Demonstration facilities for the byproducts utilization program

Radiat. Phys. Chem. Vol. 25. Nos. 1-3, pp. 251-261. 1985

0146-5720,/85 $3.00 + .00 Pergamon Press Ltd

Printed in Great Britain.

DEMONSTRATION FACILITIES FOR THE BYPRODUCTS UTILIZATION PROGRAM

Nell J. Ferrell and Daniel P. Sloan CB2M HILL, INC. 6121 Indian School Road, N.E., Suite 206 Albuquerque, New Mexico 87110

ABSTRACT

Since its inception in the early 1970's, the U.S. Department of Energy's Byproducts Utilization Program (BUP) has been firmly committed to developing and encouraging the widespread beneficial commercial use of nuclear byproducts produced in DOE programs. The specific objectives of the BUP are to: (i) identify beneficial applications for byproducts from spent nuclear fuel, (2) assess the viability of those applications, and (3) transfer the developed byproduct technology to the users. Each potential application is carefully studied to ensure that considerations of health, safety, environment, public acceptance, and cost-benefit are satisfied. One of the major isotopes produced in nuclear reactors is cesium-137, The ceslum-137 irradiator program has been ongoing for several years, liminary planning has been done, and the development of technology is Consequently, the program is directed toward the design, construction, of prototype demonstration irradlators and transfer of the technology sector.

a gamma emitter. much of the prewell established. and evaluation to the private

This paper summarizes t h e operational characteristics and design considerations key to the development of the demonstration irradiators and presents information important to researchers interested in utilizing the facilities.

INTRODUCTION Nuclear wastes from the defense production cycle at t h e U.S. Department of Energy's facilities contain many uniquely useful, intrinsically valuable, and strategically important materials. These materials have a wide range of known and potential applications in food technology, agriculture, energy, public health, medicine, industrial technology, and national security. Because of the potential value of byproduct recovery and use, as well as the desire to convert a perceived national liability into a national resource, the U.S. Department of Energy established the Byproducts Utilization Program (BUF) to plan and oversee integrated research, development, and demonstration activities which stimulate the effective use of these valuable byproducts. In particular, this program seeks to: Identify byproduct applications and assess the technical and economic viability of those applications Perform systems analysis to ensure that the cost/benefit of byproduct use compares favorably with alternative solutions o

transfer the byproduct technology to users promptly and efficiently (i)

A potentially large area for the use of irradiation technology lies in the need for new alternatives to questionable or banned fumigants, such as ethylene dibromide (EDB), in the food/agrlcultural commodity industry. Research has shown irradiation to be effectlve as a quarantine or dislnfestation treatment to rid a commodity of pests and render it acceptable for international trade, and as a preservation technique to retard or eliminate microbial food spoilage. BUP food irradiation technology transfer efforts

251

are being advanced through the design and fabricatipn of several stration facilities. These facilities include the : 0

Transportable

0

Cesium-137

0

Meat

Cesium

Irradiator

Agricultural

Irradiation

and demon-

(TPCI)

Commodities

Technology

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Center

Irradiator

(CACI)

(MITC)

The food irradiation facilities have already advanced to the design or fabrication phase Although the general purpose of the irradiation facilities, to proof their schedule. vide and transfer a technology which helps keep food plentiful and wholesome, remains the same, each facility is uniquely different in terms of food groups to be studied, degrees of emphasis on research and demonstration priorities, support equipment and These differences in food irradiation protocols necessitate that special service, etc. The facilities vary in design and purpose to design efforts be afforded each facility. It is anticipated that under proper the degree that the food industries themselves vary. management and direction, each of the BUP facilities will demonstrate the value of irradiation as a food process and answer many of the specialized research needs required by their respective food industries for technology development and transfer. To ensure that the facility will not be built and then abandoned after initial demonstration research is complete, the program calls for a commitment from the benefiting agencies and industries to support and nurture the research programs. These commitments must be honored if the facilities are to develop their full potential for technology development and transfer. This paper summarizes the operational characteristics and design considerations key to the development of the demonstration irradiators and presents information important to researchers interested in utilizing the facilities.

TPCI

Objectives Research data is needed to confirm the efficacy of irradiation treatment for zany commodities. Consequently, irradiation treatment research has been ongoing for zany years at a few fixed sites. One of the greatest needs in irradiation research is a nobile irradiation unit that can be located onsite with the appropriate industry rather than shipping the agricultural commodities great distances to existing irradiation facilities. The timely design and construction of TPCI (2) is an important part of filling this research need and achieving broad commercial acceptance. The two main purposes of TPCI are to: 0

Perform basic, accurate research irradiating specific commodities

0

Pinpoint irradiation treatment parameters for currently restricted commodities in an effort to evaluate irradiation as an alternative or recently banned methods of treatment.

