GLOVEBOXTHROUGHPUT FOR THE REMOTE OPERATION SIZE REDUCTION SYSTEM

Transcription

1 GLOVEBOXTHROUGHPUT FOR THE REMOTE OPERATION SIZE REDUCTION SYSTEM by Adam W. Smith Colorado School of Mines

2 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

3 Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

4 2 TABLE OF CONTENTS page ABSTRACT INTRODUCTION Rocky Flats Building 776/777 Background ROSRS Design and Operating Scope Visual Simulation Objectives MODEL PARAMETERS The ROSRS Process and Structure Parameter Definitions, Equations, and Assumptions RESULTS Simulation Utilization Run Parameters Results Queue Time Results Total Glovebox Processed Results CONCLUSIONS REFERENCES & ACKNOWLEDGEMENTS c,, :......*..,,. -, r.-

5 ABSTRACT In 1997, the Department of Energy (DOE) approved the Deactivation, Decontamination and Demolition (D&D) of Building 779 at the Rocky Flats Environmental Technology Site (RFETS) in Golden, Colorado. This Building was used as a Research and Development Facility for the construction of components used in United State s (U.S.) nuclear weapons arsenal. Building 779 was the first large plutonium processing facility in the U.S. to be demolished. Most of the equipment used within the facility was contaminated with plutonium and is highly radioactive. During D&D activities, the workers risked exposure to harmful radioactive contaminates and the facility risked a release of contaminated materials into the environment. These risks increase significantly during the transfer and dismantling of large equipment. Currently, two more Pu processing facilities at RFETS are performing D(%D. Each facility is more than four times as large as Building 779. Hazards present during the D&D activities performed in these buildings include handling of radioactive contaminated material in solid and liquid forms, handling of berylliumcontaminated equipment, and other industrial hazards. The DOE has requested that the amount of worker exposure to radioactive contaminates be significantly reduced. The Remote Operation Size Reduction System (ROSRS) is designed to size reduce large contaminated equipment, such as gloveboxes, using robotic

6 4 disassembly and plasma arc torch cutting. By using the ROSRS at Building 776/777, work crews will be able to size reduce and package equipment remotely and consequently, significantly reduce exposure to radioactive equipment (Ericson 2000). Simulating the ROSRS (removal, preparation, and dismantling of radioactive contaminated equipment) using the ARENA Software (Kelton 1998), will give an estimate of prep and size reduction room utilization, queue-times and contaminated equipment throughput. Using simulation results, engineering will be able to properly design the ROSRS to efficiently dismantle the contaminated equipment. Operations will be able to better staff and schedule resources. ARENA simulations will not only save valuable tax dollars at Building 776/777 but are also applicable to current and future DOE facilities scheduled for D&D. n ,, <?.r ,.,, -.., ,...:...,., ,....,.. L :.!,..,,.,,..;;~.,

7 5 INTRODUCTION Rocky Flats Environmental Technology Site (RFETS), formerly known as Rocky Flats Plant, was established in 1951 as a part of the United States nuclear, Figure W weapons production complex. At that time its primary mission was the production of plutonium (Pu), uranium (U), beryllium (Be), and stainless steel components for nuclear weapons. This mission was conducted until 1989, when nuclear - production operations were suspended in response to Department of Energy (DOE) directives. Due to evolving world politics and national priorities, efforts to resume production operations at RFETS ceased in 1992 changing RFETS missions to one of interim material storage and site closure. This mission includes.....

8 6 deactivation and decommissioning, decontamination, dismantling and size reduction, demolition and waste management activities. The complete closure of a large Pu processing facility was completed recently at RFETS. Building 779 was a nuclear weapons research and design facility that was completely dismantled and demolished by January of In this building, gloveboxes housed various equipment including lathes, mills, and inspection equipment. The gloveboxes also had several utilities including electrical, nitrogen, plant air, machine coolant, natural gas, and ventilation connected to them to operate the equipment. The process of removing and packaging the contaminated gloveboxes required the worker to manually disconnect the gloveboxes from the utilities and size reduce the equipment using non-spark-generating equipment due to fire hazards. The workers would enter a size reduction tent in Supplied Breathing Air (SBA) garments and cut the stainless steel gioveboxes using electrical saws and nibblers. The heavy glovebox parts would then be physically placed into metal waste containers. Since the risk of contamination exposure was high and the stress of working in SBA garments was intense, management is investigating ways to minimize worker exposure to the hostile work environment for current and future decommissioning.. Building 776/777, the current RFETS facility being decommissioned, was used for Pu foundry, fabrication, and assembly operations. After a major fire in,m,~~.,,,.,,.,....,i. (..., ,-...,;.. 1,.,-,.,,~....>...!-----, ?.,,.,......,.,,...-9,.,.1>...<. :,,,...,..,. A

