CA1086925A - Direct heater with axially varying power distribution - Google Patents
Direct heater with axially varying power distributionInfo
- Publication number
- CA1086925A CA1086925A CA309,773A CA309773A CA1086925A CA 1086925 A CA1086925 A CA 1086925A CA 309773 A CA309773 A CA 309773A CA 1086925 A CA1086925 A CA 1086925A
- Authority
- CA
- Canada
- Prior art keywords
- tube
- fuel element
- power distribution
- diameter
- wall thickness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C17/00—Monitoring; Testing ; Maintaining
- G21C17/001—Mechanical simulators
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/40—Heating elements having the shape of rods or tubes
- H05B3/42—Heating elements having the shape of rods or tubes non-flexible
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
ABSTRACT
DIRECT HEATER WITH AXIALLY
VARYING POWER DISTRIBUTION
An electric cartridge heater is provided to simulate a reactor fuel element for use in tests of model nuclear reactor systems.
The electric heat generating element corresponds in external shape and configuration to the fuel element and electrical current is passed through the tube from end to end. In order that the heat distribution will simulate that of the actual fuel element, the wall or thickness of the tube is varied from end to end, being thickest at each end and thinnest in the middle. This is attained by starting with a uniform tube and expanding the central section so that its internal diameter is greatest in the middle and least at each end. The external surface is then machined to its required uniform diameter whereby the wall thickness varies. By proper calculation, the desired wall thickness scan be determined to provide the proper power distribution.
DIRECT HEATER WITH AXIALLY
VARYING POWER DISTRIBUTION
An electric cartridge heater is provided to simulate a reactor fuel element for use in tests of model nuclear reactor systems.
The electric heat generating element corresponds in external shape and configuration to the fuel element and electrical current is passed through the tube from end to end. In order that the heat distribution will simulate that of the actual fuel element, the wall or thickness of the tube is varied from end to end, being thickest at each end and thinnest in the middle. This is attained by starting with a uniform tube and expanding the central section so that its internal diameter is greatest in the middle and least at each end. The external surface is then machined to its required uniform diameter whereby the wall thickness varies. By proper calculation, the desired wall thickness scan be determined to provide the proper power distribution.
Description
2 S
Electrical cartridge heaters are used extensively to simu-late reactor fuel elements in safety and thermal hydraulic tests of model nuclear reactor isystems. It has been proposed in the past that in order to properly simulate the reactor fuel ele-mentJ~ th~ cartridge heater should have a non-uniform power dis-tribution and thereby produce a more realistic simulation of the actual fuel element behaviour. It has been proposed that such cartridge heaters be produced by either winding wires of constant cross section with variable spacing or winding wires o~ variable cross-section or machining a tube of variable thickness.
The present invention was conceived to provide a tube of variable wall thickness in a convenient and accurate manner.
It is the object of the present invention to provide an electrical cartridge heater wherein the heater can be utilized to simulate a reactor fuel element~ The above object has been accomplished in the present invention by utilizing as a heat generating element, a metallic tube having an external diameter similar or equal to that of the fuel element to be simulated.
This ~ube is then expanded in a controlled manner so that its diameter is greatest in its mid section and least at each end.
The external diameter is then machined to reduce it once more to a constant diameter equal to the diameter of the fuel element.
". : , . :, . .-. .
.: . .. .. .
z~
After these two operations are accomplished, it will be evident that the tube has a variable wall thickness. By proper-ly selecting the contour of the expanded tube, the wall thick-ness can be determined so that the heat flux distribution pro-duced when electrical current is passed through the tube is substan~ially equivalent to that produced in the reactor fuel element which is desired to simulate.
Figure 1 is a graph of heat flux versus length of the reactor fuel element it is desired to simulate.
Figure 2 is a cross-section of a metallic tubing before expansion.
Figure 3 is the expanded tube.
Figure 4 is the finished tube after the exte~nal diameter is once more reduced to a constant corresponding to its original diameter.
As can be seen from Figure 1, the heat flux produced in a normal reactor fuel element is non-linear and is greatest at points between its ends. The particular contour is some-times referred to as a chopped cosine. The wall thickness o~
the tube necessary to produce this heat flux dis~ribution will of course be in accordance with Ohms law where I is a constant - . ~, . . :
... . .
, , . . ~ ~, ~ 8~9Z5 . ~
and R is inversely proportional to the wall thickness.
Recognizing tha~ after machining the outside diameter will be a constant, it will be readily appreciated that the internal diameter determines the wall thickness.
