Development of Remote Measuring System for RVI Modularization

Author(s):  
Tae-Soon Kim ◽  
Jae-Gon Lee ◽  
Je-Jun Lee ◽  
Myeong-Man Park

The construction duration of a nuclear power plant has been considered as a important factor to occupy the competitive edge. For the optimization process of APR1400 which is nuclear reactor newly developed in Korea, it has been suggested that the modularization of reactor vessel internals (RVI) was one of useful means to reduce the construction duration. In general, RVI consists of three components such as core support barrel (CSB), lower support structure/core shroud (LSS/CS) and upper guide structure (UGS). It is complicated and tedious to assemble the RVI by the conventional method which requires about 8∼10 months. In order to modularize the RVI, the gap between the CSB snubber lug and the reactor vessel (RV) stabilization lug must be measured by a remote measurement method. By using a remote measurement method, the welding of CSB and LSS/CS can be performed in advance of the reactor installation process to reduce the construction duration of a nuclear power plant. Compared with the conventional method, the duration of about 2 months required in the welding of CSB and LSS/CS is finally reduced. In this study, first of all we developed the remote measuring system that included the digital probes to measure the 72 points of gap at once. The system device consists of digital probe section, pneumatic supply and control section, electric power section, remote control computer and program. The selected digital probe of linear variable differential transformer (LVDT) type and the calibration device for the zero-point adjustment jig and the other devices have sufficient reliability and accuracy. And the digital probe connection jig has sufficient consistency. The network and system for remote measurement were very stable and no disturbance at electromagnetic interference environment. And we carried out the proof test of our remote measuring system to evaluate the application on the real plant conditions using the RV and RVI mock-up. The results of remote measurement were compared with existing manual measuring method and the reliability of the system was verified. Finally, we confirmed that our remote measuring system had the efficient reliability could be applied to measure the gap of RVI.

Author(s):  
P. Wouters ◽  
W. Van Rompay ◽  
F. Bertels ◽  
W. Van Hove ◽  
E. Gorleer ◽  
...  

Knowing exactly the nuclear core power of a nuclear reactor is one of the most important parameters for the operator; it is vital for safety as well as for economical matters. The secondary calorimetric is the only one where one can pilot on; it is a combination of measured parameters, of which the feedwater (FW) flow towards the steam generators is the most significant one. This feedwater flow can be measured by means of an ultrasonic flow meter, “LEFM CheckPlus™ system” instead of the commonly used venturis or diaphragms. In the Belgian Nuclear Power Plant (NPP) Doel 4, a new ultrasonic “LEFM CheckPlus™” feedwater flow measuring system has been installed in April 2008. The paper describes the consequences of the installation, as the total error on the secondary calorimetric decreases from the previous 1,3% to the current 0,8% with a possibility of further reduction to 0,4%. Additionally, the economical effects of the installation are calculated for a 1000 MWe power plant with venturi meters undergoing fouling. For the NPP Doel 4 it was an economically interesting investment since the payback period was only 45 days. Finally, the possibility of consuming the margin on the secondary calorimetric for a mini-power uprate is inspected, technically and economically. It is concluded that such a mini-power uprate is an interesting option for the NPP owner.


2011 ◽  
Vol 133 (08) ◽  
pp. 54-59
Author(s):  
Lee S. Langston

This article presents an overview of a pebble bed modular reactor (PBMR) power plant. A PBMR power plant is a gas turbine nuclear power plant that completely eliminates the possibility of a devastating loss-of-coolant accident. In a PBMR power plant, uranium dioxide nuclear fuel, coated with mass diffusion and radioactive fission product containment layers of pyrolytic carbon and silicon carbide, is formed into nuclear poppy seed-sized fuel particles. Some 15,000 of these are embedded in a tennis ball-sized graphite sphere, which is encased in a thin carbon shell, sintered, annealed and machined to a uniformed diameter of 6 cm. The PBMR reactor vessel, 90 ft high and 20 ft wide, is packed with about 450,000 heat-producing nuclear pebbles. Helium gas coolant then flows around and between the pebbles stacked in the reactor vessel, emerging at about 900°F. The Chinese are currently building two pebble reactors that will be used to generate steam for a conventional Rankine cycle.


Sign in / Sign up

Export Citation Format

Share Document