Dounreay Site Restoration Ltd -Waste options review

Waste options review

Dounreay is reviewing its disposal routes for all wastes to establish if its practices continue to represent the best practicable environmental options.

The last such study covering the entire site was undertaken in 2003 in support of the Dounreay Site Restoration Plan. The new study has now been carried out to optimise the site waste management strategy for gaseous, liquid and solid waste streams, based on the latest information on best practice.

The new study is a requirement of the regulatory authorisations granted under the Radioactive Substances Act 1993 for the disposal of radioactive waste from Dounreay. It is due to be submitted to the Scottish Environment Protection Agency by June 27, 2009.

Click here to read the summary of the 2008 Dounreay site waste best practicable environment options study.

Click here to see a larger version of this image and graphs

What is a BPEO Study?

A best practicable environmental option (BPEO) is the option that provides the most benefit or least damage to the environment as a whole, at acceptable cost, in the long term as well as in the short term¹. A BPEO study is a structured and systematic process to identify and compare strategic options. Alternative options are assessed against various criteria including environmental impact, socio-economic impact, health and safety, technical viability and financial cost.

The process of assessing and identifying the BPEO needs to be robust and fully transparent with all decisions recorded and arguments presented in a manner that is sound and rational. The final BPEO report is an auditable record of the option assessment process and includes appropriate justification of decisions and conclusions.

Summary of 2003 Study

The starting point for the new site waste BPEO is the 2003 study undertaken in support of the Dounreay Site Restoration Plan published in 2000. The site restoration plan has been superceded by lifetime plans produced annually for the Nuclear Decommissioning Authority since 2005.

To simplify the process, the 268 radioactive waste streams identified in the Dounreay inventory at the time were rationalised into 36 representative streams with similar physical, chemical and radiological characteristics. These were split under the headings of airborne wastes, liquid wastes, solid low-level waste and solid intermediate-level waste.

The identified BPEO was derived from the optimised strategy options for each waste group. The key features of the chosen BPEO were:

Does not require the abatement of liquid and airborne discharges using disproportionately expensive novel technologies to capture hard-to-scrub species such as tritium, Krpton-85 and Iodine-129.
Minimises the volumes of solid ILW and LLW, wherever practicable, by decontaminating, compacting, incinerating or segregating the majority of solid waste materials; and
Does not cause serious detriment to human health and the wider environment.

In summary the 2003 study identified the following BPEO for each of the broad waste types:

Airborne wastes

Wastes from active area ventilation systems are HEPA-filtered to remove particulate materials. Remaining gaseous waste discharged to the atmosphere in keeping with site discharge authorisation.

Liquid and sludge wastes

Liquid wastes which can be treated in the originating facility to comply with low level liquid effluent treatment plant (LLLETP) conditions for acceptance are discharged after treatment to the sea. Medium active liquids, raffinates and the sludges from shaft and silo and fuel storage ponds are neutralised and solidified to allow disposal. For other low level sludges, dissolution and discharge via LLLETP was identified. For solvents and oils, the BPEO was either direct solidification or incineration with cementation of any resultant solid waste.

Solid low level waste

Wastes is segregated and decontaminated (where applicable) to maximise the amount of free release material. Remaining items are supercompacted (where appropriate) and packaged / immobilised or sent for incineration.

Solid intermediate level waste

These wastes are decontaminated to LLW where practicable. Remaining wastes (excluding graphite) are segregated, supercompacted (where appropriate), immobilised in grout and packaged. Graphite wastes are incinerated and the resulting ash immobilised in grout and packaged.

What is the study about?

The Dounreay site waste BPEO covers the management of all wastes arising from current and future operations at Dounreay, both radioactive and non-radioactive, and will start with a review of current national and international best practice for minimising waste disposal. The BPEO study will also take account of more recent individual facility or waste stream BPEO studies.

The methodology to be used for undertaking the BPEO study will be based on the DSRL and regulatory guidance for BPEO assessments and will follow the steps given below:

Data collection and development of waste baseline and waste groupings for use in the study
Identification of broad list of options for each waste group
Initial screening of options to produce short list for full analysis
Selection of attributes to be used in analysis
Options assessment
Sensitivity analysis on results of options assessment
Identification of BPEO
Review of implementation of BPEO into site planning

To enable effective assessment of the options, waste streams with similar properties can be grouped and assessed together. An initial list of attributes for use in this study and against which alternative options will be assessed will be derived from the available guidance and previous BPEO study. This list will continue to develop as more information becomes available and a final list selected as the basis of the detailed option analysis.

Stakeholder Involvement

A BPEO study is required to justify the chosen approach in an open and transparent manner. A BPEO fully informed of alternative approaches takes into account the values and perspectives of a range of stakeholders.

Dounreay recognises and values the participation of the public in decisions about the decommissioning and closure of the site. The site has been at the forefront of public participation in previous BPEO studies about specific projects or wastes.

The network of site stakeholder groups established by the NDA is recognised as the primary means of engaging stakeholders about site activities. Details of this project were presented to members of Dounreay Stakeholder Group on September 10, 2008.

If you have any views or comments about any aspects of this project, click here to contact the project team.

Report of BPEO workshop

Consultation document

Reference:

1. Royal Commission on Environmental Pollution (RCEP), 1988, 12th Report, Best Practicable Environmental Option. Cm 310, HMSO, London, February 1988.