Some of the important

advantages

to evaluate

of a mobile

the technical

feasibility

of

export to existing

unit include:

1.

Doing research at the right place at the right time with regard to the varying radiation sensitivity of the insect during each stage of its life cycle to the varying phytotoxic and organoleptic sensitivities of the fruit during each stage of its life cycle, and the resultant impact on its storage characteristics.

2.

Avoiding experimental anomalies such as loss of temperature control, loss of humidity control, long storage periods, delays before and after exposure to irradiation, and other handling problems.

1 A fourth DOE facility, the Sandia Irradiator for Dried Sewage Solids (SIDSS), was constructed in 1977-78. Successful operation of the SIDSS pilot plant and positive research results have led DOE to develop a technology transfer strategy for potential municipal users. The SIDSS program was discussed by S. B. Ahlstrom in an earlier session of this conference.

Byproducts Utilization Program

253

3.

Working under the specific needs of the local situation with various commodities.

4.

Gaining industry support through first-hand observation

5.

Working with standard "unit" packaging of various agricultural industries

6.

Flexibility--opportunity to work with several commodities of interest (Florida citrus, Washington and Oregon apples, Florida tropical fruits, Florida strawberries, Florida ornamentals, Washington cherries).

Basic Design Transportable irradiators to date have been designed such that the sources remain inside the irradiators during all phases of the operation, including shipment. TPCI, however, follows a binary concept in irradiator design. This concept separates the radioactive source material from the irradiator for shipment between locations. The cesium-137 is shipped in an NRC-licensed transportation cask while the balance of the truck-mounted irradiator is moved separately under U.S. Department of Transportation and state highway regulations only. Both TPCI and the shipping cask are designed to house and safely store four ceslum-137 capsules as produced at DOE's Waste Encapsulation and Storage Facility (WESF) in Hartford, Washington, Each capsule (see Figure i) contains a maximum load of 70 kCi of cesium chloride resulting in a total source strength in TPCI of 280 kCi. The irradiator shield is designed of stainless steel clad lead with an allowable maximum dose rate at the exterior surface of 0.25 mrem/hr. It was desirable to maintain this low exposure because a large number of individuals from the general public are expected to visit YPCI.

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The TPCI system consists of an irradiator unit with support equipment mounted within an enclosed trailer specifically designed for this use. The basic design includes mechanical equipment for environmental control, refrigerated product storage compartment, operation console, and work bench. The TPCI unit is designed within the height, width, and length regulations of the U.S. Department of Transportation and is transportable over most highways with an overweight permit. A commercial tractor of appropriate size equipped with a sleeper cab completes the system. Figure 2 illustrates the basic layout of the equipment. The irradiator unit will have two basic compartments, the source chamber and the irradiation chamber. The source chamber will be sized to accommodate the shipping cask which was designed specifically for the TPCI and is presently under construction. A lifting cylinder will raise the source out of the shipping cask to expose the irradiation chamber through a bridge window connecting the two chambers. Figures 3 and 4 show the TPCI irradiator and the shipping cask, respectively. The irradiation chamber consists of a large rotating inner drum with a window cut to coincide with the bridge window between the source chamber and the irradiation chamber. The inner drum is enclosed by a stationary outer shell of additional shielding. This outer shield contains an access door to facilitate product insertion and removal from the irradiation chamber. As the inner drum rotates, the window shifts from the access door, through which the product is transferred, to the bridge or connecting window for product irradiation. During processing, the agricultural co--,odities are kept in a controlled environment and cooled by conditioned air to as low as 35°F. The products will normally be irradiated in packaged form with a maximum size limitation of 32x33x52 cm. The irradiation chamber will be equipped with a mechanism to permit horizontal positioning of the product centerline at a distance of 61 to 112 cm from the source centerline, and also a slowly revolving turntable for product rotation. The product rotation and horizontal positioning provide a margin of freedom in dictating dose rates and maximum/mlnimum ratios. Assuming a specific gravity of less than 0.6 for packaged agricultural commodities, the maximum/minimum ratio will range between approximately 1.3 and 1.5. The maximum dose rate from the four WESF capsules will be approximately 1.5 kGy/hr at 50 cm from the source, 1.0 kGy/hr at 70 cm, and 0.5 kGy/hr at i00 cm. The source can be removed from the source chamber by lowering it into the shipping cask to form the lid seal, removing the access plug, detaching the lifting cylinder clevis, installing the cask lid bolts, and activating the cask positioning mechanism which will slowly lower the shipping cask from the source chamber for removal from the facility by a mobile crane or fork lift. The source is installed into the source chamber by following the reverse order. Instrumentation and control systems return all electrical, pneumatic, or operational systems to a safe position in the event of failure of any system. Control logic is mlcroprocessor-based for reliability and provides hard-copy operational and alarm data.

