- Email: [email protected]
The minicellTMirradiator: A new system for a new market
~
Radiat. Phys. Chem. Vol. 52, Nos I 6, pp. 409~ 412, 1998 V? 1998 Elsevier Science Ltd. All rights reserved
Pergamon
THE
Printed in Great Britain 0969-806x/98 SI9.00 + 0.00
PII:S0969-806X(98)00042-5
MINICELL
TM
IRRADIATOR: A NEW NEW MARKET
SYSTEM
FOR
A
JAMES F. CLOUSER President & Chief Executive Officer, SteriGenics International ERIC W. BEERS Senior Vice President, Engineering, SteriGenics International ABSTRACT Since the commissioning of the first industrial Gamma Irradiator design, designers and operators of irradiation systems have been attempting to meet the specific production requirements and challenges presented to them. This objective has resulted in many different versions ofirradiators currently in service today, all of which had original charters and many of which still perform very well within even the new requirements of this industry. Continuing changes in the marketplace have, however, placed pressures on existing designs due to a combination of changing dose requirements for sterilization, increased economic pressures from the specific industry served for both time and location and the increasing variety of product types requiring processing. Additionally, certain market areas which could never economically support a typical gamma processing facility have either not been serviced, or have forced potential gamma users to transport product long distances to one of these existing facilities. The MiniCell TM removes many of the traditional barriers previously accepted in the radiation processing industry for building a processing facility in a location. Its reduced size and cost have allowed many potential users to consider in-house processing and its ability to be quickly assembled allow it to meet market needs in a much more timely fashion than the previous designs. The MiniCell system can cost effectively meet many of the current market needs of reducing total cost of processing and also be flexible enough to process product in a wide range of industries effectively. INTRODUCTION G a m m a irradiation was introduced into the sterilization industry with the advent of irradiator systems engineered to meet the demands of a particular application. For example, the first irradiator built in the United States for the purpose of large volume, medical device sterilization focused on operational efficiency for a specific product. The system was fully integrated into the manufacturing process and as a result, provided excellent productivity for that specific operation. As the technology progressed and more information about the ease and flexibility of gamma processing was gained, the design of irradiators began to evolve in order to accommodate the processing of a broader array of products. With the onset of more diverse products and the change in irradiator systems, came the opportunity for contract irradiation processing to emerge. Its introduction provided manufacturers with an alternative to the initial in-house operation and helped spawn the continued development of irradiator systems. Both equipment suppliers and contract irradiation providers conceived and built a variety of system designs which focused on variations in product size and loading efficiencies. These new designs ranged from pallet type systems to tote systems, each offering different presentations of the irradiation source to the product. In general, each system consisted of a single concrete cell or vault for shielding the radioisotope, a warehouse ranging in size from 20 to 40 thousand square feet, a material handling system consisting of hardware and software to transport the product into and out of the concrete cell, and a source rack mechanism to raise and lower the isotope from the containment pool. 409
410
James F. Clouser and Eric W. Beers
Continued growth in the demand for radiation processing forced both the equipment suppliers and contract service providers into a reevaluation of the traditional system designs. In light of the fact that the incremental cost to add capacity to a particular system was less than the cost to build additional stand alone facilities, larger systems with expanded cobalt capacity were introduced. Extending this concept even further, a new facility design was developed utilizing multiple cells and multiple material handling systems which resulted in cobalt-60 capacities totalling 21 million curies, a significant increase over the initial two Megacurie system. The downside of this move toward higher capacity was the inescapable fact that the total cost to construct the new systems and facilities began to increase significantly over the more traditional irradiator, thus, requiring a greater overall throughput of products in order to support the operation. Had market conditions remained stagnant, this trend might well have continued. THE CHANGING MARKET As the medical device market became more competitive, device manufacturers faced increasing pressure from their customers to reduce costs without sacrificing quality or service. One cost-reduction method employed by the manufacturers was to reduce inventories which placed additional demands on the providers of contract sterilization services. Reduced inventories for the manufacturer meant movement away from long, continuous runs of homogeneous products to smaller, more frequent runs of increasingly heterogeneous products and a demand for shorter overall turnaround times for sterilization service. The competitive sterilization technology, Ethylene Oxide (EtO) gas fumigation, began to lose its market share to radiation processing as a wider array of products was identified to be gamma compatible. The fundamental reason for this reduction was the inherent simplicity of radiation and the fact that gamma