Patent ID: 12208363

DETAILED DESCRIPTION

The present disclosure is generally directed to a sublimation apparatus that aims to address the problems with the known sublimation apparatus100described above and other sublimation apparatuses and sublimation methods for producing and isolating one or more radionuclides. More particularly, the disclosed sublimation apparatus is configured to purify and isolate one or more radionuclides while being controlled remotely from outside a shielded environment in which the sublimation apparatus is disposed. In other words, the components of the disclosed sublimation apparatus need not be manipulated (e.g., to create a vacuum tight seal), either via manipulators or manually by an operator within the shielded environment, to perform the sublimation. Instead, the components of the disclosed sublimation apparatus can be fully controlled remotely by a remotely located controller or by the operator while the operator is disposed outside the shielded environment. Thus, the disclosed sublimation apparatus is both easier and safer to use than known sublimation apparatuses. At the same time, the disclosed sublimation apparatus is just as effective (if not more) as known sublimation apparatuses, and beneficially, allows the thermal conditions in the sublimation apparatus to be quickly and easily adjusted in order to optimize the sublimation process.

FIGS.3-13illustrate one example of a sublimation apparatus300constructed in accordance with the teachings of the present disclosure and disposed in a shielded environment304(only depicted inFIG.3). In this example, the shielded environment304is a hot cell, i.e., a concrete bunker with thick walls that protects the surrounding environment from radioactive material used therein, though in other examples the shielded environment can take a different form. The sublimation apparatus300generally includes a crucible block316configured to receive and retain a crucible307containing a solid mixture including one or more radionuclides, a first (or lower) heating block350including one or more first heating elements358configured to generate heat to selectively heat the crucible307as desired, a collection vessel312selectively coupled to the crucible block316, and a second (or upper) heating block354including one or more second heating elements362configured to generate heat to selectively heat the collection vessel312as desired.

In this example, the solid mixture preferably takes the form of an isotope-enriched metal target comprising zinc-68 and copper-67 (the desired radionuclide), though other solid mixtures can be used as well. Thus, at least in this example, the sublimation apparatus300is configured to purify and substantially isolate copper-67 from the isotope-enriched metal target comprising zinc-68 and copper-67, all while being controlled remotely from outside the shielded environment304. To this end, the crucible block316is movable, relative to the lower heating block350, between an open position, specifically shown inFIGS.8and9, in which the crucible block316is spaced from the lower heating block350and the collection vessel312, and a closed position, specifically shown inFIGS.10and11, in which the crucible block316is at least partially disposed within the lower heating block350and the collection vessel312is in fluid communication with the crucible307. When it is desired to substantially sublime the solid mixture, the crucible block316is positioned in the closed position, and the one or more first heating elements358are configured to heat the crucible307carried by the crucible block316to a first pre-determined temperature that heats the solid mixture so as to produce a vapor (in this case, a metal vapor of zinc-68, which solidifies in the collection vessel312) and a solid residue in the crucible307that substantially consists only of the desired radionuclide (in this case, of copper-67). In this example, heating the crucible307will cause at least approximately 95% of metallic zinc-68 in the solid mixture to sublime, such that the solid residue will include at most approximately 5% of the metallic zinc-68 initially in the solid mixture, with the remaining solid residue being copper-67 and other trace metals. As such, as used herein, “substantially sublime” means that at least approximately 95% of the one or more metallic materials to be sublimed are in fact sublimed. On the other hand, when it is desired to substantially melt the sublimed components, the crucible block316is positioned in the closed position, and the one or more second heating elements362are configured to heat at least a portion of the collection vessel312to a second pre-determined temperature that substantially melts the metal vapor and directs the liquefied metal back into the crucible307. Likewise, as used herein, “substantially melt” means that at least approximately 95% of the sublimed components to be melted are in fact liquefied.

The crucible block316is generally configured to receive the crucible307and to retain the crucible307as the crucible block316is moved between the open and closed positions. As best illustrated inFIGS.6and7, the crucible block316is at least partially, if not entirely, surrounded by an insulation block318, such that the crucible block316is thermally insulated from the ambient environment. As best illustrated inFIGS.8-11, the crucible block316in this example takes the form of an integral flange portion that is specifically configured to receive and retain the crucible307in this manner. To this end, the integral flange portion316has a perimeter wall320and a cavity324defined by the perimeter wall320. The cavity324is sized to receive a portion of the crucible307therein, and, in turn, the perimeter wall320is configured to retain the crucible307in the cavity324.

