korea Korea’s nuclear development has been robust and steady. The data shows an unplanned shutdown rate of 0.3 trips/reactor/yr and capability loss of 0.36% in 2009, the best record in the world. Its long-term energy plan entails increasing the nuclear installed capacity to 41% and nuclear generation to 59% of the total capacity and production by 2030. The Korean government has maintained a consistent national policy for a stable energy supply by fostering nuclear power industries to offset the lack of other energy resources in the country. Nuclear power accounted for

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31.3% of the total electricity generation in Korea in 2010 [MEST, 2010]. Since the commencement of the first commercial operation of Kori Unit 1 in April 1978, 21 nuclear power plants (NPPs) are commercially operating as of 2011 with an installed capacity of 18,716 MWe. Four units out of the 21 operating NPPs are pressurized heavy water reactors (PHWRs) at the Wolsung site. The remaining 17 units, located at the Kori, Yonggwang and Ulchin sites, are pressurized light water reactors (PWRs) (Fig. 21.1). There are seven units (three units of OPR 1000, four units of APR 1400) under construction; in addition, six units are in the planning stage of construction. All nuclear plants are operated by KHNP (Korea Hydro & Nuclear Co.). In addition to the domestic nuclear plant construction, Korea is building four nuclear units of Korean design (APR 1400) in the United Arab Emirates. In August 2008, the government set out a plan to significantly reduce the nation’s dependency on fossil fuels and more than quadruple the use of renewable energy by 2030. In addition, nuclear power will expand to account for 27.8% of total energy consumption in 2030 compared to 14.9% in 2007. The International Atomic Energy Agency (IAEA) officially recognized the Republic of Korea’s nuclear transparency by approving the broader conclusion at the regular meeting of the IAEA Board of Governors held in June 2008.

Central Research Institute of KHNP

KHNP

Operation : 5 Construction : 5

Operation : 6 Construction : 4

Gyeongju LILW repository

Seoul Ulchin Daejeon Gyeongju Wolsung Yonggwang

Kori

Operation : 6

Operation : 4 Construction : 2

21.1 Current status of nuclear power in Korea, as of June 2012.

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21.1.3 The radioactive waste (RAW) management situation in Korea Spent fuel (SF) generated from nuclear power plants has been stored in spent fuel storage pools at reactors or in on-site dry storage facilities. Dry storage is currently used only for PHWR (CANDU) spent fuel sufficiently decayed for about six years in storage pools. The low- and intermediatelevel radioactive waste (LILW) generated from the NPPs has been stored in on-site radioactive waste storage facilities. Radioactive waste materials are also generated from fuel fabrication processes and they are stored on-site. In addition, the use of radioactive materials in medicine, research work and industry has increased steadily. These facilities are located throughout the country and generate various types of RAW. Radioisotope (RI) contaminated waste from these facilities is stored at an RI waste management facility. There has been much turmoil concerning public acceptance issues associated with the LILW disposal facility site selection, with a number of unsuccessful attempts to select the site. The Korean government has striven to secure a disposal site for the safe management of RAW since the early 1980s. After a number of failed attempts, the Korean government issued a Public Notice on the selection of a candidate site for the LILW disposal facility, and the city of Gyeongju was selected as the final candidate site in November 2005 following the procedures involving a site suitability assessment, local referenda, etc. as specified in the Public Notice. The Korea Radioactive Waste Management Corporation. (KRMC) was established in 2009 as a new Korean RAW management agency and is currently undertaking the construction of the LILW disposal facility in accordance with the permit issued. Spent fuel generated from NPPs is stored in the spent fuel storage facility in each unit. The storage capacity for spent fuel has been expanded as a consequence of the delayed construction schedule of the away-from-reactor (AFR) interim storage.

21.2

Radioactive waste (RAW) management strategy, practice and issues

The safe management of RAW is recognized as an essential national task for sustainable generation of nuclear energy and for energy self-reliance in South Korea. Since the early 1980s, the Korean government has attempted to prepare a disposal site for safe management of RAW but failed to secure one due to lack of public consensus and acceptance. In this context, the Atomic Energy Commission (AEC) of the Korean government, the highest decision-making body for nuclear energy policy, approved the ‘National

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Radioactive Waste Management Policy’ at the 249th meeting held on September 30, 1998. This policy stipulated that a LILW facility would be constructed and operated by 2008 and a centralized spent fuel interim storage facility by 2016. The key principles of the national policy on radioactive waste management are as follows: • • • • •

direct control by the government safety as top priority minimization of waste generation ‘polluter pays’ principle transparency for site selection process.

