US5781602A
Expired / Lapsed
US
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PGNAA system for non-invasively inspecting RPV weld metal in situ, to determine the presence and amount of trace embrittlement-enhancing element
Assignee: Westinghouse Electric Co LLC
•
Filing: 1996-05-17
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Granted: 1998-07-14
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Expires: 2016-05-17
Abstract
Abstract Prompt Gamma Neuteon Activation Analysis (PGNAA) is employed to determined in situ the content of nickel, copper, or other embrittlement-enhancing elements within the weld metal joints of nuclear reactor pressure vessels.
Inventors
- 👤 Arnold H. Fero
- 👤 Stanwood L. Anderson
- 👤 Thomas V. Congedo
- 👤 Abdul R. Dulloo
- 👤 Francis H. Ruddy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:09
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/22; G01N23/221; G01N23/222; B; B23; B23K; B23K31/00; B23K31/12; G21; G21C; G21C17/00; G21C17/003; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
132 words
A method for analyzing a weld of a reactor pressure vessel (RPV), comprising the steps of: (a) irradiating said weld with a neutron burst from a neutron source, said burst characterized by an intensity and pulse width and duty cycle, and thereby effecting an emission of fast and thermal neutron-induced gamma radiation from said weld; (b) acquiring gamma radiation data indicative of the number or intensity of gamma rays and energies of said gamma rays during a predetermined time interval, said acquiring step including a separate identification of fast neutron-induced and thermal neutron-induced gamma rays, and wherein said gamma radiation is collected over only a fraction of said duty cycle; and (c) analyzing said gamma data to detect the presence and determine the amount of a prescribed constituent element in said weld.
Claim 2
Independent Claim
132 words
A method for analyzing a weld of a reactor pressure vessel (RPV), comprising the steps of: (a) irradiating said weld with a neutron burst from a neutron source, said burst characterized by an intensity and pulse width and duty cycle, and thereby effecting an emission of fast and thermal neutron-induced gamma radiation from said weld; (b) acquiring gamma radiation data indicative of the number or intensity of gamma rays and energies of said gamma rays during a predetermined time interval, said acquiring step including a separate identification of fast neutron-induced and thermal neutron-induced gamma rays, and wherein said gamma radiation is collected over only a fraction of said duty cycle; and (c) analyzing said gamma data to detect the presence and determine the amount of a prescribed constituent element in said weld.
Claim 3
Dependent Claim
55 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein step (b) comprises acquiring groups of gamma radiation data during a plurality of time intervals, each group being indicative of the number or intensity of gamma rays and energies of said gamma rays during a corresponding time interval.
Claim 4
Dependent Claim
43 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein step (c) comprises determining the amount of said prescribed constituent element to an accuracy of about 0.1% by weight of the irradiated portion of the weld.
Claim 5
Dependent Claim
27 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein said RPV comprises a metal cladding covering the irradiated surface.
Claim 6
Dependent Claim
22 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 4, wherein said metal cladding comprises cobalt.
Claim 7
Dependent Claim
33 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein the method is performed in an environment containing a gamma radiation field of about 100 R/hr.
Claim 8
Dependent Claim
29 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 6, wherein step (a) is carried out with a neutron source submerged in water.
Claim 9
Dependent Claim
31 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein an element selected from the group consisting of copper, nickel and phosphorous is measured.
Claim 10
Dependent Claim
65 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 1, wherein the RPV is an off-line, previously irradiated, water-containing RPV having an internal metal cladding covering the weld, characterized by the steps of: (1) opening the off-line RPV; and then (2) introducing a neutron source into water in the off-line RPV before irradiating the vessel with the neutron source.
Claim 11
Dependent Claim
27 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 9, wherein the cladding contains at least about 8% by weight nickel.
Claim 12
Dependent Claim
35 words
A method for analyzing a weld of a reactor pressure vessel as recited in claim 10, wherein the weld contains less than 1% by weight nickel and the amount of nickel is to be determined.