irradiation offered the immediate release of products aRer processing. However, the radiation sterilization market began undergoing further change as new methods for establishing sterilization doses were adopted. The once standard 2.5 Megarad, or 25 kiloGrey, sterilization dose was challenged based upon actual bioburden analysis. The new dose setting techniques resulted in varying minimum dose requirements. The shift in minimum dose requirements and smaller runs of products demanded more flexibility from the large processing facilities, which resulted in less efficient product scheduling due to the size of the runs and the ability to move from one dose cycle to another. Although processors were able to meet the new challenges, product turnaround times suffered due to scheduling challenges which, in turn, began to drive up inventory costs for manufacturers using either an in-house or contract sterilization system. The longer turnaround times of the gamma facilities were now approaching the inherently longer processing times of EtO. To remain competitive, some irradiator facilities were designed to adjust to the new market needs by building multiple cells at a given facility. The design and operational layout allowed the facility to segregate products into runs that better fit the process parameters. The simplification of scheduling and increased capacity of these systems allowed products to be processed more quickly. These facilities were able to regain the inherent strength of radiation sterilization over its competition by providing expedient and flexible processing. However, the single attribute maintained as a competitive advantage for EtO was that the process' delivery system was considered to be less expensive to build than the gamma irradiation system. Consequently, many smaller EtO systems were built for a variety of applications and markets. A change in regulatory requirements forced EtO suppliers to add additional controls to their designs to reduce gas exposure, causing EtO system costs to increase significantly, and allowing radiation processing the opportunity for continued growth in its market share. Contractors began to focus on building facilities in concentrated geographic regions to which many smaller manufacturing companies could transport products for radiation processing. Based on the capital expenditures and operating requirements of gamma radiation facilities, the volumes required for an operation to be economically feasible was generally conceded to be 1.5 to 2.0 million cubic feet per year of throughput, with each incremental cubic foot of processed product yielding, and hence revenue yielding, approximately 50% gross margins. Consequently, the higher the throughput, the higher the profitability for a contract gamma facility. In contrast to EtO, the contract provider of radiation
10th International Meetingon Radiation Processing
411
services was only able to build new facilities in areas where overall volumes of products were high enough to support a profitable operation. Manufacturers lying outside the more populous medical device manufacturing markets in the country began to incur transportation costs that equalled or exceeded the cost of sterilization. With increased transportation came more frequent product damage, loss of control and tracking problems. Meanwhile, the EtO system suppliers rebounded in the early 90's with new designs to meet the more stringent regulatory and environmental requirements and although the capital expenditures were higher, the process was once more competitive to gamma processing, with several EtO systems servicing smaller markets and geographic regions which traditional radiation systems could not support. A NEW DESIGN FOR A NEW MARKET The MiniCell T M irradiation system was conceived to address many of the current economic and logistic pressures facing manufacturers. The new system breaks down the barrier of high entry cost and long term commitment previously faced by the industry with respect to radiation processing. Fundamentally, the system was developed to process volumes of product less than the standard two million cubic foot per year minimum requirement of other irradiator designs. The irradiator, including the shield, was developed as an integrated package to control all aspects of the system setup. The MiniCell system design addresses both the cost and emotional barriers to entry by removing the "construction" element from the process and replacing it with an "assembly" process, thus making the entire project less disruptive and more timely to complete. The physical size of the irradiator and product handling system, as well as the techniques used to build it, enable the entire system to be placed in an existing building. Since the system is assembled, it can also be completely disassembled if required, which resolves the long standing issue of potential decommissioning common to the industry. The system retains all the benefits of gamma processing developed over the past several years such as simplicity, reliability and high flexibility in products which can be processed. The design also addresses the issue of multiple dose ranges by using a high efficiency batch type system to deliver target doses at any range without increasing process complexity in scheduling. SYSTEM EVALUATION The essence of the MiniCell system is the shield design and manufacturing. A new approach to the traditional "poured in place concrete" design has been taken to remove the construction contractor from the loop almost completely. The entire shield design is prefabricated and assembled prior to its shipment to the site. This assures a timely setup, and when combined with the other system components, ensures all systems fit according to plan. The shield is manufactured of steel and erected on a small