A mathematical model for calculating stresses in the microfuel elements

Eremeev, V. S.; Иванова, Е. А.; Mikhailov, V. N.; Putilova, A. P.; Chernikov, A. S.

doi:10.1007/bf01125359

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“…The characteristics of the best-known computer codes designed to simulate the behavior and predict the service life of HTGR fuel are presented in Table 1 [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

Section: Mathematical Models and Computer Codes For Calculating The Bmentioning

confidence: 99%

Experimental and computational study of the pyrocarbon and silicon carbide barriers of HTGR fuel particle

2008

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HTGR safety is secured by a system of barriers limiting the emission of fission products from the core into the surrounding environment during normal operation and postulated anticipated accidents. An experimental-computational analysis of two fundamentally important barriers -fuel kernels and their coating, whose function is to contain radionuclides and to protect workers and the environment, is examined. The function of the barriers and the requirements which they must satisfy are examined for HTGR fuel particles. The results of post-reactor studies are analyzed. Mathematical models and computational codes simulating the behavior of fuel particles are analyzed. Probabilistic-statistical models and the GOLT code are being developed to evaluate the behavior of fuel particles under irradiation. Together with other models, this code is used for comparative test calculations of the behavior of particle fuel under normal irradiation conditions (<1300°C). The first results of such calculations are discussed.A system of barriers which limits the emission of radionuclides from the core into the surrounding environment during normal operation and postulated anticipated accidents secures the safety of HTGR. Two basic concepts for HTGR are currently being developed: spherical fill in the core and prismatic fill with a core assembled from graphite blocks. In both cases, fuel particles are the main fuel elements.There are five fundamentally important barriers in HTGR which confine radionuclides and provide protection for workers and the environment: fuel kernels, coatings on the fuel kernels, matrix graphite of spherical fuel elements, fuel compacts, graphite fuel blocks, airtight coolant loop which includes the reactor vessel, a connecting vessel, and a turbomachine vessel, and an outer protective shell of the reactor with a special ventilation system. Of these barriers, the multilayer coating of the fuel particles ( Fig. 1) is decisive and the silicon carbide layer, in turn, plays the main role.The capability of coatings to contain radionuclides depends on the fuel quality, which is taken to mean the minimum statistical variance of the prescribed characteristics of a large mass of fuel particles, for example, the number of particles in the core of GT-MGR, which is currently being designed [1], is ~10 10 , as well as the maximum possible stability of the coatings as the fuel burns up. The main damaging factors for the coatings of fuel particles are high fuel temperature, fast-neutron fluence, irradiation intensity, power density, and burnup as well as the chemical action of the fission products, increase of the internal pressure of CO and gaseous fission products, and other factors. The role of most of these factors can change because of a change in the fuel structure, including a change in the kernel size and composition and in the coatings of the fuel particles.

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