US5108697A — Inhibiting stress corrosion cracking in the prima…

Claim 1

Independent Claim 125 words

A method of inhibiting stress corrosion cracking in a pressurized water nuclear reactor, comprising the steps of: (a) circulating coolant water through the primary cooling circuit of a pressurized water nuclear reactor in contact with nickel base alloys comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron, (b) maintaining the coolant water composition at about 1-2500 ppm boron, about 0.1-10 ppm lithium, and about 15-75 cc (STP) hydrogen/kg water, (c) maintaining the coolant water pH between about 5.2 and about 7.4 at 20° C. and conductivity between about 1 and 30 μS/cm at 20° C.; and (d) adding zinc to the coolant water in amounts sufficient to maintain the zinc concentration between about 5 and about 1000 ppb.

Claim 2

Independent Claim 125 words

A method of inhibiting stress corrosion cracking in a pressurized water nuclear reactor, comprising the steps of: (a) circulating coolant water through the primary cooling circuit of a pressurized water nuclear reactor in contact with nickel base alloys comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron, (b) maintaining the coolant water composition at about 1-2500 ppm boron, about 0.1-10 ppm lithium, and about 15-75 cc (STP) hydrogen/kg water, (c) maintaining the coolant water pH between about 5.2 and about 7.4 at 20° C. and conductivity between about 1 and 30 μS/cm at 20° C.; and (d) adding zinc to the coolant water in amounts sufficient to maintain the zinc concentration between about 5 and about 1000 ppb.

Claim 3

Dependent Claim 60 words

The method of claim 1, wherein the coolant water is maintained between about 100 and 1000 ppm boron and between about 0.1 and 3 ppm lithium and at a pH between about 6.0 and 7.2, and the zinc is added to the coolant water in amounts sufficient to maintain a zinc concentration between about 10 ppb and about 200 ppb.

Claim 4

Independent Claim 101 words

A method of inhibiting stress corrosion cracking of nickel alloy components in a steam generator in a primary coolant circuit of a nuclear reactor, comprising the steps of: oxidizing the surfaces of components disposed in a steam generator in a primary coolant circuit of a nuclear reactor which comprise at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron; introducing zinc into the top 50 Angstroms of the oxidized surface to produce a zinc concentration therein of at least 1 w/o; and circulating primary coolant through the circuit at a temperature greater than about 330° C.

Claim 5

Independent Claim 101 words

A method of inhibiting stress corrosion cracking of nickel alloy components in a steam generator in a primary coolant circuit of a nuclear reactor, comprising the steps of: oxidizing the surfaces of components disposed in a steam generator in a primary coolant circuit of a nuclear reactor which comprise at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron; introducing zinc into the top 50 Angstroms of the oxidized surface to produce a zinc concentration therein of at least 1 w/o; and circulating primary coolant through the circuit at a temperature greater than about 330° C.

Claim 6

Dependent Claim 17 words

The method of claim 3, by producing the 1 w/o zinc concentration before circulating the primary coolant.

Claim 7

Dependent Claim 15 words

The method of claim 4, by circulating primary coolant containing less than 1 ppb zinc.

Claim 8

Dependent Claim 17 words

The method of claim 3, by producing the 1 w/o zinc concentration with the circulating primary coolant.

Claim 9

Dependent Claim 59 words

The method of claim 3, by oxidizing and introducing zinc into the surfaces of the components to produce in the top 50 Angstroms of the surfaces an oxide comprising at least about 15 w/o nickel, about 5-20 w/o chromium, about 2-20 w/o iron, about 3-7 w/o zinc and at least about 25 w/o oxygen as determined by electron spectroscopy.

Claim 10

Dependent Claim 53 words

The method of claim 3, by circulating primary coolant as an aqueous solution containing about 1-2500 ppm boron, about 0.1-10 ppm lithium, about 15-75 cc (STP) hydrogen/kg solution, and about 5-20 ppb zinc, and has a pH at 20° C. of about 5.2-7.4 and a conductivity at 20° C. of about 1-30 μS/cm.

