Operational safety of a disposal facility

The purpose of a disposal facility is to emplace radioactive waste in a place and in a manner that will provide long-term isolation of the waste fiorn the biosphere. A disposal facility is therefore primarily designed according to the needs for long-term safety. Performance assessments [1, 2] must have demonstrated prior to operation that the particular disposal conditions will ensure protection of human health and of the enviromnent according to die prevailing requirements [3]. 

The waste packr es handled at a disposal facility contain radionuclides in quantities which may be very high. Generally these packages are not opened at the disposal facility. Radioactive waste intended for disposal is generadly conditioned for disposal prior to transportation to the disposal facility. The predisposal management of radioactive waste [4] is not discussed in this paper. 

The operations at a disposal facility may be grouped into the following steps  

After the repository is full and no further packages will be emplaced, the remaining cavities are backfilled and sealed (closure of the repository). 

Depending on the type of rock within which the repository is built, radon may exhale ftom the rock in quantities which lead to harmful concentrations within the facility. Despite the fact that radon is a naturally occurring radionuclide, it s possible detrimental effects may have to be taken into account for the operational safety of a disposal facility. 

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Operational safety of a disposal facility - waste acceptance requirements ... 

Moreover, the WIPP repository would be a global first-of-a-kind facility for safe disposal of long-lived and high-energy emitting radioactive waste such as TRUW and HLW. Conceivably, its continued safe operation in compliance with several hazardous waste regulations and one of the strictest environmental radiation protection standards in the world should enhance public confidence in the safety of deep geological disposal of TRUW and HLW both in the USA and abroad. 

The behaviour of the sections of the disposal facility already backfilled should be observed during the continuing operational phase until closure of the repository. The aim of these observations is to confirm the predictions and to draw conclusions on long-term safety. These conclusions shall support the final demonstration of long-term safety which in required for the decision to close the repository (see next paper [10]). In order to strengthen the conclusions, the observations may be prolonged for a limited period of time after the end of emplacement operations. The needs or merits of a surveillance period after closure of the disposal facility will also be addressed in the next paper and in paper 21 [11]. 

The Swedish Government has recently declared, based on SKI s review, that prior to the issuance of a licence to start constructing the encapsulation facility (the first facility of the KBS disposal system), industry needs to evaluate the short and long term safety of all facilities needed for the disposal concept. So, it would not be sufficient to evaluate only the operational safety of the facility for which an actual construction licence is sought for. There will be similar demands for a licence to start the detailed investigations at a potential disposal site as such investigations, in fact, are viewed as the first st e in the construction of the repository itself. 

The overall performance assessment for the rq)ository system (overall geological situation, mine, waste package) must prove (operational phase) and give reasonable assurance (post operational phase) that the quantitative safety criteria are met. The long term safety assessment consists of the identification and description of potential pathways of radionuclide release, migration and exposure. The establishment of waste acceptance requirements based on the conq>liance of the performance assessment results with the safety criteria is the last step before a disposal facility can be licensed and operated. 

Understanding the chemistry of the process also provides the greatest opportunity in applying the principles of inherent safety at the chemical synthesis stage. Process chemistry greatly determines the potential impact of the processing facility on people and the environment. It also determines such important safety variables as inventory, ancillary unit operations, by-product disposal, etc. Creative design and selection of process chemistry can result in the use of inherently safer chemicals, a reduction in the inventories of hazardous chemicals and/or a minimization of waste treatment requirements. 

Necessary risk studies should be completed as quickly as possible. Before the HRA is completed, the Army should work with the Pueblo stakeholders to decide how the risk of a modified baseline process facility compares with that of a baseline incineration system facility. This will require that the Army increase and improve its communications with stakeholders. Finally, the Army should make safety the number one objective in the construction, systemization, operation, and closure of the Pueblo Chemical Agent Disposal Facility. 

Conduct a review of chemical agent disposal facility operations and records management for the ambient air monitoring for agent, and for exhaust stack and other waste stream emissions of agent and other substances of potential concern (SOPCs) that are characteristic of these facilities. Use Occupational Safety and Health Administration, and Environmental Protection Agency criteria for initial identification and evaluation of SOPCs. 

Finding 12. Safety programs and performance appear to be adequate to ensure that chemical demilitarization operations are being conducted safely. Even so, there is considerable opportunity for improvement. Many of the incidents at Johnston Atoll Chemical Agent Disposal System (JACADS) and Tooele Chemical Disposal Facility (TOCDF) could have been significantly mitigated—if not prevented—had a true safety culture been in place and functioning. 

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