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Dissertation Abstracts

India

Name	Naresh Kumar MAHESHWARI
Position	Scientific Officer (G) Reactor Engineering Division, Bhabha Atomic Research Centre
Japanese Advisor	Masanori ARITOMI Professor,Tokyo Institute of Technology

  Advanced Heavy Water Reactor (AHWR), a 920 MWth reactor is planned to be developed in India which would generate most of its electricity from thorium based fuel. In AHER two alternative designs for the passive cooling of containment are under consideration. In first alternative, a passive containment cooling system (PCCS) with immersed condensers (IC) kept in a pool of water has been proposed. In second alternative, passive external condensers (PECs) of PCCS is connected to a water pool above it. Steam released into the containment condenses on the outer surface of the tubes of PECs. The thesis summarizes the results obtained pertaining to the studies performed on AHWR PCCS. This is composed of seven chapters, which are briefly described below.

Chapter 1 "Introduction"
  The background and the purpose of the work are described in this chapter. Two alternative schemes envisaged in AHWR have been discussed. A review of previous works is given. The objectives of experimental and theoretical studies on condensation of steam in presence of noncondensable gas under stagnant and flowing conditions have been described. Finally the outline of the subsequent chapters is given in this chapter.

Chapter 2 "Studies on the Behavior of Passive Containment Cooling System in a Scaled Model"
  The system response tests are performed on Passive Containment Cooling System (PCCS) with IC. Experimental set-up and procedure followed have been discussed. The tests conducted have confirmed the efficacy of the PCCS in separating the noncondensables, diverting it to volume V2 and removal of energy released into the volume V1 of containment.

Chapter 3 "Theoretical Modelling and System Response of a Passive Containment Cooling System"
  The theoretical studies are carried out to study the response of PCCS with IC has been described. A comparison of theoretical results with experimental data obtained in the transient tests has been presented in this chapter. The theoretical studies on the system response with time for passive containment cooling system having immersed condensers for AHWR have also been carried out in this chapter.

Chapter 4 "Experimental Studies on Condensation of Steam Mixed with Noncondensable Gas inside Vertical Tubes"
  The local heat transfer coefficient during condensation of steam in the presence of air along the length of the tube has been estimated experimentally. Two experiments have been performed in separate set-ups. A new correlation has been developed in this chapter based on the experiments performed. A comparison in degradation coefficients estimated experimentally and calculated by using new correlation is also been made in chapter 4.

Chapter 5 "Theroretical Investigation on Condensation of steam in Presence of a Noncondensable Gas inside a Vertical Tube"
  Theoretical models for in-tube condensation in presence of noncondensable gas have been discussed. The results are compared with our own experimental data and with the data available in literature. It has been observed that the heat transfer coefficient decreases precipitously at the initial length and then slowly as the mass fraction of noncondensable gas increases along the length.

Chapter 6 "Free Convective Film Condensation in Presence of Noncondensable Gas"
  Both experimental and theoretical investigations have been performed for the condensation of steam on the outer surface of the tube of PEC of AHWR. It is found that the heat transfer coefficient is higher for PCCS with IC compared PCCS with PEC.

Chapter7 "Conclusions and Recommendation"
  A comparative study on condensation heat transfer in presence of noncondensable gas for both the alternatives has been given. Based on the comparison the recommendations have also been made.