CA1157578A - SELF-POWERED NEUTRON AND .gamma.-RAY FLUX DETECTOR - Google Patents
SELF-POWERED NEUTRON AND .gamma.-RAY FLUX DETECTORInfo
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- CA1157578A CA1157578A CA000379397A CA379397A CA1157578A CA 1157578 A CA1157578 A CA 1157578A CA 000379397 A CA000379397 A CA 000379397A CA 379397 A CA379397 A CA 379397A CA 1157578 A CA1157578 A CA 1157578A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T3/00—Measuring neutron radiation
- G01T3/006—Measuring neutron radiation using self-powered detectors (for neutrons as well as for Y- or X-rays), e.g. using Compton-effect (Compton diodes) or photo-emission or a (n,B) nuclear reaction
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Abstract
TITLE
A SELF-POWERED NEUTRON AND Y-RAY FLUX DETECTOR
INVENTOR
Colin J. Allan ABSTRACT OF THE DISCLOSURE
A self-powered neutron and Y-ray flux detector is provided having an emitter core wire and at least one band around the emitter core wire forming an emitter outer layer. The overall diameter of the emitter core wire and the band or bands is at least of the order of 0.4 mm in diameter and the surface area of the emitter core wire covered by the band or bands is at least of the order of 10 to 90%.
The band or bands are each at least of the order of 0.02 mm in thick-ness and may be shaped substantially as a right circular cylinder or an open helix. If more than one is used they may be of different metals.
A SELF-POWERED NEUTRON AND Y-RAY FLUX DETECTOR
INVENTOR
Colin J. Allan ABSTRACT OF THE DISCLOSURE
A self-powered neutron and Y-ray flux detector is provided having an emitter core wire and at least one band around the emitter core wire forming an emitter outer layer. The overall diameter of the emitter core wire and the band or bands is at least of the order of 0.4 mm in diameter and the surface area of the emitter core wire covered by the band or bands is at least of the order of 10 to 90%.
The band or bands are each at least of the order of 0.02 mm in thick-ness and may be shaped substantially as a right circular cylinder or an open helix. If more than one is used they may be of different metals.
Description
l 157S78 This inventlon relates to a self-powered neutron and Y-ray flux detector.
Self-powered neutron and Y-ray flux detectors are used extenslvely in nuclear power reactors. In some applications, they are used as the prlmary detector in the reactor safety system, while in other appllcatlons, they are used as the primary detector in the reac-tor control system. In such applications, it is highly desirable that the dynamic response of the detector match the dynamic behaviour of the nuclear fuel power. Although most of the thermal power in a nuclear fission reactor is due to the direct fission of the nuclear fuel, the so-called nuclear fission power, a significant fraction of the power is due to the ~-ray and Y-ray energy released by radioactive fission fragments, the so-called delayed power. In natural uranium, heavy water reactors, of the CANDU type, for example, about 93% of the equilibrium thermal power generated in the nuclear fuel is due to direct fission of the fuel while about 7% is due to the decay of the fission fragments. The former component follows changes in neutron flux promptly while the latter component does not since the fission fragments decay with a wide range of time constants that vary from seconds to days.
For use in nuclear reactor control-, and safety-systems, the ideal neutron and Y-ray flux detector would respond to changes in neutron flux in exactly the same manner that the nuclear fuel does.
A self-powered neutron and Y-ray flux detector usually con-sists of a co-axial mineral-insulated cable. The central electrode is called the emitter while the outer electrode is called the collector.
The two electrodes are electrically insulated from one another by a mineral oxide insulation, usually MgO or A1203, although other oxides couId be used. In many applications, the self-powered detector is used to measure the power, or flux, over a llmited region of the 7~7~
reactor core. In these appllcations, the detector is connected to a lead cable which may also be a co-axial mineral insulated cable.
However, by an appropriate choice of zeometry and materials, and sometimes al80 by using lead cable compensation techniques, the self-powered signal generated in the lead cable can be made to be a small fraction of that 8enerated in the detector.
In a power reactor, the current generated in a self-powered detector can be attributed to three separate interactions, namely:
- (n,~) interactlons in which a ~-active daughter nuclide i8 created by neutron capture in the detector, normally the emitter electrode;
- (n, y, e) interac~ions in which the Y-rays produced by neutron cap-ture in the detector liberate free electrons by Compton and photo-electric processes and, hence, cause a net flow of current between the two electrodes; and - ( y, e) interactions in which reactor y-rays produced in the fuel and reactor hardware interact in the detector and produce a net flow of curren$ between the two electrodes.
Because the (n, ~) inceraction is delayed, detectors in which such interactions are the dominant electrical current producing mechanism, ~0 such as detectors having emitters of vanadium or rhodium, are not suitable for use as the primary detector in reactor control-, and safety-systems. Therefore, detectors in which the current is essen-tially due only to (n, y , e) and (y, e) interactions are used in these applications. It should be noted that it is all but impossible to build a detector in which there are absolutely no (n,~ ) interactions but that by a careful choice of material it is possible to reduce the current fraction produced by such interactions to less than a few percent of the total signal.
An ideali~ed detector, in which 100~ of the si~nal is due to (n, y, e) interactions, would respond effec~lvely ins~antaneously to
Self-powered neutron and Y-ray flux detectors are used extenslvely in nuclear power reactors. In some applications, they are used as the prlmary detector in the reactor safety system, while in other appllcatlons, they are used as the primary detector in the reac-tor control system. In such applications, it is highly desirable that the dynamic response of the detector match the dynamic behaviour of the nuclear fuel power. Although most of the thermal power in a nuclear fission reactor is due to the direct fission of the nuclear fuel, the so-called nuclear fission power, a significant fraction of the power is due to the ~-ray and Y-ray energy released by radioactive fission fragments, the so-called delayed power. In natural uranium, heavy water reactors, of the CANDU type, for example, about 93% of the equilibrium thermal power generated in the nuclear fuel is due to direct fission of the fuel while about 7% is due to the decay of the fission fragments. The former component follows changes in neutron flux promptly while the latter component does not since the fission fragments decay with a wide range of time constants that vary from seconds to days.
For use in nuclear reactor control-, and safety-systems, the ideal neutron and Y-ray flux detector would respond to changes in neutron flux in exactly the same manner that the nuclear fuel does.
A self-powered neutron and Y-ray flux detector usually con-sists of a co-axial mineral-insulated cable. The central electrode is called the emitter while the outer electrode is called the collector.
