Abstract:
An automatic pallet loading/unloading method for radioactive waste drums is disclosed, which comprises the steps of: (a) providing a conveying pallet accommodating six radioactive waste drums; (b) arranging the pallet on an specific importing carrier; (c) performing a two-dimensional fetching position adjustment upon the pallet by the importing carrier; and (d) using a grabber crane to grab and carry the radioactive waste drums in a specific order so as to apply an continuous inspection process upon each radioactive waste drum successively. In a preferred aspect, the two-dimensional fetching position adjustment uses a transverse positioning operation cooperating with a lengthwise positioning operation to successively place each radioactive waste drum in a specific position to be grabbed by the grabber crane and thus to be inspected by the inspection process. In addition, an exporting carrier with two-dimensional position adjustment ability similar to that of the importing carrier is provided for receiving those radioactive waste drums after each has completed the inspection process, whereas an empty pallet placed on the carrier is moved with respect to the two-dimensional position adjustment of the exporting carrier so as to enable the radioactive waste drums after being inspected to set on the pallet in order appropriately. By the method of the invention, an automatic inspection process for radioactive waste drums can be achieved so as to prevent operators from getting radiation damage due to the exposure in radiation environment while operating inspection.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an automatic pallet system for allotting radioactive waste drums, and more particularly, to an automatic pallet loading/unloading method for radioactive waste drums of a nuclear waste inspection procedure capable of selectively grabbing one radioactive waste drums form a pallet accommodating at least six radioactive waste drums for enabling the grabbed radioactive waste drums to be inspected by the nuclear waste inspection procedure and arranging the radioactive waste drum to be placed on another pallet after completing the nuclear waste inspection procedure.  
       BACKGROUND OF THE INVENTION  
       [0002]     The major problem of nuclear waste is what to do with it. In fact, one of the biggest (and perhaps the single biggest) expenses of the nuclear power industry could eventually be the storage of nuclear waste. Currently, low level radioactive nuclear wastes are mostly being stored in tens of thousands of 55-gallon radioactive waste drums, which require to be stored in a specific warehouse and inspected regularly for environmental safety before they can be buried in a permanent nuclear disposal. Conventionally, in most nuclear waste warehouse, radioactive waste drums are grouped in fours to be placed on a conveying pallet and used as a storage unit. Although storing nuclear waste in radioactive waste drums can temporarily ease the concern of nuclear pollution, the physical, chemical and radioactive characteristics of each radioactive waste drum must be measured and inspected at a regular basis so as to protect the environment.  
         [0003]     Take the radioactive waste drums inspection procedure performed in Japan for instance, as the nuclear waste storage warehouse in Japan also treats four radioactive waste drums as a storage unit while place a storage unit, i.e. four tanks, on a pallet, one pallet is transported to an inspection station to be inspected while rotating the pallet for enable the four symmetrically-arranged radioactive waste drums to be fetched by a grabber crane at will smoothly.  
         [0004]     Following the progress of nuclear waste management, the concept of treating four radioactive waste drums as a storage unit is challenged since it is not economical in space usage. However, if more than four radioactive waste drums are placed on a pallet, the conventional method for loading/unloading radioactive waste drums to be inspected by an inspection procedure can not perform smoothly since the more-than-four radioactive waste drums can not be placed on the pallet symmetrically such that the grabber crane can not fetch each and every tanks at will simply by the rotation of the pallet. In addition, the inspection efficiency of a conventional inspection procedure is poor since at each effort of transporting a pallet to an inspection station, there are only four radioactive waste drums available to be inspected.  
         [0005]     Therefore, it is in need of an improved pallet loading/unloading method for radioactive waste drums that is capable of carrying more than four radioactive waste drums on a pallet while enabling each tank to be inspected smoothly.  
       SUMMARY OF THE INVENTION  
       [0006]     It is the primary object of the present invention to provide an automatic pallet loading/unloading method for radioactive waste drums of a nuclear waste inspection procedure, which enables a pallet to carry at least six radioactive waste drums while using the pallet as a storage unit for the nuclear waste inspection procedure so that not only the efficiency of space used for radioactive waste drum storage can be increased, but also the number of radioactive waste drum capable of being transported per unit time is increase.  
