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Nuclear Science and Engineering
Fusion Science and Technology
Delay, cost increase announced for U.K. nuclear project
Perspex screens and reduced seating capacity in the Hinkley Point canteens help protect the workforce during breaks, EDF Energy said. Photo: EDF Energy
The unfortunate effects of the COVID-19 pandemic on nuclear new-build projects haven’t stopped with Vogtle: EDF Energy this morning reported that the expected startup date for Unit 1 at its Hinkley Point C site is being pushed from late 2025 to June 2026.
In addition, the project’s completion costs are now estimated to be in the range of £22 billion to £23 billion (about $30.2 billion to $31.5 billion), some £500 million (about $686 million) more than the 2019 estimate, EDF said, adding the caveat that these revisions assume an ability to begin a return to normal site conditions by the second quarter of 2021.
Joshua M. Hykes, Yousry Y. Azmy
Nuclear Science and Engineering | Volume 179 | Number 4 | April 2015 | Pages 364-380
Technical Paper | dx.doi.org/10.13182/NSE13-91
Articles are hosted by Taylor and Francis Online.
We present a method to map the spectral and spatial distributions of radioactive sources using a limited number of detectors. Locating and identifying radioactive materials is important for border monitoring, in accounting for special nuclear material in processing facilities, and in cleanup operations following a radioactive material spill. Most methods to analyze these types of problems make restrictive assumptions about the distribution of the source. In contrast, the source mapping method presented here allows an arbitrary three-dimensional distribution in space and a gamma peak distribution in energy. To apply the method, the problem is cast as an inverse problem where the system’s geometry and material composition are known and fixed, while the radiation source distribution is sought. A probabilistic Bayesian approach is used to solve the resulting inverse problem since the system of equations is ill-posed. The posterior is maximized with a Newton optimization method. The probabilistic approach also provides estimates of the confidence in the final source map prediction. A set of adjoint, discrete ordinates flux solutions, obtained in this work by the Denovo code, is required to efficiently compute detector responses from a candidate source distribution. These adjoint fluxes form the linear mapping from the state space to the response space. The test of the method’s success is simultaneously locating a set of 137Cs and 60Co gamma sources in a room. This test problem is solved using experimental measurements that we collected for this purpose. Because of the weak sources available for use in the experiment, some of the expected photopeaks were not distinguishable from the Compton continuum. However, by supplanting 14 flawed measurements (out of a total of 69) with synthetic responses computed by MCNP, the proof-of-principle source mapping was successful. The locations of the sources were predicted within 25 cm for two of the sources and 90 cm for the third, in a room with an ~4- × 4-m floor plan. The predicted source intensities were within a factor of ten of their true value.