Thermohydraulic characteristics of the condenser in the natural-circulation loop of an MTR modular heavy-water reactor

As a part of “supercritical water reactor basic research”, the stability of the natural circulation research plays an important role on the feasibility of supercritical water reactor and experiment research. In this paper, the stability of a supercritical water natural circulation loop built by Department of Engineering Physics, Tsinghua University was studied by numerical method. It was confirmed that the static or Ledinegg instability doesn’t occur in HACA system, and there are no instabilities existing when the inlet enthalpy is larger than critical enthalpy. Instability was observed by numerical way, which is similar to DWOs and PDOs in two phase natural circulation loop. The system parameters’ influence on the instability of supercritical natural circulation loop was studied.

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Scaling of Natural Circulation Boiling Systems

Heat Transfer: Volume 2 ◽

10.1115/ht2003-47568 ◽

2003 ◽

Cited By ~ 1

Author(s):

Kannan N. Iyer ◽

Aboobacker Kadengal

Keyword(s):

Steady State ◽

Characteristic Equation ◽

Heavy Water ◽

Natural Circulation ◽

Pressure Tube ◽

Water Reactor ◽

Type Reactor ◽

Heavy Water Reactor ◽

Tube Type ◽

Indian Scenario

This paper lays out the procedure for arriving at the dimensions of a model facility to simulate a pressure tube type reactor. The Advanced Heavy Water Reactor, whose design is being evolved in the Indian scenario, is used as a basis for the evolution of the model facility. The non-dimensional groups that need to be preserved are identified and the design is evolved by satisfying these non-dimensional groups. The inevitable distortions that get introduced are discussed and a suitable compensation procedure evolved. Finally, the evolved model is shown to satisfy both steady state and characteristic equation similarity.

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Thermal Hydraulic Analysis Due to the Changes in Heat Removal for Advanced Heavy Water Reactor

12th International Conference on Nuclear Engineering, Volume 3 ◽

10.1115/icone12-49147 ◽

2004 ◽

Author(s):

B. Chatterjee ◽

A. Srivastava ◽

D. Mukhopadhyay ◽

P. Majumdar ◽

H. G. Lele ◽

...

Keyword(s):

Heavy Water ◽

Natural Circulation ◽

Heat Removal ◽

Reactor Power ◽

Circulation System ◽

Feed Water ◽

Set Point ◽

Water Reactor ◽

Heavy Water Reactor ◽

Pressure Controller

Advanced Heavy Water Reactor is natural circulation light water cooled and heavy water moderated pressure tube type of reactor. Changes in heat removal by primary heat transport system of a reactor have significant impact on various important system parameters like pressures, qualities, reactor power and flows. Increase in heat removal leads to Cooldown of the system subsequently reducing pressure, void increase and changes in power and flows of the system. Decrease in heat removal leads to warm-up of the system subsequently raising pressure, void collapse, and changes in power and flows of the system. The behaviour is complex as system under consideration is natural circulation system. Causes for events under category of increase in heat removal are mainly malfunctioning of feed water heaters, Isolation Condensers (IC) inlet valves and controllers. These events lead to cooldown of system and addition of positive reactivity addition due to void collapse. Various events considered are Feed Water System malfunctions that result in decrease in feed water temperature, inadvertent opening of IC valve, Failure of PHT Pressure Control System and Decrease in pressure controller set point to 67 bars. Causes for events under category of decrease in heat removal are mainly malfunctioning of controllers, feedwater valves and operating events like turbine trip. Functioning of passive cooling system and different valves play important role for these events. These events lead to increase in system pressure. Various events considered are Loss of normal feed water flow (multiple trains), Turbine trip without bypass without IC, Turbine trip without bypass with IC, Turbine trip with bypass without IC, Increase in PHT pressure controller set point, Decrease in level controller set point, Turbine Trip with setback, Decrease in steam flow and Class IV power failure. Changes in the system voids and pressures as a result of change in the heat removal leads to complex reactivity feedback due to coolant temperatures, void fraction and fuel temperatures. These changes in the reactor power together with void distribution change affect two-phase natural circulation flow. This paper brings out these aspects. It discusses descretisation of the system and brings out various design aspects. In this paper summary of analysis for each event is presented, various modeling complexities are brought out, evaluation of acceptance criteria is made and design implications of each event is discussed.

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Analysis for the Case of Channel Flow and Reactivity Changes for Advanced Heavy Water Reactor

12th International Conference on Nuclear Engineering, Volume 1 ◽

10.1115/icone12-49146 ◽

2004 ◽

Author(s):

A. Srivastava ◽

P. Majumdar ◽

D. Mukhopadhyay ◽

H. G. Lele ◽

S. K. Gupta

Keyword(s):

Heavy Water ◽

Natural Circulation ◽

Heat Removal ◽

Coolant Flow ◽

Thermal Hydraulics ◽

Primary Coolant ◽

Control Rod ◽

Water Reactor ◽

Wide Range ◽

Heavy Water Reactor

The proposed Advanced Heavy Water Reactor (AHWR) is a vertical pressure tube type boiling light water cooled and heavy water moderated reactor. One of the important passive design features of this reactor is that the heat removal is achieved through natural circulation of primary coolant at all power level with no primary coolant pumps. Decrease in coolant flow or control rod malfunction can lead to undesirable rise in clad surface temperature depending upon severity and characteristics and response of the reactor and associated systems. In this paper safety assessment of the AHWR is made due to above events of different severity. Cause for events under category of decrease in coolant flow is mainly channel blockage of different severity at different locations. There is no other reason as it is natural circulation based reactor. Effect of flow decrease can be different in different channels and at different axial locations. In this paper channel blockages of different sizes are analysed at core inlet and using slave channel approach. Changes in reactivities can occur due to inadvertent withdrawal of one or more control rods from reactor core. In this analysis one control rod assembly is assumed to be removed from core. The event is simulated by addition of 5 mk reactivity in 120 seconds depending on the speed of withdrawal of assembly. The analysis for the above events are complex due to various complex and wide range of phenomena involved during different PIEs under this category. It involves single and two phase natural circulation at different power levels, inventories and pressures, coupled neutronics and thermal hydraulics behaviour, and coupled controller and thermal hydraulics. In this paper summary of analysis for each event is presented. In this paper, various modeling complexities are brought out; evaluation of acceptance criteria is made and design implications of each event are discussed.

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