9 7 1969, Building 776/777 changed operations to waste and residue handling, disassembly of retired weapons components, special projects, and limited production operations. Processes performed in Building 776/777 included size reduction, advanced size reduction, pyrochemistry, vacuum operations, waste incineration, machining, product assembly and disassembly, testing and inspection of special weapons projects, and support operations such as laboratories. Building 776/777 also employed an extensive network of gloveboxes (see Figure #2), that were used as primary containment structures for the processes involving radlioactive materials. Figure #2 During operations, the gloveboxes became highly contaminated. Now that RFETS is planned for a year 2006 closure, facility operations are focused on

10 8 improving size reduction throughput of process equipment including gloveboxes. To facilitate site closure, Building 776/777 wishes to employ an automated system that will remotely size reduce large contaminated equipment and package it into waste containers for offsite shipment. The Remote Operation Size Reduction System (ROSRS) will use robotics and plasma-arc cutting to size reduce gloveboxes and package them into waste containers (Ericson 2000). All of this will be performed within a hard-side containment structure that will minimize operator exposure to radioactive material and contamination by allowing the operator to remain outside the containment system. The ROSRS contains several major components including the glovebox preparation rooms (prep rooms), a staging area (ballroom), the size reduction station, and the waste packaging station (see Figure #3). Glovebox and transfer to prep room.,rremove 3Transfer glovebox to staging area. Wait in queue for size reduction room availability. Size reduce glovebox using plasma-arc cutting. Place glovebox pieces into waste container. Transfer waste containerto tempora~ storage. Figure #3 To assist in the design and construction of the ROSRS, a visual simulation of the glovebox throughput will be performed in this paper. This simulation, using,,,,.,.,,.....>..z--,,,\,,,.-,- ---

11 9 the ARENA software, will demonstrate that the ROSRS will be capable of reducing over 300 gloveboxes in a two-year timeframe and will determine the appropriate amount of prep rooms that can support the giovebox throughput. The information gathered will assist engineers in developing the design parameters (i.e. room sizes and configurations) and will assist management in scheduling resources for the ROSRS operations. ARENA Software (Kelton 1998) is used to build and run the visual simulation. Arena is a modeling program that effectively represents physical constraints. This visual simulation is the first model to be applied to the removal and size reduction of gloveboxes. It provides tools for the modeler to conceptualize and represent the graphicai/pictorial forms of components to be simulated. Using this software, I will visually show the gloveboxes entering the prep rooms, where glass, gloves, and miscellaneous components are removed; the glovebox staging area, where prepared gloveboxes await size reduction; and the size reduction area, where the gloveboxes are dismantled and packaged. I will be able to determine utilization percentages for the PreP rooms and the size reduction station, and 1will determine the average and maximum waiting periods and queues for each stage of the process.....,..,-...

12 10 MODEL PARAMETERS The ROSRS is a self-contained system that will be used to disassemble gloveboxes that are currently in service. Before they are processed through the ROSRS, they are disconnected from utilities and prepared in the prep room. In the ROSRS, they are divided into small sections that are packaged into metal waste crates. These crates are subsequently shipped to a permanent off-site storage location. The glovebox removal process includes disconnecting electrical, liquid and gas piping, removing loose equipment from the glovebox interior, coating the interior with fire resistant paint, and removing lead shielding from the outside of the glovebox. The gloveboxes are then placed on carts and rolled to a prep room where the lead lined gloves and lead glass will be removed. This is required as part of waste packaging constraints. Waste must be segregated by type (i.e. lead, glass, and metal) and placed in specifically identified waste containers before they can be shipped to an offsite waste disposal facility. Finally, the glovebox is transferred to the size reduction room where a plasma-arc torch will cut the glovebox into small sections. The metal sections are mechanically loaded into a waste crate. The crate is then sealed and transferred to a temporary storage location to await offsite shipment (Ericson 2000)...!,-...,.x.,,..3.2,,,.3,?