The two electrodes are electrically insulated from one another by a mineral oxide insulation, usually MgO or A1203, although other oxides couId be used. In many applications, the self-powered detector is used to measure the power, or flux, over a llmited region of the 7~7~
reactor core. In these appllcations, the detector is connected to a lead cable which may also be a co-axial mineral insulated cable.
However, by an appropriate choice of zeometry and materials, and sometimes al80 by using lead cable compensation techniques, the self-powered signal generated in the lead cable can be made to be a small fraction of that 8enerated in the detector.
In a power reactor, the current generated in a self-powered detector can be attributed to three separate interactions, namely:
- (n,~) interactlons in which a ~-active daughter nuclide i8 created by neutron capture in the detector, normally the emitter electrode;
- (n, y, e) interac~ions in which the Y-rays produced by neutron cap-ture in the detector liberate free electrons by Compton and photo-electric processes and, hence, cause a net flow of current between the two electrodes; and - ( y, e) interactions in which reactor y-rays produced in the fuel and reactor hardware interact in the detector and produce a net flow of curren$ between the two electrodes.
Because the (n, ~) inceraction is delayed, detectors in which such interactions are the dominant electrical current producing mechanism, ~0 such as detectors having emitters of vanadium or rhodium, are not suitable for use as the primary detector in reactor control-, and safety-systems. Therefore, detectors in which the current is essen-tially due only to (n, y , e) and (y, e) interactions are used in these applications. It should be noted that it is all but impossible to build a detector in which there are absolutely no (n,~ ) interactions but that by a careful choice of material it is possible to reduce the current fraction produced by such interactions to less than a few percent of the total signal.
An ideali~ed detector, in which 100~ of the si~nal is due to (n, y, e) interactions, would respond effec~lvely ins~antaneously to
-2--` l 15757~
changes tn neutron flux, i.e. such a detector would be 100~ prompt.
Thus, its response would be too fast for an ideal detector since, as discussed above, the power in the fuel i8 only about g3~ prompt. On the other hand, an ldealized detector in which 100~ of the signal is due to (y, e) interactions would respond too slowly since about 1/3 of reactor Y-rays are delayed, so that only about 67~ of the signal component in such a detector would be prompt.
~ oweverJ a detector in which 21% of the signal was due to ~y, e) interactions and 79% of the signal was due to (n, y, e) interactions, would have a prompt fraction of 93%, i.e. it would have the same prompt fraction as the nuclear fuel power. Further, since the delayed detector response i9 due to delayed reactor y-rays, it would match, to a good approximation, the delayed nuclear fuel power, since the delayed Y-rays arise from the decay of the fuel fission products which are also the source of the delayed thermal power in the nuclear fuel.
Attempts have been made to control the dynamic response of a self-powered neutron and y-ray flux detector, in a nuclear reactor, by controlling the relative response of the det~ctor to the nuclear reac-tor y-rays and to the nuclear reactor neutron flux 60 as, for example, to closely match the dynamic response of the detector signal to the dynamic response of the total nuclear reactor fuel power.
One method of controlling the relative response of the detector to the nuclear reactor y-rays and to ~he nuclear reactor neu-tron flux, as disclosed in Canadian Patent 1,0~5,066 dated 2 September 1980, "Self-Powered Neutron and Gamma-Ray Flux ~etector , C.J. Allan et al, is to use a relatively thick emitter cladding layer, say of the order of 0.05 mm in thickness, of say platinum, as a complete covering on an emitter core of, say, Inconel [trademark]- The relative
changes tn neutron flux, i.e. such a detector would be 100~ prompt.
Thus, its response would be too fast for an ideal detector since, as discussed above, the power in the fuel i8 only about g3~ prompt. On the other hand, an ldealized detector in which 100~ of the signal is due to (y, e) interactions would respond too slowly since about 1/3 of reactor Y-rays are delayed, so that only about 67~ of the signal component in such a detector would be prompt.
~ oweverJ a detector in which 21% of the signal was due to ~y, e) interactions and 79% of the signal was due to (n, y, e) interactions, would have a prompt fraction of 93%, i.e. it would have the same prompt fraction as the nuclear fuel power. Further, since the delayed detector response i9 due to delayed reactor y-rays, it would match, to a good approximation, the delayed nuclear fuel power, since the delayed Y-rays arise from the decay of the fuel fission products which are also the source of the delayed thermal power in the nuclear fuel.
Attempts have been made to control the dynamic response of a self-powered neutron and y-ray flux detector, in a nuclear reactor, by controlling the relative response of the det~ctor to the nuclear reac-tor y-rays and to the nuclear reactor neutron flux 60 as, for example, to closely match the dynamic response of the detector signal to the dynamic response of the total nuclear reactor fuel power.
One method of controlling the relative response of the detector to the nuclear reactor y-rays and to ~he nuclear reactor neu-tron flux, as disclosed in Canadian Patent 1,0~5,066 dated 2 September 1980, "Self-Powered Neutron and Gamma-Ray Flux ~etector , C.J. Allan et al, is to use a relatively thick emitter cladding layer, say of the order of 0.05 mm in thickness, of say platinum, as a complete covering on an emitter core of, say, Inconel [trademark]- The relative
-3-- i 3 S75~
response of this type o~ detector is dependent upon the diameter of the emitter as well as on the cholce of metals for the emltter. Thus a specific response dictates a particular geometry and this may intro-duce a problem in that the geometry may not be compatible wlth one or more constralnts on the slze of the detector such as, for example, as may be imposed by the manufacturing procedure or by space limitations in the assembly used to contaln the detectors. If, for example~ a detector having an emitter co~prising an Inconel core clad with plati-num is required to have a dynamic response which matches the dynamic response of the fuel power in a heavy-water-moderated, natural-uranium reactor, then the detector emitter must have an overall diameter of about 2.9 mm. Such a detector will hflve an outside diameter of about 5.0 mm and the accommodation of such a large detector in existing heavy-water-moderated, natural-uranium reactors would introduce problems.
Another method of controlling the relative response of the detector to the nuclear reactor Y-rays and to the nuclear reactor neu-tron flux, as disclosed in United States Patent 4,123,658, dated Octo-ber 31, 1978, "Self-powered Neutron Detector", ~Ø Johansson, is to use a very thin (less than 5 microns) cladding of, for example, plati-num on a cobalt core. By controlling the thickness of the cladding layer the response to reactor Y-rays and hence, the dynamlc response can be controlled. While the detectors proposed by Johansson are use-ful, there is a manufacturing problem with them in that it is very difficult to control the thicXness of the very thin cladding layers required. Hence, it is difficult to achieve adequate control of the dynamic response of the detec~or.
