WM2014 Conference Panel Report. PANEL SESSION 112: Management of Radioactive Waste Following a Nuclear Accident or Extreme Contamination Scenario

Transcription

1 PANEL SESSION 112: Management of Radioactive Waste Following a Nuclear Accident or Extreme Contamination Scenario Co-Chairs: Larry Camper, US NRC (USA) Irena Mele, IAEA, (Austria) Panel Reporter: Rateb (Boby) Abu Eid, US NRC, (USA) Panelists: 1. Martin T. Cross, Principal Consultant, Nuvia Ltd. (United Kingdom, UK); 2. Jack Devine, Chief Decommissioning Officer, Sellafield Ltd., URS (USA); 3. Jim McIlvaine, Chesapeake Nuclear Services. (USA) 4. Robert Kury, Vice President, Nuclear Liabilities D&D, Program Management, CH2MHill. (USA); 5. Kazuhiro Suzuki, Executive Director, International Research Institute for Nuclear Decommissioning. (Japan); 6. Francis X. Cameron, Principal Consultant, Zero Gravity Group. (USA) This panel session focused on decommissioning, remediation, and waste management aspects following major nuclear accidents or cleanup of an extreme contamination scenario condition, including: Three Mile Island (TMI) Nuclear Power Plant (NPP), USA; Chernobyl NPP, Ukraine; Fukushima NPP, Japan; Windscale Pile I, UK; and Rocky Flats Infinity Rooms (USA) remediation. In addition, the panel addressed crises communication with the public, stakeholders, and the media during past accidents. Summary of Presentations Martin T. Cross outlined the UK Windscale Pile 1 Accident in 1957, and Subsequent Cleanup and Decommissioning Activities. He described the piles, their structure, the graphite core, and history of the accident, particularly the damaged core, and fuel removal aspects. He indicated that the exact cause is still conjectured that inadequate instrumentation led to overheating and clad failure on cartridges leading to runaway Wigner release and exothermic uranium, isotopes, and graphite oxidation. In this context, he described the conjectured event sequence as follows: (a) formation of hydride, (b) de-stabilization of hydride (e.g.; due to mechanical disturbance or other effects), and its subsequent oxidation; (c) uranium oxidation; and (d) graphite and isotope oxidation. He added that filters on the stack retained most of the Sr-90 and prevented a major disaster; however most releases were of I-131 estimated at TBq. Other nuclide releases included: Cs-137 (22-44 TBq), Sr-89 (3 TBq), Sr-90 ( TBq), Te-132 ( TBq), Ru-106 (3-6 TBq), and Ce-144 (3-4 TBq). He described the early decommissioning Phase I for securing the safety of the facility, followed by clearance of air and water ducts. Subsequently, he described the present condition of Pile 1 and the associated hazards and decommissioning issues. He concluded by describing results of R&D program related to the accident and summarizing lessons learned which included: (a) UKAEA was overstretched at time of accident with too many commitments; (b) there was insufficient technical support for routine operations; (c) Committed response of AEA operators averted a larger disaster. Regarding decommissioning; he emphasized the insistent need for prioritization of characterization. He particularly cautioned against over pessimism; and lack of continuity in implementation of decommissioning plans. 1

2 Jack Devine started his presentation with a statement: TMI-2, Fukushima Daichi, and Sellafield are very different events, in terms of consequences, hazards, and remediation technologies; but share important points of commonality in remediation strategies and lessons learned. Subsequently, he summarized challenges faced for TMI including: inaccessible reactor building; uncertain condition/reliability of systems; flooded RB basement, ~600,000 Cs-137 Ci; high radiation and contamination levels; core melt; uncertainty of location/condition of damaged fuel; fuel retrieval, handling and disposition; and waste management (e.g.; processing and disposal of contaminated water). For Fukushima, he summarized challenges as: six unit site, four units severely engaged; extreme site and facility accessibility issues; three reactor buildings destroyed by hydrogen explosions; fuel pool overheating /damage; prohibitively high radiation /contamination levels; extensive tsunami damage, debris; three essentially full core melts; uncertainty of location /condition of damaged fuel; and waste management (e.g.; high and continually increasing volumes of contaminated cooling water; and congested, seaside site demanding environmental protection). His perspective of Sellafield challenges included: (a) legacy storage of large quantities of nuclear and other potentially high hazard material (e.g.; storage facilities (ponds and silos); deteriorating structures of uncertain design; and uncertain quantities, character and condition of stored materials); waste management issues (e.g.; large quantities, classifications, full range of conditions post-retrieval); and congested site condition which poses significant logistics challenges. He indicated that there are compelling lessons relating to the TMI-2 and Fukushima events and their emergency responses. However, his focus was on six lessons which included: (1) public trust; (2) accelerated risk reduction; (3) adopt a philosophy of begin and proceed with the end in mind; (4) keep in mind that what you don t know is more likely to drive the program than what you do know; (5) adopt a methodology considering that in the land of surprises, flexibility and adaptability carry the day; and (6) radiological recovery work and challenges of worker safety is of paramount importance for every day activity. He closed his presentation by stating that over time, there have been vast improvements in technology, tools, and preparedness; but, much was learned and needs to be remembered and applied. Jim McIlvaine addressed Risk/Waste Management at Chernobyl. In this context, he discussed the Shelter Implementation Plan (SIP); which was developed at the time of the accident in a co-operative effort between the European Union, the United States and Ukraine. SIP main objective was to protect the personnel, population, and the environment from the threat of a huge radioactive inventory of the Chernobyl Unit 4 accident. In this context, he described the SIP packages including: Package A - civil engineering (e.g.; structure stabilization, confinement, and geotechnical aspects); Package B - operations and monitoring (e.g.; seismic, industrial safety, radiation protection, and monitoring); Package C - emergency systems (e.g.; emergency preparedness, dust suppression, criticality, and water management and containment); and Package D - fuel containing material (e.g.; characterization, removal and waste management, technology, and risk mitigation). He indicated that radiation levels are still prohibitive and waste volumes, though difficult to quantify, but are very large (i.e.; more than 95% of fuel remains inside the Unit from initial loading and total amount of nuclear fission materials is about 200 tons). He added that there are no identified burial sites within the accident zone and emphasized the significance of a comingled waste/decommissioning effort at Units 1-3. He concluded that at Chernobyl, risk management is mainly associated with waste management and there is a need for international cooperation to achieve ultimate safety goals. Robert Kury presented Lessons Learned from the Rocky Flats Infinity Room D in the context of Session 112 main topic. He described the decontamination effort at the Rocky Flats Infinity Rooms 2

