This article first appeared in the NDR September/October 2012, Page 8 by author Dr. John Collinson
Magnox aims to continuously build on its safety and environmental performance. Effective waste management for both radiological and non-radiological waste streams plays a key role in achieving this. Indeed all 10 Magnox sites have an impressive recycling rate in the 90 percentile.
The current strategy for decommissioning at Magnox sites is based upon a systematic and pragmatic hazard reduction, which takes advantage where possible of natural radioactive decay to reduce levels of radioactivity and risk to the workforce. The life cycle of sites is divided into five broadly consecutive phases:
Generation: during the generation phase, operational wastes that arise are disposed of routinely or stored for conditioning and disposal in later phases.
Defueling: when all fuel is removed from the reactors and fuel storage facilities and dispatched to Sellafield for reprocessing, drain-down of chemicals and removal of some plant machinery. Defueling has now been completed at six Magnox sites.
Care and Maintenance Preparations (C&MP): includes the removal of the majority of the plant and structures, including the turbine hall; delivery of all ponds into a safe and passive safe state; and the removal of waste from vaults and storage vessels and their structure. The reactors themselves will be left in a safe, secure, weather-proof structure known as a ‘Safestore.’ Intermediate Level Waste (ILW) will be made passively safe by conditioning, and packaged and stored in a purpose-built interim facility.
Care and Maintenance (C&M): during which the site will be largely quiescent with routine maintenance and continued storage of identified wastes onsite, to maximize the benefits of radioactive decay. During this phase, packaged ILW will be moved to the UK’s Geological Disposal Facility (GDF), which is scheduled to be available from 2040 onwards.
Final Site Clearance (FSSC): with the dismantling and removal of all remaining buildings and wastes.
Magnox, EnergySolutions (Magnox’ s parent body organization), and the NDA have developed and implemented an optimized approach to the decommissioning of the Magnox sites known as the Magnox Optimised Decommissioning Programme (MODP). The programme sets out what the business will deliver over the comprehensive spending review period, including pioneering innovative ways of working, accelerating Bradwell and Trawsfynydd sites to a state of care and maintenance, and carrying out safe and efficient cleanup. Other sites have also received additional funding to accelerate some decommissioning projects. Acceleration of work on key sites is counter balanced by a reduction in scope or deferred demolition across other parts of the programme. The MODP offers a savings of about £1.3 billion from the original Magnox decommissioning strategy.
MODP establishes common decommissioning projects across the company that allow the experience that has been gained in developing improved, fit for purpose approaches and technologies to be transferred from site to site. Waste has been identified as one of these programmes.
INTEGRATED WASTE STRATEGY (IWS)
To manage the various waste arisings generated by each phase of the decommissioning strategy, Magnox has an embedded Integrated Waste Strategy (IWS).
The IWS summarizes the overarching waste management strategy for radiological and non-radiological solid, aqueous and gaseous wastes. It focuses on opportunities for improved waste management including the pragmatic application of the waste hierarchy.
The waste hierarchy establishes a hierarchy of management options in context of increasing environmental impact, and is based on the simple premise that it is better to avoid waste generation than to treat or dispose of waste. The principles established in the hierarchy underpin good waste management practices. Avoiding waste generation is considered a priority, while disposal should only be considered as a last resort. This approach also supports the Nuclear Decommissioning Authority’s UK Low Level Waste (LLW) strategy requirements and aligns with the Low Level Waste Repository Ltd (LLWR) five-year strategy on diverting wastes where possible through other disposal routes, saving valuable space at LLWR and avoiding the need to build new waste vaults at the facility.
LLWR is the Site License Company (SLC) that provides waste management services to customers to treat and dispose of low level radioactive waste (LLW). On behalf of the Nuclear Decommissioning Authority, it manages the national LLW repository in West Cumbria. Established in 1959, the site has safely disposed of the nation’s low level waste for over 50 years. The waste is disposed of in engineered concrete vaults and, where possible, the waste is treated, containerized and grouted before placement in the vault. More than £100 million has been invested in the infrastructure of the site over the past
decade to maintain the facility as an important asset for the UK. LLWR also oversees a national LLW programme to ensure that lower activity waste is managed effectively.
Throughout all decommissioning projects within Magnox, waste minimization and recycling requirements are inherent in project development and implementation, with input from both the central and site-based Waste Programme teams. During project initiation and planning, the Best Available Technique (BAT) process is employed. This is a requirement of the Environment Agency, and the process includes an assessment of environmental aspects and waste management impacts. The preferable option for decommissioning will minimize the risk to operators, while also minimizing waste production and environmental impact.
