Method and device for discriminating between and sorting fuel elements of nuclear reactors

Claim 2

In a method of discriminating between and sorting fuel elements of nuclear reactors, wherein the fuel is in the form of coated fuel particles, such as spherical fuel elements, which are sluiced through the core of a high temperature nuclear reactor, and wherein the activity of the fuel elements is measured outside the core at a predetermined temperature whereupon, in dependence on the measured activity value, the fuel elementss are either returned to the core or are separated, the improvement which comprises: a. maintaining each fuel element individually outside the core at a predetermined elevated temperature and for a predetermined dwell period in a measuring space; b. contacting each fuel element within said measuring space during said dwell period with a predetermined amount of inert gas, whereby liberated fission gas products from said fuel element intermingle with said inert gas; c. measuring the activity of the gas mixture thus obtained; and, d. in dependence on the measured value thus obtained, either returning the fuel element to the core of the reactor or discharging the fuel element.

Claim 3

The improvement of claim 1, wherein said predetermined elevated temperature is about 300*C.

Claim 4

The improvement of claim 1, wherein said predetermined elevated temperature is about 600*C.

Claim 5

The improvement of claim 1, wherein said predetermined elevated temperature is either about equal to the temperature at which the fuel element enters the measuring space, or is about twice as high.

Claim 6

The improvement of claim 1, wherein said dwell period is about 3 minutes.

Claim 7

The improvement of claim 1, wherein the activity of the gas mixture of step (c) is measured with a detector to produce a measured value, feeding the measured value to an analyzer for comparison of the measured value with a reference value and, in dependence on said comparison, either recycling said fuel element to the reactor or separating it.

Claim 8

The improvement of claim 1, wherein the temperature of the fuel element is raised during said dwell period.

Claim 9

The improvement of claim 7, wherein the temperature of said fuel element is raised during the dwell period by at least 100*C.

Claim 12

A method as claimed in claim 9, wherein said predetermined temperature is about 300*C, while said predetermined time period is about 3 minutes.

Claim 13

A method as claimed in claim 9, wherein said predetermined temperature is about 600*C, while said predetermined time period is about 3 minutes.

Claim 14

A method as claimed in claim 9, wherein said predetermined temperature is at least about 100*C higher than the temperature of the fuel element at the time of entering said space.

Claim 15

A method as claimed in claim 9, wherein a plurality of measuring spaces are provided, one fuel element being conveyed into each of said spaces, and the total number of fuel elements conveyed into the spaces being adapted to the timing cycle at which the fuel elements are withdrawn from the reactor.

Claim 16

An arrangement for discriminating between and sorting fuel elements of a nuclear reactor, wherein the fuel elements are in the form of coated fuel particles and wherein each fuel element is individually introduced into the furnace chamber of a heatable furnace and is removable therefrom through discharge means which either return the fuel element to the reactor or discharge it to a disposal area, the improvement which comprises: a. means for heating said furnace and thus said chamber to a temperature of about above 600*C; b. gas supply means for supplying inert gas to said furnace chamber; c. gas discharge means for discharging gas from said furnace chamber; d. detector means within said gas discharge means for detecting and measuring radioactivity; and e. means operatively connected to said detector means for directing each fuel element after its discharge from said furnace chamber either to the reactor or the disposal area, in dependence on the measuring value obtained by said detector means.

Claim 17

An arrangement for discriminating between and sorting fuel elements of a nuclear reactor, wherein the fuel elements are in the form of coated fuel particles and wherein each fuel element is individually introduced into the furnace chamber of a heatable furnace and is removable therefrom through discharge means which either return the fuel element to the reactor or discharge it to a disposal area, the improvement which comprises: a. means for heating said furnace and thus said chamber to a temperature of about above 600*C; b. gas supply means for supplying inert gas to said furnace chamber; c. gas discharge means for discharging gas from said furnace chamber; d. detector means within said gas discharge means for detecting and measuring radioactivity; and e. means operatively connected to said detector means for directing each fuel element after its discharge from said furnace chamber either to the reactor or the disposal area, in dependence on the measuring value obtained by said detector means.

