Rodney A. Palanca
Westinghouse Waste Isolation Division
U. S. Department of Energy
Carlsbad Area OfficeWaste Isolation Pilot Plant
P.O. Box 2078
Carlsbad, NM 88221

A safer and more efficient method to receive remote handled transuranic waste (RH TRU) canisters at the Waste Isolation Pilot Plant (WIPP) is needed. Re-evaluation of the purpose and utility of the WIPP hot cell complex to support the current disposal mission of the WIPP suggested that direct transfer from transportation casks to the facility cask was the best alternative. This approach would bypass the WIPP hot cell complex entirely providing improved turnaround rates for RH road casks. Cost savings would also result if the reactivation of hot cell equipment is suspended or discontinued indefinitely.

The WIPP was established by Congress in 1979 (Public Law 96-164) as "a research and development facility to demonstrate the safe disposal of radioactive waste resulting from the defense activities and programs of the United States"(1) Part of the original WIPP mission was to test the feasibility of storing defense high level waste (DHLW) in bedded salt. Although no longer a part of the WIPP mission, DHLW canister handling requirements provided the basis for the hot cell design.

The DHLW experiments used canisters designed for remote loading of vitrified wastes. The DHLW disposal experiments were temporary, and all DHLW would be removed from the WIPP at the end of a planned test period; therefore, provisions were made to retrieve, inspect, survey, and reload the DHLW canisters into shielded transportation casks. If requirements for permanent disposal were not met at the end of a test period, agreements with the state of New Mexico required the retrieval of RH TRU waste. The hot cell was incorporated into the facility design to provide a shielded area for conducting inspections of retrieved DHLW canisters in preparation for their shipment off the site. Provisions were included to place damaged or corroded DHLW canisters into overpacks and to weld lids on the overpacks.

The original design specification allows only one prescribed route for the transfer of RH TRU canisters to the underground. When it came time to define the process and prepare operating procedures, the emplacement operations became the inverse of the retrieval operations for which the hot cell was designed. However, the hot cell canister inspection facilities are no longer needed since TRU wastes will not be required to be easily retrievable.

In 1995, the report Waste Isolation Pilot Plant Remote Handled Baseline Systems Reactivation Assessment, WIPP/WID-95-2133, stated that "It is likely that the hot cell complex will still be useful for overpacking operations and temporary surface staging of RH TRU waste containers "(2) This statement is based on two assumptions. First, it assumes that there is some likelihood of receiving RH canisters that are damaged or are otherwise externally contaminated; therefore, WIPP would need to inspect and survey all incoming canisters. Second, it assumes that the WIPP hot cell facilities are prepared to adequately decontaminate and/or overpack contaminated canisters. Based upon the current waste disposal philosophy, these assumptions are considered inappropriate as discussed in the following paragraphs.

After loading, all RH TRU waste canisters will be welded closed under quality controlled conditions and will be vented through filters. The sites that will ship canisters to the WIPP will be required to certify that the surface contamination limits of the WIPP Waste Acceptance Criteria(3) have been met prior to releasing shipments. The receipt of contaminated canisters at the WIPP would jeopardize the generator site's authority to certify waste and to use the RH-72B transportation cask (road cask). Considering that there are currently less than twenty RH canisters loaded and sitting in interim surface storage, it is highly unlikely that WIPP will receive canisters that have deteriorated from long term surface storage. Because of the relatively low total number (~7000) and the low rate of canister shipments (~250 per year) to the WIPP, it is also considered unlikely that canisters will arrive damaged or contaminated as a result of mishandling or oversight. If a canister is involved in a road accident, the shipment would automatically be returned to the shipping facility for evaluation. Other than gaining confidence in the generator sites and the transportation system to ship only uncontaminated, structurally sound canisters, in the absence of a retrieval requirement there are no practical or regulatory reasons for WIPP to inspect and conduct contamination surveys on all incoming RH TRU canisters. If minor contamination does occur that remains undetected by cask headspace air particulate samples, it would be better to have it confined to the interiors of the road and facility casks and to the storage borehole than to chance contaminating the hot cell complex. If there is detectable airborne particulate activity in the road cask headspace that cannot be attributed to fission gas daughter products, the cask could be resealed and returned to the shipping site or some other facility equipped to conduct remote decontamination.

