Serpent Monte Carlo Neutron Transport Code
Colloquium: Monday Colloquium | April 30 | 4-5 p.m. | 3105 Etcheverry Hall
Speaker: Dr. Jaakko Leppänen, Senior Research Scientist at VTT Technical Research Centre of Finland.
Serpent Monte Carlo code has been developed for group constant generation, burnup calculation and other reactor physics applications since 2004. The code is currently used at 67 universities and research organizations in 26 countries around the world, and distributed by RSICC and the OECD/NEA Data Bank. This presentation gives a general overview on the methods and capabilities of the Serpent code, along with some plans for the future development of the next code version, Serpent 2.
Abstract: Over the entire 55-year history of commercial nuclear power, launched in England by operation of the first Calder Hall unit in 1956, the public risk from operation of nuclear power plants has been grossly overestimated. Experiences from three severe accidents that took place in this time frame: 1979 Three Mile Island Unit 2 in the US (level 5 on the International Nuclear and Radiological Event Scale), 1986 Chernobyl Unit 4 in Ukraine (level 7), and 2011 Fukushima Daiichi units 1-3 in Japan (level 7, although 6 more likely), clearly support this bold assertion. The Fukushima Daiichi accident has not resulted in acute fatalities, acute radiation injuries, and there were no extended hospitalizations due to radiation nor is it likely to be responsible for any cancer fatalities in 50 years. However, these facts have not been reflected in the public perceptions of nuclear power safety. A scientific reassessment of public risks associated with operation of nuclear power plants is now badly needed. However, four meltdowns in about 14,000 reactor years of operation constitute unacceptable investment risks to plant owners/operators. They might experience multibillion costs if an accident results in the partial or complete core meltdown. We will discuss the overestimation of public risk and the underestimation of investment risk, and how it affects pubic opinion and investment decision to construct new NPPs.
Evidence for Formation of DNA Repair Centers and Dose-response Non-linearity in Human Cells
Colloquium: Monday Colloquium | April 23 | 4-5 p.m. | 3105 Etcheverry Hall
Dr. Sylvain Costes, Career Biophysicist Reserach Scientist, Lawrence Berkeley National Laboratory
Nuclear Engineering (NE)
The concept of DNA ‘repair centers’ and the meaning of radiation-induced foci (RIF) in human cells have remained controversial. RIFs are characterized by the local recruitment of DNA damage sensing proteins such as p53 binding protein (53BP1). Here we provide strong evidence for the existence of 'repair centers'. We used live imaging and mathematical fitting of RIF kinetics to show that RIF induction rate increases with increasing radiation dose, whereas the rate at which RIFs disappear decreases. We show that multiple DNA double strand breaks (DSB) 1 to 2 mm apart can rapidly cluster into repair centers. Correcting mathematically for the dose dependence of induction/resolution rates, we observe an absolute RIF yield that is surprisingly much smaller at higher doses: 15 RIF/Gy after 2 Gy exposure compared to ~64 RIF/Gy, after 0.1 Gy. Cumulative RIF counts from time lapse of 53BP1-GFP in human breast cells confirmed these results.
The standard model currently in use applies a linear scale, extrapolating cancer risk from high doses to low doses of ionizing radiation. However, our discovery of DSB clustering over such large distances cast considerable doubts on the general assumption that risk to ionizing radiation is proportional to dose, and instead provide a mechanism that could more accurately address risk dose dependency of ionizing radiation.
From the Inner Atom to Outer Space – Thoughts about Your Career in Nuclear Science and Technology
Lecture | April 16 | 3-4 p.m. | 3105 Etcheverry Hall / Please note the earlier time, 3-4 p.m., before the regularly scheduled Monday, April 16 colloquia.
Dr. Eric P. Loewen, American Nuclear Society President
From exploring mysteries of the inner atom to using nuclear energy for applications in outer space, there are many career opportunities in nuclear science and technology. Today’s nuclear students may work with applications ranging from medicine to agriculture, manufacturing, basic research, energy, or an application yet to be developed. Dr. Loewen will discuss some mileposts along his own career path while highlighting challenges and opportunities for those who will enter the nuclear workplace in the next few years.
The Search for Dark Matter
Colloquium: Monday Colloquium | April 16 | 4-5 p.m. | 3105 Etcheverry Hall
Mani Tripathi, Professor, Physics Department, University of California, Davis
Dark matter is now widely accepted to dominate the matter density of the universe. This non-luminous, non-baryonic substance is a new form of matter that has thus far escaped direct detection. I will describe our knowledge of dark matter and the evidence for its existence from several different types of observations. I will follow this up with a discussion of leading theories that are able to incorporate this new type of particle and predict its properties. Finally, I will enter into a survey of various experimental techniques that are aimed at gathering direct or indirect evidence for the existence of a dark matter particle. I will wrap it all up with some personal observations on how this most intriguing problem of our lifetime will shape the future of experimental particle physics.