Digital fast neutron assay of uranium

It is well known that uranium has a special property whereby when configured in a particular arrangement and concentration it can sustain a nuclear chain reaction from which a great deal of energy can be derived. It is this property that has led it to be used exclusively throughout the world as the fuel for nuclear power reactors. However, perhaps less well appreciated is the fact that in its raw, un-irradiated state prior to use in a reactor uranium is quite benign in a radioactive sense, emitting relatively little radiation that can be of use in terms of characterisation. This is extremely important because whilst its use in reactors provides much electricity for peaceful uses, it is essential that the amount of uranium in existence is quantified and recorded so that diversion of it for illicit uses is detected. Often an important requirement of this activity is to be able to detect and assess quantities of uranium remotely, without touching it so that commercial activities associated with the production of fuel for reactors etc. can continue unhindered and so that the assessment is quick and effective. The existing detection medium for this purpose is an isotope of helium gas, 3He, which is now in short supply and very expensive which relies on the detection of slow neutrons.

In this project we intend to explore the use of fast neutrons with a different detector technology, organic scintillators, for the assessment of uranium compounds that are highly enriched in 235U and 233U. To carry out this research it is essential that we transport our equipment and expertise to the Oak Ridge National Laboratory in Tennessee in the United States because this laboratory is one of the only places in the world that combines access to these materials with resident world-leading expertise in their assessment. Of particular note to this travel request is that it will enable access to enriched levels of 235U not possible anywhere else combined with the UK's ADRIANA detector system that is also unique in the world. Further it will enable 233U to be explored in quantities not possible anywhere else that is essential to exploring materials security associated with the thorium nuclear fuel cycle.

We anticipate that this project will result in impact in the following general areas:
- Extending the digital fast neutron prior art to uranium highly-enriched in 235U and the scenarios associated with such materials to bring the fast neutron technique to the attention of experts at the Oak Ridge National Laboratory (ORNL).
- Extending fast neutron techniques to significant quantities of 233U that is of great significance to current international debate around the thorium fuel cycle and resulting in debate in the industrial / national laboratory community associated with this area of the nuclear discipline.
- Establishing an international partnership between the UK's fast neutron digital assay capability and ORNL, the world's leading uranium laboratory to be established resulting in impact for the UK nuclear community, particularly that associated with the National Nuclear Users' Facility.

In a specific context, we expect impact in the following areas:
- Confirming and advancing the reputation of the UK as a leader in nuclear safeguards research at a critical time for nuclear new build.
- Consolidating the UK's position as a leader in the search for a replacement for 3He and the application of fast neutron methods.
- Highlighting the possibility of improved methods for the characterisation of uranium-based orphan wastes, particularly in the context of decommissioning, waste management and non-proliferation.
- At technical level from challenging accepted ideas associated with die-away assay of uranium and changing the way it is done to incorporate fast neutrons.
- Stimulating a programme of the exchange of UK staff and students with Oak Ridge, many of whom who benefit from EPSRC programmes.
- Consolidating Oak Ridge intentions to set-up a related capability to the NNUF (ADRIANA) capability in the near future and the related impact on UK instrumentation businesses.
- A diversity of far-reaching impact benefits associated with the clean up of contaminated areas of the Oak Ridge site, advancing safeguards activities and opening up commercial possibilities for UK businesses such as JCS Ltd., Centronic, Kromek and Hybrid Instruments etc.