3 which included: (a) 13 infinity rooms that were so contaminated that radiological monitoring equipment in use in the 1960s could not measure it; (b) B771, Room 141 airborne radioactivity was upward of 20 million DAC up to 2,000 times the maximum limit for safe entry wearing supplied breathing equipment (Respiratory protection is required at 0.3 DAC). He noted that workers at the time abandoned decontamination efforts and sealed the room; Room 141 was sealed for 25 years. Subsequently, he summarized results of decontamination effort and details of the decontamination processes. He showed that DAC was lowered to 10,000 through innovative decontamination techniques and airborne contaminants were reduced by remotely applying a glycerin-based fog. After DAC was reduced, workers entered the room with SBA and packaged the room s contents into a SWB sleeved into a tent constructed around the door. Once all equipment was stripped-out, additional fixative was applied to fix the contamination to the interior surfaces. The concrete structure was too highly contaminated to be further decontaminated and had to be size-reduced and dismantled using diamond-wire saws. Large sections of the walls (weighing up to 20 tons) were rigged, lowered, size-reduced, and packaged as LLW. The main lessons learned included adoption of methodical planning and engineered controls (fixatives, decontamination, ventilation, wet methods, fogging, wire saw cutting), and use of protective equipment, though may slow activities, but reduces risk to workers. He subsequently described cleanup criteria and activities of two types of Surface Contaminated Object (SCO) (e.g.; SCO-I and SCO-II). SCO is an object which itself is not radioactive, but has radioactive material distributed on its surface. Advantage to shipping waste as SCO is the relief from some packaging requirements because under certain conditions, SCO-I may be shipped as unpackaged. However; less than A2 quantity may use IP-1 or IP-2 packaging; whereas greater than A2 quantity only requires Type A packaging. Finally, he described activities for interaction with the public through a Site Public Relations Activities that included: (a) developed working relationship with DOE to improve stakeholder relations at nuclear sites with a history of turmoil and public distrust; (b) educating the stakeholders and public on the basics of radioactivity, radioactive dose, contamination, and decontamination and remediation approaches; (c) risk communications and proactive media relations campaign; and (d) using the concept of Infinity Room Media Event by inviting media to witness the first entry into Building 771 and Room 141 after more than 30 years of restriction. He also showed how live camera images fed to a monitor allowing the news media to record the footage. Kazuhiro Suzuki focused in his presentation on Radioactive Waste at Fukushima Daiichi Nuclear Power Station (NPS). In this regard he presented storage volumes of contaminated or treated waste at storage tanks (~ 500,000 m 3 ); secondary waste from treatment (745 m 3 ); miscellaneous waste (71,000 m 3 ) felled trees waste (71,000 m 3 ), and an undetermined large volume of contaminated soil. Subsequently, he described a Mid-and Long-term Roadmap for Decommissioning of Units 1 4 and timeframe for solid waste management. He then described the water treatment system configuration and the Kurion s Cesium Absorption Vessel (Secondary waste) as well as the design of the Temporary Storage Facility for Secondary Wastes. Mr. Suzuki then discussed their concept of Waste Reduction Management which included the concepts of: waste prevention, waste minimization, reuse of materials, recycle, and ultimate disposal. He added that the original radioactive waste incinerator ceased to operate following the earthquake and tsunami on March 11, Therefore, accumulation of wastes has occurred and TEPCO is currently installing new incinerators. Regarding release of radioactive materials he indicated that the newly released from Reactor Building Units 1 4 in air measured on-site boundaries were measured at approximately 1.3 x 10-9 Bq/cm3 for both Cs-134 and x 10-9 Bq/cm3 for both Cs-134 and Radiation exposure dose due to release of radioactive materials was 0.03 msv/year (equivalent to approx. 1/70 of annual radiation dose by natural radiation (annual average in Japan: approx. 2.1 msv/year) at site boundaries. 3