         [0007]     It is another object of the invention to provide an automatic pallet loading/unloading method for radioactive waste drums of a nuclear waste inspection procedure, which enables a carrier carrying a pallet having a plurality of radioactive waste drums arranged thereon to perform a two-dimensional adjustment including a transverse positioning operation and a lengthwise positioning operation for enabling a grabber crane to grab and carry the radioactive waste drums in a specific order so as to apply an continuous inspection process upon each radioactive waste drum successively such that not only an automatic inspection process for radioactive waste drums can be achieved, but also operators for the inspection process is prevented from getting radiation damage due to the exposure in radiation environment while operating the inspection.  
         [0008]     Yet, another object of the invention to provide an automatic pallet loading/unloading method for radioactive waste drums of a nuclear waste inspection procedure, which arranges an empty pallet capable of accommodating at least six radioactive waste drums at the exit of the nuclear waste inspection procedure for carrying and transporting the radioactive waste drums inspected by the nuclear waste inspection procedure to a storage space.  
         [0009]     To achieve the above objects, the present invention provides an automatic pallet loading/unloading method for radioactive waste drums of nuclear waste inspection procedure, comprising steps of: (a) providing a conveying pallet accommodating at least six radioactive waste drums; (b) arranging the pallet on an specific importing carrier while arranging at least three parking positions in a successive order on a lengthwise side of the importing carrier; (c) enabling the importing carrier to perform a two-dimensional fetching position adjustment upon the pallet; and (d) using a grabber crane to grab and carry the radioactive waste drums in a specific order so as to apply an inspection process upon each radioactive waste drum successively.  
         [0010]     Preferably, the two-dimensional fetching position adjustment further comprises steps of: (c1) enabling the importing carrier to perform a transverse positioning operation upon the pallet; and (c2) enabling the importing carrier to perform a lengthwise positioning operation upon the pallet. Wherein, the lengthwise positioning operation further comprises steps of: (c21) enabling the importing carrier to move the pallet following the lengthwise direction of the importing carrier; (c22) enabling the importing carrier to stop moving the pallet as soon as the pallet reaches one of the plural parking positions; and (c23) making an evaluation to determine whether a radioactive waste drums is presented at the location of the pallet corresponding to the reached parking position; if so the step (d) is initiated; otherwise, repeating the step (c21) to step (c23).  
         [0011]     Preferably, the automatic pallet loading/unloading method for radioactive waste drums further comprises a step of: (e) enabling the importing carrier to move the pallet to an initial location while no radioactive waste drum exists on the pallet.  
         [0012]     Preferably, the automatic pallet loading/unloading method for radioactive waste drums further comprises steps of: (f) providing an empty conveying pallet capable of accommodating at least six radioactive waste drums to be arranged on an exporting carrier, while arranging at least three parking positions in a successive order on a lengthwise side of the exporting carrier; (g) enabling the exporting carrier to perform a placing position adjustment upon the pallet; (h) using a grabber crane to grab and carry the radioactive waste drum passing the inspection process for placing the inspected radioactive waste drum on the pallet; and (i) enabling the exporting carrier to move the pallet to a storage location while the pallet is filled with inspected radioactive waste drums. Wherein, the placing position adjustment further comprises steps of: (g1) enabling the exporting carrier to perform a transverse positioning operation upon the pallet; and (g2) enabling the exporting carrier to move the pallet following the lengthwise direction of the exporting carrier. In addition, the lengthwise positioning operation further comprises steps of: (g21) enabling the exporting carrier to move the pallet following the lengthwise direction of the exporting carrier; (g22) enabling the exporting carrier to stop moving the pallet as soon as the pallet reaches one of the plural parking positions; and (g23) making an evaluation to determine whether there is still empty space available for accommodating inspected radioactive waste drums at the location of the pallet corresponding to the reached parking position; if so the step (h) is initiated; otherwise, repeating the step (g21) to step (g23).  
