Effects of house load operation on PSA based on operational experiences in Korea
NUCLEAR ENGINEERING AND TECHNOLOGY
Authors: Lim, Hak Kyu; Park, Jong-hoon
Abstract
House load operation (HLO) occurs when the generator supplies power to the house load without triggering reactor trips during grid disturbances. In Korea, the HLO capability of optimized power reactor 1000 (OPR1000) plants has prevented several reactor trips. Operational experiences demonstrate the difference in the reactor trip incidence due to grid disturbances between OPR1000 plants and Westinghouse plants in Korea, attributable to the availability of the HLO capability. However, probabilistic safety assessments (PSAs) for OPR1000 plants have not considered their specific design features in the initiating event analyses. In an at-power PSA, the HLO capability can affect the initiating event frequencies of general transients (GTRN) and loss of offsite power (LOOP), resulting from transients within the grid system. The initiating event frequencies of GTRN and LOOP for an OPR1000 plant are reduced by 17.7% and 78.7%, respectively, compared to the Korean industry-average initiating event frequencies, and its core damage frequency from internal events is reduced by 15.2%. The explicit consideration of the HLO capability in initiating event analyses makes significant changes in the risk contributions of the initiating events. Consequently, for more realistic at-power PSAs in Korea, we recommend incorporating plant-specific HLO-related design features when estimating initiating event frequencies. (C) 2020 Korean Nuclear Society, Published by Elsevier Korea LLC.
Duodenal Necrosis Associated with a Threatened Ruptured Gastroduodenal Artery Pseudoaneurysm Complicated by Chronic Pancreatitis: Case Report
ANNALS OF VASCULAR SURGERY
Authors: Chen, Xiyang; Ge, Jingting; Zhao, Jichun; Yuan, Ding; Yang, Yi; Huang, Bin
Abstract
Visceral artery pseudoaneurysm (PSA) complicated by pancreatitis is a relatively rare and potentially life-threatening condition. The formation of pancreatic PSA is mainly attributed to continuous inflammation response, which induces the enzymatic autodigestion of the adjacent artery wall. The spleen artery is the most affected vessel, and other vessels such as gastroduodenal artery (GDA) and pancreaticoduodenal artery are usually involved. The treatment options for pancreatic PSA include conservative therapy, open surgery (OS), and endovascular procedure. Currently, no broad consensus on the indications for pancreatic PSA treatment is available because of the rarity of the disease. We report an urgent case of a threatened ruptured GDA PSA with duodenal necrosis complicated by chronic pancreatitis that has been treated successfully with OS. The treatment choice, puzzles, and reflections of this case were all discussed in this paper.