A simple method of varying the internal diameter of a tube is by introducing hydraulic pressure into the interior of the tube while res~raining the external diameter in accordance with the desired contour.
One-convenient method o~ producing the external form is to stack a series of rings whose internal diame~ers are machined in steps to provide the various exte~nal diameters of the tube after expansion, always allowing for elastic spring back in accordance with the character of the tube being expanded. The tube is arranged within this plurality of rings, a central restraining rod is passed down the center of the tube clamping the whole assembly together including the rings, and hydraulic pressure is then introduced into the tube forcing it outwards until its external diameter corresponds to the various diame~ers of the surrounding rings.
~ y proper selection of the number of rings and the difference of di~meter between the rings9 the step ~unction can be essentially disregarded, particularly in view of the fact that the external surface is going to be removed.
' , .
.
:, .: , .
8 ~2 ~ fter khe tube has been removed from the form, it appears as shown in Figure 3.
The external diameter of the t;ube can now be machined, for example, by centreless grinding so tha~ it is once more constant and the tube appears as sho~n in Figure ~. As will be seent the wall thickness of the tube varies from end to end with the thickness being least at ~he middle and greatest at each end. As a result of this variation in wall thickness, when eleckrical current is passed through the tube9 the power distribution is substantially in accordance wikh the curve of Figure 1.
Electrical connections can now be made to the ends of the tube as desired in order to pass current ~hrough the ~ube.
It will be understood that the material from which khe tube is constructed will depend upon various limitakions including for example, its similarity to the kubing of the reactor fuel element, its electrlcal resistance characteristic, its suitability to formation and machining. Obvious~y, all other things being equal~ the thermal and chemical character-istics of the tube should correspond as closel~ as possible to the characteristics of the fuel elemenk~
.
.
' ' :
.
Electrical cartridge heaters are used extensively to simu-late reactor fuel elements in safety and thermal hydraulic tests of model nuclear reactor isystems. It has been proposed in the past that in order to properly simulate the reactor fuel ele-mentJ~ th~ cartridge heater should have a non-uniform power dis-tribution and thereby produce a more realistic simulation of the actual fuel element behaviour. It has been proposed that such cartridge heaters be produced by either winding wires of constant cross section with variable spacing or winding wires o~ variable cross-section or machining a tube of variable thickness.
The present invention was conceived to provide a tube of variable wall thickness in a convenient and accurate manner.
It is the object of the present invention to provide an electrical cartridge heater wherein the heater can be utilized to simulate a reactor fuel element~ The above object has been accomplished in the present invention by utilizing as a heat generating element, a metallic tube having an external diameter similar or equal to that of the fuel element to be simulated.
This ~ube is then expanded in a controlled manner so that its diameter is greatest in its mid section and least at each end.
The external diameter is then machined to reduce it once more to a constant diameter equal to the diameter of the fuel element.
". : , . :, . .-. .
.: . .. .. .
z~
After these two operations are accomplished, it will be evident that the tube has a variable wall thickness. By proper-ly selecting the contour of the expanded tube, the wall thick-ness can be determined so that the heat flux distribution pro-duced when electrical current is passed through the tube is substan~ially equivalent to that produced in the reactor fuel element which is desired to simulate.
Figure 1 is a graph of heat flux versus length of the reactor fuel element it is desired to simulate.
Figure 2 is a cross-section of a metallic tubing before expansion.
Figure 3 is the expanded tube.
Figure 4 is the finished tube after the exte~nal diameter is once more reduced to a constant corresponding to its original diameter.
As can be seen from Figure 1, the heat flux produced in a normal reactor fuel element is non-linear and is greatest at points between its ends. The particular contour is some-times referred to as a chopped cosine. The wall thickness o~
the tube necessary to produce this heat flux dis~ribution will of course be in accordance with Ohms law where I is a constant - . ~, . . :
... . .
, , . . ~ ~, ~ 8~9Z5 . ~
and R is inversely proportional to the wall thickness.
Recognizing tha~ after machining the outside diameter will be a constant, it will be readily appreciated that the internal diameter determines the wall thickness.
A simple method of varying the internal diameter of a tube is by introducing hydraulic pressure into the interior of the tube while res~raining the external diameter in accordance with the desired contour.
One-convenient method o~ producing the external form is to stack a series of rings whose internal diame~ers are machined in steps to provide the various exte~nal diameters of the tube after expansion, always allowing for elastic spring back in accordance with the character of the tube being expanded. The tube is arranged within this plurality of rings, a central restraining rod is passed down the center of the tube clamping the whole assembly together including the rings, and hydraulic pressure is then introduced into the tube forcing it outwards until its external diameter corresponds to the various diame~ers of the surrounding rings.
