Designing a New Highly Active Liquid Evaporator

The Highly Active Liquid Effluent Storage (HALES) plant stores, concentrates and conditions Highly Active Liquor (HAL) in evaporators for buffer storage in Highly Active Storage Tanks (HAST). Highly Active (HA) evaporators play a pivotal role in the delivery of reprocessing, historic clean up and hazard reduction missions across the Sellafield site. In addition to the engineering projects implemented to extend the life expectation of the current evaporator fleet, the UK Nuclear Decommissioning Agency (NDA) is sponsoring the construction of a new HA evaporator (Evaporator D) on the Sellafield site. The design and operation of the new HA evaporator is based on existing/recent HA evaporator technology but learning from past operational experience. Operational experience has been a key area where the existing plant operators have influenced both the new design itself and the requirements for commissioning and training. Many of the learning experiences require relatively simple engineering design modifications such as a new internal washing provision and transfer line blockage recovery systems, they are never-the-less expected to significantly improve the flexibility and operational capability of the new evaporator. Issues that the project delivery team has addressed as part of the development of the design and construction have included: • Minimising interruptions and/or changes to the normal operations of interfacing plants during construction, commissioning and operation of the new facility. • Modularisation of the plant, enabling fabrication of the majority of the plant equipment off-site within a workshop (as opposed to on-site) environment improving Quality Assurance and reducing on-Site testing needs. • Drawing out the balance between operational and corrosion resistance improvements with actual design and delivery needs. • Provision of a new facility reliant on the infrastructure of an existing and ageing facility and the competing demands of the related safety cases.