In this example, the first and second heating blocks350,354respectively define two heating zones that are operable independently of one another. The one or more lower heating elements358introduced above are configured to selectively generate heat having the first pre-determined temperature, which is sufficient to at least partially sublime the solid mixture in the crucible307. In some examples, e.g., when the solid mixture is the isotope-enriched metal target comprising zinc-68 and copper-67, the first pre-determined temperature will be equal to between approximately 650 degrees Celsius and 700 degrees Celsius, which is sufficient to substantially sublime the zinc-68 in the solid mixture. In other examples, however, the first pre-determined temperature may be less than 650 degrees Celsius (e.g., approximately 200 degrees Celsius or approximately 450 degrees Celsius), depending upon the internal pressures. Likewise, the one or more upper heating elements362introduced above are configured to selectively generate heat having the second pre-determined temperature, which is sufficient to liquefy, or melt, the metal collected in312. In some examples, the second pre-determined temperature will be equal or substantially equal to the first pre-determined temperature (e.g., between approximately 650 degrees Celsius and 700 degrees Celsius), though in other examples, the second pre-determined temperature may be less than the first pre-determined temperature.

In this example, the lower heating block350includes four lower heating elements358and the upper heating block354also includes four upper heating elements362, though the exact number of lower and upper heating elements358,362can vary. Each of the lower and upper heating elements358,362preferably takes the form of a cartridge heater (e.g., having a power rating of 125 W) disposed in a pocket364formed in the lower heating block350or the upper heating block354, with the lower cartridge heaters358generally oriented horizontally (i.e., perpendicular to a longitudinal axis366of the sublimation apparatus300), and with the upper heating cartridges362generally oriented vertically (i.e., parallel to the longitudinal axis366). In other examples, however, the lower and/or upper heating cartridges can be arranged in a different manner and/or different heating elements can be used. For example, heat pumps, heat pipes, or electrical resistance wires can be used instead of the heating cartridges.

Thus, in this example, the lower heating block350defines a first (or lower) heating zone configured to heat a first (or lower) portion of the sublimation apparatus300to the first pre-determined temperature, and the upper heating block354defines a second (or upper) heating zone that is thermally insulated from the first heating zone and is configured to heat a second (or upper) portion of the sublimation apparatus300to the second pre-determined temperature. The second heating zone is generally thermally insulated from the first heating zone (and vice-versa) via a plurality of insulation blocks (e.g., made of Marinite). In this example, the plurality of insulation blocks includes four identical solid insulation blocks368A surrounding the upper heating block354(and, more particularly, the one or more upper heating elements362), a partially open insulation block368B surrounding the upper heating block354, and a solid insulation block368C surrounding the lower heating block350. Preferably, the partially open block368B is disposed between two adjacent solid insulation blocks368A, as will be discussed in greater detail below, though in some examples, the partially open block368B can be disposed between one of the solid insulation blocks368A and the solid insulation block368C. In any event, because the first and second heating zones are thermally insulated from one another, the first and second portions of the sublimation apparatus300can be heated to different temperatures at different times. For example, the first portion of the sublimation apparatus300can be heated (e.g., to the first temperature) while the second portion of the sublimation apparatus300is not heated (or is cooled) Likewise, the second portion of the sublimation apparatus can be heated (e.g., to the second temperature) while the first portion of the sublimation apparatus300is not heated. The first and second zones can also be heated at the same time (to the same temperature or different temperatures) if desired.

The collection vessel312is generally configured to collect the metal vapor produced when the lower heating block350heats the solid mixture to the first pre-determined temperature. As best illustrated inFIGS.6and7, the collection vessel312in this example takes the form of a telescoping tube that is made of alumina (but can be made of another ceramic material or graphite) and has a first cylindrical portion370that is disposed in a second cylindrical portion374, such that the first and second cylindrical portions370,374are slidable relative to one another. The collection vessel312also includes a baffle376that is carried by the first cylindrical portion370and includes a plurality of holes that fluidly couple the first cylindrical portion370and the second cylindrical portion374(albeit to a limited degree, because of the size of the holes). In this example, the baffle376is located approximately halfway between a bottom end of the first cylindrical portion370and a top end of the second cylindrical portion374, such that the baffle376is located approximately in the middle of the upper heating block354. In other examples, however, the baffle376can be located closer to the top end of the second cylindrical portion374. For example, the baffle376can instead be located immediately adjacent the top end of the second cylindrical portion374.

As best illustrated inFIGS.6and7, the collection vessel312is disposed within a central opening378of the lower heating block350and a central opening382of the upper heating block354that is co-axial with the central opening378, both of which extend along the longitudinal axis366. The lower heating block350surrounds lower portions of both the first and second cylindrical portions370,374, as well as a portion of the crucible block316(when the crucible block316is in the closed position). Accordingly, when the lower heating elements358generate heat, the lower heating elements358are configured to heat at least the lower portion of both the first and second cylindrical portions370,374, as well as the crucible block316(when the crucible block316is in the closed position), as will also be discussed in greater detail below. Meanwhile, the upper heating block354surrounds an upper portion of the first cylindrical portion370and at least a middle portion of the second cylindrical portion374. Accordingly, when the upper heating elements362generate heat, the upper heating elements362are configured to heat at least the upper portion of the first cylindrical portion370and the middle portion of the second cylindrical portion374, as will be discussed in greater detail below.

