CS201251B1 - Alloy based on zirconium for nuclear reactors - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconium-chromium-iron-molybdenum-vanadium zirconium five-part alloy useful for advantageous properties for the coating of fuel elements of nuclear reactors in hot water or superheated steam environments.

At present, two types of zirconium alloys are industrially applied to the coating tubes of nuclear fuel. It is a five-component zirconium-tin-iron chromium-nickel alloy and a two-component zirconium-niobium alloy. The target composition of these alloys is also within the limits of zirconium - cin - iron - chromium - nickel:

1.20 - 1,70 wt. % of tin 0.07 - 0.20 wt. % irons 0.05 - 0,15 wt. % of chromium 0.03 - 0,08 wt. % nickel zirconium - niobium: 0.90 - 1.10 wt. % niobium

Both types of ee are used in pressurized water reactors where they operate in pressurized water at temperatures below 300 ° C. They are not resistant to steam at temperatures between 400 ° C - 500 ° C.

To date, several types of zirconium alloys have been reported in patent literature and scholarly literature. However, only three have the information needed to compare the properties

201 251

201 251 with the proposed alloy. However, these alloys have not been applied in practice. From zirconium-copper9-iron t-zirconium-chromium-iron alloys with guide compositions:

zirconium - me3 - iron i

1.1 - 1.3 wt. % copper

0.2 - 0.4 wt. % iron zirconium - chromium - iron:

1.0 - 1.2 wt. % chromium

0.1 - 0.16 wt. % of iron e Four-load zirconium - niobium - tin - chromium - iron or molybdenum alloys with guide composition

0.50 - 1.00 wt. % niobium 0,05 - 0.10 wt. % of tin 0,01 - 0.50 wt. % of chromium 0,02 - 0.05 wt. % irons

The main disadvantages of these alloys, in particular the two alloys used hitherto in practice, are their low corrosion i.e. oxidation and hydridation resistance in the superheated spring environment at higher temperatures. This makes it impossible to increase operating temperatures in nuclear reactors when these alloys are used.

The above-mentioned disadvantages are eliminated by the zirconium alloy for nuclear reactors according to the invention, which consists in containing alloying metal elements chromium, iron, molybdenum, vanadium in an amount of 0.2 to 1.2% by weight of chromium, 0.1 to 0.8% by weight % iron,

0.2 to 1.0 wt.% Molybdenum; 0.1 to 0.8 wt.% Vanadium, the remainder being zirconium.

The total content of all four alloying metal elements ee is in the range of 1.2 to

2.8 wt%.

The alloy's properties are the result of the interaction of all four alloying elements in the zirconium. The main advantages of the zirconium alloy according to the invention are its very good corrosion resistance, especially in an overheated spring environment while maintaining sufficient mechanical properties.

Exemplary embodiments and comparisons of the properties of the alloys of the present invention with known alloys are shown in the following tables.

Table 1.

O

Oxidation rate (mg / dm / day)

Alloy / wt. % / water 300 ° C 400 ° C steam 500 ° C blitlny podle Zr-0.3 Cr-0.4 Fe-0.7 MO-0.4V 0.10 0.19 0.90 invention Zr-0.5 Cr-0.5 Fe-0.45 Mo-0.25V 0.07 0.22 0.95

201 2S1

Zr-1,2Sn-0.15 Fa-0.1 Cr-0.05Ni 0.08 1.40 9.60 Known Zr-1,2Cu-0,3 Fa 0.02 0.22 1.00 alloys Zr-1,1 Cr-0.1 Fa 0.07 0.28 0,8-1,5 Zr-1, ONb 0.10 0.60 5.31 Zr-0.5 Nb-0.06 Sn-0.5 Cr-0.04 Fe 0.05 0.56 -

Table 2.

Hydracation rate (ppm / day) for sample thickness ~ 1 mm

Alloy / Bmot. % / water 300 ° C steam 400 ° C steam 500 ° C Blitlny podle Zr-0.3 Cr-0.4 Fa-0.7 Mo-0.4V 0.25 0.35 2.90 invention Zr-0.7 Cr-0.4 Fa-0.7 Mo-0.4V 0.20 0.38 1.98 Zr-1.2 Sn-0.15 Fe-0.1 Cr-0.05Ni - 0.68 13.00 Known Zr-1.2 Cu-0.3 Fa - 0.50 1.80 alloys Zr-1.1 Cr-0.1 Fa 0.25 0.40 3.40 Zr-1.0 Nb 6.15 1.58 10.90 Zr-0.5 Nb-0.06 Sn-0.04 Fe 0.20 0.74 -

Table 3.

Mechanical properties

Alloy / wt. % / Deň: 18 ° C 400 ° C 450 ° C <TPt / MPa / <0.2 /"Bye/ (Γ /% / <Pt / MPa / <0.2 / MPa / /% / <r pt / MPa / (U0.2 / MPa / /% / alloys according to Zr-0.7 Cr-0.4 Fa0.7 Mo-0.4 V 410 230 40 236 41 invention zu Zr-0,9 Cu-0,3 Fe- 0.95 Mo-0.55 V 450 250 37 - - - - - - Known Zr-1.2 Sn-0.15 Fa 0.1 Cr-0.05 Ni 471 382 22nd Zr-1 ,? Cu-0.3 Fa 441 382 31 186 167 48 - - - alloys Zr-1.1 Cr-0.1 Fa 350 200 45 - - - 170 - 55 Zr-1.0 Nb 539 ^X 390 412 ^X 220 15 ^X 37 205 115 35 - Zr-0.5 Nb-0.06 Sn0.5 Cr-0.04 Fe 470 350 - - - - - - -

Note: the mechanical properties are largely influenced by the admixture content and the metallurgical history of the material, eg data marked with x apply to the β alloy with an oxygen content of approximately 500 ppm.

Claims (2)

1. Zirconium iron for nuclear reactors, characterized in that it contains iron, chromium, molybdenum and vanadium alloying coffee elements in an amount of 0.2 to 1.2% by weight of chromium, 0.1 to 0.8% by weight of iron; 2 to 1.0% by weight of molybdenum, 0.1 to 0.8% by weight of vanadium, the remainder being zirconium. 2. The zirconium alloy according to claim 1, characterized in that the content of all four alloying metal elements is in the range of 1.2 to 2.8% by weight and the rest is zirconium.