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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/22864
Title: Comprehensive Safety Analysis of Station Blackout Scenario in TAPS-1&2
Authors: Raj R.
Reddy V.V.
Hajela S.
Singhal, Mukesh Kumar
Varde P.V.
Prakash R.V.
Vinod G.
Published in: Lecture Notes in Mechanical Engineering
International Conference on Reliability, Safety and Hazard, ICRESH 2019
Abstract: Tarapur Atomic Power Station-1&2 (TAPS-1&2) are the boiling water reactor units, commissioned in year 1969. TAPS-1&2 are well equipped to cater unavailability of offsite power, by having diverse route for two independent offsite power buses. Three emergency diesel generators (EDGs) of 100% capacity for a twin-unit station have been provided along with a dedicated station blackout diesel generator (SBO DG) with 100% capacity, which will provide a reliable and redundant electric power to continue operation of safety loads in case of loss of offsite power. Even in a very remote scenario of station blackout (SBO) (loss of all AC power including SBO DG) scenario, emergency condenser (EC) is provided to remove decay heat from the reactor system by thermosyphoning for around 8 h. During postulated design extension condition (DEC), time available for operator intervention to mitigate the accident progression of SBO is highly influenced by the EC operation/availability. This paper discusses the results obtained from study of postulated station blackout (SBO) scenarios with both the availability and unavailability of EC in TAPS-1&2. Following SBO, emergency condenser (EC) acts as heat sink by removing core decay heat through thermosyphoning. As a result, the reactor pressure and coolant temperature are reduced, effecting reactor core to cool down. Extended cooling of reactor system beyond 8 h will be done by adding the water in EC shell and reactor pressure vessel (RPV), whereas, in case of unavailability of EC, reactor pressure vessel (RPV) gets pressurized and pressure reaches relief valve at their set point and discharges the steam into wet well; consequently, the RPV level falls. Auto blow down system (ABDS) actuates automatically at reactor low level. Due to ABDS actuation, the RPV depressurizes quickly. This action will make EC unavailable completely, and plant will lose its first layer of defence. In order to control the accident progression, the present analysis is done to estimate the time available for operator to resume emergency condenser service upon its failure to start on auto. In such a case, due to loss of heat sink and loss of coolant through relief valves, time available for operator to bring back the EC into service is very important. Using system thermal-hydraulic code RELAP-5, both the above scenarios have been modelled to assess the availability of time for operator intervention to mitigate the accident scenario. Findings of this study are used to develop accident management guidelines. © 2020, Springer Nature Singapore Pte Ltd.
Citation: Lecture Notes in Mechanical Engineering (2020): 27-36
URI: https://doi.org/10.1007/978-981-13-9008-1_3
http://repository.iitr.ac.in/handle/123456789/22864
Issue Date: 2020
Publisher: Springer
Keywords: DEC
Emergency condenser
Operator intervention
RELAP
SBO
ISBN: 9.78981E+12
ISSN: 21954356
Author Scopus IDs: 57211202126
57211202176
15750741600
15751557600
Author Affiliations: Raj, R., Reactor Safety & Analysis, Nuclear Power Corporation of India Limited, Mumbai, 400094, India
Reddy, V.V., Reactor Safety & Analysis, Nuclear Power Corporation of India Limited, Mumbai, 400094, India
Hajela, S., Reactor Safety & Analysis, Nuclear Power Corporation of India Limited, Mumbai, 400094, India
Singhal, M., Reactor Safety & Analysis, Nuclear Power Corporation of India Limited, Mumbai, 400094, India
Corresponding Author: Raj, R.; Reactor Safety & Analysis, India; email: riteshraj@npcil.co.in
Appears in Collections:Conference Publications [HRE]

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