13 11 An ARENA visual simulation of the removal teams, prep rooms, and ROSRS process is developed to determine the appropriate number of removal crews and prep rooms that are needed to support the ROSRS. The first step in building the simulation is to design the ROSRS layout. The layout includes a maximum of five removal crews, four prep rooms, the ballroom, and the size reduction room. These items are laid out on the floor plans of Room 430 and Room 127 of Building 776/777 where the ROSRS system will be staged (see Figure W). The layout represents physical room and equipment dimensions. Figure >.,., r.!, , /-..,-.>..-..,. r,

14 12 After the layout is complete, the model parameters are defined and entered for each module. The five Arrival modules represent the removal crews with removal times, glovebox transfer times, next station routing, and animation parameters. The four prep room server modules represent the prep crews with prep times, glovebox transfer times, next station routing, animation parameters, waiting queues, and random prep room housekeeping times and occurrences. The size reduction server represents the plasma arc cutting and waste packaging and includes size reduction times, waste crate transfer times, next station routing, animation parameters, waiting queues, and random cutting room housekeeping times and occurrences. The Depart module represents the crates counter where a running total of the number of gloveboxes completed is tallied. The removal time and prep time parameters are based on random number generation. Real time process hours obtained from the Building 779 D&D Project (Hickman 2000) are used to develop distribution equations for both the prep time and removal time parameters. The removal time hours represent the time spent in removing the loose equipment, utilities, lead lining, and applying fire resistant coating to the glovebox interior. The prep time hours represent the time spent in removing glass and lead lined gloves. The times from the Building 779 D&D Project were fed into Arena s Input Analyzer to obtain a probability distribution equation that best represents the data.

15 13 time is: The distribution equation created by Arena s Input Analyzer for removal T = 3 + exponential (55.5) This exponential distribution is used to represent the random arrival of gloveboxes to the ROSRS system. It is used to describe how long it would take for a single crew to remove and transfer a glovebox to one of the prep rooms. The average removal time is 55.5 hours per glovebox. The range can be as little as 4 hours up to a maximum of several hundred hours (the maximum is bounded by the ARENA program). The distribution equation created by Arena s Input Analyzer for prep time is: T = 3 + Gamma (19.1, 0.714) This gamma distribution is used to represent the time required to prepare the gloveboxes for size reduction. A prep crew will enter the prep chamber and remove the glass and lead lined gloves from the glovebox. They will then transfer the glovebox to the ballroom where it will wait for size reduction. The average prep time is 17 hours with a minimum of 3 hours and a maximum of several hundred hours. Additional operating parameters were made from process knowledge and interviews with the ROSRS Construction Coordinator (Ericson 2000). These operating parameters include the distribution equation for housekeeping time in the prep rooms and cutting rooms, and the 8-hour processing and size reduction

16 14 times used in the ROSRS. The simulation has a run-time for 4000 hours that represents a two-year operational time frame. - All of the operating parameters are summarized in Table #1. Parameter List Table #1 Glovebox Removal lime 3 + Exponential (55.5) Hours Glovebox Prep Time 3 + Gamma (19.1, 0.714) Hours Housekeeping Occurrence Time Triangular (20,40,60) Hours Housekeeping Time 8 Hours Glovebox Size Reduction Time 8 Hours Glovebox Transfer llme 1 Hour Simulation Run Time 4000 Hours (2 years) Number of Replications 100 SIMULATION RESULTS Using the above layout and parameters the model is simulated under different scenarios. The number of removal crews are adjusted from two to five and the number of prep rooms are adjusted from two to four for a total of 12 different simulated runs. Information is obtained on the total amount of gloveboxes processed, utilization percentages for prep rooms and size reduction room, and process time for the gloveboxes. Each run is replicated 100 times to develop statistical averages, maximum and minimum values, and confidence intervals given in Tables #2 through #9. The confidence intervals are statistical numbers that imply that 95% of the replications will occur between the interval. For example, in Table #2, the average