4 He then summarized the nuclear fuel assemble for both spent fuel and fresh fuel for Units 1-6. Mr. Suzuki closed his presentation with the following conclusions: (a) there is a steadily increasing waste volume stored on site; (b) there is a need to promote dedicated R&D program for waste processing and disposal because Fukushima waste characteristics differ greatly from other radioactive wastes in Japan; (c) there is need to pursue safe storage until waste can be processed and transported to disposal site(s); and (d) there is a need to implement waste reduction program, with consideration to stabilized waste forms for safety. Francis X. Cameron, presentation topic was on Communicating with the Public during Nuclear Crises. In this regard, he discussed (a) overarching considerations; (b) challenges of effective communication; (c) the events TMI, Chernobyl, Fukushima; (d) What do the events tell us about effective communication? (e) What aids effective communication? In summary he iterated that poor planning and preparation for emergencies directly link to poor public communication. He emphasized that good communication with the public is an essential part of effective emergency planning. He summarized the needs for adequate safety measures to prevent or mitigate accidents (e.g.; filtered hardened vents, the latest controversy). He mentioned that the costs of poor communication with the public can be very high. The main challenges in communication with the public during nuclear crises were summarized succinctly as: misinformation abounds as the new social media allows it to spread quickly; exhaustion and anxiety for the decision makers and staff; explanation to the public on risks; worst case scenarios the event comes as a surprise; Murphy s Law applies if anything can go wrong, it will go wrong and confusion reigns. He described humility for TMI accident particularly due to lack records and resources. For Fukushima he emphasized communication breakdown due to difficulty to communicate with the plant power grid down, and backup generators obliterated. In addition, experts in the group seemed incapable of providing any guidance to key government and there was no specific delegation for decision-making or questioning of decisions. For Chernobyl, there were no guidelines on what to do in this type of emergency, meanwhile the hazards were downplayed by key officials describing the accident as an insignificant accident and asking to quit scaring people. Mr. Cameron, described in detail the TMI accident as presented by the U.S. news media and as reported on U.S. TV by the CBS evening news; with a show of an actual video of the famous Anchor Walter Cronkite and the China Syndrome movie. He closed his presentation with lessons learned and remedies which were summarized as follows: (a) adequate planning and good preparation particularly on the part of those in charge; (b) clear assignment of leadership responsibilities government, utility, and plant management; (c) should beware of mental models or group mindset of an expected universe if circumstances don t fit into the model, they are ignored just noise in the system; (d) culture can be a significant influence; for example a culture of complicity may result in a revolving door of industry executives and government officials; (e ) secrecy and rigidity could be a significant factor in finding remedies; and (f) avoid optimism assumptions that any and every potential accident had been defined and had been included in the Emergency Procedures; (g) communicate early, often, clearly, honestly and try to share information about the whole iceberg, not only the tip of the iceberg; (h) have responsible speculation don t leave the public alone with its fears; (i) have an adequate preparation for a systematic public information program and convey the message in plain language; avoid trust me, you don t have to worry; (j) provide timely and accurate information by a designated senior technical executive to the news media in a form that is understandable; and (k) use new technology to communicate. Finally, Mr. Cameron emphasized the importance of addressing critical infrastructural needs particularly, the need for an independent, well-funded regulator, with a technical capability and research capability. He also emphasized the need for transparency and openness in the regulatory process and the need for establishing relationships with NGOs and other affected parties or interest groups on important safety and environmental issues, well in advance of any accident. He added that failure of the imagination can be 4

5 deadly; particularly when something seemingly predictable and understandable was not planned for. He recommended using the concept of safety imagination to look beyond well-defined frames of reference. Questions and Answer & Conclusions Several questions and comments were raised regarding mitigation of accidents, availability of resources and funds to mitigate and remediate contamination after severe accident. Questions regarding on going actions, stress tests, and task force recommendations to address potential causes of sever accidents were raised. Questions were also raised regarding beyond accident design basis and use of risk-informed and defense-in-depth approach to ensure additional safety features to avoid accidents. Costs of remediation and how to deal with large volumes of waste and minimization of environmental impacts were elaborated further during discussion. New technologies and remote monitoring and characterization were recognized to be developed further. Cost/benefit analysis and graded approach to focus on immediate risk were raised as important issues. A question was raised regarding expediting licensing of waste disposal facilities after sever accident to accommodate large waste volumes. Risk communication with the public when providing KI tablets and/or decisions to evacuate were identified by participants as important issues. In summary, Session 112 was well organized, comprehensive, and covered several aspects and issues related to actions for containment and decommissioning as well as communications after severe nuclear accidents. Numerous lessons learned, decommissioning approaches, waste management issues and remedies were discussed. The presenters showed good illustrations of actual actions and activities to demonstrate lessons learned that can be of great use to all participants. 5