         [0013]     To achieve the above objects, the present invention provides an automatic pallet loading/unloading method for radioactive waste drums of nuclear waste inspection procedure, comprising steps of: (a′) providing an empty conveying pallet capable of accommodating at least six radioactive waste drums to be arranged on an exporting carrier, while arranging at least three parking positions in a successive order on a lengthwise side of the exporting carrier; (b′) enabling the exporting carrier to perform a two-dimensional placing position adjustment upon the pallet; and (c′) using a grabber crane to grab and carry the radioactive waste drum passing an inspection process for placing the inspected radioactive waste drum on the pallet.  
         [0014]     Preferably, the two-dimensional placing position adjustment further comprises steps of: (b1′) enabling the exporting carrier to perform a transverse positioning operation upon the pallet; and (b2′) enabling the exporting carrier to perform a lengthwise positioning operation upon the pallet. Wherein, the lengthwise positioning operation further comprises steps of: (b21′) enabling the exporting carrier to move the pallet following the lengthwise direction of the exporting carrier; (b22′) enabling the exporting carrier to stop moving the pallet as soon as the pallet reaches one of the plural parking positions; and (b23′) making an evaluation to determine whether there is still empty space available for accommodating inspected radioactive waste drums at the location of the pallet corresponding to the reached parking position; if so the step (c′) is initiated; otherwise, repeating the step (b21′) to step (b23′).  
         [0015]     Preferably, the automatic pallet loading/unloading method for radioactive waste drums further comprises a step of: (d′) enabling the exporting carrier to move the pallet to a storage location while the pallet is filled with inspected radioactive waste drums.  
         [0016]     Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a schematic diagram showing a radioactive waste drum inspection system of the present invention.  
         [0018]      FIG. 2  is a schematic view of a pallet used for carrying radioactive waste drums according to a preferred embodiment of the present invention.  
         [0019]      FIG. 3  is a schematic top view of an importing/exporting carrier of the present invention.  
         [0020]      FIG. 4A  is a flow chart depicting steps of a nuclear waste inspection procedure according to the present invention.  
         [0021]      FIG. 4B  is a flow chart depicting steps of positioning a pallet accommodating six radioactive waste drums on an importing carrier according to a preferred embodiment of the invention.  
         [0022]      FIG. 4C  is a flow chart depicting steps of inspecting a radioactive waste drum.  
         [0023]      FIG. 5A  is a flow chart depicting steps of using an exporting carrier carrying a pallet capable of accommodating six radioactive waste drums to transport the radioactive waste drums being inspected by an inspection procedure back to a storage location according to the present invention.  
         [0024]      FIG. 5B  is a flow chart depicting steps of positioning a pallet capable of accommodating six radioactive waste drums on an exporting carrier according to a preferred embodiment of the invention.  
         [0025]      FIG. 6A ˜ FIG. 6C  shows the progressing of the removal of radioactive waste drums from a pallet of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     For your esteemed members of reviewing committee to further understand and recognize the fulfilled functions and structural characteristics of the invention, several preferable embodiments cooperating with detailed description are presented as the follows.  
         [0027]     Please refer to  FIG. 1 , which is a schematic diagram showing a radioactive waste drum inspection system of the present invention. The radioactive waste drum inspection system  5  includes an importing carrier  2 , an exporting carrier  2 ′, four inspection stations  52 ,  53 ,  54 ,  55  and a grabber crane  50 . There is a pallet accommodating six radioactive waste drums, numbered as  12   a ,  12   b  for representative, arranged on importing carrier  2 ; and there is an empty pallet  1 ′ arranged on the exporting carrier  2 ′ to be used for accommodating radioactive waste drums passing the inspection process. The four inspection stations are arranged between the importing carrier  2  and the exporting carrier  2 ′ that are respectively used for performing an appearance inspection, a surface contaminant detection, a measurement of radioactivity and nuclide, and a record marking. Nevertheless, the number of inspection station along with the inspection procedures performed therein are dependent on actual requirement, and thus are not limited by the embodiment shown in  FIG. 1 . The transportation between inspection stations are enabled by a conveying apparatus  56 , whereas a grabber crane  50  is arranged at a trail  51  located on top of the radioactive waste drum inspection system  5  that the grabber crane is enabled to move back and forth along the trail  50  for enabling the same to fetch a radioactive waste drum located at a specific position.  