17 15 utilization time for 3 Removal Crews supporting 2 Prep Rooms is 42.90?40. The confidence interval of 0.87 Momeans that out of 100 replications, 95 of them will have average utilization timef between 42.03% and 43.77%. All of the confidence intervals are low due to the high amount of replications made in the simulation. Prep room utilization and size reduction room utilization represents the percentage of time the rooms are performing glovebox-processing activities. Low percentages imply that the room is spending significant time either waiting for a glovebox to be processed or it is reserved for housekeeping and maintenance. The goal is to get relatively high percentages for cost effectiveness. The room utilization information is given in Tables #2 through?%8. Table #2 Prep Room #1 Utilization 95% Cl. Minimum Maximum Average Half-Width Value Value. 3 Crews and 2 Prep Rooms 42.90% o % 52.50% 3 Crews and 3 Prep Rooms 28.30% -A 20.70% % 3 Crews and 4 Prep Rooms Mo 0.60% 14.40% o 4 Crews and 2 Prep Rooms 57.60% 0.88% 47.90? % 4 Crews and 3 PreDRooms 37.90% 0.68% 29.50% 45.70?40 4 Crews and 4 Prep Rooms 29.00% 0.65% % % 5 Crews and 2 Prep Rooms 71.30% 0.98% 58.50% 81.50% 5 Crews and 3 Prep Rooms 47.80% 0.79! % 60.20% 5 Crews and 4 Prep Rooms % XO 28.40% 47.40%

18 Table #3 Prep Room #2 Utilization 95% C.L Minimum Maximum Average Half-Width Value Value 3 Crews and 2 Prep Rooms 43.00% 0.78% 34.50% 52.60% 3 Crews and 3 Prep Rooms 28.40% 0.67% 20.80? % 3 Crews and 4 Preh Rooms 21.70% 0.60% 14.60% 32.00% 4 Crews and 2 Prep Rooms 57.60% 0.97% 47.50% 69.20% 4 Crews and 3 Prep Rooms 38.80% 0.78? % ? 0 4 Crews and 4 Prep Rooms 28.80% 0.64% 20.50% 37.10% 5 Crews and 2 Pre~ Rooms 71.00% 0.98% 58.50% 81.50% 5 Crews and 3 Prep Rooms 47.80% 0.87% 38.70? Y:- 5 Crews and 4 Prep Rooms 35.80% 0.69% 29.00% 44.30?40 Table #4 Prep Room #3 Utilization 95% C.L Minimum Maximum Average Half-Width Value Value 3 Crews and 2 Prep Rooms 0.00% 0.00? %0 0.00% 3 Crews and 3 Prep Rooms % 0.70% 21.50% 38.50% 3 Crews and 4 Prep Rooms %. 0.65% % 4 Crews and 2 PreDRooms ! Crews and 3 Prep Rooms 38.40% 0.76% 30.70% 48.90% 4 Crews and 4 Prep Rooms 28.80% 0.72% 21.70% 37.60% 5 Crews and 2 Prep Rooms 0.00% 0.00% 0.00% 0.00% 5 Crews and 3 Prep Rooms 48.00% 0.83% 36.70? % 5 Crews and 4 Prep Rooms 36.20% 0.72% % % Table #5 Prep Room #4 Utilization 95% C.L Minimum Maximum Average Half-Width Value Value 3 Crews and 2 PreDRooms 0.00% O.oovo 0.00% 0.00Y0 3 Crews and 3 Prep Rooms 0.00% % ~Crews and 4 Prep Rooms 21.80% 0.65% 14.40% 30.00% 4 Crews and 2 PreDRooms % 0.00% 0.00% 4 Crews and 3 Prep Rooms 0.00% 0.00% ? (0 4 Crews and 4 Prep,Rooms 28.70? % 21.30% 39.70?40 5 Crews and 2 PreDRooms %0 0.00% 0.00% 5 Crews and 3 Prep Rooms 0.00 %0 0.00% 0.00% 0.00% 5 Crews and 4 Prep Rooms ? % 45.00%.--.-.,-..T=.

19 17 Five removal crews supplying gloveboxes to two active prep rooms define the optimal conditions for the prep rooms. The results from Table #2 and Table #3 show that under optimal conditions, the prep room utilization averaged around 71?10with a maximum of 81 %. This is a very good number that allows time for unforeseen contingencies (such as equipment failures or facility work suspension) that may shut down prep room activities. These numbers show that two prep rooms are sufficient to supped the workload supplied from up to five glovebox removal crews working in various areas around the facility. Table #6 Size Reduction Room Utilization 95% Cl. Minimum Maximum Average Half-Width Value Value 3 Crews and 2 Prep Rooms %0 0.44? fo 48.40% 3 Crews and 3 Prep Rooms ? % 3 Crews and 4 Prep Rooms % 35.90% 48.30% 4 Crews and 2 Prep Rooms.54.90% 0.55? % 61.10% 4 Crews and 3 Prep Rooms 54.80% 0.61% 49.30% 63.00% 4 Crews and 4 Prep Rooms 54.70? % % 62.00% 5 Crews and 2 Prep Rooms 67.60% % % 5 Crews and 3 Prep Rooms ? % 60.40% 77.20% 5 Crews and 4 Prep Rooms 68.60% % 76.00?40