Preferably, the sublimation apparatus300also include means for selectively and controllably cooling the second heating zone (and, more particularly, the upper portion of the first cylindrical portion370) to, for example, facilitate or expedite the sublimation process when the first heating zone is heating the first (or lower) portion of the sublimation apparatus300to the first pre-determined temperature. To this end, the means for selectively cooling the second heating zone can cool the second heating zone to one or more temperatures less than the first pre-determined temperature. In some examples, the means for selectively cooling the second heating zone can cool the second heating zone to a plurality of different temperatures that decrease as the second heating zone moves away from the lower heating block350. For example, the means for selectively cooling the second heating zone can cool the second heating zone to four different temperatures, e.g., less than 30 degrees Celsius, less than 50 degrees Celsius, less than 70 degrees Celsius, and less than 120 degrees Celsius, as the second heating zone moves away from the lower heating block350. In any event, it will be appreciated that the temperature(s) can be adjusted as needed in order to control the sublimation process and the location within the collection vessel in which the vapor will condense.

The sublimation apparatus300in this example includes such a means, in the form of one or more cooling passages400, an air blower404, and one or more discharge passages408. Preferably, the sublimation apparatus300includes four cooling passages400generally arranged about the perimeter of the upper heating block354(seeFIG.6), though in other examples, the sublimation apparatus300can include more or less cooling passages400. The one or more cooling passages400are defined between the upper heating block354and the insulation blocks368, such that the one or more cooling passages400are immediately adjacent and thermally coupled to the upper heating block354. In turn, the one or more cooling passages400generally extend in a direction along the longitudinal axis366. Meanwhile, the air blower404is fluidly coupled to the one or more cooling passages400and configured to selectively direct cooling fluid, e.g., air or water from a source of cooling fluid (not shown) into the sublimation apparatus300and into the one or more cooling passages400, thereby cooling the upper heating block354(as well as the upper portion of the first cylindrical portion370). In this example, the air blower404extends through and partially outward from the insulation blocks368at a position immediately adjacent an upper portion of the second cylindrical portion374. Preferably, the sublimation apparatus300includes four discharge passages408(seeFIG.6), though in other examples, the sublimation apparatus300can include more or less discharge passages408. The one or more discharge passages408are fluidly coupled to the one or more cooling passages400in order to exhaust any cooling fluid that is provided to and flows through the one or more cooling passages400(via the air blower404). In this example, the one or more discharge passages408are defined between the partially open insulation block368B and the lowermost solid insulation block368A, such that the one or more discharge passages408are positioned upstream of the lower heating elements358. In this manner, any cooling fluid that is exhausted from the cooling passages400(and any heat pulled from the upper heating block354in turn) does not affect the temperature of the lower heating block350(or the first heating zone).

As best illustrated inFIGS.9and11, the sublimation apparatus300in this example also includes a sealing element500. The sealing element500is generally configured to seal the crucible307within the lower heating block350and from the ambient environment when the crucible block316is in the closed position. In this example, the sealing element500takes the form of a grafoil gasket (e.g., a high purity grafoil gasket or a reactor grade grafoil gasket) that is capable of withstanding higher temperatures, such as the first pre-determined temperature described herein, for partially subliming the solid mixture contained in the crucible307. In other examples, however, the sealing element500can instead take the form of a C-seal or other type of sealing element and/or can instead be made of, for example, aluminum or gold. In any event, the sealing element500is carried by the crucible block316such that the sealing element500surrounds the perimeter wall320of the integral flange portion316. Thus, when the crucible block316is in the closed position, the sealing element500sealingly engages a bottom portion of the lower heating block350and prevents any materials (or heat) from escaping the sublimation apparatus300(e.g., between the crucible block316and the lower heating block350). As best illustrated inFIG.11, when the crucible block316is in the closed position, the sealing engagement is enhanced by the fact that the sealing element500is pinched by and between first and second opposite protrusions502,503formed on the lower heating block350and the crucible block316, respectively. In other examples, e.g., when the sealing element500takes the form of a C-seal or other type of sealing element, the sealing element500can be disposed in a groove that helps to pinch the sealing element500in the desired position.

As also best illustrated inFIGS.9and11, the sublimation apparatus300in this example further includes a collar504and a spacer508. The collar504is disposed in the collection vessel312(and, more particularly, matingly engages the first cylindrical portion370) and acts as a barrier that prevents a chemical reaction between the metal being sublimed (in this case zinc-68) and the material of the lower heating block350(in this case Stainless Steel), which could damage the components of the sublimation apparatus300and cause a loss of the sublimed material. In this example, the collar504matingly engages a bottom portion of the first cylindrical portion370such that the collar504is fixedly disposed in the collection vessel312. In other examples, however, the collar504can instead be movably disposed in the collection vessel312such that the collar504occupies a first position when the crucible block316is in the open position and occupies a second position when the crucible block316is in the closed position. Meanwhile, the spacer508is sized and arranged to help maintain the sealing element500in the desired position against the integral flange portion316. In this example, the spacer508matingly engages the collar504such that the spacer508is fixedly disposed between the sealing element500and the collar504. In turn, as illustrated inFIG.11, the spacer508is surrounded by the lower heating block350and the spacer508surrounds the perimeter wall320of the integral flange portion316(and, in turn, the crucible307) when the crucible block316is in the closed position.

