Design of the HDR experimental program on blowdown loading and dynamic response of PWR-vessel internals

Krieg, R.; Schlechtendahl, E. G.; Scholl, K.-H.

doi:10.1016/0029-5493(77)90016-4

Cited by 29 publications

(11 citation statements)

References 6 publications

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“…As it is not feasible to measure the surface height at each point inside the domain, similar figures cannot be shown for the experiment. Qualitatively similar figures for real reactor situations have been presented in [1,2]. However, the azimuthal oscillations are more pronounced in the present study which is partly a consequence of the different boundary condition at the lower end of the downcomer and partly a consequence of the different equation of state.…”

Section: Sound and Outflow Velocitysupporting

confidence: 88%

“…For analysis of the dynamic loadings of the reactor vessel internals within a PWR vessel during a hypothetical blowdown accident, an extensive experimental and analytical program has been set up in which the former HDR-reactor is used as a test facility [1,2]. Of particular interest are the resultant flow velocity and pressure fields in the downcomer which is the annular gap between the vessel wall and the core barrel.…”

Section: Introductionmentioning

confidence: 99%

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PWR-depressurization and its hydraulic analogy

Kedziur

Moussiopoulos

Schumann

et al. 1978

Nuclear Engineering and Design

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The aim of this work is to provide an experimental verification of codes to be used for numerical simulation of the depressurization process in a pressurized water reactor (PWR) in case of a hypothetical blowdown accident. Here, the downcomer of a PWR is approximately treated as a two-dimensional plane region (unwrapped). The flow is simulated experimentally using the hydraulic analogy of free surface waves in a shallow water bed and compared to numerical simulations for the analogous flow of an ideal gas with an isentropic coefficient equal to two. The differences between the results of both models are less than 10%. Also reported are results of a similar study for a one-dimensional case (depressurizatioi~ in a pipe). The depressurization process can be subdivided into three phases: (1) Fluid still at rest, smooth depressurization wave, pressure drops, (2) Fluid accelerates, pressure recovers near the outlet (in 2-dim. case), (3) Quasi-steady flow, oscillations (in 2-dim. case). It is suggested that the results serve as a benchmark for blow-down accident analysis codes.

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Section: Sound and Outflow Velocitysupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

PWR-depressurization and its hydraulic analogy

Kedziur

Moussiopoulos

Schumann

et al. 1978

Nuclear Engineering and Design

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“…This is illustrated in Fig. 3 by Krieg et al 1977, and later on by Hosford et al 1981 (USNRC NUREG-0609). The depressurization wave, depending upon its amplitude and the upon subcooling of the encountered fluid, may generate voids with a delay of the order of ms after its passage, and it causes complex Fluid Structure Interaction (FSI), as partly discussed by Robbe et al 2003, andMahmoodi et al 2019.…”

Section: Depressurization Wave Induced Loadsmentioning

confidence: 84%

“…Let's start the review from Samal et al 2011, who studied the already complex rupture mechanisms of Zircaloy tubes in the absence of material degradation processes including irradiation and high temperature: they found that the re-crys- Figure 3. Propagation of depressurization wave from the break (shadowed region is at low pressure), Krieg et al 1977. tallization annealed Zircaloy-2 specimens have higher initiation fracture toughness as well as higher resistance to crack growth compared to non-annealed specimens: this can be attributed to the presence of finer grain and sub-grain micro-structure and lower density of defects in the material.…”

Section: Pcmimentioning

confidence: 99%

The technological challenge for current generation nuclear reactors

D'Auria¹,

Debrecin²,

Glaeser³

2019

NUCET

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The present paper deals with the proposal of an additional safety barrier for the class of large (1000 MWe or more) Light Water Reactors (LWR) now in operation, in construction, or under design. Emphasis is given to the motivations or the needs for the barrier. Two main parts of the paper can be distinguished. The following topics are discussed in the former part (section 2): (a) the weakness of the barrier constituted by the current design of nuclear fuel; (b) the continuously increasing complexity of the system, with main reference to the Instrumentation and Control (I&C); (c) the role that the Large Break Loss of Coolant Accident (LBLOCA) had for arriving at the current layout of the Reactor Coolant System (RCS). Furthermore avoiding the severe accidents in 1979, 1987 and 2011, is at the basis of the proposal. In the latter part (sections 3 and 4), the elements of the proposed technological safety barrier are discussed: the As-Low-As-Reasonably-Achievable (ALARA) principle, the Best Estimate Plus Uncertainty (BEPU) approach, the Extended Safety Margin Detection (E-SMD) hardware, the Emergency Rescue Team (ERT) strategy (or a virtual entity for the reactor) and the Independent Assessment (IA) concept. The additional safety barrier, although not demonstrated in the paper, is expected to reduce for a factor in the range 10–1000 the probability of core melt and to have a cost in the order of 1% the cost of a nuclear reactor unit.

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“…And through the previous works, it has been recognized that the fluid-structure interaction is important during the very early stage of blowdown(1) (2). Since the water in PWR is highly pressurized, an expansion wave is generated at the break point and it propagates through the primary coolant pipe with the sound velocity, resulting in a sudden depressurization behind the wave front.…”

Section: Introductionmentioning

confidence: 99%

Propagation of Expansion Wave in Flexible-Wall Tube

Watanabe

Mikami

1983

Journal of Nuclear Science and Technology

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As a model of the fluid-structure interaction which occurs during the loss-of-coolant accident in pressurized water reactors, the pressure variation in the expansion wave propagating through the flexible-wall tube was measured along with the deformation of the wall. An analysis of the experimentally observed phenomena is performed by solving onedimensional flow equations coupled with an equation of the wall deformation. The method employed is a numerically stable semi-implicit donor-cell difference method.The rate of the pressure decrease was found to be reduced in comparison with the case of the rigid-wall tube. The fluid-structure interaction generates the pressure profile which is, apparently, regarded as a superposition of the pressure profile of the expansion wave in the rigid-wall tube and the disturbance which is generated by the deflection of the flexible wall. The vibrations of the pressure and the flexible wall due to the inertia of the wall were also found. Both the damping of the deflection and the wall friction of the structure are found to be important parameters pertinent to the fluid-structure interaction phenomena.

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Design of the HDR experimental program on blowdown loading and dynamic response of PWR-vessel internals

Cited by 29 publications

References 6 publications

PWR-depressurization and its hydraulic analogy

PWR-depressurization and its hydraulic analogy

The technological challenge for current generation nuclear reactors

Propagation of Expansion Wave in Flexible-Wall Tube

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