Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
ACCELERATED LIFE TESTING OF COMPONENTS OF NUCLEAR RESEARCH REACTORS
Submission Author:
Vanderley Vasconcelos , MG
Co-Authors:
WELLINGTON SOARES, Antonio Carlos Lopes da Costa, Raíssa Oliveira Marques
Presenter: Vanderley Vasconcelos
doi://10.26678/ABCM.ENCIT2016.CIT2016-0249
Abstract
There are several alternatives to quantify the life data of equipment, system or component, like Mean Time-To-Failure (MTTF). The first alternative involves analyzing times-to-failure data obtained under normal operating conditions. Obtaining such life data may be very difficult or impossible for many reasons. The major limitation of this alternative is the long time of testing, making difficult the decision-making regarding the component specification, supplier selection and acceptance tests. Accelerated Life Testing (ALT) can be performed under stress conditions (higher overload, higher temperature, higher frequency of use, etc.), forcing the items to fail more quickly than they would be under normal use conditions. Piping and valve failures in nuclear reactors can have operational and safety implications, and may even lead to failures in other components of the facilities. Nuclear research reactor owners must demonstrate to regulatory bodies that design, specification, manufacture, maintenance and operation of their components, equipment and systems comply with the required safety standards in order to protect health and minimize danger to life and property. ALT of components can be needed in order to understand the failure mechanisms and to select items on the market, with adequate reliability for use in a nuclear research reactor. This paper proposes a method for planning ALT of components used in such nuclear reactors. A case study analyzing components of a boiling water irradiation circuit to be installed in a nuclear research reactor is carried out. This circuit requires a previous extensive test program for experimental validation of its design criteria, operational limits and processes used during the manufacturing of its components. Piping and valve failures in this circuit can have operational and safety implications, and may even lead to failures in other components of the facility. Failure Mode and Effect Analysis (FMEA) technique was applied in order to select the components of the circuit most important to safety and prioritize them to perform Life Data Analysis (LDA). FMEA analysis, accelerated life data analysis and life-stress relationship modeling can be carried out with support of XFMEA®, ALTA® and WEIBULL® software, developed by Reliasoft® Corporation. Reduction in the time needed to get the MTTF data from the analyzed components, generating rapid, strategic, reliable and low-cost information and a better understanding of stress effects are some expected results to be highlighted. The life data obtained can also be used in design comparisons and to assist risk assessments.
Keywords
accelerated life testing, nuclear research reactor, valves, piping