Status The TPCI is presently under contract for final design and fabrication. The design, fabrication, and assembly schedules prepared by the deslgn/manufacturer indicate that the TPCI will be operational in September of 1985. Therefore, the best estimate of availability at the present time is October I, 1985. This date is subject to change as the final design and manufacture proceed and the scheduled completion date of testing becomes better established.

Management

Plan

The introduction of this paper has described the need for irradiation and identifies those major areas targeted for utilization of the TPCI facility. It is intended that the facility will be utilized immediately upon startup to irradiate seasonal fruit crop~ such as cherries, apricots, peaches, and apples in the Northwest. These fruits will be treated for natural infestation received in the orchard. Each fruit would be treated or processed during the normal harvest season. Laboratory infested fruit could be processed at any time of the year when the facility was available. Producers of citrus fruits, mangos, etc., have also indicated interest TPCI in their research irradiation projects as it becomes available. During off-season periods, the TPCI will be scheduled to process facilities or products from controlled atmosphere storage.

in utilizing

fruit from storage

the

Byproducts Utilization Program

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While these applications are paramount in the utilization plan, other uses will also emerge as the capabilities and activities of the TPCI are disseminated throughout the industry. Some other irradiation studies may include sprout inhibition research on vegetables such as potatoes and onions, low-dose meat and fish studies, nuts, cow hides, cattle feed cubes, etc. Effective scheduling of the TPCI utilization is key to a successful and beneficial plan. It is intended that the use of this portable facility will be scheduled with the DOE at least one year in advance of the desired use date. This will enable the DOE or their contract operator, if so designated, to schedule the transportation of the unit in the most cost- and time-effective manner from one area to another. The present schedule requests indicate that if approved by the DOE, the TPCI will be first delivered to the Pacific Northwest where process studies are planned through March of 1986. A major facet of the DOE Byproducts Utilization Program is the transfer of technology acquired in their research programs to the applicable industry. Therefore, the data and information obtained from operation of the TPCI will be compiled and distributed periodically to interested users and potential users. This may include publishing a quarterly report on the TPCI activities which would be prepared by the contract operator and edited by the DOE.

CACI

Objectives The design and construction of an agricultural commodities irradiator is an important part of achieving broad commercial acceptance and use of irradiation as a dlsinfestation method for certain fruits, vegetables, and field crops (3). The two main purposes of CACI are: I.

Research o

Evaluate t h e technical feasibility of irradiating specific commodities Define and optimize irradiation treatment protocol for currently restricted export co--,odltles Evaluate irradiation as an alternative to various methods of quarantine treatment, some of which are under regulatory scrutiny

2.

Demonstration o

Demonstrate the beneficial use of cesium-137 as a gamma source

o

Develop the mechanics of product handling

o

Assess and modify irradiator design for further industry utilization Show by demonstration, to industry, the value and efficiency of irradiation for disinfestation and preservation of certain commodities at near-commercial throughputs and load sizes

Basic Design The CACI will be a fixed installation consisting of a shielded irradiation chamber, laboratory, work space, and ancillary support facilities. Operations within the irradiation chamber will be performed by a trained operator working outside the shielding using various types of automated and remote handling equipment. Suitable facilities for (I) loading and unloading of radioactive sources, (2) storage of the sources during maintenance or repair, (3) product conveyance through the irradiation chamber, and (4) the support and handling of product, will be incorporated in the design. As shown in Figure 5, basic components of the facility consist of the following: A shielded irradiation chamber and connecting labyrinth system for product entrance and exit o

A water pool inside the irradiation chamber for source storage

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A removable portion of the roof to permit the shipping cask to be lowered from the outside the irradiation chamber into the water pool for source transfer

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Approximately 3 megacuries of cesium-137 fixed to source plaques inside the irradiation chamber which can be independently raised for product irradiattin and lowered into the pool during maintenance, repair, or emergency situations

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Two basic product carriers: A variable speed carrier system for carrying boxes or small bulk quantities of agricultural commodities into the irradiation chamber, around and between the source plaques along variable paths, and then out of the irradiation chamber Rotating platforms sized for pallets which can be manually moved to different locations within the irradiator. The pallets are loaded by hand in the irradiation chamber when the source is in the stored position, irradiator control area to monitor and operate the irradiation process

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An equipment room housing such items as the electrical and pneumatic panels, pool chiller, deionization unit, water pump, air filter controls, air compressor, and fire control system

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A large insulated warehouse or work space area adjoining the irradiation chamber. A physical barrier or wall will be placed down the center of the warehouse area to prevent cross-contaminationof treated and nontreated product. At the point where the carrier conveyor system passes through the barrier, an air curtain with vertical flow could be installed to prevent crosscontamination. The warehouse will be of sufficient size to store a semitrailer of agricultural commodities in both the irradiated and uoirradiated product areas. Ambient temperature control will be provided to prevent "sweating" of the commodity.