foundation which can be easily cut into the floor slab of an existing warehouse. In the center of the foundation is a small storage pool for the isotope which, using novel excavation techniques, can be easily placed into an existing building with minimal disruption to surrounding areas. Once the foundation and pool are in place, the shield can be erected in a matter of weeks, a considerable reduction in time from the traditional shield construction which takes several months and requires either a new building or extensions to an existing building. The size of the MiniCell shield is also important to the overall design. The entire shield measures 20'1 x 21'w x 12'h, a size controlled by the material selected as well as the fact that the design does not use the traditional maze configuration for product ~ansport. Instead, it utilizes an integral shielding door system. The entire shielding system is extremely compact and fully integrated. Once the shield is assembled, a special batch type material handling system can be installed. The system is classified as a tote box, overlapping product design. This particular design was chosen to maintain a relatively high utilization of the cobalt-60 isotope and is achieved by essentially surrounding the source
412
James F. Clouser and Eric W. Beers
with product using a two-level source pass system. A slight increase in machine complexity is required over the more traditional batch type, overlapping source, carrier designs; however, this feature is easily supported in increased cobalt-60 utilization efficiency. The tote box design optimizes both the physical volume available for product loading and the overall size of a complete batch of products. Each tote within the system measures 15 cubic feet, allowing a maximum batch size of 315 cubic feet or the equivalent of up to three standard size pallets of product to be processed in a single batch. The totes have been designed to handle a maximum load of 450 pounds of product which allows for flexibility within the system to process medical products as well as other applications. The source pass area of the irradiator uses a unique dual parallel source configuration which, combined with the optimized source to product separation, allows the system to maintain extremely fight dose uniformity values while maintaining high utilization of the source. The shielding door and batch type process are totally integrated into the design. The batch system incorporates a special feature which both highlights operator safety as well as process efficiency. The system automatically interchanges the product totes within the cell area with new products awaiting processing, eliminating the need for operators to manually remove products from the cell area as with traditional batch irradiators. This feature not only improves system safety by reducing cell access, but also increases operational efficiency through the speed and accuracy of the interchange process, allowing the irradiator to operate on a more regulated schedule. The system features a product loading and unloading system which allows the operation to take full advantage of the batch type environment. By utilizing a unique tilting system, entire batches of product, or totes, can be presented to the operator simultaneously, allowing a complete setup of the run prior to releasing a single product into the process. The operator is then able to perform a more thorough check of all work prior to completing the loading or unloading of products. In addition, the system is designed to ensure that the handlers do not have to extend or reach during their work which also increases overall performance at these stations and helps to reduce the possibility of either injury to the individuals or errors due to physical constraints placed on the handlers. The entire motion control of the totes through the system is executed using simple air cylinders controlled by a fully integrated and validated Programmable Logic Control system. This ensures that the system maintains the high degree of simplicity of operations and reliability which have become synonymous within the gamma processing industry. Any system problems can be easily diagnosed and resolved in a matter of minutes which ensures reliable operation of the irradiator system. The MiniCeU's safety control system utilizes features for redundancy of control and interlocks. All safety features have been fully tested and validated to meet and exceed US-N-RC, local state and international requirements. A formal documentation package is produced for every system which demonstrates the level of testing and validation for both safety and operational control. CONCLUSION By revisiting traditional approaches to the construction and operation of gamma irradiation systems, a new system addressing evolving needs has been developed. This new system, the patented MiniCell, diminishes the requirement for large capital expenditures, lessens the overall construction time, and can be disassembled and moved to an alternative location. The inherent operational benefits realized by manufacturers include reduced transportation cost, faster turnarounds and more direct control. The system can be utilized as a contract facility in both domestic regions and international markets which have not been able to economically justify a traditional system because of their size. Similarly, this system can be leased directly to manufacturers and installed on site to operate as an integral part of the manufacturing process. Gamma irradiation remains the most reliable technology for providing sterilization services. With the advent of the MiniCell, gamma processing systems can now be scaled to lower volumes to be the most cost effective technology across a broader array of products and a wider range of product volumes.
