Radioactive Waste Management — WIA-ENE-026
This chapter aligns with IAEA WS-G-2.1 (Decommissioning of Nuclear Power Plants and Research Reactors) and the OECD/NEA Cost Estimation for Decommissioning methodology to cover the full decommissioning lifecycle of nuclear facilities, from End of Operation through Site Release. The WIA-ENE-026 standard carries every decommissioning envelope, stage identifier, and waste stream classification result inside a single envelope class so that multi-jurisdiction projects share one audit trail across regulators.
IAEA WS-G-2.1 defines three canonical decommissioning strategies: DECON (immediate dismantling), SAFSTOR (safe enclosure followed by delayed dismantling), and ENTOMB (entombment). The selection criteria across six decision variables — radionuclide decay time, financial assurance, worker exposure, site reuse target, residual hazards, and adjacent operations — are formalized in §5.3 of this chapter. The reference simulator panel 0 (Radioactive Decay Calculator) computes nuclide-specific decay curves over 30-60 year SAFSTOR periods, and panel 3 (Repository Capacity) compares immediate DECON LLW/ILW volumes against repository capacity.
The IAEA Safety Report Series No. 50 (Decommissioning Strategies for Facilities Using Radioactive Material) defines a five-stage flow: (1) Final Shutdown, (2) Post-Operational Transition, (3) Dismantling, (4) Site Remediation, and (5) Site Release (with or without restrictions). The WIA-ENE-026 envelope emits state-machine transitions for entry and exit of each stage, and the Phase 3 §3.2 federation handshake lets neighboring regulators subscribe to transition events in near-real-time. The envelope field decommissioningStage uses the IAEA Safety Glossary 2018 Edition terminology to eliminate semantic drift across national regulators.
The OECD/NEA Cost Estimation for Decommissioning: An International Overview of Cost Elements, Estimation Practices and Reporting Requirements publishes the International Structure for Decommissioning Costing (ISDC), which standardizes 11 top-level cost categories and 374 detailed activities. The costElement field of the WIA-ENE-026 envelope carries an ISDC code directly so that decommissioning projects in Korea, the United States, France, and the United Kingdom report against the same cost baseline. This is the foundation for international benchmarking of nuclear operator decommissioning funds.
WS-G-2.1 §3 mandates that the Decommissioning Plan be refreshed across the entire operational lifetime: the Initial Decommissioning Plan at licensing, the Updated Decommissioning Plan every 5-10 years during operation, and the Final Decommissioning Plan 2-3 years before Final Shutdown. In Korea, Article 87 of the Nuclear Safety Act Enforcement Decree and Nuclear Safety and Security Commission Notice 2017-37 impose equivalent procedures, with the Korea Institute of Nuclear Safety (KINS) performing conformance review. The WIA envelope carries both the IAEA plan revision and the KINS review identifier in the planRevision field, satisfying both national and international audit dimensions.
WS-G-2.1 §4.2 enumerates 12 decision factors: radionuclide inventory, spent fuel removal feasibility, site reuse plan, waste disposal infrastructure availability, financial assurance instruments, worker ALARA exposure, public dose limits, non-radiological hazards (asbestos, heavy metals), site occupancy intent, political and policy consensus, technology readiness (TRL), and impact on adjacent operational facilities. The WIA-ENE-026 Phase 2 endpoint /decommissioning-strategy/recommend accepts these 12 variables and returns DECON/SAFSTOR/ENTOMB/Hybrid scores on a 0-100 scale.
DECON restores the site to free-release condition within 5-10 years after Final Shutdown. Benefits include immediate site reuse, single-cycle asset disposition, retention of operating staff, and minimal policy uncertainty. Drawbacks include concentrated short-term LLW/ILW generation, one-time worker dose peak, and one-time financial burden. Maine Yankee (1996-2005), Connecticut Yankee (1996-2007), and Trojan (1993-2005) are flagship DECON cases in the United States, with mean unit decommissioning costs of $400-600M (2020 USD).
