[en] Unitary operators are the basis of all calculations in quantum computers and play an important role in quantum mechanics. The presented results show that matrix forms of representation of structured DNA and RNA alphabets can be considered as a set of sparse unitary matrices. These results are useful for the development of models of quantum-algorithmic genetics, from the point of view of which living organisms are quantum-information entities. (paper)

[en] Core debris retention in the reactor vessel (in-vessel retention) is an important area of research in the field of nuclear power reactor severe accident analysis. The understanding of the behaviour of molten corium, prediction of crust formation in-vessel, and the evaluation of vessel integrity are essential to determining the progression and consequences of a severe accident. In CANDU severe accident analysis, the modelling of corium behaviour and assessment of severe accident progression is performed with the MAAP-CANDU code. The corium behaviour models in the MAAP-CANDU code are assessed and improved through benchmarking exercises which simulate experiments. In this paper, MAAP-CANDU is benchmarked against data obtained from the LIVE (late in-vessel experiments) tests (LIVE-L1 and LIVE-L3), conducted at Forschungszentrum Karlsruhe (now Karlsruhe Institute of Technology) in Germany. The tests involved crust formation within an externally cooled vessel using a corium simulant. This is similar to the late phase of a CANDU severe accident where molten core debris is located at the bottom of the calandria vessel that is surrounded by a water-filled reactor vault or shield tank. A modified version of the MAAP-CANDU code (v4.0.7E) that includes capabilities to model the LIVE tests was used for this assessment. The post-test calculations of the LIVE-L1 and LIVE-L3 tests using MAAP-CANDU were compared with the experimental data (including corium temperature, through-wall heat flux, and crust thickness and temperature). Sensitivity analysis demonstrated that variations in corium properties and heat transfer coefficients can affect calculated melt temperature and crust thickness. The calculations generally agree with the data in most respects, providing some assurance that the various models in MAAP-CANDU used in the simulation of the late phase of CANDU severe accidents are adequate. (author)