A Case Study of a Valve Failure Due to Condensation-Induced Waterhammer

2002 ◽  
Author(s):  
Henry E. Harling
Keyword(s):  
Cold Water ◽  
Lower Pressure ◽  
Bubble Collapse ◽  
Horizontal Line ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Initial Flow ◽  
Flash Tank ◽  
Pressure Spike ◽  
Moisture Separator

In preparation for a power reduction at a Pressurized Water Reactor (PWR) power plant, the Moisture Separator Drain Tanks (MSDT) were being transitioned from pumping to a flash tank to dumping to the Condenser. This evolution includes initially transitioning to pressure feeding to a lower pressure flash tank first. As soon as the MSDT Pump was tripped, a waterhammer occurred in the 6″ line that contained a valve that isolated the flow path to the lower pressure flash tank. The waterhammer caused the operator of this valve to fail due to a fracture of the yoke on the actuator. Several thermal-hydraulic mechanisms were evaluated and it was postulated that the failure mechanism was a bubble collapse in a 6″ horizontal line upstream of the failed isolation valve leading to the lower pressure (a.k.a., “D”) flash tank. A prerequisite for this mechanism is that the isolation valve leading to the “D” flash tank is “tight” such that line is “cold.” As the valve opens the initial flow regime would be annular before transitioning to a dispersed regime. The vapor and cold water interacted leading to the collapse of an assumed 1″ diameter “trapped” bubble. The collapse of the postulated bubble yielded an unbalanced impulse force of 6000 lbs. for approximately 5 – 10 milliseconds. The pressure spike that generated the unbalanced force was estimated at 208 psid. The initial acceleration of the pipe was estimated to have been as high as 21 g, which was greater than the 11 g estimated necessary to fail the valve actuator.

Cold Water Injection and Rod Ejection Analysis of Annular Fueled PWRs by a Hybrid Lumped Parameter Model

2014 ◽  
Author(s):  
Juliana P. Duarte ◽  
José de Jesus Rivero ◽  
Antonio Carlos M. Alvim ◽  
José Roberto C. Piqueira ◽  
Paulo F. F. Frutuoso e Melo
Keyword(s):  
Solid Fuel ◽  
Cold Water ◽  
Hot Spot ◽  
Water Injection ◽  
Lumped Parameter Model ◽  
Pressurized Water Reactor ◽  
Fuel Temperature ◽  
Pressurized Water ◽  
Steady State Condition ◽  
Lumped Parameter

Annular fuels are being studied to increase the power of advanced third-generation reactors by 50%. This paper aimed to analyze transient scenarios through a hybrid lumped parameter-finite difference model in a pressurized water reactor with annular fuel. The model used in this work is more detailed than the double lumped parameter one, but still simple enough to model some transients in PWR fuels, as rod ejection accident and cold water insertion accident. The heat transfer equations are solved by the numerical semi-implicit Crank-Nicolson method together with point kinetics equations with six groups of delayed neutrons and a lumped parameter model for the reactor coolant. The model takes into account in an approximate way the hot spot by using a composed peaking factor equal to 2.5. The reactivity feedback is taken into account by considering the Doppler effect of fuel temperature, and also moderator temperature variation. The results were compared with solid fuel performance and showed that the annular fuel reached considerable lower fuel temperature profiles even for 150% power, as compared to 100% power for solid fuel, thus showing that this kind of fuel has a better safety performance for the transients analyzed. The rod ejection accident showed that feedback effects can lead the reactor to a new safe steady state condition.

scholarly journals Visualization and Finding Ways to Intensify the Processes of Non-isothermal Mixing Flows

2018 ◽  
Vol 3 (3) ◽  
pp. 240
Author(s):  
Sataev A.A. ◽  
Duntsev A.V.
Keyword(s):  
Fluid Dynamics ◽  
Cold Water ◽  
Density Structure ◽  
Pressurized Water Reactor ◽  
Thermal Reliability ◽  
Reactor Plant ◽  
Pressurized Water ◽  
Real Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Isothermal Mixing

Simulation of mixing flows of different temperature, density structure has important implications for the assessment of thermal reliability of reactor plants, thermo-cyclic pulsations, and safety analysis. To study the mixing model was used for the mixing, which was visualized by using imaging methods. The injection of cold water into the hot volume was examined, which simulates the flow of the coolant in the pressurized-water reactor. The obtained results have given the basis for further analysis of non-isothermal mixing flows. However, the model is still far from the real geometry of the reactor plant. The construction of a reactor reduced model with a simulation of one loop of a coolant flow with low settings has been developed for a more detailed study of the processes of non-isothermal mixing flows has planned. In the future, these data will be used in the programs of computational fluid dynamics (CFD). 

Leaching Studies of Cement-Glass Package Containing Sodium Borate

1986 ◽  
Vol 84 ◽  
Author(s):  
Masahiro Okamoto ◽  
Koichi Chino ◽  
Tsutomu Baba ◽  
Tatsuo Izumida ◽  
Fumio Kawamura ◽  
...  
Keyword(s):  
Sodium Silicate ◽  
Liquid Waste ◽  
Sodium Borate ◽  
Pressurized Water Reactor ◽  
X Ray Diffraction ◽  
Adsorption Ability ◽  
Pressurized Water ◽  
X Ray ◽  
Solidification Reaction ◽  
Main Components

AbstractA new solidification technique using cement-glass, which is a mixture of sodium silicate, cement, additives, and initiator of the solidification reaction, was developed for sodium borate liquid waste generated from pressurized water reactor (PWR) plants. The cement-glass could solidify eight times as much sodium borate as cement could, because the solidifying reaction of the cement-glass is not hindered by borate ions.The reaction mechanism of sodium silicate and phosphoric silicate (initiator), the main components of cement-glass, was studied through X-ray diffraction and compressive strength measurements. It was found that three- dimensionally bonded silicon dioxide was produced by polymerization of the two silicates. The leaching ratio of cesium from the cement-glass package was one-tenth that of the cement one. This low value was attributed to a high cesium adsorption ability of the cement-glass and it could be theoretically predicted accordingly.

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