However, a revision of the government policy was made at the 253rd AEC meeting on December 17, 2004, after the government failed repeatedly to find a candidate site for the radioactive waste management complex. Therefore, a new government plan for radioactive waste management was announced, basically to separate the sites for the LILW disposal facility and the spent fuel interim storage facility instead of constructing both facilities on one site. The LILW disposal facility is now being constructed in Gyeongju after local referenda. Conversely, the key decision to directly dispose of or recycle spent fuel has not yet been made in Korea. Spent fuel is currently stored at reactor sites under the responsibility of Korea Hydro and Nuclear Power Co. (KHNP), because the 253rd AEC meeting stipulated that the national policy for spent fuel management will be decided later, taking account of domestic and international technological developments.

21.2.1 Sources, types and quantities of radioactive waste Radioactive wastes arise from the generation of electricity in nuclear power stations and from the use of radioactive materials in industry, medicine, research, and military. There is a wide spectrum of wastes, from those that contain high concentrations of radioactive materials, to general industry and laboratory wastes which are only lightly contaminated with activity. The Atomic Energy Act (AEA, Article 2.18) of the Republic of Korea defines ‘radioactive waste’ as radioactive materials or materials contaminated with radioactive materials which are subject to disposal, including spent fuel. The Enforcement Decree of the AEA defines high-level radioactive waste (HLW) as radioactive waste with radioactivity concentration and heat generation over the limiting volume specified by the Ministry of Education, Science, and Technology (MEST). In the strict sense, wastes other than HLW belong to the LILW category in accordance with the AEA. The limiting values on radioactivity and heat generation rate are specified in the MEST Notice No. 2008-31 (Notice of the Standards on Radiation Protection, etc.) [MEST, 2008] as follows:

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radioactivity: ≥4,000 Bq/g for alpha-emitting radionuclides with a halflife of longer than 20 years heat generation rate: ≥2 kW/ m3.

The AEA also defines the clearance level adopted from the ‘exempt waste’ concept of the IAEA radioactive waste classification. The clearance levels in Korea are such that annual individual radiation dose shall be less than 10 μSv/y and the total collective dose below one person-Sv/y concurrently. These are the same as the levels specified in the IAEA Safety Series No. 115 (1996) [IAEA, 1996]. All radioactive wastes are still to be stored in on-site temporary storage until a permanent disposal facility has been constructed. The amount of radioactive waste being stored by April 2012 is 89,865 drums from nuclear power plants (KHNP, 2012). (Hereafter, ‘drum’ means ‘200-liter drum equivalent’ unless otherwise stated.) The total capacity of temporary storage in NPP sites is 109,900 drums and the accumulated radioactive waste stored at each NPP site is around 77.7% of their storage capacity, as shown in Table 21.1. Although the volume of waste arising from radioisotope use is still relatively small compared to power reactor waste volume, the annual generation rate is expected to rise rapidly as industrial use of radioisotopes increases. The waste type and volume of LILW is shown in Fig. 21.2.

21.2.2 Radioactive waste treatment To ensure its safe discharge into the environment, liquid radioactive waste has to fulfill very strict requirements connected with the limits of radioactive substances and other impurities (suspended particulates, chemical, biological, heavy metals, etc.). To achieve the standards described in national

Table 21.1 The status of the LILW storage in nuclear power stations (as of April 2012) Nuclear power stations Location

Number of reactors

Kori Yonggwang Ulchin Wolsong Shin-kori Total

4 6 6 4 1

Storage capacity (no. of drums)

Cumulative amount (no. of drums)

50,200 23,300 18,929 13,240 10,000 115,669

41,012 21,601 16,020 10,987 245 89,865

Source: KHNP (2012) from http://www.khnp.co.kr.

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2% 14% Spent resin Spent filters 28% Solidified liquid waste 56% Dry active waste

21.2 The composition of LILW waste generated in Korea, as of 2005 (Ahn et al., 2009).

regulations, radioactive waste has to be treated, including volume reduction and reduction of radioactive compounds and other solutes in the effluent. NPPs currently in operation in Korea have their own gaseous, liquid, and solid waste treatment facility and on-site storage facilities to ensure the safe management of RAW generated in the process of operation. The gaseous waste treatment system comprises gas decay tanks and/or charcoal delay beds. The liquid waste treatment system is equipped with either liquid waste evaporators or selective ion exchangers. The solid waste treatment facility has spent resin drying systems, spent filter processing and packaging systems, concentrated waste drying systems, and dry waste compactors. The RI waste generated from domestic medical research, industrial RI users, and research institutes is collected and stored at the Central Research Institute (CRI) of KHNP in Daejeon. Around 90% of LILW comes from NPP and the rest arises from industry, medicine, and research institutes. Generally, the type of LILW is classified as follows: •

power plants: dry active waste, spent resin, spent filter, and concentrated waste • non-power plant sources (RI waste): dry active waste (combustible or non-combustible), hepatitis waste, organic liquid waste, spent sealed source, spent resin, spent filters, and concentrated waste.