Radiat. Phys. Chem. Vol. 52, Nos I 6, pp. 409~ 412, 1998 V? 1998 Elsevier Science Ltd. All rights reserved
Pergamon
THE
Printed in Great Britain 0969-806x/98 SI9.00 + 0.00
PII:S0969-806X(98)00042-5
MINICELL
TM
IRRADIATOR: A NEW NEW MARKET
SYSTEM
FOR
A
JAMES F. CLOUSER President & Chief Executive Officer, SteriGenics International ERIC W. BEERS Senior Vice President, Engineering, SteriGenics International ABSTRACT Since the commissioning of the first industrial Gamma Irradiator design, designers and operators of irradiation systems have been attempting to meet the specific production requirements and challenges presented to them. This objective has resulted in many different versions ofirradiators currently in service today, all of which had original charters and many of which still perform very well within even the new requirements of this industry. Continuing changes in the marketplace have, however, placed pressures on existing designs due to a combination of changing dose requirements for sterilization, increased economic pressures from the specific industry served for both time and location and the increasing variety of product types requiring processing. Additionally, certain market areas which could never economically support a typical gamma processing facility have either not been serviced, or have forced potential gamma users to transport product long distances to one of these existing facilities. The MiniCell TM removes many of the traditional barriers previously accepted in the radiation processing industry for building a processing facility in a location. Its reduced size and cost have allowed many potential users to consider in-house processing and its ability to be quickly assembled allow it to meet market needs in a much more timely fashion than the previous designs. The MiniCell system can cost effectively meet many of the current market needs of reducing total cost of processing and also be flexible enough to process product in a wide range of industries effectively. INTRODUCTION G a m m a irradiation was introduced into the sterilization industry with the advent of irradiator systems engineered to meet the demands of a particular application. For example, the first irradiator built in the United States for the purpose of large volume, medical device sterilization focused on operational efficiency for a specific product. The system was fully integrated into the manufacturing process and as a result, provided excellent productivity for that specific operation. As the technology progressed and more information about the ease and flexibility of gamma processing was gained, the design of irradiators began to evolve in order to accommodate the processing of a broader array of products. With the onset of more diverse products and the change in irradiator systems, came the opportunity for contract irradiation processing to emerge. Its introduction provided manufacturers with an alternative to the initial in-house operation and helped spawn the continued development of irradiator systems. Both equipment suppliers and contract irradiation providers conceived and built a variety of system designs which focused on variations in product size and loading efficiencies. These new designs ranged from pallet type systems to tote systems, each offering different presentations of the irradiation source to the product. In general, each system consisted of a single concrete cell or vault for shielding the radioisotope, a warehouse ranging in size from 20 to 40 thousand square feet, a material handling system consisting of hardware and software to transport the product into and out of the concrete cell, and a source rack mechanism to raise and lower the isotope from the containment pool. 409
410
James F. Clouser and Eric W. Beers
Continued growth in the demand for radiation processing forced both the equipment suppliers and contract service providers into a reevaluation of the traditional system designs. In light of the fact that the incremental cost to add capacity to a particular system was less than the cost to build additional stand alone facilities, larger systems with expanded cobalt capacity were introduced. Extending this concept even further, a new facility design was developed utilizing multiple cells and multiple material handling systems which resulted in cobalt-60 capacities totalling 21 million curies, a significant increase over the initial two Megacurie system. The downside of this move toward higher capacity was the inescapable fact that the total cost to construct the new systems and facilities began to increase significantly over the more traditional irradiator, thus, requiring a greater overall throughput of products in order to support the operation. Had market conditions remained stagnant, this trend might well have continued. THE CHANGING MARKET As the medical device market became more competitive, device manufacturers faced increasing pressure from their customers to reduce costs without sacrificing quality or service. One cost-reduction method employed by the manufacturers was to reduce inventories which placed additional demands on the providers of contract sterilization services. Reduced inventories for the manufacturer meant movement away from long, continuous runs of homogeneous products to smaller, more frequent runs of increasingly heterogeneous products and a demand for shorter overall turnaround times for sterilization service. The competitive sterilization technology, Ethylene Oxide (EtO) gas fumigation, began to lose its market share to radiation processing as a wider array of products was identified to be gamma compatible. The fundamental reason for this reduction was the inherent simplicity of radiation and the fact that gamma irradiation offered the immediate release of products