SAFSTOR places the facility in safe enclosure for 30-60 years following Final Shutdown, allowing short-lived nuclides (Co-60, Cs-134, etc.) to decay through natural radioactive decay before dismantling begins. NRC 10 CFR §50.82 caps the SAFSTOR period at 60 years after permanent shutdown certification. The reference simulator panel 0 (Radioactive Decay Calculator) computes that Co-60 (half-life 5.27 yr) decays approximately 99.96% over 60 years and Cs-137 (half-life 30.07 yr) decays approximately 75% over the same period. SAFSTOR reduces cumulative worker dose and spreads waste generation and cost across decades, at the cost of site opportunity cost, intergenerational burden transfer, and long-term surveillance expenditures.
ENTOMB encases the facility in concrete and steel for permanent on-site retention rather than dismantling. The entombment structure must persist until residual nuclides reach free-release levels (hundreds to thousands of years). United States cases include Hallam, Piqua, and BONUS, all small research or experimental reactors where activation products dominate. ENTOMB has no application to large commercial reactors, and IAEA SSG-47 §6 cautions that ENTOMB permanently assigns long-term stewardship to the site.
The OECD/NEA ISDC decomposes decommissioning cost into 11 top-level categories: (1) Pre-decommissioning Actions, (2) Facility Shutdown Activities, (3) Additional Activities for Safe Enclosure or Entombment, (4) Dismantling within the Controlled Area, (5) Waste Processing, Storage, and Disposal, (6) Site Infrastructure and Operation, (7) Conventional Dismantling and Site Restoration, (8) Project Management, Engineering, and Support, (9) Research and Development, (10) Fuel and Nuclear Material, and (11) Miscellaneous Expenditures. The WIA-ENE-026 Phase 1 envelope isdcCode field carries a four-level hierarchical code (e.g., 04.02.03.01 = Reactor Vessel Internals Segmentation).
The Korea Hydro & Nuclear Power (KHNP) Kori Unit 1 decommissioning plan submitted to MOTIE (approved June 2021) places the per-unit decommissioning fund at KRW 872.6 billion (2020 baseline), distributed across ISDC category 4 (Dismantling) at 38%, category 5 (Waste) at 24%, categories 6-8 (Site & Management) at 21%, categories 1-3 (Pre/Shutdown) at 11%, and Miscellaneous at 6%. The reference simulator panel 3 (Repository Capacity) compares ISDC distribution against the US NRC GTCC EIS (2016) baseline.
IAEA GSR Part 6 §5.18 defines two site release criteria: Unrestricted Release (free release, no further regulatory control) and Restricted Release (conditional release with land-use restrictions). Unrestricted release requires residual annual effective dose to the public of 10 μSv or less (NRC 10 CFR §20.1402 uses 25 mrem/yr = 250 μSv/yr), and restricted release aligns with ICRP Publication 122 §4.3 reference levels. The WIA Phase 2 endpoint /site-release/criteria accepts site coordinates and residual nuclide inventory and returns conformance against both criteria.
WS-G-2.1 §6 partitions decommissioning waste using the IAEA GSG-1 six-tier scheme: EW (Exempt Waste), VSLW (Very Short Lived Waste), VLLW (Very Low Level Waste), LLW (Low Level Waste), ILW (Intermediate Level Waste), HLW (High Level Waste). A reference 1,000 MWe PWR generates approximately 8,000-12,000 m³ of LLW, 800-1,200 m³ of ILW, and 50-80 m³ of HLW (activation products) over the decommissioning campaign. The simulator panel 4 (Waste Classification) applies IAEA GSG-1 thresholds (EW ≤ 1 Bq/g, VLLW ≤ 100 Bq/g, etc.) for automated classification.
/decommissioning-strategy/recommend to obtain DECON/SAFSTOR/ENTOMB scores.https://github.com/WIA-Official/wia-standards-public/tree/main/radioactive-waste.Korea entered the decommissioning era with Kori Unit 1 permanent shutdown on 18 June 2017 and Wolsong Unit 1 permanent shutdown on 24 December 2019, after Kori Unit 1 began commercial operation in 1978. KHNP is the decommissioning operator, KINS performs conformance review, and the Nuclear Safety and Security Commission (NSSC) issues licensing decisions. The Korea Radioactive Waste Agency (KORAD) operates the Gyeongju Low- and Intermediate-Level Waste Repository and the interim storage of spent nuclear fuel.