         [0028]     Please refer to  FIG. 2 , which is a schematic view of a pallet used for carrying radioactive waste drums according to a preferred embodiment of the present invention. The pallet used in the method of the present invention is a pallet capable of accommodating at least six radioactive waste drums. In the embodiment shown in  FIG. 2 , the pallet  1  only carries six radioactive waste drums  11   a ,  11   b   1   12   a ,  12   b ,  13   a ,  13   b . However, the number of radioactive waste drums carried by the pallet of the present invention is not limited thereby, that it is dependent on the increasing of the space efficiency used for radioactive waste drum storage. It is noted that the radioactive waste drum used in the embodiment of  FIG. 2  is a 55-gallon tank.  
         [0029]     Please refer to  FIG. 3 , which is a schematic top view of an importing/exporting carrier of the present invention. Since the structure of the importing carrier is the same as that of the exporting carrier, only an importing carrier  2  is shown in  FIG. 3  for illustration. The importing carrier is comprised of a supporting deck  20 , a baffle plate  21 , a boundary switch  23 , and at least three position sensors  22  which are respective the first position sensor  221 , the second position sensor  222  and the third position sensor  223  as shown in  FIG. 3 . The supporting deck  20  is used for carrying the pallet  1  accommodating six radioactive waste drums, whereas the placing of such pallet  1  on the supporting deck  20  can be varied with respect to actual requirement, such as it can be disposed on the supporting deck  20  manually or by automatic guided vehicle. Moreover, the supporting deck  20  is capable of enabling the pallet  1  to more in the lengthwise direction of the supporting deck  20  represented by the Y coordinate of  FIG. 3 , i.e. along the arrow  90 , and to move transversely along the X coordinate of  FIG. 3 , i.e. along the arrow  91 . That is, the supporting deck  20  is equipped with a transportation device for moving the pallet  1  transversely to abut against the baffle plate  21  for positioning the pallet  1  at a specific position on the X coordinate of the same.  
         [0030]     Furthermore, the transportation device also can drive the pallet  1  to move following the Y coordinate of the support deck  20  for positioning the pallet  1  at specific positions in the lengthwise direction, whereas the specific positions are respectively defined by the locations of position sensors  22 , that is, the moving of the pallet  1  is stopped as soon as any one of the sensors  22  is trigger by the pallet  1 . As the lengthwise moving of the pallet  1  is stopped, the grabber carne  50  is activated to fetch a radioactive waste drum arranged at a position corresponding to the triggered sensor  22  while placing the grabbed radioactive waste drum on the conveying apparatus  56  to be send to those inspection stations for inspection, as shown in  FIG. 1 . After the radioactive waste drum finishes all the inspection operation specified in the inspection process of  FIG. 1 , the grabber crane  50  is once again being activated to fetch the inspected radioactive waste drum and place the same on the empty pallet  1 ′ of the exporting carrier  2 ′. In the preferred embodiment shown in  FIG. 3 , the position sensor can be a limit switch or any other sensor capable of detection the position of the pallet; and the number of the sensors arranged on the importing/exporting carrier is correspondence to the amount of radioactive waste drums capable of being accommodated by the pallet  1 . As the pallet capable of accommodating six radioactive waste drums shown in  FIG. 2  that it is considered to have three pairs of radioactive waste drums arranged along the lengthwise direction of the pallet, i.e. the Y coordinate, it is therefore required to have three position sensors to be arranged along the lengthwise direction of the importing/exporting carrier. Similarly, if there are four pairs, then four sensors are required, and so forth. The boundary switch  23  is acted as a safety prevention device for preventing the malfunction of the supporting deck  20 .  