aRer processing. However, the radiation sterilization market began undergoing further change as new methods for establishing sterilization doses were adopted. The once standard 2.5 Megarad, or 25 kiloGrey, sterilization dose was challenged based upon actual bioburden analysis. The new dose setting techniques resulted in varying minimum dose requirements. The shift in minimum dose requirements and smaller runs of products demanded more flexibility from the large processing facilities, which resulted in less efficient product scheduling due to the size of the runs and the ability to move from one dose cycle to another. Although processors were able to meet the new challenges, product turnaround times suffered due to scheduling challenges which, in turn, began to drive up inventory costs for manufacturers using either an in-house or contract sterilization system. The longer turnaround times of the gamma facilities were now approaching the inherently longer processing times of EtO. To remain competitive, some irradiator facilities were designed to adjust to the new market needs by building multiple cells at a given facility. The design and operational layout allowed the facility to segregate products into runs that better fit the process parameters. The simplification of scheduling and increased capacity of these systems allowed products to be processed more quickly. These facilities were able to regain the inherent strength of radiation sterilization over its competition by providing expedient and flexible processing. However, the single attribute maintained as a competitive advantage for EtO was that the process' delivery system was considered to be less expensive to build than the gamma irradiation system. Consequently, many smaller EtO systems were built for a variety of applications and markets. A change in regulatory requirements forced EtO suppliers to add additional controls to their designs to reduce gas exposure, causing EtO system costs to increase significantly, and allowing radiation processing the opportunity for continued growth in its market share. Contractors began to focus on building facilities in concentrated geographic regions to which many smaller manufacturing companies could transport products for radiation processing. Based on the capital expenditures and operating requirements of gamma radiation facilities, the volumes required for an operation to be economically feasible was generally conceded to be 1.5 to 2.0 million cubic feet per year of throughput, with each incremental cubic foot of processed product yielding, and hence revenue yielding, approximately 50% gross margins. Consequently, the higher the throughput, the higher the profitability for a contract gamma facility. In contrast to EtO, the contract provider of radiation
10th International Meetingon Radiation Processing
411
services was only able to build new facilities in areas where overall volumes of products were high enough to support a profitable operation. Manufacturers lying outside the more populous medical device manufacturing markets in the country began to incur transportation costs that equalled or exceeded the cost of sterilization. With increased transportation came more frequent product damage, loss of control and tracking problems. Meanwhile, the EtO system suppliers rebounded in the early 90's with new designs to meet the more stringent regulatory and environmental requirements and although the capital expenditures were higher, the process was once more competitive to gamma processing, with several EtO systems servicing smaller markets and geographic regions which traditional radiation systems could not support. A NEW DESIGN FOR A NEW MARKET The MiniCell T M irradiation system was conceived to address many of the current economic and logistic pressures facing manufacturers. The new system breaks down the barrier of high entry cost and long term commitment previously faced by the industry with respect to radiation processing. Fundamentally, the system was developed to process volumes of product less than the standard two million cubic foot per year minimum requirement of other irradiator designs. The irradiator, including the shield, was developed as an integrated package to control all aspects of the system setup. The MiniCell system design addresses both the cost and emotional barriers to entry by removing the "construction" element from the process and replacing it with an "assembly" process, thus making the entire project less disruptive and more timely to complete. The physical size of the irradiator and product handling system, as well as the techniques used to build it, enable the entire system to be placed in an existing building. Since the system is assembled, it can also be completely disassembled if required, which resolves the long standing issue of potential decommissioning common to the industry. The system retains all the benefits of gamma processing developed over the past several years such as simplicity, reliability and high flexibility in products which can be processed. The design also addresses the issue of multiple dose ranges by using a high efficiency batch type system to deliver target doses at any range without increasing process complexity in scheduling. SYSTEM EVALUATION The essence of the MiniCell system is the shield design and manufacturing. A new approach to the traditional "poured in place concrete" design has been taken to remove the construction contractor from the loop almost completely. The entire shield design is prefabricated and assembled prior to its shipment to the site. This assures a timely setup, and when combined with the other system components, ensures all systems fit according to plan. The shield is manufactured of steel and erected on a small foundation which can be