Figure 21.3 summarizes the process steps for treatment of solid, liquid and gaseous wastes in Korea. Solid radioactive waste (SRAW) Most SRAW consists of dry active waste (DAW) and secondary process waste. The DAW is generated during maintenance and repair of contaminated systems and includes items such as used parts, paper, clothes, gloves and shoes. Secondary waste is generated from the liquid RAW treatment system and includes concentrated wastes from evaporators, spent resin from demineralizers, and spent filters from liquid purification systems.

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Storage tank

Gas

Filter

Ventilation fo NPP

Charcoal adsorber Detergent waste tank

Liquid

Environmental detector

Filtration

Laundry waste Other liquid waste

Exhaustion

Distilled water

Detection of activity

Draining

Environmental detector

Reuse for coolant

Concentrates

Filtration Evaporation desalinization concentration Resins, sludges, etc.

Solidification

Solid Paper, clothes, etc.

Storage tank

Attenuation Transportation Compression incineration

Storage Environmental detector

21.3 Process steps for radioactive waste treatment.

The DAW is compressed by a conventional compactor (capacity: 2,000 tons) into 200 L drums. Solidification by Portland cement, which had been commonly applied in the past, is no longer used. Instead, the concentrated waste is now dried and stabilized by paraffin wax in drums, and spent resin is kept in a high-integrity or equivalent container after drying in the spent resin drying facility. Spent filters are stored in shielded high integrity containers (HIC). Liquid radioactive waste Liquid RAW can be divided into process drains, floor drains and laundry drains based on the sources of waste generation. It is mainly generated from the clean-up and maintenance processes of reactor coolant and related systems containing radioactivity. In general, liquid RAW is treated with evaporators, demineralizers, and/or filters. The effluent is released to the sea after monitoring whether the radioactivity of liquid effluent is lower than regulatory limits. It is also common for liquid wastes to be treated with ultracentrifugation, ion exchange, and reverse osmosis. The Ministry of Education, Science, and Technology (MEST Notice No. 2008-31) prescribes the effluent control limit (ECL) for liquid effluent being discharged into the environment at the restricted area boundary. Operators

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must conduct periodic assessments for the expected off-site dose due to the liquid effluent discharged into the environment, and routinely report results to the regulatory body (Korea Institute of Nuclear Safety, KINS). Gaseous radioactive waste Gaseous RAW is mainly generated from degassing of the primary system and ventilation systems in the radiation controlled area of NPPs. Gaseous waste from the primary system is treated by gas decay tank or charcoal decay bed to reduce radioactivity, and released into the atmosphere through a radiation monitor. Gaseous waste from the building ventilation system is also exhausted under continuous monitoring through high-efficiency particulate (HEPA) and charcoal filters into the environment. The MEST addresses the maximum radioactivity concentration, ECL, for gaseous effluent being released into the atmosphere at the restricted area boundary (MEST Notice No. 2008-31). The licensee must conduct a periodic evaluation of the anticipated off-site dose due to gaseous effluent released into the environment, and routinely report results to the KINS. The Enforcement Decree of the AEA and the MEST Notice No. 2008-31 (Standards on Radiation Protection, etc.) prescribe discharge limits of gaseous and liquid radioactive effluents to be released from nuclear facilities into the environment, along with annual dose constraints of the population living around nuclear facilities. In practice, nuclear facilities are operated with targets which are more restrictive than the discharge limits. In addition, some facilities also apply the derived release limits based on a small fraction of the dose limits for convenience for a field application. Whether related limits are met is verified by periodic inspection or the examination of regular reports submitted to the regulatory body. The radiation dose and its effect on individuals around nuclear facilities are assessed monthly by using the Off-site Dose Calculation Manual (ODCM, Reg. Guide 1.109) [US-NRC, 1977]. The assessments are based on the radioactivity of released liquid and gaseous effluents, atmospheric conditions, metabolism, and social data including agricultural and marine products of the local community within a radius of 80 km. The Korea Atomic Energy Research Institute (KAERI) in Daejeon and KHNP carry out R&D on RAW management. Treatment and disposal of HLW/SF is studied by KAERI. KHNP studies the treatment and disposal of LILW and interim storage of spent fuel. Technological developments are currently focused on the following topics: • •

waste treatment and volume reduction technology low-level waste vitrification technology

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• LILW disposal and safety assessment technology • improvement of existing technology for spent fuel storage and transportation, and development of advanced spent fuel storage technology. In addition to current use of conventional treatment methods such as evaporation, compaction, drying and cementation, advanced technology for LILW treatment is being developed. Vitrification has been identified as the most promising innovative technology from the point of view of being environmentally sound and of being able to substantially reduce the volume of LILW, to improve the waste stability and to enhance the public acceptance of its disposal. Vitrification immobilizes the radionuclides in a stable solid glass form and the associated volume reduction should result in efficient and prolonged use of a repository, which is most important for a small, densely populated country. A feasibility study of the vitrification process was initiated in 1994 and a pilot-scale vitrification facility was installed in July 1999. This facility consists of an induction heater, cold crucible melter (CCM) for combustible waste, a plasma torch melter (PTM) for non-combustible waste, and an off-gas treatment system. KHNP’s research center (CRI) located in Daejeon has developed the technology with a target for commercialization of the process from 2005. The Ulchin Vitrification Facility (UVF) is the world’s first commercial facility for the vitrification of LILW generated from NPPs using CCM technology. The construction of the facility began in 2005 and was completed in 2007. From December 2007 to September 2009, all key performance tests, such as the system functional test, the cold test, the hot test, and actual waste testing, were performed successfully. The UVF started commercial operation in October 2009 for the vitrification of LILW waste (Jo et al., 2010).