Claim 18

The improvement of claim 14, wherein said means (e) comprises analyzing means operatively connected to said detector means, control means operatively connected to said analyzing means and switch means arranged in the discharge from said furnace chamber and being capable of directing fuel elements either to said reactor or said disposal area, said switching means being operatively connected to said control means and controllable by said control means in response to directions obtained from said analyzing means.

Claim 19

The improvement as claimed in claim 14, wherein said furnace comprises a plurality of said furnace chambers, each of said furnace chambers being operatively associated with a detector means.

Claim 20

In combination with a nuclear reactor employing coated fuel particles as fuel elements and having a fuel element discharge, an arrangement for distinguishing between and sorting said fuel elements, in dependence on their radioactivity, said arrangement comprising: a. a heatable furnace having a furnace chamber with an inlet end and an outlet end; b. first valve controlled conduit means for establishing communication with the fuel element discharge of the reactor and the inlet end of said chamber; c. second valve controlled conduit means, said second valve controlled conduit means having an end portion connected to the outlet end of said furnace chamber and forming first and second branches, said first branch communicating with said reactor and said second branch communicating with a disposal area; d. switch means within said second valve controlled conduit means for selectively establishing communication between said end portion of said second valve controlled conduit means and said first branch and thus said reactor and said end portion of said second valve controlled coNduit means and said second branch and thus said disposal area; e. gas supply means for supplying inert gas to said furnace chamber; f. gas discharge means for discharging gas from said furnace chamber; g. measuring means within said gas discharge means for measuring radioactivity of gas flowing through said gas discharge means; h. an analyzer operatively connected with said measuring means for comparing the measured value supplied by said measuring means with a threshold value; and i. control means operatively connected to said analyzer and said switch means, said control means selectively switching said switch means, in dependence on directions received by said control means from said analyzer means.

Claim 21

In combination with a nuclear reactor employing coated fuel particles as fuel elements and having a fuel element discharge, an arrangement for distinguishing between and sorting said fuel elements, in dependence on their radioactivity, said arrangement comprising: a. a heatable furnace having a furnace chamber with an inlet end and an outlet end; b. first valve controlled conduit means for establishing communication with the fuel element discharge of the reactor and the inlet end of said chamber; c. second valve controlled conduit means, said second valve controlled conduit means having an end portion connected to the outlet end of said furnace chamber and forming first and second branches, said first branch communicating with said reactor and said second branch communicating with a disposal area; d. switch means within said second valve controlled conduit means for selectively establishing communication between said end portion of said second valve controlled conduit means and said first branch and thus said reactor and said end portion of said second valve controlled coNduit means and said second branch and thus said disposal area; e. gas supply means for supplying inert gas to said furnace chamber; f. gas discharge means for discharging gas from said furnace chamber; g. measuring means within said gas discharge means for measuring radioactivity of gas flowing through said gas discharge means; h. an analyzer operatively connected with said measuring means for comparing the measured value supplied by said measuring means with a threshold value; and i. control means operatively connected to said analyzer and said switch means, said control means selectively switching said switch means, in dependence on directions received by said control means from said analyzer means.

Claim 22

An arrangement as claimed in claim 17, further comprising means for heating said furnace and said furnace chamber to between about 300* to 600*C.

Claim 23

An arrangement as claimed in claim 17, wherein said first valve controlled conduit means is a thermally insulated conduit member extending between the inlet end of said furnace chamber and the fuel element discharge of said reactor and a lock arranged within said conduit member.

Claim 24

An arrangement as claimed in claim 17, further comprising conduit means for connecting said gas supply means (e) and said gas discharge means (f) with each other to form a gas circulation means through which gas can be continuously circulated through said furnace chamber.

Claim 25

A arrangement as claimed in claim 20, further comprising gas purification means within said gas circulation means.