easily cut into the floor slab of an existing warehouse. In the center of the foundation is a small storage pool for the isotope which, using novel excavation techniques, can be easily placed into an existing building with minimal disruption to surrounding areas. Once the foundation and pool are in place, the shield can be erected in a matter of weeks, a considerable reduction in time from the traditional shield construction which takes several months and requires either a new building or extensions to an existing building. The size of the MiniCell shield is also important to the overall design. The entire shield measures 20'1 x 21'w x 12'h, a size controlled by the material selected as well as the fact that the design does not use the traditional maze configuration for product ~ansport. Instead, it utilizes an integral shielding door system. The entire shielding system is extremely compact and fully integrated. Once the shield is assembled, a special batch type material handling system can be installed. The system is classified as a tote box, overlapping product design. This particular design was chosen to maintain a relatively high utilization of the cobalt-60 isotope and is achieved by essentially surrounding the source
412
James F. Clouser and Eric W. Beers
with product using a two-level source pass system. A slight increase in machine complexity is required over the more traditional batch type, overlapping source, carrier designs; however, this feature is easily supported in increased cobalt-60 utilization efficiency. The tote box design optimizes both the physical volume available for product loading and the overall size of a complete batch of products. Each tote within the system measures 15 cubic feet, allowing a maximum batch size of 315 cubic feet or the equivalent of up to three standard size pallets of product to be processed in a single batch. The totes have been designed to handle a maximum load of 450 pounds of product which allows for flexibility within the system to process medical products as well as other applications. The source pass area of the irradiator uses a unique dual parallel source configuration which, combined with the optimized source to product separation, allows the system to maintain extremely fight dose uniformity values while maintaining high utilization of the source. The shielding door and batch type process are totally integrated into the design. The batch system incorporates a special feature which both highlights operator safety as well as process efficiency. The system automatically interchanges the product totes within the cell area with new products awaiting processing, eliminating the need for operators to manually remove products from the cell area as with traditional batch irradiators. This feature not only improves system safety by reducing cell access, but also increases operational efficiency through the speed and accuracy of the interchange process, allowing the irradiator to operate on a more regulated schedule. The system features a product loading and unloading system which allows the operation to take full advantage of the batch type environment. By utilizing a unique tilting system, entire batches of product, or totes, can be presented to the operator simultaneously, allowing a complete setup of the run prior to releasing a single product into the process. The operator is then able to perform a more thorough check of all work prior to completing the loading or unloading of products. In addition, the system is designed to ensure that the handlers do not have to extend or reach during their work which also increases overall performance at these stations and helps to reduce the possibility of either injury to the individuals or errors due to physical constraints placed on the handlers. The entire motion control of the totes through the system is executed using simple air cylinders controlled by a fully integrated and validated Programmable Logic Control system. This ensures that the system maintains the high degree of simplicity of operations and reliability which have become synonymous within the gamma processing industry. Any system problems can be easily diagnosed and resolved in a matter of minutes which ensures reliable operation of the irradiator system. The MiniCeU's safety control system utilizes features for redundancy of control and interlocks. All safety features have been fully tested and validated to meet and exceed US-N-RC, local state and international requirements. A formal documentation package is produced for every system which demonstrates the level of testing and validation for both safety and operational control. CONCLUSION By revisiting traditional approaches to the construction and operation of gamma irradiation systems, a new system addressing evolving needs has been developed. This new system, the patented MiniCell, diminishes the requirement for large capital expenditures, lessens the overall construction time, and can be disassembled and moved to an alternative location. The inherent operational benefits realized by manufacturers include reduced transportation cost, faster turnarounds and more direct control. The system can be utilized as a contract facility in both domestic regions and international markets which have not been able to economically justify a traditional system because of their size. Similarly, this system can be leased directly to manufacturers and installed on site to operate as an integral part of the manufacturing process. Gamma irradiation remains the most reliable technology for providing sterilization services. With the advent of the MiniCell, gamma processing systems can now be scaled to lower volumes to be the most cost effective technology across a broader array of products and a wider range of product volumes.