Creating Disposable Waste Packages

As a pioneer in the development and use of nuclear technology, the UK has accumulated a substantial legacy of radioactive waste and nuclear materials from electricity generation, defence programmes and other industrial, medical and research activities. Some of this waste is already in storage, but much of it will only become waste over the next century or so as plants are shut down, decommissioned and cleaned-up. A portion of this waste, referred to as Higher Activity Radioactive Waste (HAW), will be disposed of in a Geological Disposal Facility (GDF) in England and Wales.

A GDF in the UK does not yet exist. In the future, radioactive waste disposed of in a GDF will need to meet strict Waste Acceptance Criteria (WAC) for that facility to ensure that it is suitable for safe disposal. The WAC will be produced by the GDF operator and overseen by the relevant regulatory authorities. The WAC will be based on detailed safety cases to ensure safety while the waste packages are being placed in the GDF and following closure of the facility.

In the UK, plans for the geological disposal of Higher Activity Radioactive Waste are still at an early stage and so the information needed to develop the WAC is not yet complete. In the meantime, NWS has produced generic Waste Package Specifications (WPS) to inform expected performance requirements that waste packages will need to meet to ensure safe transport to, and disposal in, a GDF. As such, they can be considered as the preliminary WAC for a future GDF.

NWS produce WPS for different groups of waste, as different wastes require different packaging solutions to ensure the packages remain safe. The three waste types are Low Heat Generating Waste (LHGW), High Heat Generating Waste (HHGW) and Depleted Natural and Low Enriched Uranium (DNLEU). In the UK, most Lower Activity Waste (LAW) will not be disposed in a GDF, however there are some with certain chemical and physical properties that make it unsuitable for current disposal routes which will be assessed against the WPS for disposal at a GDF.​

The figure below indicates the structure of the WPS for LHGW. The WPS are organised in a hierarchical structure from the Disposal System Specification (DSS) Part A to the WPS Part D in increasing detail, as shown in the figure below. This is supplemented by the Part E which defines the justification for the WPS requirements. The WPS for HHGW and DNLEU are currently less well developed. Part C equivalents exist for both categories, however the more detailed specifications are under development and the structure may differ from that of the LHGW WPS when they are issued.​

The role of each document is as follows:

Disposal System Specification (Parts A and B)

The Disposal System Specification (DSS) defines the overall requirements to make the GDF safe and secure. It has two parts:​

• Part A explains the high-level external requirements of the disposal system. This covers the processes required to transport, receive and place waste packages in a GDF

• Part B explains the technical requirements for disposal of the waste packages, outlined by NWS, to meet the demands of Part A

All waste packages to be disposed of in the GDF must be compatible with the DSS.​

Waste Package Specifications (Parts C and D)

The WPS state what the packages containing HAW need to do to satisfy the DSS. The WPS for LHGW have two parts.

Part C defines the design envelope for waste packages defined by the DSS. This is for waste packages containing a broad category of waste (for example, LHGW). Part C allows proposed waste packages to be assessed against the GDF disposal concept.

Part D defines the design and performance requirements for a specific waste package so that they meet the envelope of Part C. There are many types of LHGW package for wastes with different physical, chemical and radiological properties that require specific package designs. Each Part D document will define key features of a waste package, for example dimensions and handling features. It will also explain minimum performance expectations, for example how much radiation is emitted from the package, and impact accident performance. Part D defines a waste package that is compatible with all aspects outlined by Part C. This means that the package will be compatible with guidelines for transport to, and disposal in, a GDF.

The WPS are used by waste packagers, industry regulators and stakeholders interested in packaging radioactive material for geological disposal. They are also used by NWS to assess waste packages. The WPS will define only what is required of a waste package, not how this can be achieved. However, the WPS are supported by guidance documents that demonstrate how they have been, or could be, achieved in practice. This guidance is available by emailing HAW.Packaging.and.Disposal@nuclearwasteservices.uk.

Justification (Part E)

NWS is in the process of defining and developing the LHGW Part E, which will document the justification behind the WPS requirements.​

Current status​

NWS has updated the WPS for LHGW; Part C and D. Part E is currently being developed for use by NWS.

A generic specification (Part C) is also available for HHGW and DNLEU.

NWS has produced supporting information to provide introductory information on HAW packages and how they are managed in the UK. More detailed guidance to support waste packagers and the supply chain in meeting WPS requirements is available by emailing HAW.Packaging.and.Disposal@nuclearwasteservices.uk.