Laser-driven multi-modal probe beams for nuclear waste inspection
Lead Research Organisation:
University of Bristol
Department Name: Interface Analysis Centre
Abstract
This proposal aims to develop a revolutionary new tool for the stand-off inspection of nuclear waste packages using laser-driven x-rays and neutron beam pulses. This will be a collaborative project between the University of Bristol's Interface Analysis Centre (IAC), Sellafield Limited, Queen's University Belfast (QUB) and the STFC Central Laser Facility (CLF). By firing an extremely high-energy laser for a very short duration, an intense spot of x-ray radiation is generated and projected towards detector plates. In a similar manner to medical x-rays, any object placed between the bright source of x-rays and either photographic film or digital image plates, is captured in detail. However, because a very high energy is used, imaging of packages containing uranium waste, one of the densest materials on Earth, is possible.
Since 1952, Sellafield has been responsible for safe storage and reprocessing of all the UK's nuclear waste. Decades of research and development have resulted in more manageable forms of nuclear waste. However, a number of problems remain, particularly with the ageing 'legacy' nuclear waste that has been stockpiled since the 1960s. Before long term storage in a geological disposal facility is considered, the composition and degradation state of the waste material and containment vessels needs to be established. Due to the radioactivity and dangerous corrosion products formed during storage, a destructive investigation of the waste containers is considered far too hazardous to be performed. Therefore, a non-destructive, stand-off evaluation of the containers is proposed.
For a visual inspection of the internals of a nuclear waste package, high-energy x-rays are used to create an image of the sample. Typical means of producing x-rays do not achieve either the resolution required or the energy to penetrate through the large, dense waste containers. Therefore, it has been proposed that the petawatt Vulcan laser at the CLF is utilised to generate the necessary high-energy x-rays required for this analysis.
In addition, the Vulcan laser facility is capable of producing a beam of neutrons in parallel with the high-energy x-rays. By probing the waste containers with a neutron beam any fissile material contained inside will undergo a small amount of fission and emit secondary neutrons. Depending on the fissile material that reacts, the emitted neutrons will generate a unique signature which can be used to identify the particular isotope present in the sample. Analysis of this data holds the potential for isotopic quantification, thus identifying the exact quantity of highly radioactive uranium-235 compared to the isotopically different, and far less radioactive, uranium-238.
Whilst the initial aims of this proposal are for characterisation of samples via a single-shot approach, the end goal is the development of a system capable of firing up to ten times a second by construction of a small footprint, high-energy DiPOLE laser with the corresponding sensors capable of rapid data acquisition. In anticipation of such a system, one component of this project aims at improving existing detector technology with a focus on rapid image capture and neutron detection.
The final section of the project is the production of a business case to pursue the eventual development of a fast firing analysis system to form the basis of a nuclear waste package scanning facility. Much like CT scanning, by rotating the waste container during multiple image acquisition a 3D profile of the contents can be constructed. This technique would allow us to probe deep inside the waste containers and assess their contents in detail without any destructive investigation or disturbance to the potentially toxic, pyrophoric, and radioactive contents. We consider that this technology would have excellent global export potential to other nations producing nuclear waste.
Since 1952, Sellafield has been responsible for safe storage and reprocessing of all the UK's nuclear waste. Decades of research and development have resulted in more manageable forms of nuclear waste. However, a number of problems remain, particularly with the ageing 'legacy' nuclear waste that has been stockpiled since the 1960s. Before long term storage in a geological disposal facility is considered, the composition and degradation state of the waste material and containment vessels needs to be established. Due to the radioactivity and dangerous corrosion products formed during storage, a destructive investigation of the waste containers is considered far too hazardous to be performed. Therefore, a non-destructive, stand-off evaluation of the containers is proposed.
For a visual inspection of the internals of a nuclear waste package, high-energy x-rays are used to create an image of the sample. Typical means of producing x-rays do not achieve either the resolution required or the energy to penetrate through the large, dense waste containers. Therefore, it has been proposed that the petawatt Vulcan laser at the CLF is utilised to generate the necessary high-energy x-rays required for this analysis.
