Science and Technology of Nuclear Installations 
Volume 2008 (2008), Article ID 458316, 11 pages
doi:10.1155/2008/458316
Research Article

Effect of Coolant Inventories and Parallel Loop Interconnections on the Natural Circulation in Various Heat Transport Systems of a Nuclear Power Plant during Station Blackout

Avinash J. Gaikwad,1 P. K. Vijayan,2 Sharad Bhartya,3 Kannan Iyer,4 Rajesh Kumar,1 A. D. Contractor,1 H. G. Lele,1 S. F. Vhora,5 A. K. Maurya,5 A. K. Ghosh,1 and H. S. Kushwaha1

 1Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
2Reactor Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
3Chemical Engineering Department, Indian Institute of Technology (IIT), Powai, Mumbai 400076, India
4Mechanical Engineering Department, Indian Institute of Technology (IIT), Powai, Mumbai 400076, India
5Nuclear Power Corporation of India (NPCIL), NUB, Anushaktinagar, Mumbai 400094, India
Received 21 June 2007; Accepted 25 January 2008

Recommended by Dilip Saha

Abstract

Provision of passive means to reactor core decay heat removal enhances the nuclear power plant (NPP) safety and availability. In the earlier Indian pressurised heavy water reactors (IPHWRs), like the 220 MWe and the 540 MWe, crash cooldown from the steam generators (SGs) is resorted to mitigate consequences of station blackout (SBO). In the 700 MWe PHWR currently being designed an additional passive decay heat removal (PDHR) system is also incorporated to condense the steam generated in the boilers during a SBO. The sustainability of natural circulation in the various heat transport systems (i.e., primary heat transport (PHT), SGs, and PDHRs) under station blackout depends on the corresponding system's coolant inventories and the coolant circuit configurations (i.e., parallel paths and interconnections). On the primary side, the interconnection between the two primary loops plays an important role to sustain the natural circulation heat removal. On the secondary side, the steam lines interconnections and the initial inventory in the SGs prior to cooldown, that is, hooking up of the PDHRs are very important. This paper attempts to open up discussions on the concept and the core issues associated with passive systems which can provide continued heat sink during such accident scenarios. The discussions would include the criteria for design, and performance of such concepts already implemented and proposes schemes to be implemented in the proposed 700 MWe IPHWR. The designer feedbacks generated, and critical examination of performance analysis results for the added passive system to the existing generation II & III reactors will help ascertaining that these safety systems/inventories in fact perform in sustaining decay heat removal and augmenting safety.