RECENT CASE STUDIES
Waste management and recycling initiatives are run across all Magnox sites, following the waste hierarchy of reduce, reuse, recycle, recover and dispose. The sites have a requirement to bag, segregate and label all wastes at source; this has seen the introduction of segregated waste bins for paper, card, plastic, cans and glass. There are also segregated skips for metals, cable, wood and general wastes. Recycling also takes place on a major scale as outlined in the two recent case studies below.
Bradwell Turbine Hall De-planting and Demolition
The skyline at Bradwell site in Essex changed forever in January 2012, when the former power station’s turbine hall demolition was completed. When built, the turbine hall occupied the same size space of a standard football pitch. The de-planting and demolition generated over 12,000 tons of waste, which, through segregation, allowed for a recycling rate of 95 percent. Of this total only 630 tons were disposed of to landfill. Magnox worked closely with contractors to ensure maximum recycling rates were achieved and any environmental impact was minimized. Through a ‘lead and learn’ approach, learning and best practices will be shared with other Magnox sites.
Berkeley Boilers Removal Project
Recycling on an epic scale was achieved at Berkeley site in Gloucestershire. In March 2012, five of the 15 redundant heat exchangers (boilers) were removed from the site. Each 310-ton boiler measured 21 meters in length and five meters in diameter. The boilers were transported in whole by road, river and sea to a specialist treatment facility in Sweden (see Image 1). The boilers were characterized as LLW and contained very small amounts of radiological contamination internally. Using specialist treatment techniques, 90 percent of each boiler will be recycled back into the metal market, representing some 1,395 tons.
Recent Magnox Waste Management Developments
Through its Joint Waste Management Plan (JWMP), Magnox has been an industry leader on the management of LLW. Through collaborative working with LLWR on an integrated LLW program the plan looks to optimize other waste disposal routes so to preserve space at the LLWR. The plan encompasses metals, combustibles, and super compactable waste streams, and with the application of the waste hierarchy looks to reuse and recycle where possible. It also considers diverting very low level waste (VLLW) to specialist landfill facilities. There are clearly benefits being realized from the plan, both environmental and cost in nature. Last year Magnox diverted 672 tons of metal and 460m3 of solid combustible waste away from LLWR, saving valuable space.
Magnox has also pioneered an innovative approach to waste tracking with the implementation of an electronic tracking system at all of its sites. This approach for the first time allows access to a real-time inventory data, further assisting with effective waste management and recycling activities. The ‘cradle to
grave’ system means all waste streams can be tracked through their disposal routes and provides confidence to the regulator that all waste packages contain what is stated on the label. Using bar code technology, waste packages in the system can now be scanned for an instant report detailing their contents, saving considerable amounts of time and effort.
Waste itself is a valuable asset and Magnox, working on behalf of the site owners the NDA, looks where possible to maximize the return on the waste. This includes the reuse of redundant plant and equipment, which may be of use to other sites or other parts of the NDA estate. To enable this sharing, the NDA and other SLCs have developed an asset transfer database to advertise unwanted equipment which could potentially be used at other sites and, in doing so, save money. The scheme has been a great success and has seen some real cost-savings made.
Moving forward, Magnox continuously seeks to use waste routes that further increase use of the waste hierarchy, either for individual waste streams or large items of waste.
Over the next 12 months, Magnox will continue to set challenging targets, which includes diverting some 644 tons of metal and 515 tons of combustible waste away from LLWR and down over disposal routes, making significant cost savings and space in this valuable asset.
Finally, the business mission is to progressively transform Magnox into a world-class, high performing decommissioning organization. Key to meeting this is the company’s dedication to environmental protection and innovative waste management practices.
About the Author:
Dr. John Collinson has worked in the nuclear industry for 28 years, in which time he has held various senior management roles within Magnox and its predecessor companies. He has particular expertise in technical, project management, safety and regulatory affairs, while acting as company lead on key areas of Engineering, Operations, Safety and Outage Management.
Collinson’s previous roles have included Deputy Site Director, Plant Manager, Operations Manager, Engineering Manager, Outage Manager and Environment, Health, Safety and Quality Manager.
Collinson is currently the Waste Director at Magnox Ltd.
Visit www.ndreport.com/BerkeleyVideo to watch a video showing the full journey of the Berkeley Boilers.
Visit www.ndreport.com/BradwellVideo to watch a video showing the crane removal at Bradwell Turbine Hall.