In addition, the Vulcan laser facility is capable of producing a beam of neutrons in parallel with the high-energy x-rays. By probing the waste containers with a neutron beam any fissile material contained inside will undergo a small amount of fission and emit secondary neutrons. Depending on the fissile material that reacts, the emitted neutrons will generate a unique signature which can be used to identify the particular isotope present in the sample. Analysis of this data holds the potential for isotopic quantification, thus identifying the exact quantity of highly radioactive uranium-235 compared to the isotopically different, and far less radioactive, uranium-238.
Whilst the initial aims of this proposal are for characterisation of samples via a single-shot approach, the end goal is the development of a system capable of firing up to ten times a second by construction of a small footprint, high-energy DiPOLE laser with the corresponding sensors capable of rapid data acquisition. In anticipation of such a system, one component of this project aims at improving existing detector technology with a focus on rapid image capture and neutron detection.
The final section of the project is the production of a business case to pursue the eventual development of a fast firing analysis system to form the basis of a nuclear waste package scanning facility. Much like CT scanning, by rotating the waste container during multiple image acquisition a 3D profile of the contents can be constructed. This technique would allow us to probe deep inside the waste containers and assess their contents in detail without any destructive investigation or disturbance to the potentially toxic, pyrophoric, and radioactive contents. We consider that this technology would have excellent global export potential to other nations producing nuclear waste.
Publications
Armstrong C
(2019)
Bremsstrahlung emission from high power laser interactions with constrained targets for industrial radiography
in High Power Laser Science and Engineering
Brenner C M
(2018)
Special Issue on Prospects for Academic and Industrial Applications of Laser-driven Neutron Sources: A Review of Recent UK Activities on Laser-driven Neutrons for Industrial Applications
in The Review of Laser Engineering
Jones CP
(2016)
Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages.
in Journal of hazardous materials
Stitt C
(2017)
Real time, in-situ deuteriding of uranium encapsulated in grout; effects of temperature on the uranium-deuterium reaction
in Corrosion Science
| Description | The award demonstrate that it was possible to use a high-power laser system to generate multimodal probe beams (gamma-rays and neutrons) for the inspection of nuclear waste packages and other ultra-dense objects. Using the Vulcan and Gemini laser systems at the STFC's Central Laser Facility we conducted a series of experiments to demonstrate gamma and neutron production, including example gamma radiographs through uranium-metal containing simulant concrete waste objects. Due to the density of these objects, normal X-rays will not pass through making X-ray radiography analysis impossible. Instead, much higher energy gamma photons (which can pass through) are needed to perform non-invasive diagnostic analysis (health checks) to determine if the waste form is behaving as predicted. Our project has demonstrated that this laser-driven approach for producing bright and directional flashes of gamma rays could be harnessed by future dipole pumped laser systems, which have very high power but also high rates of firing laser flashes (Hz). |
| Exploitation Route | There are two aspects: 1) The outcomes have already been taken forwards for the diode-pumped laser sources by the CLF and University of Strathclyde, with the latter forming their PANAMA facility via National Nuclear User Facility Funding. 2) Now that this technology has been demonstrated, the focus has now switched to the development of high density scintillator imaging plates which are suitable for gamma and fast neutron imaging. This has lead to Bristol University working with LLNL and the AWE to accelerate and upscale the development of doped Gadolinium Lutecium Oxide (GLO) as a novel scintillator material optimised for this application. |
| Sectors | Aerospace, Defence and Marine,Energy |
| Description | This award has helped to promote the case for the development for high-power dipole-pumped laser systems to be used as multimodal sources for diagnostic inspection and experimentation on materials. For example, the National Nuclear user Facility has, in November 2019, funded the PANAMA facility at Strathclyde, to provide a user facility for academic users to benefit from a system capable of 1-5 fsec pulses at a 1 Hz rate, making this system an alternative to the Synchrotron facility at Diamond. I am on the advisory board for this new facility, which is now an operating NNUF facility. The work on this project also led me to start research and development work with the AWE and Lucideon Ltd. on the fabrication of GLO, as a next generator scintillator material for neutron radiography - a technology required to match with the laser-driven gamma sources for nuclear waste inspection |