Optionally, the sublimation apparatus300in this example further includes a funnel512that is coupled to the crucible307to help to direct melted metal that had sublimed (condensed metal vapor collected in the collection vessel312) back into the crucible307(or into a new crucible307) when desired. In this example, the funnel512is coupled to the crucible307such that the funnel512receives and surrounds a portion of the perimeter wall320. In turn, the funnel512is movable along with the crucible307(and the crucible block316), relative to the collar504and the spacer508, as the crucible block316is moved between the open and closed positions. As the crucible block316is moved towards and into the open position, the spacer508helps to guide the funnel512(as well as the crucible307) into the proper position. When the crucible block316reaches and is in the closed position shown inFIGS.10and11, the funnel512is disposed within the collection vessel312and engages both the collar504and the spacer508such that the funnel512is substantially disposed between the collar504and the spacer508. Conversely, when the crucible block316is in the open position shown inFIGS.8and9, the funnel512is also disposed outside of the collection vessel312, such that the funnel512is spaced from both the collar504and the spacer508.

Turning now toFIGS.12and13, the sublimation apparatus300in this example further includes a compensator assembly600that is operatively coupled to the crucible block316. The compensator assembly600is generally configured to maintain a relatively constant load on the sealing element500in order to compensate for thermal expansion and seal creep conditions during operation of the sublimation apparatus300. In this example, the compensator assembly600includes a plurality of compensator housing plates608, two pairs of compensator springs612, and upper and lower spring plates616,620for retaining the compensator springs612. The compensator housing plates608are coupled (e.g., bolted) together so as to form a housing for the springs612. The compensator springs612are disposed in this housing such that the compensator springs612of each pair of compensator springs612are concentrically arranged, with one end of each compensator spring612seated against the upper spring plate616, which is fixedly coupled to the housing. However, as best illustrated inFIGS.12and13, the other end of each compensator spring612extends through a respective opening formed through the lower spring plate616, which is movable within the housing to adjust the total load (i.e., spring force) generated by the pair of compensator springs612.

The compensator assembly600in this example also includes a shaft plate624and a pair of spring shafts628that extend between and connect a bottom one of the compensator housing plates608and the shaft plate624. Each of the spring shafts628extends in a direction parallel to the longitudinal axis366. As illustrated inFIGS.12and13, each of the spring shafts628is at least partially surrounded by a respective one of the pairs of compensator springs612. Accordingly, the total load generated by the two pairs of compensator springs612is subsequently transferred to the pair of spring shafts624, which in turn transfers the total load to the shaft plate624.

With reference now toFIGS.4,5,8, and10, the sublimation apparatus300in this example also includes a plurality of compensator shafts650and a drive assembly654. The plurality of compensator shafts650are generally configured to operably couple the compensator assembly600to the crucible block316. As best illustrated in these FIGS., the plurality of compensator shafts650are arranged so that a first end658of each shaft650is disposed in and fixed to the lower heating block350and a second end662of each shaft650extends through and is fixed to the shaft plate624. Because the plurality of compensator shafts650are fixed in this way, the total load generated by the two pairs of compensator springs612and transferred to the shaft plate624is likewise transferred to the compensator shafts650, which in turn apply a first force on the sealing element500in a first direction (downwards in this case), away from the lower heating block350. Each of the compensator shafts650extends in a direction parallel to the longitudinal axis366, such that the crucible block316is movable along the plurality of compensator shafts650(via apertures formed in the crucible block316) as the crucible block316moves between the open position and the closed position.

Like the plurality of compensator shafts650, the drive assembly654is also operably coupled to the crucible block316, but so as to drive movement of the crucible block316between the open position and the closed position along the plurality of compensator shafts650. In this example, the drive assembly654takes the form of a jack assembly including a jack tube700, a jack plate704, a jack shaft708, an extension tube712, and a screw jack716, along with a drive motor720configured to drive the components of the jack assembly to achieve the desired movement of the crucible block316. Moreover, the drive assembly654is configured to generate a second force that is applied (via the jack tube700) on the sealing element500in a second direction (upwards in this case), towards the lower heating block350.

As best illustrated inFIGS.4,5,8, and9, the jack tube700is fixedly coupled to the crucible block316such that the jack tube700and the crucible block316move together in unison along the longitudinal axis366. More particularly, the jack tube700has a first end720that is fixedly coupled against a bottom surface of the integral flange portion316. The jack tube700also has a second end724that is fixedly coupled to the jack plate704, such that the jack tube700and the jack plate704also move together in unison along the longitudinal axis366. While somewhat difficult to see, but best seen inFIGS.8and10, the jack plate704has a pair of shaft openings728sized to receive the pair of compensator shafts650, which respectively extend therethrough.

The jack shaft708is fixedly coupled to the jack plate704such that the jack shaft708also moves in unison with the jack plate704(and the jack tube700and the crucible block316). More particularly, the jack shaft708has a first end fixedly coupled to a surface of the jack plate704opposite the second end724of the jack tube700. On the other hand, the jack shaft708has a second end that is movably (e.g., slidably) disposed within the extension tube712, which is fixed in place (e.g., by the upper spring plate616). Thus, the crucible block316, the jack tube700, the jack plate704, and the jack shaft708are all movable relative to the extension tube712by moving the second end of the jack shaft708further within or further outside of the extension tube712along the longitudinal axis366.

The screw jack716is operably coupled to a portion of the jack shaft708in a known manner so as to control the position of the second end of the jack shaft708(and the crucible block316) relative to the extension tube712. Likewise, the drive motor720is operably coupled to the screw jack716so as to control the screw jack716, and, in turn, the position of the second end of the jack shaft708relative to the extension tube712. In this example, the drive motor720is a direct current (DC) motor having a variable speed controller. In other examples, however, the drive motor720can be an alternating current motor. Moreover, in this example, there is a large gear ratio from the drive motor720to the jack shaft708in order to prevent overloading by the jack assembly. Optionally, in this example, the drive assembly654also includes a slip clutch arranged between the screw jack716and the drive motor720. The slip clutch helps to control the torque between the screw jack716and the drive motor720in order to further prevent overloading by the jack assembly.

In some examples, such as the example illustrated inFIGS.3-13, the sublimation apparatus300includes a support structure750configured to retain and support the components of the sublimation apparatus300. As best illustrated inFIGS.4and5, the support structure750in this example takes the form of a table having a plurality of legs754, a first support758coupled to the plurality of legs754, and a second support762coupled to the plurality of legs754. As best illustrated inFIGS.4and5, the compensator assembly600is generally disposed between the first and second supports758,762. More particularly, a bottom housing plate608of the plurality of compensator housing plates608is directly coupled (e.g., bolted) to the first support758, and a top housing plate608of the plurality of compensator housing plates608is directly coupled (e.g., bolted) to the second support762, with the remaining compensator housing plates608, the pair of compensator springs612, and the upper and lower spring plates616,620disposed between the first and second supports758,762. However, the second support762includes a pair of apertures through which the pair of spring shafts628respectively extend, such that the shaft plate624is disposed above the second support762and the pair of spring shafts628are partially disposed above the second support762. On the other hand, the drive assembly654is generally coupled to and disposed above the second support762. More particularly, the screw jack716and the drive motor720are directly coupled to the second support762, the jack tube700and the jack plate704are disposed above the second support762, and the jack shaft708and the extension tube712are partially disposed above the second support762.

As discussed above, the sublimation apparatus300is configured to purify and isolate one or more radionuclide (in this example copper-67) while being controlled remotely from outside the shielded environment304. To this end, the sublimation apparatus300includes a local control system800that is communicatively connected (via a wired or wireless connection) to the sublimation apparatus300in order to control operation of the sublimation apparatus300. More particularly, the local control system800is configured to control the temperatures and heat rate within the sublimation apparatus300by controlling the lower heating elements358, the upper heating elements362, the air blower404, the drive assembly654, and other components (e.g., sensors, switches) of the sublimation apparatus300.

In this example, the local control system800includes a local controller804, a plurality of sensors communicatively connected to the local controller804, and a plurality of valves (e.g., a plurality of solenoid valves) communicatively connected to the local controller804to open, close, or otherwise adjust the components of the sublimation apparatus300. The local controller804, which is preferably a J-KEM controller, is communicatively connected to the lower heating elements358, the upper heating elements362, the air blower404, the drive motor720, the plurality of sensors, and the plurality of valves, such that the local controller804can control operation of the sublimation apparatus300. The local controller804can, in turn, be communicatively connected (via a wired or wireless connection) to and automatically controlled by a remotely located controller (e.g., a central controller located outside of the shielded environment304) or can be manually controlled by an operator located outside of the shielded environment304.

The plurality of sensors are generally coupled to components of the sublimation apparatus300in order to sense pressure, temperature, force, and other variables within the sublimation apparatus300. In this example, the plurality of sensors include a plurality of load cells, a plurality of thermocouples, and a pressure gauge that measures the pressure in the collection vessel312. While not illustrated herein, the plurality of load cells are distributed throughout the compensator assembly600in order to detect the total load generated by the compensator assembly600. While also not illustrated herein, the plurality of thermocouples are disposed in the lower heating block350and the upper heating block354in order to detect the temperature(s) and heat rate in the lower heating block350and the upper heating block354, respectively. In other examples, however, the plurality of sensors can include different and/or additional sensors. In any event, the local controller804can in turn, collect data from the sensors employed in the sublimation apparatus300for use in controlling the sublimation apparatus300to ensure that the sublimation and melting processes are being properly performed. For example, the local controller804can use temperature data from a plurality of thermocouples in the lower heating block350and the upper heating block354in order to adjust the temperature of the heat generated by the lower heating elements350and the upper heating elements354. The plurality of valves are also not illustrated herein, but include one or more valves to open and close the collection vessel312to vacuum pressure or to inert gas, depending upon the desired operation of the sublimation apparatus300, as well as one or more valves to control the screw jack716. In other examples, however, the plurality of valves can include different and/or additional valves.

When it is desired to operate the sublimation apparatus300to purify and substantially isolate copper-67 (or other radiopharmaceutical) from the isotope-enriched metal target comprising zinc-68 and copper-67 (or other metal target) contained in the crucible307, the local controller804(in response to a request from the remotely located controller or the remotely located operator) generally causes the crucible block316, which includes the crucible307, to move from the open position to the closed position. The local controller804does so by activating the drive motor720, which in turn drives rotation of the screw jack716in a first direction (e.g., a clockwise direction), which in turn causes the jack shaft708to move upwards, from the position shown inFIGS.8and9to the position shown inFIGS.10and11. Because the jack tube700and the jack plate704move in unison with the jack shaft708, this simultaneously causes the jack tube700and the jack plate704to move upwards, from the position shown inFIGS.8and9to the position shown inFIGS.10and11. Because the crucible block316also moves in unison with the jack tube700, this also simultaneously causes the crucible block316to move upwards, from the position shown inFIGS.8and9until the crucible block316reaches its closed position, shown inFIGS.10and11. As discussed above, when the crucible block316is in the closed position, the crucible block316is at least partially disposed within the lower heating block350. More particularly, the integral flange portion316is partially disposed within the lower heating block350, such that the lower heating elements358are positioned immediately adjacent and substantially surround the crucible307carried by the integral flange portion316. At the same time, the sealing element500sealingly engages the bottom portion of the lower heating block350, and the collection vessel312is in fluid communication with the crucible307, thereby creating a sealed process chamber that is within the collection vessel312and seals the crucible307from the ambient environment. The first and second forces, which are respectively generated and applied by the compensator shafts650and the drive assembly654, also help to maintain this sealed process chamber when the sealing element500sealingly engages the bottom portion of the lower heating block350. Further, while not illustrated, it will be appreciated that at some point before the sublimation process begins, the collection vessel312will be subjected to a dynamic or static vacuum by coupling a vacuum source to the second cylindrical portion374of the collection vessel312.

In turn, the local controller804activates the lower heating elements358, causing the lower heating elements358to produce heat having the first temperature, which heats the lower portion of the sublimation apparatus300, particularly the integral flange portion316and the crucible307, to the first pre-determined temperature (which is monitored by the plurality of thermocouples). As the solid mixture contained in the crucible307is heated to the first pre-determined temperature, substantially all (i.e., at least approximately 95%) of the zinc-68 in the solid mixture is converted into metal vapor that is collected by and condenses within the collection vessel312, particularly within the upper portion of the first cylindrical portion370of the collection vessel312. The conversion of the zinc-68 into metal vapor leaves the crucible307with the solid residue substantially consisting only of copper-67 (which has a lower vapor pressure than the zinc-68 at the first temperature and hence is not converted into vapor).

Generally speaking, while the lower heating elements358are producing heat having the first temperature to sublime substantially all of the zinc-68, the local controller804keeps the upper heating elements362off, such that the upper heating elements362do not provide any heat to the second heating zone. In some cases, it may be necessary to actually lower the temperature in the second heating zone in order to facilitate or expedite sublimation of the zinc-68. In these such cases, the local controller804activates the means for selectively cooling the second heating zone. More particularly, the local controller804causes the air blower404to draw in cooling fluid, which is subsequently routed through the one or more cooling passages400, thereby cooling the upper heating block354as well as the upper portion of the first cylindrical portion370. The cooling fluid is then routed out of the second heating zone (and the sublimation apparatus300) via the one or more discharge passages408.

When the sublimation process is complete (i.e., substantially all of the zinc-68 has been sublimed, which in some cases takes a minimum of 100 minutes but in other cases takes between 200 and 230 minutes), the local controller804causes one or more of the valves to open and return the collection vessel312to ambient pressure and then generally causes the crucible block316to move from the closed position back to the open position. The local controller804does so by again activating the drive motor720, but this time so as to drive rotation of the screw jack716in a second direction (e.g., a counter-clockwise direction), which in turn causes the jack shaft708to move downwards, from the position shown inFIGS.10and11to the position shown inFIGS.8and9. Movement of the jack shaft708in this manner simultaneously causes the jack plate704, the jack tube700, and the crucible block316to move downwards, from the position shown inFIGS.10and11to the position shown inFIGS.8and9. As discussed above, when the crucible block316is in the open position, the crucible block316is spaced from the lower heating block350and the collection vessel312. Likewise, the jack tube700and the jack plate704are spaced from the lower heating block350and the collection vessel312, with the jack plate704located approximately halfway between the lower heating block350and the shaft plate624.

When the crucible block316is back in the open position, the crucible307can be removed (e.g., via the manipulators described above or other robot means), and the solid residue contained therein subjected to further processing in order to fully purify and isolate the copper-67. At the same time, if desired, the sublimation apparatus300can be operated to melt the zinc-68 condensed within the collection vessel312(more particularly solidified on an internal sidewall of the first cylindrical portion370) and to collect the melted zinc-68 in a new crucible307installed on the crucible block316. To this end, the local controller804again causes the crucible block316, which now includes the new crucible307, to move from the open position back to the closed positon just as described above. The local controller804activates the upper heating elements362, causing the upper heating elements362to produce heat having the second pre-determined temperature, which heats the upper portion of the sublimation apparatus300, particularly the upper portion of the first cylindrical portion370and the middle portion of the second cylindrical portion374, to the second pre-determined temperature. The local controller804may also activate the lower heating elements358, causing the lower heating elements358to produce heat having the first pre-determined temperature, which is sufficient to at least help melt the zinc-68 and which heats the lower portion of the sublimation apparatus300, particularly the lower heating block350, to the first pre-determined temperature (which may be the same as or different than the second pre-determined temperature). At some point before this happens, the collection vessel312(particularly the second cylindrical portion374) is back-filled with an inert gas, e.g., argon, helium, nitrogen (or any combination of these gases) or any combination of these gases mixed with hydrogen. In turn, the zinc-68 that has condensed in the collection vessel312is heated, thereby converting substantially all of the zinc-68 from solid to liquid. The liquefied zinc-68 subsequently falls in the collection vessel312and is directed by the collar504and the funnel512into the new crucible307. The liquefied zinc-68 collected by the new crucible307can then be solidified by allowing the system to return to ambient temperature and can in turn be recycled or re-used in further production of a radionuclide and further sublimation processes.

It will be appreciated that the sublimation and melting processes described herein can be repeated any number of times with any number of different crucibles and different solid mixtures. It will also be appreciated that the sublimation apparatus300can include a number of other components not specifically illustrated herein. In some examples, the sublimation apparatus300can include a fan that helps to maintain the compensator assembly600at the ambient temperature.

The following list of aspects reflects a variety of the embodiments explicitly contemplated by the present application. Those of ordinary skill in the art will readily appreciate that the aspects below are neither limiting of the embodiments disclosed herein, nor exhaustive of all the embodiments conceivable from the disclosure above, but are instead meant to be exemplary in nature.

1. A sublimation apparatus adapted to be disposed in a shielded environment and configured to be controlled remotely from outside the shielded environment, the sublimation apparatus comprising: a crucible block adapted to retain a crucible containing a solid mixture comprising one or more radionuclides; a first heating block comprising one or more first heating elements configured to selectively generate heat having a first temperature sufficient to at least partially sublime the solid mixture; and a collection vessel coupled to the first heating block, wherein the crucible block is movable, relative to the first heating block, between an open position, in which the crucible block is spaced from the first heating block and the collection vessel, and a closed positon, in which the crucible block is at least partially disposed within the first heating block and the collection vessel is in fluid communication with the crucible, and wherein when the crucible block is in the closed position, the one or more first heating elements are configured to heat the crucible block to the first temperature, thereby heating the solid mixture and producing a vapor that is collected by the collection vessel and leaving a solid residue in the crucible that substantially consists only of the one or more radionuclides.

2. The sublimation apparatus of aspect 1, further comprising a second heating block thermally insulated from the first heating block, the first heating block comprising the one or more first heating elements configured to selectively generate the heat having the first temperature, and the second heating block comprising one or more second heating elements configured to selectively generate heat having a second temperature sufficient to melt the vapor collected by the collection vessel.

3. The sublimation apparatus of claim2, wherein when the crucible block is in the closed position, the crucible block is at least partially disposed within the first heating block and the one or more first heating elements are configured to generate the heat having the first temperature to heat the crucible block to the first temperature.

4. The sublimation apparatus of aspect 2 or 3, wherein the second heating block surrounds an upper portion of the collection vessel.

5. The sublimation apparatus of any one of aspects 1 to 4, further comprising one or more cooling passages formed immediately adjacent the second heating block, the one or more cooling passages configured to selectively direct cooling fluid toward the collection vessel to facilitate condensation of the metal vapor.

6. The sublimation apparatus of any one of aspects 1 to 5, wherein the crucible block further comprises a sealing element configured to seal the crucible from the ambient environment when the crucible block is in the closed position.

7. The sublimation apparatus of aspect 6, further comprising a compensator assembly operatively coupled to the crucible block, the compensator assembly comprising one or more springs configured to apply a constant load on the sealing element.

8. The sublimation apparatus of aspect 7, further comprising a plurality of compensator shafts coupled to the first heating block and to the compensator assembly, wherein the crucible block is movable, relative to the first heating block, between the open position and the closed position via the plurality of compensator shafts.

9. The sublimation apparatus of any one of aspects 1 to 8, further comprising a drive assembly operably coupled to the crucible block to move the crucible block between the open position and the closed position.

