ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2021)
February 9–11, 2021
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Latest Journal Issues
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.
Nuclear Science and Engineering | Volume 179 | Number 4 | April 2015 | Pages 411-422
Technical Paper | dx.doi.org/10.13182/NSE14-75
Articles are hosted by Taylor and Francis Online.
We propose a novel application of a method to compute the nearest positive semidefinite matrix. When applied to covariance matrices of multigroup nuclear data, the method removes unphysical components of the covariances while preserving the physical components of the original covariance matrix. The result is a mathematically proper covariance matrix.
We show that the method preserves the so-called zero sum rule of covariances of distributions in exact arithmetic. The results also hold for typical cases of finite precision arithmetic. We identify conditions that might damage the zero sum rule.
Rounding can distort the eigenvalues of a symmetric matrix. We give a known bound on how large distortions can occur due to round-off. Consequently, there is a known upper bound on how large negative eigenvalues can be attributed to round-off error. Current evaluations and processing codes do produce larger negative eigenvalues.
Three practical examples are processed and analyzed. We demonstrate that satisfactory results can be achieved.
We discuss briefly the relevance of the method, its properties, and alternative approaches. The method can be used as a part of a quality assurance program and would be a valuable addition to nuclear data processing codes.