         [0031]     Please refer to  FIG. 4A , which is a flow chart depicting steps of a nuclear waste inspection procedure according to the present invention. The inspection starts at step  30 . In step  30 , a pallet accommodating six radioactive waste drums is placed on the supporting deck of an importing carrier, whereas the placing of the pallet can be performed manually or by an automatic guided vehicle in an automatic manner, and then the flow proceeds to step  31 . In step  31 , the supporting deck drives the pallet to move transversely to abut against the baffle plate for positioning the pallet at a specific position on the X coordinate of the same, and then the flow proceeds to step  32 . In step  32 , the supporting deck drives the pallet to move following the Y coordinate of the support deck for positioning the pallet at specific positions in the lengthwise direction, and then the flow proceeds to step  33 . In addition, detailed description of step  32  is provided hereinafter.  
         [0032]     As soon as the step  32  is complete, the radioactive waste drum to be inspected is positioned at a location suitable to be fetch by the grabber crane for inspection. In step  33 , a grabber crane is activated to fetch a radioactive waste drum out of the six from the pallet for inspection, and the flow proceeds to step  34 . As the fetched radioactive waste drum is being sent for inspection, the inspection can be divided into four stages according to a preferred embodiment as shown in  FIG. 4C , which are the first stage  331 , where an appearance inspection is performed upon the fetched radioactive waste drum; the second stage  332 , where a surface contaminant detection is performed upon the fetched radioactive waste drum; the thirds stage  333 , where the radioactivity and the nuclide of the fetched radioactive waste drum is measured; and the fourth stage  334 , the result relating to the above inspection is marked on the fetched radioactive waste drum. In this preferred embodiment, the four stages are connected using a conveying apparatus for transporting the fetched radioactive waste drum smoothly from one stage to another.  
         [0033]     In step  34 , an evaluation is being made to determine whether there is still any radioactive waste drum presented on the pallet at a location corresponding to current parking position while the fetched radioactive waste drum is being inspected; if so, then the flow goes back to step  33 ; otherwise, the flow proceeds to step  35 . In step  35 , an evaluation is being made to determine whether there is still any radioactive waste drum presented on the pallet; if so, then the flow goes back to step  32  for enabling the pallet to move along the lengthwise direction until it trigger next position sensor; otherwise, the flow proceeds to step  36  as the last position sensor had already been trigger and all the radioactive waste drums arranged on the pallet had already been fetched. In step  36 , the supporting deck of the importing carrier drives the pallet to move back to an initial location, and then the flow proceeds to step  37 . In step  37 , the pallet is removed from the supporting deck for making the same available to next pallet accommodating six radioactive waste drums.  
         [0034]     The detailed description of the lengthwise positioning adjustment of the step  32  of  FIG. 4A  is disclosed in the steps shown in  FIG. 4B  with reference to the arrangement shown in  FIG. 3 . As seen in  FIG. 3 , there are three position sensors, i.e. a first position sensor  221 , a second position sensor  222  and a third position sensor, respectively being arranged at three parking position in a successive order on a lengthwise side of the importing carrier  2 . The lengthwise positioning adjustment of the pallet on the supporting deck starts at step  321 . In step  321 , the support deck drives the pallet to move following the Y coordinate of the support deck, i.e. to perform a lengthwise positioning operation  90 , and then the flow proceeds to step  322 . In step  322 , an evaluation is being made to determine whether the first sensor  221  is trigger by the pallet as the moving of the pallet; if so, then the moving of the pallet is stopped and then the flow proceeds to step  323 . It is noted that as the pallet is stopped as the first position  221  is triggered, the positioning of the pallet is just at a location suitable for the grabber crane to fetch the radioactive waste drums  11   a ,  11   b  as shown in  FIG. 6A . In step  323 , an evaluation is being made to determine whether there is still any radioactive waste drum present on the pallet at a location corresponding to current parking position, i.e. the location of the first position sensor  221 ; if so, the flow proceeds to the step  33  for enabling a grabber crane to fetch a radioactive waste drum located at a position corresponding to the current parking position for inspection.  