The WIPP hot cell complex is ill-equipped to prevent the spread of alpha contamination from a contaminated canister. The WIPP relies on the principle of a dynamic barrier to the spread of contamination. The nature of this principle, the maintenance of a negative pressure in the hot cell, results in air flow past canisters as they are removed from road casks and moved to the various stations in the hot cell. If a canister were to arrive with substantial loose surface radioactive contamination, it probably would not stay confined to the surface of the canister. Even if the canister is overpacked, with the current equipment there is no guarantee that the external surfaces of the overpack canister will not become contaminated in the process. This could result in a difficult, large scale, time consuming decontamination effort. Contamination cleanup would require personnel to enter the hot cell in personal protective clothing and equipment because the hot cell is not equipped to conduct extensive remote decontamination. Since the hot cell is the only route available for sending canisters underground, such a contamination event would bring all RH TRU waste emplacement operations to a halt until it is cleaned up.

Eliminating the additional handling steps needed to move RH TRU waste canisters through the hot cell complex (hot cell and canister transfer cell) reduces the number of times a canister must be lifted and set down (three versus one). Handling accidents scenarios with the potential for canister damage are similarly reduced.

Some equipment, such as the hot cell crane and the canister shuttle car, are subject to failures for which there may be no backup system. Recoveries from these single point failures have the potential to require personnel radiation exposure beyond operational limits. These failures are also eliminated.

Computer simulations of the baseline RH TRU waste handling systems indicate that WIPP does not have the capacity to handle the design throughput rate of 250 canisters per year without a second shift working on the surface at least five days a week (see Fig. 1). Two programmatic delays will probably result in a requirement for throughput rates of greater than 250 canisters per year: 1) start-up of major RH TRU waste processing facilities will probably not occur until after the commencement of WIPP RH operations in 2002, and 2) WIPP RH operations are not scheduled to start until four years after initiation of CH waste operations. Three shift operations on the surface may be required to support these higher RH TRU canister receipt rates unless there is a significant improvement in the capacity of the RH TRU waste handling systems.

Simulation studies indicate some improvement in the time it takes to move the canisters through the hot cell and in the time needed to return the road casks to the TRU waste transportation system could be realized by eliminating contamination surveys and visual inspections. If the assumption is made that canisters will not arrive damaged or contaminated, the hot cell complex need only be set up for those waste handling operations necessary to move the canisters from the road cask to the facility cask. The primary impact of this alternative is that radiological contamination protection equipment beyond that provided by the RH TRU waste canisters and the casks would not be required. The cost avoidance for this alternative would be minimal since nearly all hot cell equipment currently requiring reactivation would still be needed. The total estimated cost avoidance for this alternative is $212,110. However, since the canisters are to be routinely moved through the hot cell in this option, it is likely that at least some random surveys and inspections of canisters will be requested. Since the possibility of contaminated canisters - although considered remote - exists, the hot cell may still be required to provide at least some level of protection against the spread of contamination. These two factors may eventually require the full reactivation of the hot cell.

Since inspection of RH TRU canisters before emplacement is not a requirement, processes that bypass the hot cell, such as direct road cask-to-facility cask transfers or emplacement directly from the road cask were also considered. The efficacy of alternative designs were tested through the use of computer simulation studies of conceptual alternative designs. One such study was conducted on a process where canisters are unloaded from the road cask directly into the facility cask in the RH Bay. An important assumption made in this alternative simulation was that contamination surveys and visual inspections of canister surfaces would not be a prerequisite for emplacement. A 36 percent reduction in the average time needed to unload and return a road cask to the transportation cycle resulted when the hot cell complex was bypassed using this cask-to-cask transfer process. An average 33 percent increase in throughput capacity (canister emplacement rate) was observed. Figure 1 illustrates the improvement indicated by this computer study.