~ y proper selection of the number of rings and the difference of di~meter between the rings9 the step ~unction can be essentially disregarded, particularly in view of the fact that the external surface is going to be removed.
' , .
.
:, .: , .
8 ~2 ~ fter khe tube has been removed from the form, it appears as shown in Figure 3.
The external diameter of the t;ube can now be machined, for example, by centreless grinding so tha~ it is once more constant and the tube appears as sho~n in Figure ~. As will be seent the wall thickness of the tube varies from end to end with the thickness being least at ~he middle and greatest at each end. As a result of this variation in wall thickness, when eleckrical current is passed through the tube9 the power distribution is substantially in accordance wikh the curve of Figure 1.
Electrical connections can now be made to the ends of the tube as desired in order to pass current ~hrough the ~ube.
It will be understood that the material from which khe tube is constructed will depend upon various limitakions including for example, its similarity to the kubing of the reactor fuel element, its electrlcal resistance characteristic, its suitability to formation and machining. Obvious~y, all other things being equal~ the thermal and chemical character-istics of the tube should correspond as closel~ as possible to the characteristics of the fuel elemenk~
.
.
' ' :
.
Claims (3)
1. A method of producing a non-linear electrical cart-ridge heater for simulating a reactor fuel element in tests of reactor systems comprising:
expanding a metallic tube having an original uniform external diameter equal or similar to said fuel element so that its internal diameter at a point intermediate its ends is greater than its internal diameter at its ends; and, machining the external surface of said tube to the required said uniform diameter whereby the wall thickness of said tube varies being greatest at each end and least in the middle and such that when electrical current is passed through said tube the power distribution along the tube corresponds essentially to the power distribution of said fuel element in operation.
expanding a metallic tube having an original uniform external diameter equal or similar to said fuel element so that its internal diameter at a point intermediate its ends is greater than its internal diameter at its ends; and, machining the external surface of said tube to the required said uniform diameter whereby the wall thickness of said tube varies being greatest at each end and least in the middle and such that when electrical current is passed through said tube the power distribution along the tube corresponds essentially to the power distribution of said fuel element in operation.
2. The method in accordance with claim 1, wherein said expanding step is performed by hydraulically forcing said tube into a form having a contour corresponding to the desired internal contour.
3. The method in accordance with claim 1 or 2, wherein the external surface is machined to its required diameter by means of centreless grinding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA309,773A CA1086925A (en) | 1978-08-22 | 1978-08-22 | Direct heater with axially varying power distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA309,773A CA1086925A (en) | 1978-08-22 | 1978-08-22 | Direct heater with axially varying power distribution |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1086925A true CA1086925A (en) | 1980-10-07 |
Family
ID=4112180
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA309,773A Expired CA1086925A (en) | 1978-08-22 | 1978-08-22 | Direct heater with axially varying power distribution |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1086925A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4704514A (en) * | 1985-01-11 | 1987-11-03 | Egmond Cor F Van | Heating rate variant elongated electrical resistance heater |
| EP0709858A1 (en) * | 1994-10-25 | 1996-05-01 | General Electric Company | Apparatus and method for simulating a nuclear fuel rod bundle transient |
| CN107180656A (en) * | 2017-05-16 | 2017-09-19 | 中广核研究院有限公司 | Simulate the heater of the dead pipeline section phenomenon of nuclear power station |
| CN113939049A (en) * | 2021-10-13 | 2022-01-14 | 中国核动力研究设计院 | Axial non-uniform heat generation electric heating rod and preparation process and application thereof |
-
1978
- 1978-08-22 CA CA309,773A patent/CA1086925A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4704514A (en) * | 1985-01-11 | 1987-11-03 | Egmond Cor F Van | Heating rate variant elongated electrical resistance heater |
| EP0709858A1 (en) * | 1994-10-25 | 1996-05-01 | General Electric Company | Apparatus and method for simulating a nuclear fuel rod bundle transient |
| CN107180656A (en) * | 2017-05-16 | 2017-09-19 | 中广核研究院有限公司 | Simulate the heater of the dead pipeline section phenomenon of nuclear power station |
| CN107180656B (en) * | 2017-05-16 | 2024-04-09 | 中广核研究院有限公司 | Heating device for simulating dead pipe section phenomenon of nuclear power station |
| CN113939049A (en) * | 2021-10-13 | 2022-01-14 | 中国核动力研究设计院 | Axial non-uniform heat generation electric heating rod and preparation process and application thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |