Functional Information of System Components Influenced by Counteractions on Computer-Based Procedure

2018 ◽  
Vol 4 (4) ◽  
Author(s):  
Tulis Jojok Suryono ◽  
Akio Gofuku

In an emergency condition of nuclear power plant, operators have to mitigate the accident in order to remove the decay heat and to prevent the release of radioactive material to the environment following the emergency operating procedures (EOPs). The action of operators on a component, for example, changing the parameter level of a component, which is described in a procedure step, will impact other components of the plant and the plant behavior. Nowadays, the advanced main control rooms have been equipped with the computer-based procedures (CBPs) which provide some features and benefits which are not available in paper-based procedures. However, most of CBPs do not provide information of the impact of the counteractions on each procedure step (components influenced and future plant behavior) although it is useful for operators to understand the purpose of the procedure steps before making decisions and taking the actions. This paper discusses the functional information and the method to generate the information using multilevel flow modeling (MFM) model of operator actions on some procedure steps of a simplified EOP of pressurized water reactor (PWR) plant, as an example.


Author(s):  
Tulis Jojok Suryono ◽  
Akio Gofuku

Computer-based emergency operating procedures offer some benefits compared with the paper-based EOP. However, most of them do not fully provide clear and necessary information related to the procedure steps, such as future plant behavior and the affected components after taking an action of each step because of the limited space available on the virtual display unit. This paper investigates a technique to derive and indicate such kind of information using a Multilevel Flow Modeling model of simplified EOP of steam generator tube rupture accident of a pressurized water reactor plant. In this case, the MFM model is built based on operator’s action on each procedure step. Then, by using the influence propagation rules for function primitives of MFM model, the influenced functions of plant components necessary for confirming the procedure step can be gathered. This information will help operators to understand and take the actions in order to achieve the objective of each procedure step.



2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mohamed M. A. Ibrahim ◽  
Mohamed R. Badawy

In this study, the thermal analysis for the impact of the cooling seawater site specific conditions on the thermal efficiency of a conceptual pressurized water reactor nuclear power plant (PWR NPP) is presented. The PWR NPP thermal performance depends upon the heat transfer analysis of steam surface condenser accounting for the key parameters such as the cooling seawater salinity and temperature that affect the condenser overall heat transfer coefficient and fouling factor. The study has two aspects: the first one is the impact of the temperature and salinity within a range of (290 K–310 K and 0.00–60000 ppm) on the seawater thermophysical properties such as density, specific heat, viscosity, and thermal conductivity that reflect a reduction in the condenser overall heat transfer coefficient from 2.25 kW/m2 K to 1.265 kW/m2 K at temperature and salinity of 290 K and 0.00 ppm and also from 2.35 kW/m2 K to 1.365 kW/m2 K at temperature and salinity of 310 K and 60000 ppm, whereas the second aspect is the fouling factor variations due to the seawater salinity. The analysis showed that the two aspects have a significant impact on the computation of the condenser overall heat transfer coefficient, whereas the increase of seawater salinity leads to a reduction in the condenser overall heat transfer coefficient.



2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Said M. A. Ibrahim ◽  
Mohamed M. A. Ibrahim ◽  
Sami. I. Attia

This paper presents a methodology for studying the impact of the cooling water temperature on the thermal performance of a proposed pressurized water reactor nuclear power plant (PWR NPP) through the thermodynamic analysis based on the thermodynamic laws to gain some new aspects into the plant performance. The main findings of this study are that an increase of one degree Celsius in temperature of the coolant extracted from environment is forecasted to decrease by 0.39293 and 0.16% in the power output and the thermal efficiency of the nuclear-power plant considered, respectively.



Author(s):  
Tao Hongxin ◽  
He Yinbiao ◽  
Cao Ming ◽  
Shen Rui

One of the fundamental requirements on nuclear safety is to prevent the radioactive material from being released. Therefore, it is paramount to maintain the structural integrity of the pressure boundary of the reactor coolant system. The reactor pressure vessel (RPV), under high temperature, high pressure and high radiation in operation, is the most important as well as a Class I nuclear safety equipment. For a pressurized water reactor (PWR), the life of the RPV determines the service life of the entire nuclear power plant. The key factor controlling the life of a RPV is the accumulation of the neutron flux and which induces irradiation embrittlement degrading the anti-fracture capability of the RPV material. Several anti-fracture capability assessments carried out for the Qinshan 320MWe (QS1) RPV, such as (a) the structural integrity assessment against pressurized thermal shocks; (b) the fracture mechanics assessment under irradiation; (c) the P-T limit curves revised; (d) the evaluation of USE. They all demonstrated that the structural integrity of the QS1 RPV would be maintained for the extended service life.