The work scope and associated cost avoidances (2) that could be realized if the hot cell is not required for the start of RH operations in 2002 is estimated at $1,228,000. Depending on the complexity of design, a preliminary estimate for the cost of the additional equipment required for the cask-to-cask transfers is approximately $600,000. This gives an overall potential cost avoidance for the project of approximately $600,000.

Several alternatives were considered that bypass the hot cell complex. One alternative uses the road cask to double as a facility cask. Another alternative involves placing the road cask in a stand similar to the road cask transfer car and lifting the facility cask over the road cask. A third alternative requires lifting the road cask and loading the facility cask while on the existing facility cask transfer car. Maintaining shielding around the junctures between the casks outside of the shielded hot cell is a major concern common to the cask to cask transfer alternatives. These alternatives are discussed below.

Designing or adapting the road cask to double as a facility cask was considered too expensive and time consuming to be able to meet FY 2002 RH TRU waste receipt. It would probably involve the development of shield valves for installation on the road cask at the WIPP since certification of a cask with built in shield valves for over the road use would be difficult. It would also require a totally new road cask design that would have to be either double ended or have a shielded access port so that a transfer mechanism, such as the hydraulic ram on the horizontal emplacement and retrieval equipment, could be used to emplace canisters. Although possible, this configuration would still require shielded remote operations for removal of the road cask lids and installation of the shield valve(s). Operations would still require shielded facilities similar to the hot cell. This alternative may be reconsidered in the future for different size waste containers.

In the process that would require lifting the facility cask, except for the inner lid operations, this process would be similar to that used in the cask loading room to bring a canister from the transfer cell into the facility cask. Since the road cask inner lid will not fit through the facility cask, provisions must be made to allow the inner lid to be set aside before the facility cask is installed which poses some difficult shielding problems. This operation may also require modifying the facility cask for lifting from some points other than the support trunnions or the forklift pockets. The rotation trunnions, or pivot pins as they are also referred to, are not designed to support the full weight of a loaded facility cask. This alternative does not involve major modifications to the building structure; however, it requires the routine lifting of two heavy casks instead of one. A horizontal version of this alternative was also considered but was found to be more complex and would result in increased wear on the casks.

This cask-to-cask transfer alternative was the most promising. It calls for a new partially shielded cell to be constructed in the floor of the RH Bay aligned with the facility cask maintenance rails that are currently in existence. New equipment unique to this alternative includes: a combination road cask stand and vertical positioning system (referred to as the cradle); a shield bell with a grapple and hoist; a shield valve similar to those used on the Facility Cask; and a HEPA filtered ventilation exhaust system. Figure 2 shows the major components of the canister transfer system (CTS) concept.

The following is a conceptual sequence of operations:

• The CTS shield valve housing, which moves horizontally on rails to align with the road cask, is retracted to allow the road cask to enter the new cell.
• A crane is used to place the road cask in the road cask cradle. Cradle elevation is controlled by two single stage hydraulic cylinders.
• Technicians have access to the road cask lids and test ports allowing the removal of the outer lid to its lid stand, and the installation of the inner lid handling fixture (a WIPP pintle).
• Samples of the inner vessel headspace gas are taken.
• Inner vessel lid closure bolts are loosened and retracted to allow lid removal.
• The road cask is lowered to the bottom position.
• The filtered exhaust and monitoring systems are started and the shield valve housing is moved horizontally and centered over the road cask.
• The shield bell and grapple assembly is moved with a floor mounted jib crane to rest on the shield valve.
• The shield bell grapple is lowered to the road cask inner lid.
• After the grapple has latched onto the inner lid, it is raised into the shield bell, and the shield valve is closed. Gross radioactive contamination of the interior of the road cask would be detected by the exhaust monitoring system.
• The inner lid is removed and deposited on the inner lid stand.
• The facility cask transfer car with cask is driven over and aligned with the top of the road cask.
• The facility cask is rotated to vertical.
• Air hoses, power and control cables are connected to the facility cask.
• The shield bell is positioned on the facility cask top shield valve.
• Elevating the road cask cradle moves the road cask and CTS shield valve housing up together until the shield valve collar contacts the facility cask bottom shield valve housing. This condition is shown in Fig. 2.
• The CTS shield valve is opened.
• The facility cask shield valves are opened.
• The grapple is lowered to the canister, and the canister pintle is engaged.
• The canister is raised high enough out of the road cask to allow identification using TV, vision cameras, or bar code readers.
• The canister is raised into the facility cask.
• The bottom facility cask shield valve is closed.
• The canister is lowered to rest on the facility cask bottom shield valve gate.
• After positive indication that the canister is securely supported by the facility cask bottom shield valve, the canister is released, and the grapple is retracted into the shield bell.
• With the canister in the facility cask and the facility cask top shield valve clear, the facility cask top shield valve is closed, allowing the removal of the shield bell.
• The CTS shield valve is closed and the road cask cradle is lowered to its bottom position which also lowers the shield valve housing.
• The CTS shield valve housing is retracted.
• The facility cask is now clear to be rotated back to horizontal and moved to the waste hoist by the facility cask transfer car.