The Kori Unit 1 plan adopts a SAFSTOR variant: 5 years for spent fuel removal followed by 8 years of safe enclosure before active dismantling, for a total schedule of 15-16 years and a decommissioning fund of KRW 872.6 billion (2020 baseline). Wolsong Unit 1 is under review for a DECON conversion given the CANDU 6 heavy-water reactor characteristics; the Korea Atomic Energy Research Institute (KAERI) leads pressure tube segmentation and tritium (H-3) treatment R&D. The High-Level Radioactive Waste Management Special Act (enacted 9 January 2024, effective July 2024) defines siting procedure, public consultation, special accounting, and the staged provisioning of interim storage and permanent disposal facilities. The Ministry of Trade, Industry and Energy (MOTIE) targets 10% global decommissioning market share by 2030.
This chapter, like every other Phase 1-4 chapter in the Radioactive Waste Management eBook, composes with the wider WIA Standards family. Implementations that adopt the decommissioning envelope reuse the cross-standard audit transport (W3C Trace Context plus OpenTelemetry semantic conventions), the cross-standard identity (WIA-OMNI-API), and the cross-standard runtime trust list (WIA-AIR-SHIELD) without per-standard re-implementation. WIA-INTENT declares decommissioning intent (e.g., "PWR Unit 1 entering SAFSTOR 30y"), and WIA Secure Enclave seals sensitive payloads such as site coordinates and nuclide inventories. The Phase 3 §3 federation handshake lets adjacent regulators (e.g., Korea NSSC and Japan NRA, or EU ENSREG members) subscribe to stage transition events in real time.
The Kori Unit 1 decommissioning project, following the 18 June 2017 permanent shutdown decision, proceeded through staged plan submissions by Korea Hydro & Nuclear Power (KHNP) to the Ministry of Trade, Industry and Energy (MOTIE) and the Nuclear Safety and Security Commission (NSSC). The MOTIE-approved plan of 1 June 2021 sets a 20-year schedule: spent fuel removal 5 years (2017-2022), safe enclosure 8 years (2022-2030), and active dismantling 7 years (2030-2037), at a total project cost of KRW 872.6 billion (2020 baseline). The cost was mapped to approximately 280 of the 374 OECD/NEA ISDC detailed activity codes, with conformance verification performed by the Korea Institute of Nuclear Safety (KINS).
Kori Unit 1, a 587 MWe Westinghouse PWR, began commercial operation on 29 April 1978 and received a 10-year life extension on 18 June 2007 before permanent shutdown on 19 June 2017. Its decommissioning strategy is classified as Modified SAFSTOR per OECD/NEA categories. Spent fuel remains in the on-site interim storage pool and will be transferred to the future interim storage facility in the early 2030s. The Korea Atomic Energy Research Institute (KAERI) conducted pressure vessel segmentation and steam generator dismantling R&D at the KURT (KAERI Underground Research Tunnel) facility.
Wolsong Unit 1, a 679 MWe CANDU 6 heavy-water reactor from AECL Canada, began commercial operation on 22 April 1983 and reached permanent shutdown on 24 December 2019. The CANDU heavy-water characteristics impose additional decommissioning steps: 380 pressure tubes, four boilers, primary heavy-water recovery, and tritium (H-3, half-life 12.3 years) treatment. KAERI launched the CANDU Decommissioning Core Technology Development Project (2020-2029, total KRW 150 billion) covering pressure tube segmentation, tritium recovery, and heavy-water purification. Wolsong Unit 1's decommissioning fund is approximately KRW 900 billion per unit, reflecting the additional cost of heavy-water recovery.
