Requirements Management and Systems Engineering

Development of a Disposal System Specification (2018)

MCM was contracted to support LLW Repository Ltd in their challenge to develop a Requirements Management System (RMS). Through face to face discussions and comprehensive scouring of relevant documentation, MCM was able to draw out high-level, external requirements imposed on LLW Repository Ltd by important stakeholders such as The Environment Agency, Cumbria County Council, The Department for Business, Energy and Business Strategy (BEIS) and the Office for Nuclear Regulation (ONR).

Once the high-level, external requirements were agreed with LLW Repository Ltd, lower level system requirements were determined. These system requirements were written in order to formally describe the required functionality of the repository system and its management as a whole. Further articulation of the requirements was carried out through the crystallisation of sub-system requirements, covering each of the facility structures, systems and components at a generic design level. In this way, solution design was left unconstrained – by meeting the sub-system requirements, a design inherently meets the high-level, external requirements due to the requirements hierarchy. Finally, a set of component specification requirements was set out in order to provide detailed specifications for the design, construction and manufacturing of each structure, system and component of the facility.

The determination of the requirements in four hierarchical levels supports requirements-led concept design and optioneering for the facility itself. The demonstration of a specific design at each level ultimately leads to validation that LLW Repository Ltd’s high-level, external requirements are met, resulting in project success.

In order to provide comprehensive management of the requirements which have been documented, MCM provided LLW Repository Ltd with an RMS by populating the IBM Rational Dynamic Object-Oriented Requirements System (DOORS) software tool with their newly formed set of requirements. A populated DOORS database provides LLW Repository Ltd with an easily-communicable method to show the traceability of their requirements, allows LLW Repository Ltd to maintain formally documented change control over their requirements and inherently captures the relationships between the requirements at different levels.


Development of a conceptual design for a type B transport container (2018)

MCM was sub-contracted to ARUP to support the development of a User Requirements Document, Systems Requirements Document and the conceptual design of a Type B transport container suitable for transporting the GNS and SSB boxes in which ILW is currently stored by Magnox Ltd and Sellafield Ltd respectively.

Through interaction with the customer, end users and reference to regulatory documentation, user requirements for the transport container were determined for Magnox Ltd and Sellafield Ltd separately, given the different ILW containment boxes they currently use. Documentation of the user requirements was carried out and agreed with the end users, maintaining traceability to external and internal policy driving the requirements. Determining a level of priority for each requirement was important at this stage in order to allow trade-offs to be made in the event of conflicting user requirements between the two end users.

A systems engineering approach was carried out, whereby system requirements were formed in order to meet the user requirements of both Magnox Ltd and Sellafield Ltd. Such a process of articulating requirements in a layered manner provides a linkage between user requirements, specified at the beginning of the project, and the final design – qualifying a product design against the lowest level component specifications will allow demonstration of the conformation of the product to the user requirements.

Once established and agreed with the customer, the User Requirements Document and System Requirements Document were used as a basis for the consideration of conceptual design elements, features and layouts which would satisfy the previously elaborated system requirements. An optioneering process was then undertaken, resulting in a single design option for developed into an initial concept design.

In developing the requirements leading into a concept design, MCM has been able to efficiently aid RWM, Sellafield Ltd and Magnox Ltd in ensuring their final product will meet their user requirements, with a logical and documented traceability from product design up to the initially declared requirements.

Development of a larger waste container design (2016)

MCM, and their partners AMEC Foster Wheeler, were contracted to RWM in order to design a waste container which could be used to package  large  volumes  of  ILW  which  exceed  the  activity  and  fissile  limits  for  transport  as  an  Industrial  Package (IP) in accordance with IAEA SSR-6 transport regulations.

MCM’s systems engineering expertise was used to define a set of user requirements for the larger waste container, from which a set of system requirements was developed. A key requirement lay in the transport of such a container within Large Waste Transport Container (LWTC), as shown below.

Initial analysis resulted in the choice of an Unshielded Intermediate Level Waste (UILW) container design for which an Integrated Test, Evaluation, and Acceptance Plan (ITEAP) and design guidance was developed. RWM was provided with a design implementation plan covering the scope of work, costs and timescales in order for a larger waste container which sufficiently meets user requirements to be manufactured.

Review of the underpinning and justification for the 500 year integrity requirement placed on UK disposal containers for intermediate level waste (2014)

MCM has led a review for RWM to document the origins and supporting evidence for the intermediate level waste container integrity requirements and re-evaluate their relevance. This has included quantification and formulation in the context of the current GDF programme boundary conditions and to identify options for alternative solutions (other than placing the requirements on the waste container) to meeting the generic safety functions for the range of potential compatible engineered barriers to be used together with the range of potential intermediate level waste containers. As part of the review, definitions of waste container safety functions during each phase has been outlined, uncertainties associated with each phase have been identified and consideration of additional aspects relating to activities and conditions of waste packages during interim storage prior to transportation to a GDF have been introduced. A workshop was also held to preview the initial outputs of the review with invited experts and RWM staff. The outputs of the work will be used to develop a number of the recommendations that may lead to improved definition, justification and quantification of the current waste container integrity target.

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