This completes the canister transfer and the road cask cradle raised to the top position to allow access to the top of the road cask for survey, inspection and reassembly. The process does not provide for detailed visual inspection or contamination checks of the RH TRU waste canister. Recorded remote video inspections can be incorporated into the process, providing a permanent record of the condition of the canister as received at the WIPP. Contamination surveys conducted on the road cask interior surfaces after the canister has been removed to the facility cask should be sufficient to determine if extra care is required during and after canister emplacement.

This study produced the following conclusions:

• There are no regulatory requirements or other drivers for inspecting and conducting radioactive contamination surveys on all incoming waste canisters.
• The hot cell layout and ventilation design is not conducive to preventing the spread of loose surface contamination from canisters to hot cell surfaces.
• The hot cell is not adequately equipped for performing remote decontamination of the internal surfaces of the hot cell or contaminated canisters.
• The likelihood of receiving a damaged and/or contaminated RH TRU waste canister is remote.
• Canister shipments that are determined to be potentially contaminated based on sampling the headspace of the cask inner vessel, should be returned to the shipping site or other facility equipped to conduct remote decontamination.
• The increase in RH waste handling capacity achieved by avoiding the hot cell complex, may be sufficient to preclude operating more than one shift per day or more than five days per week, except at peak receipt rates. This provides the most cost savings over the lifetime of the equipment.
• The cost avoidance realized by not reactivating hot cell systems should offset the development and procurement cost for the new canister transfer system.
• Cask-to-cask transfer operations may allow for future development of smaller, simpler, and more volume efficient waste containers and smaller, lighter, less expensive, and easier to handle casks.
• Cask-to-cask transfer operations reduce the likelihood of canister handling accidents. Radiation exposures to personnel involved in recovery from hot cell equipment breakdowns would be eliminated.
• Surveying the road cask for loose surface contamination after the canister has been removed should suffice to confirm the shipment was "clean" or to indicate the need for further surveys and/or decontamination of the casks and RH waste handling equipment.
• Contamination control provisions could be incorporated to confine contamination to the insides of the road cask, the facility cask and the storage borehole. Engineered controls such as vent shrouds, transfer sleeves, or inflatable seals could be incorporated into the connections between the road cask and facility cask, into the facility cask itself, and around the borehole shield plug.

WID is conducting feasibility and cost studies of Canister Transfer System conceptual designs. Pending the results of these studies, the RH systems reactivation schedule has been revised to postpone the reactivation of hot cell equipment. The alternative designs are also being evaluated for impacts on Waste Handling Building certification, radiation protection, safety analyses, permits, and schedules.

1. U.S. Congress, "Waste Isolation Pilot Plant, Delaware Basin, New Mexico," Section 213 of Public Law 96-164 (December 1979)
2. U.S. Department of Energy, "Waste Isolation Pilot Plant Remote Handled Baseline Systems Reactivation Assessment," WIPP/WID-95-2133, Waste Isolation Pilot Plant (September 1995)
3. U.S. Department of Energy, "Waste Acceptance Criteria for the Waste Isolation Pilot Plant," WIPP/DOE-069, Rev. 5, Waste Isolation Pilot Plant (April 1996)

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