US4057463A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of operating a nuclear reactor which maintains a substantially constant axial power distribution profile with changes in load
Assignee: Westinghouse Electric Corp
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Filing: 1974-08-29
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Granted: 1977-11-08
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Expires: 1994-08-29
Abstract
Abstract This invention provides a method of operating a nuclear reactor with the object of maintaining a substantially symmetric axial xenon distribution during normal power operation including load follow. Variations in the xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. Procedures are described for maintaining the axial offset value of the core, as an indicia of the axial power distribution, substantially equal to a target value, which is modified periodically to account for core burnup. In one embodiment a neutron absorbing element within the core coolant, or moderator, is employed to assist control of reactivity changes associated with changes in power with the full length control rods mainly employed to adjust variations in the axial power distribution, while the part length rods remain completely withdrawn from the fuel region of the core. In a second embodiment reactivity changes associated with changes in power are controlled by the full length rods, while the part length rods are used to adjust the axial power distribution and the neutron absorbing element within the core coolant or moderator is used to compensate for xenon buildup or depletion.
Inventors
- 👤 Toshio Morita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:53
CPC Classifications
G; G21; G21D; G21D3/00; G21D3/08; G21D3/12; G21D3/16; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
118 words
A method of operating a nuclear reactor having a reactive core including fissile material with an axial dimension and adjustable control means for controlling the reactivity within the core, comprising the steps of: monitoring a parameter representative of the power generated within the core at a first and second axial location; obtaining from the core power parameters measured at said first and second axial locations a representation of the axial power distribution within the core; and adjusting the control means to produce an axial power distribution to maintain a uniform and symmetric xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow.
Claim 2
Independent Claim
118 words
A method of operating a nuclear reactor having a reactive core including fissile material with an axial dimension and adjustable control means for controlling the reactivity within the core, comprising the steps of: monitoring a parameter representative of the power generated within the core at a first and second axial location; obtaining from the core power parameters measured at said first and second axial locations a representation of the axial power distribution within the core; and adjusting the control means to produce an axial power distribution to maintain a uniform and symmetric xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the core is divided axially into upper and lower halves corresponding to said first and second monitored locations.
Claim 4
Dependent Claim
21 words
The method of claim 2 wherein the representation of the axial power distribution corresponds to the axial offset of the core.
Claim 5
Dependent Claim
33 words
The method of claim 3 wherein the adjusting step activates the control means to maintain the axial offset substantially equal to a predetermined target value throughout reactor operation including changes in reactor power.
Claim 6
Dependent Claim
44 words
The method of claim 4 wherein the control means includes control rods and the target value is obtained from the step of determining the axial offset at full power with equilibrium xenon and all control rods removed from the fuel region of the core.
Claim 7
Dependent Claim
12 words
The method of claim 4 wherein the target value is determined periodically.
Claim 8
Dependent Claim
24 words
The method of claim 6 wherein the interval between the determination of the target value is substantially equal to an equivalent full power month.
Claim 9
Dependent Claim
47 words
The method of claim 4 wherein the axial power distribution can vary during reactor operation to have a flux difference within a band of approximately plus or minus 5 percent of a predetermined value for the flux difference corresponding to the target value of the axial offset.
Claim 10
Dependent Claim
77 words
The method of claim 1 wherein the control means includes a plurality of elongated control rods comprising neutron absorbing material which are axially aligned with the core along the longitudinal control rod dimension and longitudinally movable into and out of the core with the longitudinal length of the rods at least substantially equal to the axis length of the core and a core cooling medium or moderator having a controlled variable concentration of a neutron absorbing element.
Claim 11
Dependent Claim
46 words
The method of claim 9 wherein the changes in reactor power are in part controlled to a desired level by variation of the concentration of the neutron absorbing element and wherein said adjusting step positions the control rods to maintain the substantially symmetric axial power distribution.
Claim 12
Dependent Claim
28 words
The method of claim 10 wherein the movement of the control rods within the core are approximately linearly proportional to changes in the power output of the core.
Claim 13
Dependent Claim
88 words
The method of claim 9 wherein the control means includes part length elongated control rods comprising neutron absorbing material which are axially aligned with the core along the longitudinal dimension and longitudinally movable within the core with the longitudinal length of the part length rods substantially less than the axial length of the core, wherein the control rods are adjusted for the reactivity control associated with changes in core power output and the adjusting step positions the part length rods to maintain the substantially symmetric axial power distribution.
Claim 14
Dependent Claim
67 words
The method of claim 12 wherein as a byproduct of the fission reaction of the fissile material the element xenon is created within the core having a neutron absorption property and wherein said adjusting step controls the concentration of the neutron absorbing element within the core to control the reactivity change due to xenon buildup or depletion corresponding to and associated with changes in core power output.
Claim 15
Dependent Claim
25 words
The method of claim 12 wherein the part length rod neutron absorbing capability is substantially equal to the control rod absorption capability of equivalent length.
Claim 16
Dependent Claim
38 words
The method of claim 12 wherein said adjusting step employs the part length rods for axial power distribution control for a power operating period approximately equal to less than 60 percent of every 30 equivalent full power days.
Claim 17
Dependent Claim
48 words
The method of claim 12 wherein the part length rods are inserted to a distance of approximately 30 percent from the bottom of the core at full power operation and the insertion linearly increases to approximately 10% from the bottom of the core at 50 percent core power.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-07 | 1981-05-09 | 1981-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-07 | 1985-05-09 | 1985-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-07 | 1989-05-09 | 1989-11-08 | $7700.00 | Window Closed / Lapsed |