| First Year Of Impact | 2019 |
| Sector | Education |
| Impact Types | Policy & public services |
| Description | AWE summer internship project on modelling of neutron interactions with isotopic diamond wafers |
| Amount | £5,000 (GBP) |
| Organisation | Atomic Weapons Establishment |
| Sector | Private |
| Country | United Kingdom |
| Start | 05/2018 |
| End | 09/2018 |
| Description | AWE high energy imaging partnership |
| Organisation | Atomic Weapons Establishment |
| Department | National Nuclear Security Programme |
| Country | United Kingdom |
| Sector | Public |
| PI Contribution | For the AWE we have been providing expertise on laser-driven gamma and neutron pulses as well as novel fast neutron imaging technologies using Diamond with a scintillation backing material. We are also supporting them in the establishment of a national high energy imaging facility. |
| Collaborator Contribution | The AWE have co-funded a Royal Academy of Engineering professorial fellowship for me to run for 5 years until February 2021. This is a financial contribution of £50,000 per year, plus additional funding specifically for projects and secondments of members of my team. |
| Impact | Outputs have inlcuded: - A modelling study report on the use of diamond for fast neutron imaging - Conducting a joint experiment at the LANSCE neutron facility in the USA to test deuterium infused diamond with a scintillator backing material as a fast neutron imaging material. - Undertaking a deuterium infusion study of diamond (at the AWE) to determine the deuterium (H-2) solubility as a function of pressure and temperature. The collaboration is ongoing and we will conduct further experiments in the next 12 months. |
| Start Year | 2017 |
| Description | Central Laser Facility (CLF) |
| Organisation | Rutherford Appleton Laboratory |
| Department | Central Laser Facility |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | The project involves working closely with the CLF using the Vulcan petawatt laser system to perform experiments to prove the feasibility of using a petawatt dipole pumped laser to inspect nuclear waste packages. |
| Collaborator Contribution | The have provided access to the Vulcan laser system, assistance with co-writing and filing a patent and in developing the business case for future commercialisation of the gamma and neutron flash technology. |
| Impact | This research collaboration has resulted in 1 paper in an international journal, 2 conference journal articles, 2 conference presentations and a patent. The collaboration has been inherently cross disciplinary due to the need for nuclear scientists, materials scientists and laser physicists. |
| Start Year | 2016 |
| Description | Waste inspection partnership with Sellafield Ltd |
| Organisation | Sellafield Ltd |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | We have been developing feasibility data and a business case towards proving the use of petawatt lasers for generating multi-modal gamma-ray and neutron beams to conduct nuclear waste package inspection. We have been developing a series of test samples in partnership with the CLF and Sellafield for testing with the Vulcan laser system at the CLF. |
| Collaborator Contribution | Sellafield have been assisting in development of our understanding of the application for the technology at Sellafield site. Sellafield have also been assisting with the provision of some test samples (10 years old) to be shipped from Springfields to Bristol to then subsequently be examined using Vulcan. |
| Impact | In addition to having published the initial feasibility work we have also filed a joint patent (GB 1519758.5) . |
| Start Year | 2016 |
| Title | Laser-driven multi-modal probe beams for nuclear waste inspection |
| Description | Process for generating laser-driven multi-modal probe beams for nuclear waste inspection, involving both gamma and neutron beams. |
| IP Reference | GB1519758.5 |
| Protection | Patent application published |
| Year Protection Granted | 2016 |
| Licensed | No |
| Impact | None as yet but the business case for a pre-commercial prototype is currently under way. |
| Description | Babcock-Cavendish collaboration and meetings on nuclear waste and plant inspection |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Professional Practitioners |
| Results and Impact | A workshop organised by the South West Nuclear Hub for the purposes of sharing information on our research on nuclear waste and nuclear plant inspection. This specifically included diamond detectors as well as laser-driven gamma and neutron imaging of waste packages. |
| Year(s) Of Engagement Activity | 2019 |
| Description | Nuclear Waste & Decommissioning Research Forum |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Industry/Business |
| Results and Impact | Presenting on technological developments to solve nuclear challenges |
| Year(s) Of Engagement Activity | 2019 |