Fully-funded PhD Studentship in SICODELIQ - SImulated COntamination assisted DEcontamination of highly active LIQuid facilities

At Sellafield, a number of major facilities will enter Post-Operational Clean Out (POCO) and decommissioning over the next 10 years. These include:

• The Thermal Oxide Reprocessing Plant (THORP);

• Magnox Reprocessing; and

• The Highly Active Liquid Evaporation & Storage plant (HALES).

All three of these major facilities involve the handling of highly active (HA) liquids within a variety of plant (pipework, vessels, evaporators etc) primarily comprised of a range of steels and associated metal alloys; POCO will therefore necessarily involve the decontamination of these metal surfaces. Contamination deposition mechanisms range from simple sorption (precipitation of solids) to sophisticated corrosion processes (passive, pitting, transpassive etc) resulting in radionuclides being affixed in a number of ways. Given this wide range of possible contamination mechanisms, a similarly wide range of decontamination methods has been developed.

The selection and/or design of a cost effective, waste minimal and efficient decontamination method has two principal requirements:

1. Knowledge of the chemical nature of that contamination and how it is affixed.

2. The capacity to test the decontamination techniques identified as being potentially appropriate by that knowledge.

Therefore, in light of requirement 1, there is a need to chemically characterise the contamination that may arise from exposure of process plant surfaces to highly active liquid process and effluent streams in order to inform the development or selection of the optimum decontamination method.

Fortunately, a means by which such characterisation may be achieved is available. As part of the general plant monitoring of the Magnox Reprocessing Plant, a number of steel, nickel and zirconium alloy coupons were suspended in the Magnox HA liquid process streams wherein they necessarily became contaminated. These now form a library of samples whose contamination can be considered to be truly representative of that found on plant.

In light of requirement 2, testing on the actual system where the contamination arises is appropriate. However, this is expensive, time consuming and presents challenges in terms of minimising operator exposure. Simulating contamination with substitute contaminants provides an inherently safer, less expensive and often more informative means by which to trial decontamination methods. The development of such simulants again requires a detailed and fundamental understanding of the original “real” contamination system.

Thus this PhD project, SICODELIQ, will have three main objectives:

1. Using the plant monitoring coupons, to characterise chemically the nature of the contamination entrained or adsorbed thereon. This will be achieved by materials characterisation using the microscopy and spectroscopy facilities available within NNL’s Central and Windscale Laboratories.

2. Based on the materials characterisation data obtained from the contaminated coupons, we will develop representative non-active simulant systems for a range of plant metals and alloys that have been exposed to highly active liquid process streams.

3. Finally, employing these simulant systems, we will determine the efficiency of metal surface decontamination using a range of chemically based decontamination methods including those based on aqueous and non-aqueous solvents, redox reagents, chelants, acid/base treatments, gels and foams.

This work is a collaboration with the UK National Nuclear Laboratory (NNL) and will be based at the Centre for Innovative Nuclear Decommissioning (CINDe) at NNL’s Workington Laboratory.

Deadline for applications: 28th February 2021

Interview date: On or shortly after 14^th March 2021

Studying within the Engineering Department at Lancaster

Through its Engineering Department, Lancaster hosts one of the UK’s strongest university nuclear centres with internationally recognised capabilities in: nuclear process chemistry; actinide (electro-)chemistry, radiation detection & safe guards. With a nuclear research portfolio of >£12M, they receive funding from, inter alia, IAEA, the UK research councils (EPSRC, NERC), InnovateUK, UK Government’s Office of Nuclear Development, the Nuclear Decommissioning Authority, the EU and numerous industrial bodies including Sellafield Sites Ltd, the UK National Nuclear Laboratory (NNL) and Dounreay Site Restoration Ltd. This work is also with a number of SMEs also, including Createc Ltd., REACT Engineering Ltd., Centronic, JCS Ltd.

Internationally, Lancaster has extensive links with the US and collaborate widely in Europe. Lancaster is host to UTGARD Lab (Uranium / Thorium Beta-Gamma Activity R&D Laboratory). Funded by the UK Government, UTGARD Lab is a process chemistry and materials preparation laboratory for work on beta/gamma active fission products, U, Th and low level alpha tracers. UTGARD is a national facility for the study of nuclear process chemistry and spent nuclear fuel simulants, offered to external users on an open access basis through the UK National Nuclear Users’ Facility (NNUF).