21.2.3 Radioactive waste disposal Since the creation of the legal grounds for the implementation of the project by the 1986 revision of the Atomic Energy Act (AEA), the Korean government has actively implemented the selection of the sites for radioactive waste disposal facilities. There have been nine failed attempts to secure a disposal site from 1986 to 2004 due to: • • •

safety concerns about the disposal facility, lack of transparency and fairness during project implementation, lack of social consensus among the stakeholders.

In February 2004, the Ministry of Knowledge Economy (MKE) announced new site selection procedures, and MKE/KHNP made various efforts to enhance the acceptance by local residents of disposal facilities. As a result,

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local residents voluntarily petitioned to host the facilities in ten areas, but site selection ultimately halted due to the absence of preliminary applications by local government leaders. In March 2005, MKE organized the Site Selection Committee (SSC) in order to guarantee the transparency and fairness of the site selection process. The SSC, consisting of 17 civilian experts from diverse fields, managed and supervised the entire site selection process. In addition, the ‘Special Act on Support for Areas Hosting Low and Intermediate Level Radioactive Waste Disposal Facilities’ (MKE Notice No. 2005-146) was legislated and announced in March 2005 to stipulate support for areas hosting LILW disposal facilities, including special financial support, entry fees, and relocation of the KHNP headquarters. The act also stipulated the following to enhance the democracy and transparency of the selection process: • the host area was to be selected through resident voting in accordance with the Referendum Act, • the selection plan, site survey results, and selection process were to be implemented openly and transparently, • open fora and discussions were to be held for local residents. Accordingly, in June 2005, the MKE announced the candidate site selection method and procedures as well as the support to be provided to the host areas and initiated the process through an announcement regarding LILW disposal facility candidate site selection. Regarding candidate site selection procedures, as shown in Fig. 21.4, the local governors must apply to host the facilities with consent from local councils. Then, in accordance with the results of the site suitability assessment, the MKE requested local governors to conduct local referenda in appropriate regions as required by the Referendum Act. Local governors proposed and held the referenda. Based on the results of local referenda, areas with the highest percentage of favorable responses were selected as the final candidate sites. Local governments that had appropriately applied to host the LILW disposal facility by August 31, 2005 were in the four areas of Gunsan, Gyeongju, Pohang, and Yeongdeok County, and these four local governments conducted referenda. In accordance with the results of local referenda (Table 21.2), the city of Gyeongju was selected as the final candidate site (MKE Notice No. 2005-133).

Announcement of the procedures

Applications to host LILW disposal facility (local governors)

Requests for local referenda

Implementation of local referenda

Selection of final candidate site

21.4 Site selection procedures of the LILW disposal facility.

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The area of the disposal site accommodates a total of 800,000 drums of LILW, and, as the first stage of construction, a rock cavern type of repository for up to 100,000 drums was chosen. However, the disposal method for further expansion will be decided depending on the nature of the site condition. The disposal facility to be constructed in Gyeongju was named ‘Wolsong Low- and Intermediate-level Radioactive Waste Disposal Center’ operated by KRMC under the jurisdiction of MKE which was established on January 1, 2009 (Figs 21.5 and 21.6). As of June 2012, the disposal facility is almost 90% complete (Fig. 21.7) and the date for initial operation is mid2014, taking into account the construction period. In the main review phase, after completion of three rounds of Q&A, a few key technical issues (KTIs) were brought out and profiled for further intense deliberation. The KTIs that needed to be taken into consideration throughout the later part of the main review phase can be summarized as follows:

Table 21.2 Results of referenda for site selection in 2005 Classification

Gyeongju

Gunsan

Yeongdeok

Pohang

No. of eligible voters No. of voters (absentees) Voter turnout Vote for

208,607

196,980

37,536

374,697

147,636 (70,521) 70.8% 89.5%

138,192 (65,336) 70.2% 84.4%

30,107 (9,523) 80.2% 79.3%

178,586 (63,851) 47.7% 67.5%

Source: Park et al., 2009.