20 18 The optimal conditions for the Plasma Cutting Room are five removal crews supplying gloveboxes to four prep rooms. The Cutting Room utilization averaged 68?40with a maximum of 76%, which are again very good numbers. The Plasma Cutting Room throughput is sufficient to handle the glovebox workload as long as the ROSRS can process one glovebox in eight hours. The queue time defines the average, minimum, maximum time would wait for the prep room or size reduction room resource to open. a glovebox The goal is to minimize queue times that in turn minimize storage space required for staging gloveboxes waiting to be processed. The room queue time information is presented in Tables #7 and #8. Table #7 Plasma Cutting Room Queue Time Average Cl. Minimum Maximum Hours Half-Width Value Value ~Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 PreDRooms _4 Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 PreD Rooms Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms

21 19 Table #8 Prep Room Queue Time Average 95% Cl. Minimum Maximum Hours Half-Width Value Value 3 Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 PreD Rooms Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms Under minimum support condition, three removal crews and two prep rooms, the ROSRS system would process an average of 206 gloveboxes in a twoyear time frame. This is enough to remove and size reduce approximately 67% of all gloveboxes within Building 776/777. An average of 5 removal crews is required to remove approximately 300 gloveboxes in two years using two prep rooms (300 gloveboxes would be the total amount of gloveboxes contained within Building 776/777). The information for total gloveboxes processed in given in Table #9. Table #9 Total Gloveboxes Processed 95% (2.1: Minimum Maximu-m Average Half-Width Value Value 3 Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms Crews and 2 Prep Rooms Crews and 3 Prep Rooms Crews and 4 Prep Rooms

22 20 The final layout of the ROSRS is shown in Figure #5 with only two prep rooms. :Hmm - MK4 F, -? :#&p{ oz7 j.:: I : G -.$,; ::...,.<,.. =-,,-.., CONCLUSIONS In this paper, I performed a visual simulation on the process of size reducing contaminated glovebox using the ROSRS. During the simulation, the number of removal crews and prep rooms was adjusted to determine the most appropriate operating design parameters. The original design scope was to have

23 21 four prep rooms. With the use of the simulation, I was able to show that two prep rooms would be sufficient to meet the building needs as dictated by schedule requirements for processing gloveboxes through the ROSRS. This would equate to total cost savings of approximately $130,000. These savings include the cost of designing, purchasing, and building two prep room tents. The savings do not include the cost of operating and maintaining the two tents. The estimate is summarized in Table #1 O. Table #1O Activity Engineering Support Resource 1 Mechanical Engineer Hours (ea.) 40 Cost/Hour 125 Total Cost $5000 Interference Removal Tent Construction 1 RadiologicalEngineer 2 RadiologicalControlTechnicians 5 Crewmen 1 Foreman 2 RadiologicalControlTechnicians $5000 $8000 $20000 $5000 $8000 Cost of Materials 5 Crewmen 1 Foreman 2 Tents and Frames $20000 $5000 $ Airmovem 4000 Grand Total I I I $ This simulation is a good foundation for the overall picture of running the ROSRS system. Further improvements to the simulation would include defining detailed parameters for the plasma arc cutting system. These parameters would include failure rates, programming times, plasma arc cutting speeds, waste crate loading times, scheduled shutdowns for preventive maintenance, and glovebox

24 22 loading times. Some of these parameters would require information on glovebox sizes and sheet metal thickness to generate the appropriate distribution equations. From these parameters a sensitivity study could be generated for the ROSRS system. Also, the simulation could be used to estimate the number of waste crates and drums generated during the two-year time frame. This information could be used to determine waste crew support requirements and waste storage spacing requirements. Finally, the simulation can be used to track the amount of Pu holdup contained within the gloveboxes as they are processed through the ROSRS system to ensure that levels would not become high enough to cause a nuclear safety concern.,,. -...

25 23 REFERENCES & ACKNOWLEDGEMENTS David Ericson, ROSRS Construction Coordinator, Rocky Flats Environmental Technology Site, Golden, CO. Project Interview January 14, Mark Hickman, Building 779 Demolition Integration Manager, Rocky Flats Environmental Technology Site, Golden, CO. Project Interview January 14,2000. W. David Kelton, Randall P. Sadowski, and Deborah A. Sadowski, Simulation with Arena. The McGraw-Hill Companies 1998.