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Dolgov, V. V.

doi:10.1023/a:1016597709055

Cited by 5 publications

(2 citation statements)

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“…The most natural source of turbulence in the early universe is a first order phase transition (see [13] for another potential source of turbulence), where bubbles of the broken phase nucleate and expand into the symmetric phase. Therefore we concentrate on this case.…”

Section: Gravitational Waves From Turbulencementioning

confidence: 99%

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

2006

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The power spectrum of a homogeneous and isotropic stochastic variable, characterised by a finite correlation length, does in general not vanish on scales larger than the correlation scale. If the variable is a divergence free vector field, we demonstrate that its power spectrum is blue on large scales. Accounting for this fact, we compute the gravitational waves induced by an incompressible turbulent fluid and by a causal magnetic field present in the early universe. The gravitational wave power spectra show common features: they are both blue on large scales, and peak at the correlation scale. However, the magnetic field can be treated as a coherent source and it is active for a long time. This results in a very effective conversion of magnetic energy in gravitational wave energy on super-horizon scales. Turbulence instead acts as a source for gravitational waves over a time interval much shorter than a Hubble time, and the conversion on super-horizon scales is much less effective. We also derive a strong constraint on the amplitude of a primordial magnetic field when the correlation length is much smaller than the horizon.

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Section: Gravitational Waves From Turbulencementioning

confidence: 99%

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

2006

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“…WWER reactors use water pressurized up to 16 MPa with a temperature of up to 324 °C as the coolant. Increasing the coolant pressure to 25 MPa and the reactor outlet coolant temperature to 550 °C increases the thermal efficiency of the units (up to 45%) and reduces the environmental impact by reducing heat losses in the thermodynamic cycle from 67% (WWER-1000) to 55% (WWER SWC) [ 1 , 2 , 3 , 4 , 5 ]. Another advantage of SWCR is the possibility of different active core designs: with a thermal neutron spectrum for operation in an open fuel cycle with UO 2 fuel and with a fast neutron spectrum for operation in a closed fuel cycle with MOX fuel [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Stress Corrosion Cracking Resistance of Irradiated 12Cr Ferritic-Martensitic Stainless Steel in Supercritical Water Environment

et al. 2023

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The supercritical water-cooled reactors (SWCR) belong to Generation IV of reactors. These reactors have a number of advantages over currently operating WWERs and PWRs. These advantages include higher thermal efficiency, a more simplified unit design, and the possibility of incorporating it into a closed fuel cycle. It is therefore necessary to identify candidate materials for the SWCR and validate the safety and effectiveness of their use. 12Cr ferritic–martensitic (F/M) stainless steel is considered a candidate material for SWCR internals. Radiation embrittlement and corrosion cracking in the primary circuit coolant environment are the main mechanisms of F/M steels degradation during SWCR operation. Here, the stress corrosion cracking (SCC) in supercritical water at 390 and 550 °C of 12Cr F/M steel irradiated by neutrons to 12 dpa is investigated. Autoclave tests of specially designed disk specimens in supercritical water were performed. The tests were carried out under different constant load (CL), temperature 450 °C, and pressure in autoclave 25 MPa. The threshold stress, below which the SCC initiation of irradiated 12Cr F/M steel does not occur, was determined.

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Reactor with a fast-resonance neutron spectrum, cooled by supercritical-pressure water with a bidirectional coolant flow scheme

Glebov

Klushin

2006

At Energy

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A scheme for circulating coolant and cooling the core that has advantages over the designs of similar nuclear power systems is proposed for light-water reactors with supercritical coolant parameters and a fast-resonance neutron spectrum. A negative void coefficient of reactivity is obtained for the entire run of a fuel assembly without building a blanket. A more uniform distribution of the energy release over the core volume is achieved without using complicated fuel-enrichment schemes. The nonuniformity of the coolant temperature distribution at the core exit is decreased. The fuel assemblies operate with a much lower temperature drop over the core height. The core has a small reactivity excess on burnup and a BR of about 1, for which the most difficult operating regimes (flooding with cold water) can be handled with standard means (placement of absorbing organs of the safety and control system in ~2/3 of the fuel assemblies).The cost of the equipment of the steam-generating facility comprises 70% of the capital costs of constructing the power-generating units of a nuclear power plant. If the thermal scheme is complicated and the coolant parameters are low, the efficiency of nuclear power plants with VVÉR and RBMK reactors is 33-35% as compared with 50% for thermoelectric power plants. The main problems of new designs are to decrease the specific capital investments in a facility, use simplified schemes and processes, and decrease the construction time while ensuring a high level of safety. Reactors with light-water coolant at supercritical pressure permit solving these problems most completely. A simple thermal scheme (steam from the reactor flows directly onto the turbine) and the elimination of a large amount of expensive equipment (steam generators, pumps, pipelines, second-loop fixtures) decrease the metal content by 60%. High steam parameters (pressure ~25 MPa, temperature 535-545°C) and a single-loop scheme will make it possible to obtain a facility efficiency of 44%. Reducing the required amount of coolant in the core will make it possible to arrange the fuel elements in closely-spaced lattices, and the reactor will have a fast neutron spectrum with a breeding ratio of about 1.The GIF international program for developing generation-IV reactors has been ongoing since 2000. In this program, water-cooled reactors with supercritical-pressure coolant will also be among the advanced future reactors.Japanese scientists are working most intensively in this field. They have proposed reactor designs with a thermal neutron spectrum SCPR [1, 2] and a fast neutron spectrum SCFR [3]. The latter reactor will use a mixed fuel based on depleted uranium oxide and uranium oxide enriched with weapons plutonium. The core consists of 270 fuel assemblies with uranium and plutonium dioxide fuel and 163 fuel assemblies with fuel consisting of depleted uranium (blanket). The reactor vessel and blanket are cooled with 280°C and 25 MPa water moving from top to bottom. At the bottom, the flows are mixed and cool the core in the up c...

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Cited by 5 publications

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Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

Gravitational waves from stochastic relativistic sources: Primordial turbulence and magnetic fields

Investigation of Stress Corrosion Cracking Resistance of Irradiated 12Cr Ferritic-Martensitic Stainless Steel in Supercritical Water Environment

Reactor with a fast-resonance neutron spectrum, cooled by supercritical-pressure water with a bidirectional coolant flow scheme

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