Thus, there is a need for a self-powered neutron and Y-ray flux detector which has a dynamic response which closely matches the dynamic response of the fuel power which can readily be accommodated in, for example, existing heavy-~7ater-moderated, natural-uraniumr reactor detector assemblies,-and which presents no particular ~ 15757~
manufacturing problems.
According to the present invention there is provided a self-powered neutron and y-ray flux detector, comprising:
a) an emitter core wire;
b) an emitter outer layer around the emitter core wire and of dlffer-ent metal thereto;
c) a metal collector around the emitter core wire and the emitter outer layer; and d) dielectrlc insulation electrically insulating the emitter core wire and the emitter outer layer from the metal collec~or;
and wherein the lmprovement comprises:
e) the overall diameter of the emitter core wire and the emltter outer layer is at least of the order of 0.4 mm in diameter;
f) the emitter outer layer covers only of the order of 10% to of the order of 90~ of the emitter core wire surface area and omprises at least one band around the emitter core wire and is of a thickness Ln the range of the order 0.02 mm to of the order of 0.07 mm; and g) the metal of the emitter core wire~ the metal of the emitter outer layer, the metal of the metal collector, the overall diameter of the emitter core wire and the emitter outer layer and the sur~ace area of the emitter core wire that is covered by the emitter outer layer are selected so that the detector has a prompt fraction in the range of the order of 90~ to of the order of 96% and has a dynamic response which substantially matches the dynamic response of the power in the fuel of the nuclear reactor in which the detector is to be used.
In some embodiments of the present invention, a) the emitter core wire is of a material selected frolD the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer is of a material selected from the group _5_ 1 1~7S~
consisting of platinum, palladiu~, tantalum, osmlnm, molybdenum, cerium, tin~ ruthenlum, nlobium, zlrconlum and alloys based on at least one of these ~etals.
In other embodiments of the present invention the emitter outer layer comprises in the range of five to ten bands of e~ual width equally spaced longitudinally along the length of the emltter core wire.
In oth~r embodiments of the present invention, the emitter outer layer overlies of the order of 40 to 60% of the emitter core wlre surface area.
In other embodiments of the present lnvention, the emitter core wire is a nickel-base alloy nominally containing 76% nickel, 15.8% chromium, and 7.20% iron, by weight, and the emitter outer layer is of platinum.
In the embodiments of the present invention which are for use as a fuel power detector in a heavy-water-moderated, natural-uranium reactor, the emitter core material is preferably of a nickel-base alloy nominally containing 76% nickel, 15.8% chromium~ and 7.20%
iron, by weight, or of high purity iron, or of high purity nickel; the emitter outer layer is preferably of platinu~l, or of tin, or of molyb-denum; and the overall diameter of the emitter core wire and the outer layer is preferably less than or of the order of 2 mm.
In other embodiments of the present invention, the emitter core wire is of substantially pure nickel and the emitter outer layer is platinum.
In some embodiments of the present invention, a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromiu~, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer comprises at least two bands of different l 1~7~78 materials selected from the group consisting of platinum, palladium, tantalum, osmium, molybdenum, cerium, tin, ruthenium, niobium, 71rcon-ium, and alloys based on at least one of these metals.
Figure l is a broken, sectional side view o a self-powered neutron and ~-ray flux detector, and Figure 2 is a broken, sectional side view of a different self-powered neutron and y-ray flux detector to that shown in figure 1.
In f:Lgure 1 there is shown a self-powered neutron and ~-ray flux detector comprising:
a) an emitter core wire 1;
b) an emitter outer layer, generally designated 2, around the emit-ter core wire l and of different metal thereto;
c) a metal collector 4 around the emitter core wire l and the emit-ter outer layer 2; and d) dlelectric insulation 6 electrically insulating the emitter core wire l and the emitter outer layer 2 from the metal collector 4; and wherein th~ improvement comprises:
ej the overall diameter of the emitter core wire l and the emitter outer layer 2 i8 at least of the order of 0.4 mm in diameter, f) the emitter outer layer 2 covers only of the order of 10% to of the order of 90% of the emitter core wire surface area and comprises at lease one band, in this embodiment typically five to ten, four of which are shown and desi~nated 12 to lS~ around the emitter core wire 1 and are of a thickness in the range of the order of 0.02 mm to o~
the order of 0.07 mm; and ~) the metal uf the emitter core wire l, the metal of the emitter outer layer 2~ the metal of the metal collector 4, the overall ~7-~ 1~7S~
diameter of the emltter core wire 1 and the emitter outer layer 2 and the æurface area of the emitter core wire 1 that is covered by the e~itter outer layer 2 are æelected so that the detector has a prompt fraction in the range of the order of 90~ to of the order of 96~ and a dynamlc ~esponse which substantially matches the dyna~ic response of the power in the fuel of the nuclear reactor in which the detector is to be used.
In one embodiment, the emitter core wire 1 is of Inconel and has platinum tube lengths formlng the emltter bandst such as 12 to 15~
drawn thereon from oversize tube lengths so that the emltter core wire 1 and the emitter bands, such as 12 ~o 15, are ln electrically conduc-tive contact along their lengths. A meanæ 8 for measuring the magni~
tude of an electrical current between the emitter core wire 1 and the collector 4 is connec~ed to these electrodes by a coaxlal extenslon cable 10. The dlelectric insulation 6, ln this embodiment, ls a com-pressed metal oxide powder, for example, magneslum oxlde powder. The dielectric lnsulatlon is sealed by a closed end 20 of the collector electrode 4 and an electrically-insulating, epoxy-resin seal 22 at the end of the cable 10.
The dynamic response of such a detector dependæ on:
(1) the fraction of the emitter core wlre l that ls covered, the higher the fractlon the slower the response;
(ii) the dlameter of the emltter, in that the smaller the diameter of the emitter, the slower the response;
~iii) and the atomic number of the metal of the bands, such as 12 to 15, the lower the atomic number the faster the response.