15 SERVICE BUILDING AREA 10 11

7

8

9

1 2 3 4 5 6

12

6 14

13 16 UNDERGROUND 5 DISPOSAL AREA

2 3

4 17

21.5 View of the Wolsong LILW disposal center.

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7 8 9 10 11 12 13 14 15

SILO REPOSITORY CONSTRUCTION TUNNEL OPERATING TUNNEL PORTAL ACCESS SHAFT RADWASTE RECEIPT/ STORAGE BLDG RADWASTE BLDG SERVICE BLDG.1 SERVICE BLDG.2 OFFICE GARAGE SUBSTATION BLDG WASTE WATER TREATMENT BLDG. GUARD HOUSE SUPER COMPACTOR BLDG.

Republic of Korea 1550

27300 23000

1200 1550 1200

1200

685

15000

24000

2300 FACLITY LIMT R300 24000 CORRDOP 750 500 CATLE TRAY CRANE CRDER CTO. 2000 400

5500

UNLOADING TUNNEL

CONOMIC CONTAINER HC CONTAINER

CONSTRUCTION TUNNEL

CONCEIT CONTAINER (2,73LOC2.73MX1.14M)

UNLOADING TUNNEL

34500

ACCESS SHAFT EL,(–)80 m

EL,(–)130 m

CONSTRUCTION TUNNEL

SILO

400

23400

400

1200

OPERATING TUNNEL

21.6 Cross-section view of the underground facilities in the LILW repository.

21.7 Construction of the LILW repository (87% complete, as of June 2012; KRMC, 2012).

• • •

• • •

groundwater infiltration rate into silos: re-estimation of the groundwater infiltration rate into the concrete silos during the post-closure phase, in combination with justification of the human intrusion scenarios quality control of geochemical data: reconfirmation of the representativeness of empirically determined site-specific geochemical data (e.g. sorption coefficients, diffusion coefficients, etc.) long-term management of uncertainties in geochemical data seismic safety and design: verification of the geological structure model and tectonic activity of the site structural stability of the rock caverns and silos.

The above KTIs were resolved through regulatory dialogues and requests for more detailed information along with the applicant’s amendments to the license application documents, reflecting the results of further supplementary site surveys, safety assessments, and design changes, which occurred during the review process.

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KAERI underground research tunnel (KURT) A small-scale underground research laboratory, KAERI Underground Research Tunnel (KURT) at KAERI in Daejeon, was constructed to develop a Korean disposal system for the HLW repository, including spent fuels, between March 2005 and November 2006. The KURT, with an access tunnel and two research modules, as shown in Fig. 21.8, is located in a mountainous area inside the KAERI territory. The KURT, has a total length of 255 m with a 180 m long access tunnel and two research tunnels 75 m long in total. The maximum depth of 90 m could be effectively achieved by selecting the tunnel direction to the peak of a mountain. The horseshoe shaped tunnel, 6 m wide and 6 m high, is located in a granite rock body (Fig. 21.8). Regardless of limited applications of KURT, which only handles naturally occurring radionuclides, the KURT facility will be a major infrastructure for validating the safety and feasibility of the suggested disposal system by various in-situ experiments: 1. Single hole heater test in rock. 2. THM (thermal-hydraulic-mechanical) behavior of engineered barrier systems (EBS). 3. EDZ (excavation disturbed zone) characteristics and mechanical stability of rock. 4. Retardation of solute migration through fractured rock. 5. Site investigation techniques. 6. Hydrogeological and geochemical baseline data (Kwon et al., 2009). The current 10-year plan for mid- and long-term nuclear R&D on HLW disposal was accepted by the AEC in 1997. This plan includes a program for development of a Korean repository for HLW disposal and for the associated system performance assessment. After completion of the El.(m) 120 100 80 60 40 20 0 –20 –40 –60 –80 –100 –120

207 m

Research module 1

140 m

nnel Access tum 0 0 2

10%

Research module 2

6m 6m Access ramp

21.8 Schematic internal configuration of KURT [Cho et al., 2007].

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combined research output of this 10-year study, the Korean government will define the direction and prioritization of further R&D activities for HLW disposal. Since 1997, KAERI has been developing a permanent disposal facility for HLW and a total system performance assessment (TSPA). Its current R&D activities are focused on the preliminary conceptual design of the Korean Reference Disposal System (KRS), development of the key technologies, and geo-environmental studies to confirm the KRS’s safety, as shown in Fig. 21.9. Currently, the four major projects underway at KAERI are: 1. 2. 3. 4.

repository system development; a TSPA; geo-environmental science research; and construction and operation of a KAERI underground research tunnel (KURT) to demonstrate the KRS’s performance relevant to the functional criteria established in the disposal concept (Fig. 21.8).

