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Belov S.E.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Borovkov M.N.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Golovko V.F.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Dmitrieva I.V.,Joint Stock Company Afrikantov OKB Mechanical Engineering | And 7 more authors.
Nuclear Engineering and Design | Year: 2012

The special feature of high-temperature gas-cooled reactors (HTGRs) is stressed operating conditions for equipment due to high temperature of the primary circuit helium, up to 950 °C, as well as acoustic and hydrodynamic loads upon the gas path elements. Therefore, great significance is given to reproduction of real operation conditions in tests. Experimental investigation of full-size nuclear power plant (NPP) primary circuit components is not practically feasible because costly test facilities will have to be developed for the power of up to hundreds of megawatts. Under such conditions, the only possible process to validate designs under development is representative tests of smaller scale models and fragmentary models. At the same time, in order to take in to validated account the effect of various physical factors, it is necessary to ensure reproduction of both individual processes and integrated tests incorporating needed integrated investigations. Presented are approaches to experimental validation of thermohydraulic and vibroacoustic characteristics for main equipment components and primary circuit path elements under standard loading conditions, which take account of their operation in the HTGR. Within the framework of the of modular helium reactor project, including a turbo machine in the primary circuit, a new and difficult problem is creation of multiple-bearing flexible vertical rotor. Presented are approaches to analytical and experimental validation of the rotor electromagnetic bearings, catcher bearings, flexible rotor electromagnetic bearings system operability. © 2012 Elsevier B.V.

Vilenskij O.Yu.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Krylov A.N.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Osipov S.L.,Joint Stock Company Afrikantov OKB Mechanical Engineering | Osetrov D.L.,Joint Stock Company Afrikantov OKB Mechanical Engineering | And 5 more authors.
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2015

In order to examine the condition of intermediate sodium-To-sodium heat exchangers (IHX) and to substantiate their operation life extension to 45 years in the BN-600 reactor plant at Beloyarsk NPP Unit 3, one of the six heat exchangers was removed from the reactor in April 2006. Results of inspection showed that there were cracks 7 mm deep maximum on the outer surface of the upper tubesheet and adjacent shell. To predict durability of substantially fatigued metal, a need arose to verify the existing relationship for the threshold stress intensity factor range for the 10Cr18Ni9 steel. To this end, respective testing was conducted on specimens of two structural elements in the IHX-upper tubesheet and protection block. To identify failure mechanisms, fractographic studies were performed on the surface of cracks detected in the tubesheet and made in the specimens. Based upon the studies, a conclusion was made that the failure mechanism for cracks detected on the tubesheet was identical to the mechanism generated in the test specimens. In both the cases, the intergranular failure prevailed that is typical for the material loading level testifying to termination of the crack growth. This result makes it possible to speak about crack initiation and propagation in the IHX tubesheet in the high-cycle fatigue region at a low-level strain ranges and stress intensity factor ranges. An analysis of causes of crack formation showed that the cracks could have formed as a result of the temperature pulsation effect produced by mixing of sodium flows having different temperatures-sodium entering the IHX inlet and sodium coming from the reactor vessel cooling system. Based upon computational analysis results, for all thermal pulsation conditions and crack propagation cross-sections under consideration, the leak-Tightness condition is met for the upper tubesheet and IHX outlet chamber shell that divide the primary and secondary coolant circuits. The computational and experimental studies have proved that presence of these cracks does not limit the possibility of service life extension to 45 years for the IHX in the BN-600 reactor plant.

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