For a given emitter dlameter, a given core wire 1 materlal, and a given mater~al for the bands, such as 12 to 15, there wlll, ln gener-al, be an optimum value for the fraction of the surface area of the emitter core wire 1 to be covered such that the dynamic response of the detector beæt matches the delayed power in the nuclear fuel. This fraction can be readily determined by experimentally measuring the dyna,nic respon~e of a detector, havin~ a core wire 1 with no emitter outer layer 2 and by measuring the dynamic response of a detector having an e~itter core wire l which is completely covered by an emltter outer layer 2. Thus, for example, if Fl is the prompt fraction of the detector having the first type of emitter, i.e. one with no emitter outer layer 2, and F2 is the prompt fractLon of the detector having the second type of emitter, i.e. one for which the emitter outer }ayer completely covers the emitter core wire 1, and if FfUel i8 the fraction of the fuel power tha~ is prompt then a detector in which the emitter outer layer 2 covers a fraction X of the emitter core wire l would have a prompt fraction equal to the prompt fraction of the fuel power if Fl - Ff Fl - F2 Experi~ents have shown that for a detector which is 3.0 mm in diame-ter, having an emitter overall diameter, about 1.5 mm in diameter, with a collector 4 of nickel, an emitter core wire l o~ nickel, and an emitter outer lAyer 2 of platinum, Fl i8 about 1.02; and ~2 i8 about 0.90. Thus to obtain a prompt fraction of 0.93, which is the fraction of the power in the fuel that is prompt in a natural-uranium, deute-rium-moderated nuclear reactor of the CANDU type, a detector having a wire core l of nickel, of which approximately 75% is covered with an emltter outer layer 2 of platinum, is used. For use in a reactor safety system, it would be desirable if the detector respanse were sli~htly faster than the power in the fuel so that a somewhat smaller fraction of the emitter core wire l would preferably be covered.
The dynamic response of a detector having a givan type of emitter also depends on the material used ~or the collector 4. Thus, for e~ample, it has been found that if the nickel collector 4 of the above detector is replaced by a collector 4 of Zircaloy, then Fl is _g_ 7 ~
about 1.04; and F2 is about 0.80, so that to achleve a prompt frac-tion of about 0.93 with a Zircaloy-sheathed detector, preferably a detector in which only about 46% of the nickel emitter core wire I is covered with the platinum emitter outer layer 2 is used, assuming an overall emitter diameter of 1.5 mm.
In practice, matching the prompt fraction of the detector to the prompt power in the fuel, using a single material for the emitter outer layer 2, will not necessarily re~ult in a perfect match of all the delayed components, since it is not in general possible to fabri-cate a detectin~ having a zero contributlon from (n, ~) lnteractions.
For example, uslng the above emitter materials, namely nickel and platinum, small delayed currents will be attributable to the ~-decay of 199Pt which has a half-life of 30.8 minutes and to the ~-decay of 65Ni which has a half-life of 2.57 hours. Nonetheless, a close over-all match of the dynamic response of the detector to that of the fuel power will be possible.
It is known from the previously mentioned Canadian Patent No. 1,085,066, that the ~-ray sensitivity of an eMitter comprising a core and a cladding, is saturated at a cladding thickness of about 0.02 mm. By using one or more bands, such as 12 to 15, the band or bands can be made at least of the order of 0.02 mm in thickness so that the detector sensitivity is not sub~ect to variations introduced during manufacture by variations in the thickness of the bands, such as 12 to 15. Furthermore, by varying the total percentage of the sur-face area of the emitter core wire 1 that is covered by the bands, such as 12 to 15, a particular dynamic response can be achieved for a detector having a particular overall diameter and an emitter core wire 1 and bands, such as 12 to 15, of particular metals. Thus, for a detector having a particular overall diameter and particular metals for the emitter core wire 1 and bands such as 12 to 15, the total percentage of the surface area of the emitter core wire 1 that is ~ ~ 15757f~
covered can be selected for a practlcal overall dlameter for the emit-ter and for a deslred dynamlc response. Since the overall sensltlvity of the detector decreases wlth smaller and smaller overall emttter dlameters there is a practical lower limit to the overall emitter dlameter that can be used, and thls is of the order of 0.4 mm~
AB stated above, the percentage of the surface area of the emitter core wire 1 that is covered by the bands, such as 12 to 15, ls the most lmportant factor affecting the dynamic response for given metals for the emitter core wire 1 and bands such as 12 to 15. How-ever, the location of the band or bands, if only one or two bands cover the emitter core wire, will cause a second order effect to be lntroduced. Hence, to minimize the second order effect, it ls prefer-able to cover the emitter core wire 1 with a relatively largP number of bands, preferably five to ten bands, of equal width and equally spaced along the length of the emitter core wire 1, in order to obtain the deslred coverage.
In figure 2, similar parts to those shown in flgure 1 are designated by the same reference numerals and the prevlous description is relied upon ~o describe them.
Referring to figure 2, it is possible to Improve the match by using a first set of bands, such as 16 and 17, of a different material to that of a second set of bands, such as 18 and 19~ for a given material for the emltter core wire 1. ~hus for example, one could use a combinatlon of Pt, for tha first set of bands (16 and 17), and Mo, for the second set of bands (18 and 19), on an emitter core wire 1 of nickelO The prompt fraction would then be given by:
F ~ FN~ Xpt - XMo) + XPtFNi ~ ~ o Ni 3 157$~3 where FC i9 the prompt fraction o~ the compound detector;
FNi ls the prompt fraction obtained with a detector having a bare nickel emitter core wire 1, i.e. one with no bands 16 to 19;
FNi is the prompt fraction of a detector having a nickel emitter core wire 1 completely covered with a layer of Pt;
~i is the prompt fraction of a detector havlng a nickel emitter core wire 1 completely covered with a layer of Mo;
XPt is the fraction of the nickel emitter core wire 1 that is covered with bands, such as 16 and 17, of Pt; and is the fraction of the nickel emitter core wire 1 that is covered with bands, such as 18 and 19, of Mo.
Similarly, the delayed components will be a linear combination of the delayed responses obtained with the three arch-typical emltters. The optimum response would normally be determined by a trial and error calculation process by comparing the dynamic response obtained for a given set of values for ~t and ~ with the dynamic behaviour of the fuel power.
It should be noted that the bands 16 and 17 need not be of the same thickness as ~he bands 18 and 19. Similarly, the bands 16 and 17 need not be of the same width as bands 18 and 19.
There are a number of methods of manufacturing the emitter core w~re with the band or bands according to the present invention, and t~is will largely be dictated by the metals used for the `emitter core wire and the band or bands.
If the emitter core wire is of a metal which is highly duc-tile, such as substantially pure nickel, and ~he band or bands metal is relatlvely hard compared to that of the emitter core wire, then one or more tubul~r lengths for the band material or materlals, can be placed over an oversized emitter core ~ire and the assembly passed through a swaging die to press the band or bands into the surface of the emitter core wire while the latter is being reduced to the desired diameter.
