Thursday, 18 July 2019

Thursday at #UNTF2019

#UNTF2019 continues today after yesterday's talks, poster session, and conference dinner, with two sessions in the morning, followed by the end of the conference and lunch.  Here's a summary of the first session's first two talks (with the third being designated for attendees-eyes only)

Toby Wright from Manchester started the morning with a comprehensive survey of all kinds of nuclear data being collected at the n_TOF (neutron time-of-flight) facility at CERN.  This includes things like neutron absorption cross sections and fission data, which provide useful input for applications - particularly nuclear reactors. Toby presented a lot of results of data, improving on older measurements and evaluations

The second talk had the title "Robots used to mitigate nuclear disasters", with a discussion of exactly that -- how robots can be made and used in nuclear disasters.  They need to be very radiation-resistant, for examples, which has consequences for the design.  Also, you can't go in and fix it if it has a small problem, so it has to be very reliable.  Ideally you'd like to communicate with it wirelessly, but nuclear reactors tend to be heavily shielded.  The environment (radiation aside) can be pretty hazardous; flooding, fallen masonry etc.  All-in-all, quite a challenge to the robot builder. We had
The talk covers robots used historically;  the "RadRobot", "RedBot", and "WorkHorse" used at Three Mile Island; At Chernobyl there is a museum dedicated to the robots used there, though full details of the ~60 robots used there have been lost.  The most succssful robot used there, "MoBot" was destroyed when a helicopter accidentally dropped it.  Some robots used, such as converted tanks and bulldozers, broke down very quickly due to the environmental hazards.   Some years after the initial disaster further more advanced robots were sent in to assess the continuing status of the ruined reactor;   The robots used at Three Mile Island and Chernobyl were built reactively after the disasters, while in Fukushima there were a number of robots built in advance to be used in case of problems (as well as to routinely monitor).  Unfortunately, they were not very usable in Fukushima because the robot projects had been defunded and the robots left in cupboards, lacking maintenance, and lacking expertise of the staff who had left or moved on to other projects.  Instead, "Packbots" and "Warrier" robots were bought off the shelf from the US and deployed.  They weren't radiation-hardened but were well-developed in other technological areas.  Many other robots were then deployed -- e.g. the "quince" which could go up stairs and over rubble, the "RaBot", a radiation-hardened robot which could handle very high radiation doses (10,000 Sv per hour).

The talk ended with a couple of robots designed for the future;  Honda's E2-DR and the Centauro from Italy.  We were treated to a video of the E2-DR which looks a little like it's trying to get back from a conference dinner after one too many drinks:

Wednesday, 17 July 2019

Conrerence photo from UNTF

Today, as #UNTF2019 continues, we had our conference photo.  Here it is.  If you click on it, it should come up larger. I'm the one nearest the top border of the image file.

Tuesday, 16 July 2019

Session 1 at #UNTF2019

It's a busy time conference-wise in the UK.  The week after next sees the world's largest periodic nuclear physics conference, INPC, taking place in Glasgow.  Next week I'll be at a conference organised here at Surrey on ab initio methods, designed to attract delegates attending INPC the following week.  That clashes with a workshop on octupole shapes in nuclei, taking place even more conveniently for INPC attendees, in Paisley.

This week there is a workshop at the University of York to celebrate the conferring of an honorary degree on Witek Nazarewicz, which would have been nice to attend, but I am staying in Surrey this week to attend our graduation ceremony (on Friday) and the Universities Nuclear Technology Forum (UNTF2019) today to Thursday.

The topics of #UNTF2019 cover a wide range of nuclear science and engineering, so I hope to learn a lot of things that are not so close to my own area.  

