Extended analysis of VVER-1000 surveillance data

Kryukov, A.; Erak, D.; Debarberis, L.; Filippo, Sevini; Acosta, B.

doi:10.1016/s0308-0161(02)00069-8

Cited by 27 publications

(11 citation statements)

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“…The coefficient of radiation embrittlement obtained by the reconstitution method is greater than the result obtained using the regular control-sample program. In the present case, the degree of embrittlement of the main metal was found to be close to the embrittlement of the weld-seam metal with a high nickel content, which does not agree with the data for other units and known behavior of the radiation embrittlement of VVER-1000 vessel materials [4,5].…”

contrasting

confidence: 99%

Analysis of tests performed on materials of VVER-1000 vessels for impact toughness according to the standard control-sample program

Vasil'chenko¹,

Kovyrshin²,

Grinik

et al. 2008

At Energy

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An additional assessment and analysis of the degree of radiation embrittlement of the materials used in the VVER-1000 vessels of nuclear power plants in Ukraine are performed according to the standard (regular) program of irradiation and investigation of control samples. New results for samples tested for impact toughness are presented and compared with the results obtained using reconstitutive procedures. It is shown that the results of control-sample tests performed according to the standard program (with a fluence deviation of ±15% above the norm in a group of 12 samples) can be used to assess the state of the material and preliminary substantiation of the serviceability of vessels before obtaining more accurate data on embrittlement using reconstituted samples.The most crucial structure of a nuclear power plant with VVER-1000 is the vessel, which is exposed to substantial mechanical and thermal loads (constant and cyclic) during operation and cannot be replaced before the service life is exhausted. In addition, its wall is irradiated by a flux of fast neutrons, which results in radiation embrittlement, which is characterized by a gradual decrease of the fracture toughness of the materials. To avoid uncontrollable fracture of the vessel during emergency cool-down of a power-generating unit, the normative documentation which regulates the safe operation of nuclear power plants specifies observation of the state of the vessel metal over the entire service life [1].A complex of measures (periodic nondestructive monitoring, monitoring of the conditions of irradiation of the critical elements of the vessel), including monitoring of the change of the properties of vessel materials with the aid of control samples, to assess the state of the material in the vessel in a nuclear power plant has been planned and is being implemented. Since there are drawbacks in the regular control-sample program because of different circumstances, one such drawback being an unfortunate design of the container assemblies and the associated relatively large variance of the neutron fluence for groups of Charpy samples, which are used to determine the shift of the critical brittleness temperature ∆T F . The large variance of the fluence (i.e., with a deviation from the requirements of [2]) for regular control samples has presented difficulties in obtaining reliable values and objective interpretation of the data when estimating the coefficients of radiation embrittlement A F of vessel materials.Specialists at the Russian Science Center Kurchatov Institute proposed a method of reconstituting tested control samples in order to obtain representative data on the degree of embrittlement of reactor-vessel materials. This method makes

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contrasting

confidence: 99%

Analysis of tests performed on materials of VVER-1000 vessels for impact toughness according to the standard control-sample program

Vasil'chenko¹,

Kovyrshin²,

Grinik

et al. 2008

At Energy

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“…The data have shown, as suggested in [2], that the dependences expressed in Eq. (1) are not always conservative, especially for materials with high nickel content (i.e., more than 1.5% Ni) [3][4][5]. Moreover, the nickel content of most operating VVER-1000 RPV welds exceeds 1.5% Ni and, in some cases it even reaches 1.9% Ni.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the manganese and copper contents in the VVER-1000 steels is lower, and the nickel content is much higher. Higher nickel weld metals have been shown to have an increased sensitivity to neutron irradiation at high fluences [3][4][5], as accounted for, e.g., in the US Regulatory Guide 1.99, Revision 2 [26,27].…”

Section: Introductionmentioning

confidence: 99%

Evolution of the nanostructure of VVER-1000 RPV materials under neutron irradiation and post irradiation annealing

Miller

Chernobaeva

Shtrombakh

et al. 2009

Journal of Nuclear Materials

107

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“…A strong effect of nickel on A F was noted in many publications [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]18]. Figures 5 and 6 illustrate the dependence of A F and ΔT F on the nickel content for various levels of impurity concentrations.…”

Section: Determination Of the Dependence Of A F On The Chemical Compomentioning

confidence: 89%

“…The alloying elements such as nickel and manganese were found to raise the radiation embrittlement rate, i.e., the radiation embrittlement coefficient A F [6][7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

A new approach to description of in-service embrittlement of WWER-1000 reactor pressure vessel materials

et al. 2010

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Based on available published data and experimental findings, the in-service embrittlement of materials has been analyzed. The contributions of thermal ageing and neutron irradiation to embrittlement of the base and weld metals of WWER-1000 reactor pressure vessels are discussed. Equations have been derived which describe the shift of the critical brittle temperature depending on the irradiation time and neutron fluence. For a nickel-rich weld metal a relation between the radiation embrittlement coefficient and the amount of alloying elements Ni, Mn, and Si has been defined.Keywords: embrittlement, reactor pressure vessel, shift of critical brittle temperature, irradiation, neutron fluence. Introduction. Investigations [1-25] of embrittlement behavior of WWER-1000 reactor pressure vessel (RPV) materials [the base metal (BM) is 15Kh2NMFA-A steel and the weld metal (WM) -the weld joints of steel 15Kh2NMFA-A] give rather conflicting findings. This applies primarily to the description of the shift of the critical brittle temperature ΔT k k as a function of the neutron fluence [1]:

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Extended analysis of VVER-1000 surveillance data

Cited by 27 publications

References 0 publications

Analysis of tests performed on materials of VVER-1000 vessels for impact toughness according to the standard control-sample program

Analysis of tests performed on materials of VVER-1000 vessels for impact toughness according to the standard control-sample program

Evolution of the nanostructure of VVER-1000 RPV materials under neutron irradiation and post irradiation annealing

A new approach to description of in-service embrittlement of WWER-1000 reactor pressure vessel materials

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