If, however, the emitter core wire ls of a relatively hard metal compared to that of the band or bands, then, the band or bands, can be formed by irst wrapping, for each band, a layer of the metal Ln the form of a wire, strlp, or sheet along a lengthwise extending portion of the emitter core wire and then flattening each metal band o _ the surface of the emitter core wire. In this instance, the band or bands may be at least partially proud of the emitter core wire surface.
A third method of manufacturing the emitter core ~lre with the band or bands is, for each band, to wrap a closed or open helix of thin metal foil or wire around the emitter core wire and to fasten the ends of the helix to the core wire by, for example, weldlng~ peening, or crimping and then to rely upon the swaging of the collector and di electric insulation to press and hold the band or bands in position.
In nuclear reactors the power in the nuclear fuel is gener-ally 93% prompt and so the detector i8 preferably 93 to 95~ prompt because it i9 desirable to use a detector that responds slightly faster than the nuclear fuel.
It wLll be clear from the previous description of the pres~
ent invention that the same general technique can be used to obtain other dynamic response characteristics of a self-powered neutron and y-ray detector to, for example, canc~l the delayed response due to reactor y-rays and 30 match substantially the response of the neutron flux.
response of this type o~ detector is dependent upon the diameter of the emitter as well as on the cholce of metals for the emltter. Thus a specific response dictates a particular geometry and this may intro-duce a problem in that the geometry may not be compatible wlth one or more constralnts on the slze of the detector such as, for example, as may be imposed by the manufacturing procedure or by space limitations in the assembly used to contaln the detectors. If, for example~ a detector having an emitter co~prising an Inconel core clad with plati-num is required to have a dynamic response which matches the dynamic response of the fuel power in a heavy-water-moderated, natural-uranium reactor, then the detector emitter must have an overall diameter of about 2.9 mm. Such a detector will hflve an outside diameter of about 5.0 mm and the accommodation of such a large detector in existing heavy-water-moderated, natural-uranium reactors would introduce problems.
Another method of controlling the relative response of the detector to the nuclear reactor Y-rays and to the nuclear reactor neu-tron flux, as disclosed in United States Patent 4,123,658, dated Octo-ber 31, 1978, "Self-powered Neutron Detector", ~Ø Johansson, is to use a very thin (less than 5 microns) cladding of, for example, plati-num on a cobalt core. By controlling the thickness of the cladding layer the response to reactor Y-rays and hence, the dynamlc response can be controlled. While the detectors proposed by Johansson are use-ful, there is a manufacturing problem with them in that it is very difficult to control the thicXness of the very thin cladding layers required. Hence, it is difficult to achieve adequate control of the dynamic response of the detec~or.
Thus, there is a need for a self-powered neutron and Y-ray flux detector which has a dynamic response which closely matches the dynamic response of the fuel power which can readily be accommodated in, for example, existing heavy-~7ater-moderated, natural-uraniumr reactor detector assemblies,-and which presents no particular ~ 15757~
manufacturing problems.
According to the present invention there is provided a self-powered neutron and y-ray flux detector, comprising:
a) an emitter core wire;
b) an emitter outer layer around the emitter core wire and of dlffer-ent metal thereto;
c) a metal collector around the emitter core wire and the emitter outer layer; and d) dielectrlc insulation electrically insulating the emitter core wire and the emitter outer layer from the metal collec~or;
and wherein the lmprovement comprises:
e) the overall diameter of the emitter core wire and the emltter outer layer is at least of the order of 0.4 mm in diameter;
f) the emitter outer layer covers only of the order of 10% to of the order of 90~ of the emitter core wire surface area and omprises at least one band around the emitter core wire and is of a thickness Ln the range of the order 0.02 mm to of the order of 0.07 mm; and g) the metal of the emitter core wire~ the metal of the emitter outer layer, the metal of the metal collector, the overall diameter of the emitter core wire and the emitter outer layer and the sur~ace area of the emitter core wire that is covered by the emitter outer layer are selected so that the detector has a prompt fraction in the range of the order of 90~ to of the order of 96% and has a dynamic response which substantially matches the dynamic response of the power in the fuel of the nuclear reactor in which the detector is to be used.
In some embodiments of the present invention, a) the emitter core wire is of a material selected frolD the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer is of a material selected from the group _5_ 1 1~7S~
consisting of platinum, palladiu~, tantalum, osmlnm, molybdenum, cerium, tin~ ruthenlum, nlobium, zlrconlum and alloys based on at least one of these ~etals.
In other embodiments of the present invention the emitter outer layer comprises in the range of five to ten bands of e~ual width equally spaced longitudinally along the length of the emltter core wire.
In oth~r embodiments of the present invention, the emitter outer layer overlies of the order of 40 to 60% of the emitter core wlre surface area.
In other embodiments of the present lnvention, the emitter core wire is a nickel-base alloy nominally containing 76% nickel, 15.8% chromium, and 7.20% iron, by weight, and the emitter outer layer is of platinum.
In the embodiments of the present invention which are for use as a fuel power detector in a heavy-water-moderated, natural-uranium reactor, the emitter core material is preferably of a nickel-base alloy nominally containing 76% nickel, 15.8% chromium~ and 7.20%
iron, by weight, or of high purity iron, or of high purity nickel; the emitter outer layer is preferably of platinu~l, or of tin, or of molyb-denum; and the overall diameter of the emitter core wire and the outer layer is preferably less than or of the order of 2 mm.
In other embodiments of the present invention, the emitter core wire is of substantially pure nickel and the emitter outer layer is platinum.
In some embodiments of the present invention, a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromiu~, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer comprises at least two bands of different l 1~7~78 materials selected from the group consisting of platinum, palladium, tantalum, osmium, molybdenum, cerium, tin, ruthenium, niobium, 71rcon-ium, and alloys based on at least one of these metals.
Figure l is a broken, sectional side view o a self-powered neutron and ~-ray flux detector, and Figure 2 is a broken, sectional side view of a different self-powered neutron and y-ray flux detector to that shown in figure 1.