21.3

Spent fuel management strategy, practice and issues

21.3.1 Spent fuel inventory Spent fuels can be categorized into those from commercial NPPs and those from research reactors. Spent nuclear fuels from commercial NPPs are

21.9 Korean Reference Disposal System.

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stored on site in spent fuel storage (water) pools or in a dry storage facility. All the spent fuels from the 17 PWRs in Korea are stored in pools on site. About half of the spent fuels from the four CANDU reactors is stored in pools and the other half is stored in dry silos or dry casks on site. As of September 2011, 5,408 tons of spent fuel from PWRs and 6,431 tons of spent fuel from CANDU reactors are stored at four sites: three sites for PWRs, one site for CANDUs (NSSC, 2011). The annual addition to the amount of spent fuel is about 690 mtu. After 2045, spent fuel stores from the CANDU reactors will be full because of decommissioning of the CANDU reactors. The capacities, inventories and types of spent fuel in storage are given in Table 21.3 (NSSC, 2011). Spent fuel and irradiated fuel from the HANARO research reactor are stored in the storage pool on site at the Korea Atomic Energy Research Institute (KAERI). Up to 20 PWR fuel assemblies can be stored in the storage pool after irradiation tests. As of September 2011, 4 tons of spent fuel from HANARO was stored in the pool on site (NSSC, 2011). HANARO is a multi-purpose research reactor used for fuel performance testing, material irradiation testing, radio isotope (RI) production, and basic science and applications studies.

21.3.2 Spent fuel storage Spent fuel generated from NPPs is stored in the spent fuel storage facility in each unit. The storage capacity for spent fuel has been expanded as a consequence of the delayed construction schedule of the away-from-reactor (AFR) interim storage in accordance with the conclusions of the 249th and the 253rd meetings of the AEC. Taking into consideration the sufficiency of spent fuel storage capacity beyond 2016, the national policy for spent fuel management, including the construction of the interim storage facility for spent fuel, shall be decided in a timely manner through national consensus by public consultation among the stakeholders. To expand the spent fuel storage capacity, the utility company, Korea Hydro & Nuclear Power Co. (KHNP), is installing high density storage Table 21.3 Spent fuel storage (as of September 2011) NPP Site

Type of storage

Capacity* (mtu)

Inventory (mtu)

Kori Yonggwang Ulchin Wolsong Total

Wet Wet Wet Wet and dry

2,472 2,686 2,328 9,441 16,927

1,869 1,949 1,591 6,431 11,839

* Except emergency core.

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racks, transferring spent fuel between units and building dry storage. High density storage racks have been installed in Kori 3 and 4, Ulchin 1, 2, 3 and 4, and Yonggwang 3 and 4. Dry storage facilities have been installed on the Wolsong site for Wolsong 1, 2, 3 and 4 units which are CANDU reactors. By adding 100 canisters in 2006, 300 canisters are installed on site. In addition to the canisters, seven modules of MACSTOR (Modular Air-Cooled STORage)-400 with 3,175 mtu total capacity have been installed and in operation since May 2010. The spent fuel storage pool of the HANARO reactor is a heavy concrete structure, lined with stainless steel plate. The vault comprises three storage lattices. The vault has enough capacity for temporarily storing new fuel as well as spent fuel to be generated during normal operation of HANARO for 20 years. The Korean government has striven to secure a spent fuel management site since the early 1980s. However, the national policy for spent fuel management including construction of the centralized spent fuel interimstorage facility was to be decided in view of domestic and international technology developments later on. The national policy for spent fuel management will be decided later in consideration of domestic and international technology developments. Reprocessing activities have not been conducted in Korea.

21.3.3 Advanced fuel cycle to address spent fuel issues The international nuclear community recognizes the potential of nuclear energy systems to cope with increasing energy demand and international protocol for climate change even after the Fukushima accident. International cooperative programmes have been initiated to develop new systems that secure stable energy supply and have improved public acceptance, safety, and cost-effectiveness. The Republic of Korea is actively participating in these programmes currently, such as the Generation IV International Forum (GIF) and the International Project on Innovative Nuclear Reactors and Fuel Cycle (INPRO). Korea has been a chartered member of GIF since 2000 and plays a significant role in the development of Gen-IV. GIF was organized for collaborative development of new generation nuclear energy systems aiming for 2030 that can be accepted by the public and the energy market with excellent technical features and competitive economics, with 13 members leading nuclear utilization and development in the world taking part in GIF. GIF selected six systems of the most promising concepts as the Generation IV nuclear energy systems (Gen-IV) in 2002 and has been conducting collaborative R&D for each system through multilateral agreements since 2005. Korea focuses on SFR (sodium-cooled fast reactor-see Fig. 21.10) and © Woodhead Publishing Limited, 2013

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VHTR (very high temperature reactor) among the six Gen-IV systems. SFR is expected to use and recycle uranium resources effectively and minimize high-level radioactive waste with proliferation resistant fuel cycles. Korea is participating in six collaborative projects, tackling safety and operation, advanced fuels, and component design and balance of plant in SFR. Korea’s Long-term Development Plan for Future Nuclear Energy Systems, approved in December 2008, also presents a milestone and deliverables of SFR and pyro-processing technology. KAERI has been developing pyro-processing technology (Fig. 21.10) for recycling useful resources from spent fuel since 1997. The process includes pre-treatment, electro-reduction, electro-refining, electro-winning, and a waste salt treatment system. The removal of transuranic elements (TRU), Cs, and Sr from spent fuel allows the repository burden to be reduced by a factor of 100, compared with the case without removal. Fission products (FP) are recovered and transferred to a repository. As a result of pyroprocessing, both repository efficiency and uranium usage are increased up to 100-fold with strong proliferation resistance. According to the analysis of KAERI, spent nuclear fuel stock at the end of this century can be maintained at a level lower than that of today by introducing SFRs coupled with pyro-processing technology in the 2030s (Fig. 21.11). Korea has had an open fuel cycle, without reprocessing in compliance with the terms of its nuclear cooperation agreement with the USA, which