Korea's decommissioning workforce comprises a five-operator consortium (KHNP, Doosan Enerbility, Hyundai E&C, Samsung C&T, and SK ecoplant), with technology cooperation agreements signed with EnergySolutions (US), Orano (France), SNC-Lavalin (Canada), IHI (Japan), and NUKEM (Germany). The KAERI Decommissioning Technology Verification Research Center (founded 2019, Gijang, Busan) provides specialised training for decommissioning EPC personnel and has trained approximately 1,200 personnel cumulatively as of 2024. KINGS (KEPCO International Nuclear Graduate School) runs a 2-year master's programme in decommissioning, graduating 30 students annually.
Decommissioning waste is classified per IAEA GSG-1: (i) EW (Exempt Waste, ≤ 1 Bq/g), (ii) VSLW (Very Short Lived Waste, ≤ 100 day half-life), (iii) VLLW (Very Low Level Waste, ≤ 100 Bq/g), (iv) LLW (Low Level Waste, ≤ 4×10⁹ Bq/g), (v) ILW (Intermediate Level Waste), and (vi) HLW (High Level Waste). Expected Kori Unit 1 waste volumes are approximately 9,500 m³ LLW, 1,000 m³ ILW, and 60 m³ HLW (activation products). The simulator panel 4 (Waste Classification) performs automated GSG-1 threshold classification from a nuclide inventory input. LLW and ILW transfer to the KORAD-operated Gyeongju repository, while HLW transfers to the future High-Level permanent disposal facility (planned operation 2060).
For international peer review, Korea hosted the IAEA ARTEMIS (Integrated Review Service for Radioactive Waste and Spent Fuel Management, Decommissioning and Remediation) review in 2017 and a follow-up review in 2023. The ARTEMIS report rated Korea's decommissioning legislation, financial assurance, and KINS technical capability above the OECD average, and recommended accelerating the timeline for spent fuel permanent disposal. The 2024 High-Level Radioactive Waste Management Special Act is the policy response to this recommendation. MOTIE has formulated the Decommissioning Industry Development Five-Year Plan (2024-2028) targeting 10% global market share by 2030.
Korean decommissioning operations follow a staged procedure under Article 24 (permanent shutdown) and Article 85 (waste procedures) of the Nuclear Safety Act. After a permanent shutdown decision, the operator submits six staged documents to the Nuclear Safety and Security Commission (NSSC): (a) permanent shutdown application, (b) spent fuel removal plan, (c) safe enclosure plan, (d) dismantling plan, (e) site restoration plan, and (f) site release application. The Korea Institute of Nuclear Safety (KINS) performs conformance review of each document, and the NSSC commission holds public deliberation before licensing decisions.
Kori Unit 1 progressed through stages (a)-(d) after 19 June 2017 shutdown, and as of 2024 is finalising the 5-year spent fuel removal step. Wolsong Unit 1 progressed through stages (a)-(c) after 24 December 2019 shutdown. Both units adopted a SAFSTOR variant strategy for the safe enclosure stage, with active dismantling planned for 2030 (Kori 1) and 2032 (Wolsong 1). KHNP submits an annual decommissioning progress report to NSSC, MOTIE, and the National Assembly.
KAERI developed five core decommissioning R&D technologies: (1) pressure vessel segmentation (laser, plasma, electrical-discharge machining), (2) steam generator dismantling (remote cutting robotics), (3) heavy-water recovery and purification (for Wolsong), (4) tritium (H-3) treatment (heavy-water separation), and (5) activated concrete decontamination (precision milling). These five technologies emerged from the Decommissioning Core Technology Development Project (2018-2027, total KRW 350 billion), with the five-operator EPC consortium (Doosan Enerbility, Hyundai E&C, Samsung C&T, SK ecoplant, and KHNP) executing demonstration trials.
Korean decommissioning waste follows four disposal routes: (i) Exempt Waste (EW) and Very Low Level Waste (VLLW) to designated landfills (separate from the Gyeongju repository), (ii) Low Level Waste (LLW) to Gyeongju Stage 1 cavern disposal, (iii) Intermediate Level Waste (ILW) to Gyeongju Stage 2 surface trenches, and (iv) High Level Waste (HLW, activation products and fuel assemblies) to the future High-Level repository (planned operation 2060). KORAD operates routes (ii)-(iv), with MOTIE in overall policy oversight.