In f:Lgure 1 there is shown a self-powered neutron and ~-ray flux detector comprising:
a) an emitter core wire 1;
b) an emitter outer layer, generally designated 2, around the emit-ter core wire l and of different metal thereto;
c) a metal collector 4 around the emitter core wire l and the emit-ter outer layer 2; and d) dlelectric insulation 6 electrically insulating the emitter core wire l and the emitter outer layer 2 from the metal collector 4; and wherein th~ improvement comprises:
ej the overall diameter of the emitter core wire l and the emitter outer layer 2 i8 at least of the order of 0.4 mm in diameter, f) the emitter outer layer 2 covers only of the order of 10% to of the order of 90% of the emitter core wire surface area and comprises at lease one band, in this embodiment typically five to ten, four of which are shown and desi~nated 12 to lS~ around the emitter core wire 1 and are of a thickness in the range of the order of 0.02 mm to o~
the order of 0.07 mm; and ~) the metal uf the emitter core wire l, the metal of the emitter outer layer 2~ the metal of the metal collector 4, the overall ~7-~ 1~7S~
diameter of the emltter core wire 1 and the emitter outer layer 2 and the æurface area of the emitter core wire 1 that is covered by the e~itter outer layer 2 are æelected so that the detector has a prompt fraction in the range of the order of 90~ to of the order of 96~ and a dynamlc ~esponse which substantially matches the dyna~ic response of the power in the fuel of the nuclear reactor in which the detector is to be used.
In one embodiment, the emitter core wire 1 is of Inconel and has platinum tube lengths formlng the emltter bandst such as 12 to 15~
drawn thereon from oversize tube lengths so that the emltter core wire 1 and the emitter bands, such as 12 ~o 15, are ln electrically conduc-tive contact along their lengths. A meanæ 8 for measuring the magni~
tude of an electrical current between the emitter core wire 1 and the collector 4 is connec~ed to these electrodes by a coaxlal extenslon cable 10. The dlelectric insulation 6, ln this embodiment, ls a com-pressed metal oxide powder, for example, magneslum oxlde powder. The dielectric lnsulatlon is sealed by a closed end 20 of the collector electrode 4 and an electrically-insulating, epoxy-resin seal 22 at the end of the cable 10.
The dynamic response of such a detector dependæ on:
(1) the fraction of the emitter core wlre l that ls covered, the higher the fractlon the slower the response;
(ii) the dlameter of the emltter, in that the smaller the diameter of the emitter, the slower the response;
~iii) and the atomic number of the metal of the bands, such as 12 to 15, the lower the atomic number the faster the response.
For a given emitter dlameter, a given core wire 1 materlal, and a given mater~al for the bands, such as 12 to 15, there wlll, ln gener-al, be an optimum value for the fraction of the surface area of the emitter core wire 1 to be covered such that the dynamic response of the detector beæt matches the delayed power in the nuclear fuel. This fraction can be readily determined by experimentally measuring the dyna,nic respon~e of a detector, havin~ a core wire 1 with no emitter outer layer 2 and by measuring the dynamic response of a detector having an e~itter core wire l which is completely covered by an emltter outer layer 2. Thus, for example, if Fl is the prompt fraction of the detector having the first type of emitter, i.e. one with no emitter outer layer 2, and F2 is the prompt fractLon of the detector having the second type of emitter, i.e. one for which the emitter outer }ayer completely covers the emitter core wire 1, and if FfUel i8 the fraction of the fuel power tha~ is prompt then a detector in which the emitter outer layer 2 covers a fraction X of the emitter core wire l would have a prompt fraction equal to the prompt fraction of the fuel power if Fl - Ff Fl - F2 Experi~ents have shown that for a detector which is 3.0 mm in diame-ter, having an emitter overall diameter, about 1.5 mm in diameter, with a collector 4 of nickel, an emitter core wire l o~ nickel, and an emitter outer lAyer 2 of platinum, Fl i8 about 1.02; and ~2 i8 about 0.90. Thus to obtain a prompt fraction of 0.93, which is the fraction of the power in the fuel that is prompt in a natural-uranium, deute-rium-moderated nuclear reactor of the CANDU type, a detector having a wire core l of nickel, of which approximately 75% is covered with an emltter outer layer 2 of platinum, is used. For use in a reactor safety system, it would be desirable if the detector respanse were sli~htly faster than the power in the fuel so that a somewhat smaller fraction of the emitter core wire l would preferably be covered.
The dynamic response of a detector having a givan type of emitter also depends on the material used ~or the collector 4. Thus, for e~ample, it has been found that if the nickel collector 4 of the above detector is replaced by a collector 4 of Zircaloy, then Fl is _g_ 7 ~
about 1.04; and F2 is about 0.80, so that to achleve a prompt frac-tion of about 0.93 with a Zircaloy-sheathed detector, preferably a detector in which only about 46% of the nickel emitter core wire I is covered with the platinum emitter outer layer 2 is used, assuming an overall emitter diameter of 1.5 mm.
In practice, matching the prompt fraction of the detector to the prompt power in the fuel, using a single material for the emitter outer layer 2, will not necessarily re~ult in a perfect match of all the delayed components, since it is not in general possible to fabri-cate a detectin~ having a zero contributlon from (n, ~) lnteractions.
For example, uslng the above emitter materials, namely nickel and platinum, small delayed currents will be attributable to the ~-decay of 199Pt which has a half-life of 30.8 minutes and to the ~-decay of 65Ni which has a half-life of 2.57 hours. Nonetheless, a close over-all match of the dynamic response of the detector to that of the fuel power will be possible.
It is known from the previously mentioned Canadian Patent No. 1,085,066, that the ~-ray sensitivity of an eMitter comprising a core and a cladding, is saturated at a cladding thickness of about 0.02 mm. By using one or more bands, such as 12 to 15, the band or bands can be made at least of the order of 0.02 mm in thickness so that the detector sensitivity is not sub~ect to variations introduced during manufacture by variations in the thickness of the bands, such as 12 to 15. Furthermore, by varying the total percentage of the sur-face area of the emitter core wire 1 that is covered by the bands, such as 12 to 15, a particular dynamic response can be achieved for a detector having a particular overall diameter and an emitter core wire 1 and bands, such as 12 to 15, of particular metals. Thus, for a detector having a particular overall diameter and particular metals for the emitter core wire 1 and bands such as 12 to 15, the total percentage of the surface area of the emitter core wire 1 that is ~ ~ 15757f~
covered can be selected for a practlcal overall dlameter for the emit-ter and for a deslred dynamlc response. Since the overall sensltlvity of the detector decreases wlth smaller and smaller overall emttter dlameters there is a practical lower limit to the overall emitter dlameter that can be used, and thls is of the order of 0.4 mm~
AB stated above, the percentage of the surface area of the emitter core wire 1 that is covered by the bands, such as 12 to 15, ls the most lmportant factor affecting the dynamic response for given metals for the emitter core wire 1 and bands such as 12 to 15. How-ever, the location of the band or bands, if only one or two bands cover the emitter core wire, will cause a second order effect to be lntroduced. Hence, to minimize the second order effect, it ls prefer-able to cover the emitter core wire 1 with a relatively largP number of bands, preferably five to ten bands, of equal width and equally spaced along the length of the emitter core wire 1, in order to obtain the deslred coverage.
