Inservice Testing Program Research Articles

Feasibility Study on the In-Service Testing Program Plan for Safety-Related Dampers of Advanced Power Reactor-1400

Abstract In-service testing (IST) program including test and examination has been emphasized to assess the operability of the safety-related components in nuclear power plants. Since the issuance of ASME N511 in 2007 concerning IST for air treatment, heating, ventilating, and air conditioning (HVAC) systems, the IST program plan for those systems should be needed to establish prior to setting up the detailed program. The proper plan can contribute to enhance the effectiveness of allotment of the resources inevitable for implementation of the program and ultimately save operation and maintenance costs. In order to achieve the purposes, this paper presents the methodologies to establish IST program plan for safety-related dampers including their selection process of the dampers to be included in the program and representative template made by applying the methodologies. In addition, the method to identify testing types per damper for part of selected dampers is also provided in this paper.

ASME in-service inspection and in-service testing programs for Angra 1

The in-service inspection program of the Angra 1 plant is updated every 10 years, according to applicable standards - designer (American Project - are followed NRC requirements) and Cnen. NRC approves the use of ASME Section XI (In-service Inspection of Nuclear Power Plant Components). The object of in-service inspection of components in nuclear power plants is to provide a continuing assurance that they are safe. To provide this assurance for those components that are subject to the requirements of the ASME Boiler and Pressure Vessel Code, a set of rules has been formulated to provide assurance that the functional requirements of the components are available when required. The rules have been arranged to provide appropriate levels of assurance according to the importance of the component in its relationship to plant safety. The classifications that are established during design and manufacturing have been adopted to provide the levels of importance for the components. The types of components typically found in the various classifications have then been identified and rules formulated for each type. For each type of component in each classification, the functions have been considered and methods of inspecting, testing, or monitoring each component is specified. These rules include methods of determining the limits of acceptance of the results. Should it be necessary to take corrective action to repair various components, rules have been provided to establish acceptable methods of repair or replacement. Angra 1 started the Renewal License and Long-term Operation project and there are three important Aging Management Programs (AMP) that are based on ASME section XI. This article will discuss the ASME section XI subsections that are important for the License Renewal and Long-term Operation for Angra 1.

Risk-informed developments and comparisons for the safety related valves of Inservice Testing Program at Taiwan BWR and PWR nuclear power plants

Safety related valves within the nuclear power plant were governed by the Inservice Testing Program (IST) for scheduling tests or maintenances during the plant normal operation. Based on the program definitions, series of tests for these valves have to be performed and conducted periodically. Safety functions of safety related valves such as Motor Operated Valve (MOV), Air Operated Valve (AOV) and Check Valve (CV) under the event of Design Basis Accident (DBA) could be performed properly. IST program plays an important role for constantly maintaining these safety related valves under operable conditions; therefore safety functions such as emergency reactivity control, post-accident residue heat removal, post-accident radioactivity removal and containment isolation could be performed and satisfied during the DBA event or abnormal plant operation occurrences.This study performed the Risk-informed evaluations for safety related valves in the IST program for BWR and PWR nuclear power plants in Taiwan. Outcome from this study, safety classifications for the safety related valves under IST program could be categorized, HSSC category valves could be identified, testing frequency relieves for the LSSC category could be suggested, systematic comparison of the safety significant classification between BWR and PWR nuclear power plants was presented and finally, due to the advantages of the RI-IST, both dose exposure for the plant staffs and outage cost reductions for the utility managements could be achieved.

Risk evaluation for motor operated valves in an Inservice Testing Program at a PWR nuclear power plant in Taiwan

Safety related valves such as Motor Operated Valves (MOV), Air Operated Valves (AOV) or Check Valves (CV) play an important role in nuclear power plant. Functioning of these valves mainly aim at emergency reactivity control, post-accident residue heat removal, post-accident radioactivity removal and containment isolation when a design basis accident occurred. In order to maintain these valves under operable conditions, an Inservice Testing Program (IST) is defined for routine testing tasks based on the ASME Boiler & Pressure Vessel Code section XI code requirements.Risk based Inservice Testing Programs have been studied and developed extensively in the nuclear energy industry since the 1990s. Risk Based evaluations of IST can bring positive advantages to the licensee such as identifying the vulnerability of the system, reducing unnecessary testing burden, concentrating testing resources on the critical pass oriented valves and saving plant’s personnel dose exposure. This risk evaluation is incorporated with quantitative and qualitative analyses to the Motor Operated Valves under current Inservice Testing Program for PWR nuclear power plant in Taiwan.With the outcome of the risk classifications for the safety related MOVs through numerical or deterministic analyses, a risk based testing frequency relief is suggested to demonstrate the benefits received from the risk based Inservice Testing Program. The goal made of this study, it could be as a reference and cornerstone for the licensee to perform overall scope Risk-Informed Inservice Testing Program (RI-IST) evaluation by referring relevant methodologies established in this study.

An application of risk-informed evaluation on MOVs and AOVs for Taiwan BWR-type nuclear power plants

Implementing a risk-informed inservice testing (RI-IST) program provides a good aspect to the nuclear power plant licensee as an alternating program in the current ASME Section XI and 10 CFR 50.55a relevant testing programs. RI-IST concentrates testing resources on highly significant components, reduces excess testing burden, increases plant's availability, decreases dose rate on the plant's staff and also reduces cost on plant's operation and maintenance under nuclear safety expectations. Furthermore, RI-IST also gives a feature on prospective licensing change basis to a nuclear power plant's licensee. This study will focus on safety-related and PRA-molded motor-operated valves (MOVs) and air-operated valves (AOVs) under the inservice testing program in boiling water reactor (BWR)-type nuclear power plant. As MOVs and AOVs have crucial safety functions throughout the nuclear power plant's safety systems, the steady operation and performance of MOVs and AOVs will definitely ensure that the nuclear power plant operates under safety expectations; therefore, this is the key reason to implement risk-informed evaluation for MOVs and AOVs in this study and being able to provide the safety significance classification for MOVs and AOVs under the current IST program to the plant's management. As a pilot study of RI-IST, the methodology of qualitative assessment will incorporate with probabilistic risk assessment (PRA) analyzing MOVs’ and AOVs’ safety significance within the current PRA model. The evaluating result will then classify its safety significance into a high-safety significant component (HSSC) and a low-safety significant component (LSSC) for MOVs and AOVs based on relevant regulatory criteria. With this initiating achievement, it can provide a cornerstone for further studies on the other types of valves and pumps in RI-IST program and also provide a valuable reference as proposing license change to the licensee.