Volume 9 issue 1 Nuclear Future
Figure 2: SDP trial rigs
receive and process MBGW to produce encapsulated 3m3 boxes suitable for long term storage and the completion of this project is a key priority for Sellafield Ltd. In principle SDP provides a simplistic solution, comprising
receipt bays for flasks of waste, waste tipping and sorting cells, mixing and encapsulation cells and curing and discharge areas. However, the reality is much more complex and the design of SDP presents a wide range of challenges which Nuvia Limited in conjunction with Sellafield Limited have been working to address over the last few years. These challenges include working with a largely unique and diverse waste stream, coping with hydrogen evolution and developing technical equipment which will operate sustainably for extended periods in high dose rates. This is not to mention the challenges of off-gas management and simply designing a process which will reliably operate inside the thick concrete shield wall with no human intervention. In designing this plant, Nuvia has looked at its previous experience with the design and build of waste processing facilities, and particularly hot cells, to identify lessons learnt and to ensure that these are captured in the processes for SDP. What might be difficult to appreciate is the complexity of the plant, yet there remains absolutely no margin for error. The process waste stream is such that once operational, modification to the plant will present a massive challenge. It is therefore essential that potential problems are identified and ironed out at the design stage. To support this objective Nuvia embarked on a programme
of work to construct a series of trial rigs which have helped to develop and prove key elements of the overall plant process. The rigs, which have been constructed at a facility in the North West (see figure 2) represent a key part of the overall risk mitigation strategy for the plant. In total, it is anticipated that up to 100 different elements of the plant process will be trialled to varying degrees of similarity to help confirm the final plant design. Key elements of plant, such as the tipping and mixing process, are being built to exactly replicate the quality and conditions expected in the facility (minus the activity!). In particular the tipping rig, which empties the 5tonne skips of waste into a large mixing vessel, has been developed to extremely high levels of integrity.
Each element of the plants operation will be meticulous trialled under a wide range of scenarios, allowing detailed analysis of the performance of plant items under normal operating conditions
Figure 3: Testing Berkeley recovery systems
and in the event of failure. During each trial volumes of data is recorded to allow further analysis of performance so as to optimise the plants performance and to minimise the potential for future failure. The trials process also allows the designers to produce detailed models of the plants performance which can be used to develop an accurate understanding of the plant future operation and maintenance requirements as well as influencing the design of both donor and feed plants. In 2011 Nuvia Ltd was award a contract under the Magnox
ILW framework to provide equipment to enable the recovery of solid waste from the chute silo at the Berkeley Power Station, Gloucestershire. The ILW material includes the Fuel Element Debris (FED), Miscellaneous Contaminated Items (MCI) and Miscellaneous Activated Components (MAC) which where produced over the plant’s operational life. The recovery of these items present a major milestone for the site as it allows entry into Care and Maintenance. Nuvia’s main focus within the project has been on the development
and installation of Chute Silo Retrieval Systems. The scheme requires the use of the Chute Silo Machine inside the silo to handle the waste. Nuvia’s first task was to recondition the existing chute silo machines. The two machines where stripped down and refurbished to meet the requirement of the future operations. To simulate the process Nuvia constructed a full scale replica of
the silo. Simulate control rods and charge chutes and bomb doors where then manufactured to allow full demonstration of the retrieval equipment, prior to installation on site. A simulant was also developed to replicate the gravel found within the vault, and extensive testing was undertaken to refine the operation for collecting the gravel and transferring it into a waste drum. Following the successful trials process the machines have been
transported to Berkeley, where one of them has now been installed within the waste vault. A key milestone was reached in July 2012 when the first bucketful of gravel was recovered from the vault. The benefits of trialling operations are clear as the upfront
investment offers the chance to iron out problems with equipment and to practice installation operations, and commissioning activities. Development of rigs allows the training of operators in non-active environments and can significantly de-risk nuclear projects.
For more information contact Jennie Osborne, Corporate Communications Manager on T: +44 (0)1925 858 250 E:
jennie.osborne@nuvia.co.uk W:
www.nuvia.co.uk
Nuvia 29
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56