In figure 2, similar parts to those shown in flgure 1 are designated by the same reference numerals and the prevlous description is relied upon ~o describe them.
Referring to figure 2, it is possible to Improve the match by using a first set of bands, such as 16 and 17, of a different material to that of a second set of bands, such as 18 and 19~ for a given material for the emltter core wire 1. ~hus for example, one could use a combinatlon of Pt, for tha first set of bands (16 and 17), and Mo, for the second set of bands (18 and 19), on an emitter core wire 1 of nickelO The prompt fraction would then be given by:
F ~ FN~ Xpt - XMo) + XPtFNi ~ ~ o Ni 3 157$~3 where FC i9 the prompt fraction o~ the compound detector;
FNi ls the prompt fraction obtained with a detector having a bare nickel emitter core wire 1, i.e. one with no bands 16 to 19;
FNi is the prompt fraction of a detector having a nickel emitter core wire 1 completely covered with a layer of Pt;
~i is the prompt fraction of a detector havlng a nickel emitter core wire 1 completely covered with a layer of Mo;
XPt is the fraction of the nickel emitter core wire 1 that is covered with bands, such as 16 and 17, of Pt; and is the fraction of the nickel emitter core wire 1 that is covered with bands, such as 18 and 19, of Mo.
Similarly, the delayed components will be a linear combination of the delayed responses obtained with the three arch-typical emltters. The optimum response would normally be determined by a trial and error calculation process by comparing the dynamic response obtained for a given set of values for ~t and ~ with the dynamic behaviour of the fuel power.
It should be noted that the bands 16 and 17 need not be of the same thickness as ~he bands 18 and 19. Similarly, the bands 16 and 17 need not be of the same width as bands 18 and 19.
There are a number of methods of manufacturing the emitter core w~re with the band or bands according to the present invention, and t~is will largely be dictated by the metals used for the `emitter core wire and the band or bands.
If the emitter core wire is of a metal which is highly duc-tile, such as substantially pure nickel, and ~he band or bands metal is relatlvely hard compared to that of the emitter core wire, then one or more tubul~r lengths for the band material or materlals, can be placed over an oversized emitter core ~ire and the assembly passed through a swaging die to press the band or bands into the surface of the emitter core wire while the latter is being reduced to the desired diameter.
If, however, the emitter core wire ls of a relatively hard metal compared to that of the band or bands, then, the band or bands, can be formed by irst wrapping, for each band, a layer of the metal Ln the form of a wire, strlp, or sheet along a lengthwise extending portion of the emitter core wire and then flattening each metal band o _ the surface of the emitter core wire. In this instance, the band or bands may be at least partially proud of the emitter core wire surface.
A third method of manufacturing the emitter core ~lre with the band or bands is, for each band, to wrap a closed or open helix of thin metal foil or wire around the emitter core wire and to fasten the ends of the helix to the core wire by, for example, weldlng~ peening, or crimping and then to rely upon the swaging of the collector and di electric insulation to press and hold the band or bands in position.
In nuclear reactors the power in the nuclear fuel is gener-ally 93% prompt and so the detector i8 preferably 93 to 95~ prompt because it i9 desirable to use a detector that responds slightly faster than the nuclear fuel.
It wLll be clear from the previous description of the pres~
ent invention that the same general technique can be used to obtain other dynamic response characteristics of a self-powered neutron and y-ray detector to, for example, canc~l the delayed response due to reactor y-rays and 30 match substantially the response of the neutron flux.
Claims (8)
1. A self-powered neutron and y-ray flux detector, comprising:
a) an emitter core wire;
b) an emitter outer layer around the emitter core wire and of different metal thereto;
c) a metal collector around the emitter core wire and the emitter outer layer; and d) dielectric insulation electrically insulating the emitter core wire and the emitter outer layer from the metal collector;
and wherein the improvement comprises:
e) the overall diameter of the emitter core wire and the emitter outer layer is at least of the order of 0.4 mm in diameter;
f) the emitter outer layer covers only of the order of 10%
to of the order of 90% of the emitter core wire surface area and comprises at least one band around the emitter core wire and is of a thickness in the range of the order of 0.02 mm to of the order of 0.07 mm; and g) metal for the emitter core wire, metal for the emitter outer layer, metal for the metal collector, the overall diameter of the emitter core metal wire and the emitter outer layer and the sur-face area of the emitter core wire that is covered by the emitter outer layer are selected so that the detector has a prompt fraction in the range of the order of 90% to of the order of 96% and a dynamic response which substantially matches the dynamic response of the power in the nuclear fuel of the nuclear reactor in which the detector is to be used.
a) an emitter core wire;
b) an emitter outer layer around the emitter core wire and of different metal thereto;
c) a metal collector around the emitter core wire and the emitter outer layer; and d) dielectric insulation electrically insulating the emitter core wire and the emitter outer layer from the metal collector;
and wherein the improvement comprises:
e) the overall diameter of the emitter core wire and the emitter outer layer is at least of the order of 0.4 mm in diameter;
f) the emitter outer layer covers only of the order of 10%
to of the order of 90% of the emitter core wire surface area and comprises at least one band around the emitter core wire and is of a thickness in the range of the order of 0.02 mm to of the order of 0.07 mm; and g) metal for the emitter core wire, metal for the emitter outer layer, metal for the metal collector, the overall diameter of the emitter core metal wire and the emitter outer layer and the sur-face area of the emitter core wire that is covered by the emitter outer layer are selected so that the detector has a prompt fraction in the range of the order of 90% to of the order of 96% and a dynamic response which substantially matches the dynamic response of the power in the nuclear fuel of the nuclear reactor in which the detector is to be used.
2. A self-powered neutron and y-ray flux detector according to claim 1 wherein:
a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and CLAIMS (cont.) 2.(cont.) b) the emitter outer layer is of a material selected from the group consisting of platinum, palladium, tantalum, osmium, molyb-denum, cerium, tin, ruthenium, niobium, zirconium, and alloys based on at least one of these metals.
a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and CLAIMS (cont.) 2.(cont.) b) the emitter outer layer is of a material selected from the group consisting of platinum, palladium, tantalum, osmium, molyb-denum, cerium, tin, ruthenium, niobium, zirconium, and alloys based on at least one of these metals.