Claim 13
Independent Claim
120 words
A method for analyzing a metal body having a surface, comprising the steps of: (a) irradiating said surface with a neutron burst from a neutron source, said burst characterized by a duty cycle, and thereby effecting an emission of gamma radiation from said surface; (b) acquiring gamma radiation data indicative of the number or intensity of gamma rays and energies of said gamma rays during a predetermined time interval, said acquiring step including a separate identification of fast neutron-induced and thermal neutron-induced gamma rays, and wherein said gamma radiation is collected over only a fraction of said duty cycle; and (c) analyzing said gamma data to detect the presence and determine the amount of prescribed constituents of said metal body.
Claim 14
Independent Claim
120 words
A method for analyzing a metal body having a surface, comprising the steps of: (a) irradiating said surface with a neutron burst from a neutron source, said burst characterized by a duty cycle, and thereby effecting an emission of gamma radiation from said surface; (b) acquiring gamma radiation data indicative of the number or intensity of gamma rays and energies of said gamma rays during a predetermined time interval, said acquiring step including a separate identification of fast neutron-induced and thermal neutron-induced gamma rays, and wherein said gamma radiation is collected over only a fraction of said duty cycle; and (c) analyzing said gamma data to detect the presence and determine the amount of prescribed constituents of said metal body.
Claim 15
Dependent Claim
46 words
A method as recited in claim 12, wherein step (b) comprises acquiring groups of gamma radiation data during a plurality of time intervals, each group being indicative of the number or intensity of gamma rays and energies of said gamma rays during a corresponding time interval.
Claim 16
Dependent Claim
33 words
A method as recited in claim 12, wherein step (c) comprises determining the amount of said constituents to an accuracy of about 0.1% by weight of the irradiated portion of the metal body.
Claim 17
Dependent Claim
19 words
A method as recited in claim 12, wherein said metal body comprises a metal cladding covering the irradiated surface.
Claim 18
Dependent Claim
13 words
A method as recited in claim 15, wherein said metal cladding comprises cobalt.
Claim 19
Dependent Claim
24 words
A method as recited in claim 12, wherein the environment surrounding the neutron source contains a gamma radiation field of at about 100 R/hr.
Claim 20
Dependent Claim
22 words
A method as recited in claim 12, wherein said neutron source is submerged in water while it is irradiating the metal body.
Claim 21
Dependent Claim
22 words
A method as recited in claim 12, wherein an element selected from the group consisting of copper, nickel and phosphorous is measured.
Claim 22
Dependent Claim
24 words
A method as recited in claim 12, wherein the metal body is formed of sections welded together and constituents of the weld are determined.
Claim 23
Dependent Claim
17 words
A method as recited in claim 20, wherein the metal body is a reactor pressure vessel (RPV).
Claim 24
Dependent Claim
57 words
A method as recited in claim 21, wherein the RPV is an off-line, previously irradiated, water-containing RPV having an internal, cobalt-containing, metal cladding covering the weld, characterized by the steps of: (1) opening the off-line RPV; and then (2) introducing a neutron source into water in the off-line RPV before irradiating the vessel with the neutron source.
Claim 25
Dependent Claim
24 words
A method as recited in claim 22, wherein the constituents of a weld between adjacent sections of the RPV under the cladding are determined.
Claim 26
Dependent Claim
22 words
A method as recited in claim 23, wherein a constituent selected from the group consisting of copper, nickel and phosphorous is determined.
Claim 27
Dependent Claim
18 words
A method as recited in claim 24, wherein the cladding contains at least about 8% by weight nickel.
Claim 28
Dependent Claim
26 words
A method as recited in claim 25, wherein the weld contains less than 1% by weight nickel and the amount of nickel is to be determined.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-07-13 | 2002-01-12 | 2002-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-07-13 | 2006-01-12 | 2006-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-07-13 | 2010-01-12 | 2010-07-14 | $7700.00 | Window Closed / Lapsed |