‘07

’11

’16

’20

’26

’28 Completion

Gen IV SFR

Advanced design concept

System performance test

Licensing technology development

Pyroprocess

Mock-up facility (Nat. U, 10t/Yr)

Eng.-scale facility (10t/Yr)

Standard design

Detailed design

Demonstration plant

Metal fuel irradiation test

Prototype facility (100t/Yr)

Prototype facility operation

21.10 The Republic of Korea’s long-term development plan for future nuclear energy systems (Kim, 2010).

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SF accumulated (ktHM)

Republic of Korea 100 90 80 70 60 50 40 30 20 Once-through cycle 10 0 Introduction of SFR 2010 020 2 0 3 0 2 0 204 050 2 0 206 0 207 080 Year 2 0 209 0 210

691

89

5

(Capacity factor 85%)

21.11 Cumulative PWR spent fuel (Kim, 2010).

needs to be renewed in 2014. In 2008, the IAEA approved an electrorefining laboratory – the Advanced Spent Fuel Conditioning Process Facility (ACPF) at KAERI which is to be built by 2011 and expanded to engineering scale by 2012. This is envisaged as the first stage of a Korea Advanced Pyro-processing Facility (KAPF) to start experimentally in 2021 and become a commercial-scale demonstration plant in 2025. In connection with renewal of the US-ROK agreement in or by 2014, discussions are proceeding on pyro-processing.

21.4

Decommissioning and decontamination (D&D) strategy, practice and issues

Korean decommissioning and decontamination (D&D) work on the retired research reactors KRR-1 and 2 and the uranium conversion facility (UCF) at KAERI is under way. Hundreds of tons of metallic and concrete wastes are expected from the D&D of these facilities. Therefore, countermeasures are being taken to deal with the amount of waste generated by dismantling these retired nuclear facilities. Recycling or volume reduction of the large quantities of metallic and concrete wastes are key waste management options due to the difficulty in securing a waste disposal site in Korea and the capacity limitation of the temporary waste storage facility at KAERI. Recycling or volume reduction through application of appropriate treatment technologies has merits from the viewpoint of resource recycling as well as a decrease in the amount of waste to be disposed of resulting in reduced disposal cost and enhanced disposal safety.

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21.4.1 D&D of TRIGA Mark-II and III research reactors TRIGA Mark-II, the first Korean research reactor (KRR-1), started operation in 1962, and the second, TRIGA Mark-III (KRR-2) located in Seoul, has been operational since 1972. These two research reactors, located at the former KAERI site in Seoul, were permanently shut down at the end of 1995. As a replacement for the TRIGA research reactors, the 30 MWth multipurpose HANARO research reactor was constructed in 1995 located at KAERI in Daejeon and has operated successfully since then. The D&D of KRR-1 and 2 research reactors was started in January 1997. The decommissioning plan, environmental impact assessment and decommissioning design were carried out in 1998. In July 1998, all SF from the TRIGA Mark-II and III reactors was safely transported to the US. At the end of 1998, the decommissioning plan was submitted to the Ministry of Education, Science, and Technology for licensing, and the Korea Institute of Nuclear Safety (KINS) reviewed it in 1999. The report of their review was considered in January 2000 by the Expert Group for Environmental Radiation, one of the four groups of the Nuclear Safety Commission, and the recommendation made by that Expert Group was submitted to the Commission for its final approval. At the moment, KRR-2 has been completely dismantled, whereas the decommissioning of KRR-1 was started in 2011 and will be completed by the end of 2014. Radioactive wastes from the decommissioning of KRR-1 and 2 were classified according to their characteristics and radioactivity levels, packed into 200 L drums or 4 m3 containers and stored in the reactor hall of the KRR-2 according to the process scheme of radioactive waste treatment from decommissioning sites, shown in Fig. 21.12 Radioactive waste generated from KRR-1 and 2 contains 60Co and 152Eu as major radionuclides in the activated waste and 60Co and 137Cs in the case of the contaminated waste. The current status of KRR-1 and 2 is shown in Fig. 21.13, and complete D&D of both will be performed within a few years later.