3. A detector according to claim 1 wherein the emitter outer layer comprises in the range of five to ten bands of equal width and equally spaced longitudinally along the length of the emitter core metal wire.
4. A detector according to claim 1 wherein the emitter outer layer overlies of the order of 40 to 60% of the emitter core wire surface area.
5. A self-powered detector according to claim 1 wherein the emitter core wire is a nickel-base alloy nominally containing 76%
nickel, 15.8% chromium, and 7.20% iron, and the emitter outer layer is platinum.
nickel, 15.8% chromium, and 7.20% iron, and the emitter outer layer is platinum.
6. A detector according to claim 5 for use as a fuel power detector in a heavy-water-moderated, natural-uranium reactor, wherein the emitter core wire is a nickel-base alloy nominally containing 76%
nickel, 15.8% chromium, 7.20% iron, by weight, the emitter outer layer is of platinum, and the overall diamter of the emitter core wire and the outer layer is less than of the order of 2 mm.
nickel, 15.8% chromium, 7.20% iron, by weight, the emitter outer layer is of platinum, and the overall diamter of the emitter core wire and the outer layer is less than of the order of 2 mm.
7. A detector according to claim 1 wherein the emitter core wire is of substantially pure nickel and the emitter outer layer is platinum.
CLAIMS (cont.)
CLAIMS (cont.)
8. A detector according to claim 1 wherein:
a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer comprises at least two bands of different materials selected from the group consisting of platinum, palladium, tantalum, osmium, molybdenum, cerium, tin, ruthenium, niobium, zirconium, and alloys based on at least one of these metals.
a) the emitter core wire is of a material selected from the group consisting of nickel, iron, titanium, chromium, cobalt, and alloys based on at least one of these metals; and b) the emitter outer layer comprises at least two bands of different materials selected from the group consisting of platinum, palladium, tantalum, osmium, molybdenum, cerium, tin, ruthenium, niobium, zirconium, and alloys based on at least one of these metals.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379397A CA1157578A (en) | 1981-06-09 | 1981-06-09 | SELF-POWERED NEUTRON AND .gamma.-RAY FLUX DETECTOR |
| SE8203224A SE448122B (en) | 1981-06-09 | 1982-05-25 | NEUTRON AND GAMMASTRALE FLOOD DETECTOR, OF BETA DRUM TYPE |
| DE19823220959 DE3220959A1 (en) | 1981-06-09 | 1982-06-03 | Neutron and gamma ray flux detector which can be operated without auxiliary energy |
| MX10159882U MX6299E (en) | 1981-06-09 | 1982-06-07 | IMPROVEMENTS IN RANGE FLOW DETECTOR AND NEUTRONS SELF-ACTIVATED |
| RO107823A RO84285B (en) | 1981-06-09 | 1982-06-08 | Independent supplied detector for y-rays and neurons |
| FR8209977A FR2507328B1 (en) | 1981-06-09 | 1982-06-08 | SELF-SUPPLIED NEUTRON AND G-RAY FLOW DETECTOR |
| JP9837982A JPS57211574A (en) | 1981-06-09 | 1982-06-08 | Self-output supply neutron bundle and gamma-ray bundle detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379397A CA1157578A (en) | 1981-06-09 | 1981-06-09 | SELF-POWERED NEUTRON AND .gamma.-RAY FLUX DETECTOR |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1157578A true CA1157578A (en) | 1983-11-22 |
Family
ID=4120191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379397A Expired CA1157578A (en) | 1981-06-09 | 1981-06-09 | SELF-POWERED NEUTRON AND .gamma.-RAY FLUX DETECTOR |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS57211574A (en) |
| CA (1) | CA1157578A (en) |
| DE (1) | DE3220959A1 (en) |
| FR (1) | FR2507328B1 (en) |
| RO (1) | RO84285B (en) |
| SE (1) | SE448122B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11715577B2 (en) | 2021-03-03 | 2023-08-01 | Westinghouse Electric Company Llc | Detectors, systems, and methods for continuously monitoring neutrons with enhanced sensitivity |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2796197B1 (en) * | 1999-07-05 | 2001-10-12 | Framatome Sa | METHOD AND DEVICE FOR MONITORING AT LEAST ONE OPERATING PARAMETER OF THE CORE OF A NUCLEAR REACTOR |
| FR2796196B1 (en) * | 1999-07-05 | 2001-10-19 | Framatome Sa | METHOD AND DEVICE FOR MONITORING AT LEAST ONE OPERATING PARAMETER OF THE CORE OF A NUCLEAR REACTOR |
| JP7408468B2 (en) * | 2020-04-07 | 2024-01-05 | 日立Ｇｅニュークリア・エナジー株式会社 | Gamma ray measurement device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3872311A (en) * | 1973-07-05 | 1975-03-18 | Westinghouse Electric Corp | Self-powered neutron detector |
| SE397734B (en) * | 1976-03-12 | 1977-11-14 | Atomenergi Ab | BETASTROM DETECTOR |
| CA1085066A (en) * | 1978-04-20 | 1980-09-02 | Colin J. Allan | Self-powered neutron and gamma-ray flux detector |
-
1981
- 1981-06-09 CA CA000379397A patent/CA1157578A/en not_active Expired
-
1982
- 1982-05-25 SE SE8203224A patent/SE448122B/en not_active IP Right Cessation
- 1982-06-03 DE DE19823220959 patent/DE3220959A1/en not_active Withdrawn
- 1982-06-08 RO RO107823A patent/RO84285B/en unknown
- 1982-06-08 FR FR8209977A patent/FR2507328B1/en not_active Expired
- 1982-06-08 JP JP9837982A patent/JPS57211574A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11715577B2 (en) | 2021-03-03 | 2023-08-01 | Westinghouse Electric Company Llc | Detectors, systems, and methods for continuously monitoring neutrons with enhanced sensitivity |
Also Published As
| Publication number | Publication date |
|---|---|
| RO84285B (en) | 1984-07-30 |
| FR2507328A1 (en) | 1982-12-10 |
| DE3220959A1 (en) | 1982-12-23 |
| RO84285A (en) | 1984-05-23 |
| SE8203224L (en) | 1982-12-10 |
| JPS57211574A (en) | 1982-12-25 |
| FR2507328B1 (en) | 1985-09-27 |
| JPS648795B2 (en) | 1989-02-15 |
| SE448122B (en) | 1987-01-19 |
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