How hydraulics play a key part in nuclear decommissioning
29 September 2015
Author: Simon Pykett, general manager, Penny Nuclear, a division of Penny Hydraulics Ltd
I have come across many articles relating to the cost of decommissioning nuclear power plants and how much this is costing the country’s taxpayers, but little information is ever given on what is actually involved with decommissioning work and what equipment and processes are used.
I have been working in the nuclear industry for more than five years now and specialise in hydraulic and mechanical handling equipment for nuclear decommissioning, working on projects at sites including Bradwell in Essex and Sellafield in Cumbria.
According to the World Nuclear Association, to date, about 110 commercial power reactors, 46 experimental or prototype reactors, 250 research reactors and a number of fuel cycle facilities have been retired from operation – some of which have been fully dismantled.
Common misconception that materials from retired sites cannot be reused
A common misconception is that materials from these sites cannot be reused when, in fact, most of the metal can be recycled. Proven techniques and equipment are available to dismantle nuclear facilities safely, which is where I play a part, and these have now been well demonstrated in several parts of the world. Decommissioning costs for nuclear power plants, including disposal of associated wastes, are reducing and contribute only a small fraction of the total cost of electricity generation.
Sellafield Ltd is one of the Site Licence Companies (SLC) responsible for safely delivering decommissioning, reprocessing and nuclear waste management activities on behalf of the Nuclear Decommissioning Authority (NDA) – its primary mission being the accelerated clean-up of legacy facilities. Sellafield intends to receive material at the Sellafield site in Cumbria for long-term safe storage.
A key element of this mission is known as the Dragon Waste Project, and Penny Nuclear has the responsibility of designing and manufacturing the mechanical handling equipment for this project. The Dragon Waste Project is an excellent example of what is commonly involved with a nuclear decommissioning project and how hydraulics and mechanical handling equipment play a part.
The project involves the receipt at Sellafield of waste material in licensed transport containers for encapsulation and long-term storage. I am managing the design and manufacture of all of the lifting equipment required to undertake the various lifting procedures for the programme, as well as the storage of that equipment in the form of designated park stands.
Breaking it down, our company, Penny Nuclear is responsible for the supply of a fully substantiated detailed design package, manufacture, CE marking and testing of the items and equipment.
Model of project on screen using CAD software
Utilising the latest 3D computer aided design (CAD) software, we were able to offer a model of the entire project on screen. This gave the advantage of being certain the design was suitable for the job before reaching the manufacturing or testing stage.
Working remotely, we reviewed and developed Sellafield’s proposed solutions, starting at the high-level design proposal drawing phase, different ideas were communicated and discussed, thereby streamlining the decision process and allowing the detailed design to commence early. The software used allowed for other parties’ models to be incorporated into the designs, giving Sellafield reassurance that all systems interfaced correctly, thereby minimising project risk.
Designs were then progressed to manufacture, there were four lifting beams and two dedicated parking stands (one of which accepts three of the beams) in total.
Each of the lifting beams have two hydraulically operated arms which open and close around a Ramshorn lifting hook. The arms are operated using a manual hydraulic pump and move the arms simultaneously in a master-slave arrangement, eliminating the need for two rams and a flow divider. This leads to a simpler, more reliable and robust design. The arms are opened and closed while the beams are sat in the parking stands.
Each lifting beam is designed for a specific purpose, so has dedicated lifting attachments underslung from the main beams itself. These attachments take the form of chain slings, hook arms or trunnion arms, and provide either a two- or four-point lift.
CNC machining, large-scale milling and other precision services
In-house capabilities we are using for this project include profiling, turning, boring and milling. CNC machining, large-scale milling and other precision services have been offered through our robust local supply chain.
All sub-contracted items are rigorously inspected before being released for use, as well as the subcontractors meeting our full quality assurance requirements. As a firm supporter of businesses in the local community for the past 37 years, we are proud to be supporting the local SME supply chain and helping them to also gain experience within the nuclear sector.
The project, which is now well under way, is due to be completed ahead of schedule. By streamlining the design, we have been able to reduce the project lead time and the project risk. The major item to be manufactured is a SWL 25 tonne Transport Package Lifting Beam, which is to be proof-load-tested to 50 tonnes, but designed to remain safe at 75 tonnes (3x SWL). This beam is in fact the largest SWL item we have produced to date.
Working in line with BS EN ISO 3834
Even in advance of completion, the project has had many positive impacts on our company. We have invested in new equipment to allow us to deliver the contract to the highest standard and we are embedding working practices developed through delivering this contract into the rest of the business, such as working in line with BS EN ISO 3834 on the fabrication of the lifting beams. We have also upskilled the workforce which is allowing us to continue developing the business in further areas.
The majority of nuclear products are designed and manufactured bespoke, in order to fulfil activity-specific customer requirements, yet sometimes our serial production products may be more than suitable for our customers’ needs. All projects are carried out under detailed consultancy with the customer, and draw upon Penny Hydraulics‘ experience of providing mechanical handling equipment to various industries.
Penny Nuclear designs and manufactures lifting equipment, mechanical handling solutions and hydraulic systems for all stages of the nuclear plant lifecycle and nuclear fuel cycle. Whether it is for decommissioning, generating, research or new build sites, we have the knowledge and experience to provide customers with robust, cost-effective solutions within extremely competitive lead timeshttp://www.engineersjournal.ie/2015/09/29/how-hydraulics-play-a-key-part-in-nuclear-decommissioning/http://www.engineersjournal.ie/wp-content/uploads/2015/10/hydraulics-nuclear-commissioning-10.pnghttp://www.engineersjournal.ie/wp-content/uploads/2015/10/hydraulics-nuclear-commissioning-10.pngMech3D,United Kingdom,waste