0

A palletizer and depalletizer with associated conveyors. These units may be only temporarily installed in CACI.

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A laboratory with the necessary equipment and work space for product preparation and conditioning (e.g., hot dip, modified environments), dosimetry, and quality control testing

0

Separate walk-in refrigeration units for irradiated and nonirradiated products. The units will be used not only for storage but also to study the relationship between temperature conditioning and radiation injury.

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Separate loading docks and access ramps for ingoing and outgoing product

The CACI must be versatile and flexible to fill the role of both research and demonstration facility. It should be capable of processing a semitrailer load of commodities to a dose of 1 kGy within a single 8-hour working shift. Low dose uniformity ratios (maximum dose/minimum dose) are especially critical for researchers and should be attainable. Status The request for proposal has been issued and a contractor selected to provide preliminary and final design services as well as construction of the facility. The completion date for the facility is estimated to be March 1986. The responsibility of the DOE is to provide a turnkey irradiation facility to an interested research organization which will then plan, direct, support, and provide the necessary resources and backup for facility operation. At the time of this report the facility operator as well as the future site location of CACI is still indeterminate.

MITC

Objectives The objectives of MITC are very similar to those of CACI except that MITC will focus on meats, with emphasis on pork, rather than agricultural commodities.

260

N.J. FERRELL A~D D P. StOA.~

Research has shown that low-level irradiation of pork (under 30 krad) is sufficient to inactivate the parasitic nematode, Trlchinella spiralis, the causative agent of pork trichinosis. It is well documented that the "stigma of pork trichinosis" severely limits domestic use and export to world markets, resulting in considerable economic loss for the pork industry (4). It is, therefore, of considerable importance to demonstrate the feasibility of producing pork "certified trlchlna-safe" using existing gamma irradiation technology.

Basic Design Many design considerations for a pork irradiation facility are necessarily different from those for an irradiator used to disinfest citrus fruit or disinfect sewage sludge and algae. Preliminary designs for a pork irradiator have dealt with the irradiation of the whole, slaughtered hogs. Unlike citrus fruit, the pork carcass is not geometrically sy~mnetrical nor is it homogeneous llke sewage sludge when irradiated. A demonstration facility would be designed to establish the optimum cesium-137 source configuration and arrangement of the materlals-handling systems which could be used to expose the hog carcasses to a uniform dose from the source. Existing irradiator design technology, such as that currently used by industry in sterilization of medical and health related products and by Sandia National Laboratories in its prototype sludge irradlator, would provide the basis for design of the demonstration unit. The prototype irradiator for pork should have the capacity to process on a large enough scale that the source, shielding, and handling equipment designs are directly applicable to larger-scale commercial units. Figure 6 illustrates a possible arrangement for a pork irradiator.

Status At the time of this report, the conceptual design criteria is being formulated and the Request for Proposal to obtain a turnkey contractor should be issued soon. Early construction and operation of a prototype irradiator for meat products could be carried out under the auspices of a federally owned research laboratory or perhaps at a state educational institution, where there are already significant animal-production and meat-processing-related research programs. The extensive research support facilities available at either of these locations could also conveniently provide unbiased verification of the efficacy of irradiator design and dose level in disinfestatlon of meat products. Such third-party verification would be essential to domestic and world market consumer acceptance of a product treated by a commercial irradiation facility. Participation in the program by the trade associations of the pork industry would also be encouraged. The MITC would be invaluable for research and development, as a site for technology observation by the industry, and as an operator training and design refinement facility for subsequent irradiators constructed by and for the meat industry.

SUMMARY Since the inception of the BUP in the early 1970's, the BUP has successfully proven the utility of many byproduct applications, and has also contributed significantly toward the encouragement and development of widespread commercial use of nuclear byproducts. The demonstration cesium-137 irradiators being developed by DOE are an integral part of the BUP and will greatly aid industry in obtaining the data base necessary for technology transfer.

BIBLIOGRAPHY I. 2. 3. 4.

U.S. Department of Energy C1983). Department of Energy plan for recovery and utilization of nuclear byproducts from defense wastes. DOE/DP-0013, Vol. 2 CH2M HILL (1983). TransPortable Cesium Irradiator Preliminary Design Report for Department of Energy Albuquerque Operations. U.S. Department of Energy (1984). Byproduct Utilization Program cesium-137 Agricultural Commodities Irradiator (CACI), Request for Proposal, No. DE-RP04-84AL25763. CH2M HILL (1983). Trlchlna-Safe Pork by Gamma Irradiation Processing--A Feasibility Study, Prepared for Albuquerque Operations Office, U.S. Department of Energy.

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