Here is a live-blog summary of the first session:

First up is Sam Bennett (Manchester) who has performed new measurements on the capture of neutrons on C–13 in order to help understand how the long-lived radioactive contaminant C–14 is generated in graphite-moderated reactors.  The cross section for this reaction has been measured a few times historically, going back around 60 years, but there is inconsistency in the data.  Sam's work uses a method different to the past measurements -- irradiating a sample of carbon and using atomic mass spectroscopy to anaylse the results.  He discussed in some detail how to counter the problem of N–14 contamination in the samples.   The conclusion:  Good agreement with the most recent calculation which has been taken as the adopted value.  

Second, Emma Braysher (Surrey/NPL), talks about the need to improve measurements of half-lives of long-lived isotopes for their use in things like radio-dating.  Surprising (to me) is that Uranium-238 has only had its mass measured once before (until very recently) and that the experimental uncertainty is a million years.  Emma talks about using mass spectroscopy to measure half-lives;  either one can use isotope dilution in which the isotope which one wants to measure is diluted with (preferably a stable) isotope of the same element as a reference and mass spectrometry is used to measure the ratio of the isotopes;  or one uses the in-growth method in which ones looks at the build-up over time of the daughter produces of the decay of the isotope in question.  The work presented showed the speaker's theoretical studied so far, with the experimental realisation the next stage in her project.

The third speaker is Rhiann Canavan (Surrey/NPL) who begins by asking what can be done with the large amount of U–238 waste from our standard nuclear reactors.  U–238 is not fissile, but is fertile so can be turned into a fissile material (in this case, isotopes of plutonium) by reaction with fast neutrons.  The fissile material can then be used as commercial fission reactor fuel.  The goal of Rhiann's work is to better understand the fast-breeding reactions which convert U–238 in to a fissile material and the resulting range of fission fragments.  In Orsay, near Paris, Rhiann and co-workers used an intense neutron source, LICORNE, to breed U–238 into fissile isotopes, and then a gamma-ray detector, NuBall, to look at the decay of the hot fission fragments.  A phenomenal amount of data is collected from the reactions, which then has to be painstakingly analysed, both for the fission decay products of interest, and also to avoid the background signal (e.g. from decay of germanium isotopes in the gamma-ray detector itself).  It's the first time I've seen a description of gamma-ray gating in spectroscopic analysis in terms of selecting coloured jelly-babies from a pile of sweets.

The final speaker is Thomas Fried (Lancaster).  As well as his affiliation to Lancaster Uni, Thomas works at Sellafield and is concerned with long-term decommissioning of the site.  This includes, in particular, older waste that has been processed for storage.  Some of it is known as "heat-generating sludge" and Thomas's project aims to develop a mechanism for assessing the properties (mechanical, thermodynamic) properties of the stored sludge.  The slide shows a schematic of the prototype mechanism.

I don't think I'll live-blog the whole thing, but I hope this gives you a flavour of the conference.  Next up: Coffee break :-D

Tuesday, 2 July 2019

Rutherford Medal Winner Prof Phil Walker

The Institute of Physics have just announced that the 2019 winner of their Rutherford Medal is Prof Phil Walker.  

Phil is an emeritus professor here at the University of Surrey who straddles the experimental–theoretical divide and specialises in understanding metastable isomeric states in nuclei;  excited states that decay much more slowly that you'd expect for such an excitation.  The full citation is on the IoP's new story, as linked above. 

Phil has been a good friend and colleague to me during my time at Surrey.  It was thanks to him that I got my first post-doctoral position here, joining the reaction-theory dominated theoretical group, though my specialty is in nuclear structure.  We have since worked together on various project together over the years, writing 14 co-authored papers together, which for me is one short of my record of 15 (with one of my two PhD co-supervisors, Irena Stone).  I've always found his way of thinking very clear, grasping the context of a problem and the bigger picture.  Hopefully I can up this figure of 14 with him.

My opinion may be biased, but I think his prize is very well deserved, and overdue. Cheers, Phil!

I attach to this post a rather blurry photo of Phil that I happen to have in my collection, from a meeting in Krakow a few years ago.