21.4.2 D&D of uranium conversion facility (UCF) The uranium conversion facility (UCF) located at KAERI was operated from 1982 to 1992. After the localization of nuclear fuel fabrication technology, it was shut down in 1993. UCF decommissioning began in 2001 and radioactive waste from UCF has been stored in a temporary storage building in the conversion facility. All the wastes are contaminated mainly with natural uranium. Currently, the dismantling of 26 out of 27 rooms at UCF has been conducted (Fig. 21.14), including decontamination of concrete surfaces, removal of contaminated soil, and completion of treatment of sludge waste in a lagoon.

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Non-contaminated waste

Contaminated waste

Compactable Non-compactable Spent ion-exchange Liquid waste resins solid waste solid waste Membrane separation 200 L drum

Container (large size)

Solidification Natural (asphalt or cement) evaporation

Interim storage Final disposal site

Industrial burial

21.12 Procedures for the treatment of contaminated wastes.

KRR-2

KRR-1

KRR-2 (1997)

21.13 KRR-1 and 2 and decommissioning status of KRR-2.

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KRR-2 (2009)

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(2011)

21.14 Decommissioning of UCF.

Research achievements to date are: • development of volume reduction technology for large amounts of radioactive concrete wastes • development of soil decontamination technology for remediation of nuclear sites after decommissioning • development of melting technology for decontamination of a hundred tons of slightly contaminated metallic wastes generated from KRR-1 and 2 and UCF • development of technologies for safe management of irradiated graphite arising from decommissioning of KRR-1 and 2 • development of a database system for management and data assessment from D&D activities • development of chemical decontamination technology applicable to metal wastes contaminated with UN (uranium nitride), AUC (ammonium uranyl carbonate), and UO2 generated by dismantling UCF • development of the safety assessment methodology of the decommissioning process • simultaneous remote measurement of alpha/beta contamination in highly contaminated facility

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Republic of Korea • •

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decontamination technology development waste treatment technology development.

Major R&D activities are now concentrated on development of the decommissioning waste reduction and recycling technology for commercial NPPs and nuclear facilities.

21.5

Conclusion

Given the scarcity of Korea’s primary energy resources, nuclear power is vitally important as an engine of growth for the nation. Korea has followed a set of consistent policies and executed steady plans to expand nuclear power. With a significant share of nuclear power in the energy mix, the disposal of RAW and SF is looming large as a high-visibility national issue. A low-and intermediate-level waste disposal site has been selected and the facilities are currently under construction with its full operation expected in 2014. Spent fuel management has also become imminent. Although no satisfactory resolution is in sight in the foreseeable future, various options are being studied with the government’s keen interest and full support. Korea has also designed a rigorous process for decontaminating waste materials.

21.6

References

Ahn, M.H., S.C. Lee and K.J. Lee (2009), ‘Disposal Concept for LILW in Korea: Characterization Methodology and the Disposal Priority’, Progress in Nuclear Energy, 51(2), 327–333. Cho, W.-J., S. Kwon, J.-H. Park and J.-W. Choi (2007), ‘KAERI Underground Research Tunnel (KURT)’, Journal of Korean Radioactive Waste Society, 5(3), 239–255. IAEA (1996), ‘International Basic Safety Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources’, IAEA Safety Series No. 115. Jo, H.-J., C.W. Kim and T.-W. Hwang (2010), ‘Commercialization Project of Ulchin Vitrification’, ASME 2010 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM2010), Tsukuba, Japan, October 3–7. Kim, Y.-I. (2010), ‘Current Status and Prospects for SFR Development in Korea’, 7th Tsuruga International Energy Forum, Tsuruga, Japan, November 19. Korea Hydro & Nuclear Power Co. (KHNP) (2012), Statistics of cumulative LILW, available from http://www.khnp.co.kr Kwon, S., C.S. Lee, S.W. Cho, S.W. Jean and W.J. Cho (2009), ‘An Investigation of the Excavation Damaged Zone at the KAERI Underground Research Tunnel’, Tunneling and Underground Space Technology, 24(1), 1–13. Ministry of Education, Science and Technology (MEST) of Republic of Korea (2008), ‘Korean Third National Report under the Joint Convention on the Safety

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of Spent Fuel Management and on the Safety of Radioactive Waste Management’, October. Ministry of Education, Science and Technology (MEST) of Republic of Korea (2010), Nuclear Safety White Paper. NSSC (Nuclear Safety and Security Commission of Republic of Korea) (2011), Nuclear Safety Yearbook. Park, J.B., H. Jung, E.Y. Lee, C.L. Kim, G.Y. Kim, K.S. Kim, Y.K. Koh, K.W. Park, J.H. Cheong, C.W. Jeong, J.S. Choi and K.D. Kim (2009), ‘Wolsong Low- and Intermediate-level Radioactive Waste Disposal Center: Progress and Challenges’, Nuclear Engineering and Technology, 41(4), 477–492. US-NRC (1977), ‘Calculation of annual dose to man from routine releases of reactor effluents for the purpose of evaluating compliance with 10CFR part 50, Appendix I’, US-NRC Regulatory Guide 1.109.

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