         [0035]     In step  323 , if there is no radioactive waste drum present on the pallet at a location corresponding to current parking position, i.e. the location of the first position sensor  221 , there are still four radioactive waste drums presented on the pallet, the flow will go back to repeat the step  32  for driving the pallet to move again until the second position  222  is triggered. As the pallet is stopped at a location when the second position sensor  222  is triggered, the positioning of the pallet is just at a location suitable for the grabber crane to fetch the radioactive waste drums  12   a ,  12   b  as shown in  FIG. 6B . Therefore, as the progressing of the flow depicted in  FIG. 4B , the steps  33 ,  34 ,  35  are proceeded thereafter.  
         [0036]     Similarly, as there is no radioactive waste drum present on the pallet at a location corresponding to current parking position, i.e. the location of the second position sensor  222 , the flow will go back to repeat the step  32  for driving the pallet to move again until the third position  223  is triggered. As the pallet is stopped at a location when the third position sensor  223  is triggered, the positioning of the pallet is just at a location suitable for the grabber crane to fetch the radioactive waste drums  13   a ,  13   b  as shown in  FIG. 6C . Thereafter, the flow will proceed similarly as above description that is not described further herein.  
         [0037]     Please refer to  FIG. 5A , which is a flow chart depicting steps of using an exporting carrier carrying a pallet capable of accommodating six radioactive waste drums to transport the radioactive waste drums being inspected by an inspection procedure back to a storage location according to the present invention. As the step  30  of  FIG. 4A  id progressing, the step  40  of  FIG. 5A  is also initiated. In step  40 , an empty pallet is capable of accommodating six radioactive waste drums is placed on an exporting carrier, and then the flow proceeds to step  41 . In step  41 , the supporting deck drives the pallet to move transversely, and then the flow proceeds to step  42 . In step  42 , the supporting deck drives the pallet to move following the lengthwise direction of the exporting carrier for positioning the pallet at specific positions similar to those shown in step  32  of  FIG. 4A , and then the flow proceeds to step  43 . The detailed description of the lengthwise positioning adjustment is revealed in steps shown in  FIG. 5B , which is similar to those of  FIG. 4B .  
         [0038]     As soon as the step  42  is complete, the empty pallet is located at a position suitable to receive the inspected radioactive waste drums, so that step  43  can be proceeded. In step  43 , a grabber crane grabs and carries a radioactive waste drum passing an inspection process for placing the inspected radioactive waste drum on the pallet, and the flow proceeds to step  44 . In step  44 , an evaluation is being made to determine whether there is still any space pace available on the pallet at the location corresponding to the current parking position for receiving inspected radioactive waste drums; if so, the flow goes back to step  43 ; otherwise, the flow proceeds to step  45 . In step  45 , an evaluation is made to determine whether the pallet is full; if so, the flow proceeds to step  46 ; otherwise, the flow goes back to step  42  for driving the pallet is move until the next positioning sensor is trigger and then the flow proceeds. In step  46 , the exporting carrier is enabled to move the pallet to a storage location, and then the flow proceeds to step  47 . In step  47 , the pallet is removed from the exporting carrier.  
         [0039]     It is noted that the sizes of the importing carrier and the exporting carrier can be adjusted with respect to the size of the pallet. In the pallet disclosed in the preferred embodiment shown in  FIG. 2 , the pallet is able to accommodate six radioactive waste drums by arranging two tanks parallelly at locations respectively corresponding to each parking positions while arranging three parking positions in a successive order on a lengthwise side of the importing/exporting carrier. In another word, if the pallet used in the present invention is able to accommodate eight radioactive waste drums while also arranging two tanks two tanks parallelly at locations respectively corresponding to each parking positions, there will be four parking positions arranged on a lengthwise side of the importing/exporting carrier. As description disclosed above, the present invention is able to use a pallet capable of accommodating at least six radioactive waste drums, so that not only the efficiency of space used for radioactive waste drum storage can be increased, but also the number of radioactive waste drum capable of being transported per unit time is increase.  
         [0040]     While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.