10. The sublimation apparatus of aspect 9, wherein the drive assembly comprises a screw jack; a screw jack shaft operatively coupled to the screw jack and to the crucible block; and a drive motor configured to drive the screw jack to move the screw jack shaft, thereby moving the crucible block between the open position and the closed position.

11. The sublimation apparatus of aspect 10, further comprising a slip clutch installed between the drive motor and the screw jack.

12. A sublimation apparatus adapted to be disposed in a shielded environment and configured to be controlled remotely from outside the shielded environment, the sublimation apparatus comprising: a crucible block adapted to retain a crucible containing a solid mixture comprising one or more radionuclides; a lower heating block, the lower heating block comprising one or more lower heating elements configured to selectively generate heat having a first temperature sufficient to at least partially sublime the solid mixture; an upper heating block thermally insulated from the lower heating block; and a collection vessel coupled to the upper heating block, wherein the crucible block is movable, relative to the lower heating block, between an open position, in which the crucible block is spaced from the lower heating block and the collection vessel, and a closed positon, in which the crucible block is at least partially disposed within the lower heating block and the collection vessel is in fluid communication with the crucible, wherein when the crucible block is in the closed position, the one or more lower heating elements are configured to heat the crucible block to the first temperature, thereby heating the solid mixture and producing a metal vapor that is collected by the collection vessel and leaving a solid residue in the crucible that substantially consists only of the one or more radionuclides, and wherein the upper heating block comprises one or more upper heating elements configured to selectively generate heat having a second temperature sufficient to melt the vapor in the collection vessel.

13. The sublimation apparatus of aspect 12, further comprising one or more cooling passages formed through the upper heating block, the one or more cooling passages configured to selectively direct cooling fluid toward the collection vessel to facilitate condensation of the metal vapor.

14. The sublimation apparatus of aspect 13, further comprising an air blower fluidly coupled to the one or more cooling passages and configured to direct the cooling fluid into the one or more cooling passages.

15. The sublimation apparatus of aspect 13 or 14, further comprising one or more discharge passages formed between the upper heating block and the lower heating block, the one or more discharge passages fluidly coupled to the one or more cooling passages to exhaust the cooling fluid.

16. The sublimation apparatus of any one of aspects 12 to 15, wherein the crucible block further comprises a sealing element configured to seal the crucible from the ambient environment when the crucible block is in the closed position.

17. The sublimation apparatus of aspect 16, further comprising a compensator assembly operatively coupled to the crucible block, the compensator assembly comprising one or more springs configured to apply a constant load on the sealing element.

18. The sublimation apparatus of aspect 17, further comprising a plurality of compensator shafts coupled to the heating block and to the compensator assembly, wherein the crucible block is movable, relative to the heating block, between the open position and the closed position via the plurality of compensator shafts.

19. The sublimation apparatus of aspect 12, further comprising a drive assembly operably coupled to the crucible block to move the crucible block between the open position and the closed position.

20. The sublimation apparatus of aspect 12, wherein the second temperature is substantially equal to the first temperature.

21. A sublimation apparatus adapted to be disposed in a shielded environment and configured to be controlled remotely from outside the shielded environment, the sublimation apparatus comprising: a crucible block adapted to retain a crucible containing a solid mixture comprising one or more radionuclides; a lower heating block comprising one or more lower heating elements configured to selectively generate heat having a first temperature sufficient to at least partially sublime the solid mixture; an upper heating block thermally insulated from the lower heating block; a collection vessel coupled to the upper heating block, the upper heating block comprising one or more upper heating elements configured to selectively generate heat to heat the collection vessel; and one or more cooling passages formed through the upper heating block, the one or more cooling passages configured to selectively direct cooling fluid or gas toward the collection vessel to facilitate condensation of the metal vapor, wherein the crucible block is movable, relative to the lower heating block, between an open position, in which the crucible block is spaced from the lower heating block and the collection vessel, and a closed positon, in which the crucible block is at least partially disposed within the lower heating block and the collection vessel is in fluid communication with the crucible, and wherein when the crucible block is in the closed position, the one or more lower heating elements are configured to heat the crucible block to the first temperature, thereby heating the solid mixture and producing a vapor that is collected by the collection vessel and leaving a solid residue in the crucible that substantially consists only of the one or more radionuclides.

22. A sublimation apparatus adapted to be disposed in a shielded environment and configured to be controlled remotely from outside the shielded environment, the sublimation apparatus comprising: a crucible block adapted to retain a crucible; a collection vessel comprising vapor condensate; and a heating block coupled to the collection vessel and comprising one or more heating elements configured to selectively generate heat having a temperature sufficient to melt the vapor condensate in the collection vessel, wherein the crucible block is movable, relative to the heating block, between an open position, in which the crucible block is spaced from the heating block and the collection vessel, and a closed positon, in which the collection vessel is in fluid communication with the crucible, wherein when the crucible block is in the closed position, the one or more heating elements are configured to heat the heating block surrounding the collection vessel and the crucible block to the first temperature, thereby melting substantially all of the metal vapor condensate in the collection vessel, and wherein the crucible collects the melted vapor condensate.