Author(s):  
Nolan A. Anderson ◽  
George L. Mesina

Condensation of steam on the primary side of a steam generator in a pressurized water reactor (PWR) is one means of removing decay heat during some accident scenarios, including small break loss of coolant accident (SBLOCA). However, when noncondensable gasses mix with steam, it impairs condensation. To correctly predict plant behavior, nuclear power plant (NPP) safety analysis codes such as RELAP5-3D must model the effect of condensation in the presence of noncondensables properly. A potential error in the RELAP5-3D code was reported in the condensation model in the presence of noncondensables by the University of Wisconsin[1]. The report indicated that the calculated condensation heat flux was under-predicted due to the modeling of the mass transfer in the gas mixture. The original documentation describing the implementation of the model was reviewed and compared with alternative formulations. An alternative that uses saturation vapor density at temperature of total pressure instead of the saturation vapor density at vapor partial pressure for calculating vapor mass flux was implemented. Comparison of the alternative method with the original against experimental data for several test cases showed improvement for most test cases.



Author(s):  
Jun Zhao ◽  
Xing Zhou ◽  
Jin Hu ◽  
Yanling Yu

The Qinshan Nuclear Power Plant phase 1 unit (QNPP-1) has a power rating of 320 MWe generated by a pressurized water reactor that was designed and constructed by China National Nuclear Corporation (CNNC). The TELEPERM XS I&C system (TXS) is to be implemented to transform analog reactor protection system (RPS) in QNPP-1. The paper mainly describes the function, structure and characteristic of RPS in QNPP-1. It focuses on the outstanding features of digital I&C, such as strong online self-test capability, the degradation of the voting logic processing, interface improvements and CPU security. There are some typical failures during the operation of reactor protection system in QNPP-1. The way to analyze and process the failures is different from analog I&C. The paper summarizes typical failures of the digital RPS in the following types: CPU failure, communication failure, power failure, Input and output (IO) failure. It discusses the cause, risk and mainly processing points of typical failure, especially CPU and communication failures of the digital RPS. It is helpful for the maintenance of the system. The paper covers measures to improve the reliability of related components which has been put forward effective in Digital reactor protection system in QNPP-1. It will be valuable in nuclear community to improve the reliability of important components of nuclear power plants.



2020 ◽  
Vol 6 ◽  
pp. 2 ◽  
Author(s):  
Claire Le Gall ◽  
Fabienne Audubert ◽  
Jacques Léchelle ◽  
Yves Pontillon ◽  
Jean-Louis Hazemann

The objective of this work is to experimentally investigate the effect of the oxygen potential on the fuel and FP chemical behaviour in conditions representative of a severe accident. More specifically, the speciation of Cs, Mo and Ba is investigated. These three highly reactive FP are among the most abundant elements produced through 235U and 239Pu thermal fission and may have a significant impact on human health and environmental contamination in case of a light water reactor severe accident. This work has set out to contribute to the following three fields: providing experimental data on Pressurized Water Reactor (PWR) MOX fuel behaviour submitted to severe accident conditions and related FP speciation; going further in the understanding of FP speciation mechanisms at different stages of a severe accident; developing a method to study volatile FP behaviour, involving the investigation of SIMFuel samples manufactured at low temperature through SPS. In this paper, a focus is made on the impact of the oxygen potential towards the interaction between irradiated MOX fuels and the cladding, the interaction between Mo and Ba under oxidizing conditions and the assessment of the oxygen potential during sintering.



Author(s):  
Yuriy V. Parfenov ◽  
Oleg I. Melikhov ◽  
Vladimir I. Melikhov ◽  
Ilya V. Elkin

A new design of nuclear power plant (NPP) with pressurized water reactor “NPP-2006” was developed in Russia. It represents the evolutionary development of the designs of NPPs with VVER-1000 reactors. Horizontal steam generator PGV-1000 MKP with in-line arrangement of the tube bundles will be used in “NPP-2006”. PGV test facility was constructed at the Electrogorsk Research and Engineering Center on NPP Safety (EREC) to investigate the process of the steam separation in steam generator. The description of the PGV test facility and tests, which will be carried out at the facility in 2009, are presented in this paper. The experimental results will be used for verification of the 3D thermal-hydraulic code STEG, which is developed in EREC. STEG pretest calculation results are presented in the paper.



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