Claim 11

Dependent Claim 79 words

A nuclear reactor having a primary coolant circuit with mechanically stressed components wetted by a primary coolant, which components are fabricated from an alloy comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron and have oxidized surfaces wetted by the primary coolant comprising about 1-10 w/o zinc (as determined by electron spectroscopy) in their top 50 Angstroms, the oxidized surfaces of the components at a temperature of at least about 330° C.

Claim 12

Dependent Claim 79 words

A nuclear reactor having a primary coolant circuit with mechanically stressed components wetted by a primary coolant, which components are fabricated from an alloy comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron and have oxidized surfaces wetted by the primary coolant comprising about 1-10 w/o zinc (as determined by electron spectroscopy) in their top 50 Angstroms, the oxidized surfaces of the components at a temperature of at least about 330° C.

Claim 13

Dependent Claim 68 words

A steam generator in a primary coolant circuit of a nuclear reactor having mechanically stressed components wetted by a primary coolant; which components are fabricated from an alloy comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron and have oxidized surfaces wetted by the primary coolant comprising about 1-10 w/o zinc (as determined by electron spectroscopy) in their top 50 Angstroms.

Claim 14

Dependent Claim 68 words

A steam generator in a primary coolant circuit of a nuclear reactor having mechanically stressed components wetted by a primary coolant; which components are fabricated from an alloy comprising at least about 60 w/o nickel, about 13-30 w/o chromium and about 0.3-12 w/o iron and have oxidized surfaces wetted by the primary coolant comprising about 1-10 w/o zinc (as determined by electron spectroscopy) in their top 50 Angstroms.

Claim 15

Dependent Claim 46 words

The steam generator of claim 10, wherein the top 50 Angstroms of the oxidized surfaces of the mechanically stressed components comprise at least about 15 w/o nickel, about 5-20 w/o chromium, about 2-20 w/o iron, about 3-7 w/o zinc and at least about 25 w/o oxygen.

Claim 16

Dependent Claim 42 words

The steam generator of claim 11, wherein the top 50 Angstroms of the oxidized surfaces of the mechanically stressed components comprise about 24-36 w/o nickel, about 8-12 w/o chromium, about 5-10 w/o iron, about 4-6 w/o zinc and about 35-45 w/o oxygen.

Claim 17

Dependent Claim 56 words

The steam generator of claim 11, wherein the mechanically stressed components are fabricated from alloys comprising 14-17 w/o chromium, 6-10 w/o iron, up to 0.5 w/o silicon, up to 10 w/o manganese, no more than 0.5 w/o carbon, no more than 0.015 w/o sulfur and the balance nickel, the nickel concentration being at least 72 w/o.

Claim 18

Dependent Claim 12 words

The steam generator of claim 10, wherein the components comprise bent tubes.

Claim 19

Dependent Claim 12 words

The steam generator of claim 14, wherein the tubes have U bends.

Claim 20

Dependent Claim 12 words

The steam generator of claim 10, wherein the components comprise expanded tubes.

Claim 21

Dependent Claim 12 words

The steam generator of claim 10, wherein the components comprise tube plugs.

Claim 22

Dependent Claim 12 words

The steam generator of claim 10, in a pressurized water reactor system.

Claim 23

Dependent Claim 18 words

The steam generator of claim 10, wherein the components are at a temperature greater than about 330° C.

Claim 24

Dependent Claim 13 words

The method of claim 1, wherein the zinc is added as zinc borate.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-04-28	1995-10-28	1996-04-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-04-28	1999-10-28	2000-04-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-04-28	2003-10-28	2004-04-28	$7700.00	Window Closed / Lapsed

Inhibiting stress corrosion cracking in the primary coolant circuit of a nuclear reactor

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