Search

The Simplified PN(SPN)method is applied to the axial solution of the two-dimensional (2-D) method of characteristics (MOC) solution based whole core transport calculation. A sub-plane scheme and the nodal expansion method (NEM) are employed for the solution of the one-dimensional (1-D) SPNequations involving a radial transverse leakage. The SPNsolver replaces the axial diffusion solver of the DeCART direct whole core transport code to provide more accurate, transport theory based axial solutions. In the sub-plane scheme, the radial equivalent homogenization parameters generated by the local MOC for a thick plane are assigned to the multiple finer planes in the subsequent global three-dimensional (3-D) coarse mesh finite difference (CMFD) calculation in which the NEM is employed for the axial solution. The sub-plane scheme induces a much less nodal error while having little impact on the axial leakage representation of the radial MOC calculation. The performance of the sub-plane scheme and SPNnodal transport solver is examined by solving a set of demonstrative problems and the C5G7MOX 3-D extension benchmark problems. It is shown in the demonstrative problems that the nodal error reaching upto 1,400 pcm in a rodded case is reduced to 10pcm by introducing 10 sub-planes per MOC plane and the transport error is reduced from about 150pcm to 10pcm by using SP3.Also it is observed, in the C5G7MOX rodded configuration B problem, that the eigenvalues and pin power errors of 180 pcm and 2.2% of the 10 sub-planes diffusion case are reduced to 40 pcm and 1.4%, respectively, for SP3with only about a 15% increase in the computing time. It is shown that the SP5case gives very similar results to the SP3case.

In Korea, an advanced reactor system of 330 MWt power called SMART is being developed by KAERI to supply energy for seawater desalination as well as electricity generation. As the basic design of SMART has recently been completed, a national project to construct a scaled-down reactor of the SMART system called ‘SMART-P’ for demonstrating the safety and performance of the SMART system is underway. The SMART-P is a small-sized advanced integral PWR that produces a thermal energy of 65.5 MWt under full power operating conditions. A shielding design for the SMART-P reactor assembly is established by two-dimensional discrete ordinates radiation transport analyses. The DORT two-dimensional discrete ordinates transport code is used to evaluate the shielding designs for the reactor assembly of the SMART-P. The SMART-P reactor assembly is divided into three separate calculation models, each of which is modeled by R-Z geometry. The results indicate that the maximum neutron fluence at the bottom of the reactor vessel is 2.0x1018n/cm2and that on the radial surface of the reactor vessel is 40x1017n/cm2. These results meet the requirements, l.OxlO20n/cm2and the integrity of the SMART-P reactor vessel during the lifetime of the reactor, is confirmed.

The correlation between the clinical manifestations and fecal viral load of norovirus (NoV) infection remains unknown.