Facility decommissioning

Decommissioning may be achieved in different ways, depending on the facilities type and the location. This section will also briefly look at the ways in which decommissioning can be deferred by extending the field life, and then at the main methods of well abandonment and facilities decommissioning. 

DOE-STD-1120 provides guidance for preparing a DSA for decommissioning of nuclear facilities, as well as environmental restoration activities that involve work not done within a permanent structure (DOE-STD-1120-2005). Methodologies provided in this standard are compliant with 10 CFR 830, Subpart B—Safety Basis Requirements. The standard is written to make the maximum utilization of the provisions of 29 CFR 1910.120 or 29 CFR 1926.65— Hazardous Waste Operations and Emergency Response (HAZWOPER). Derivation of controls is also necessary for facility decommissioning projects that involve more than "low level residual fixed radioactivity."... 

Information International Associates, Inc., Oak Ridge National Laboratory. 1980-1997. Nuclear Facility Decommissioning and Site Remedial Actions A Selected Bibliography. 

In high permeability reservoirs, wells may produce dry oil for a limited time following a shut-in period, during which gravity forces have segregated oil and water near the wellbore. In fields with more production potential than production capacity, wells can be alternately produced and shut in (intermittentproduction) to reduce the field water cut. This may still be an attractive option at reduced rates very late in field life, if redundant facilities can be decommissioned to reduce operating costs. 

Initially, if operating costs can be divided based on production throughput, the satellite development project may look attractive. However, the unit costs of the declining host field will eventually exceed income and the satellite development may not be able to support the cost of maintaining the old facilities. If the old facilities can be partly decommissioned, and provision made for part of the abandonment cost, then the satellite development may still look attractive. The satellite development option should always be compared to options for independent development. 

Each of the main facility types, e.g. steel jacket, gravity structure, tension leg and floating platform, have different options for decommissioning. The main factors which need to be considered and which will impact on costs are type of construction, size, distance from shore, weather conditions and the complexity of the removal, including all safety aspects. The following options are available ... 

Subsea facilities are easily decommissioned as they are relatively small and easy to lift. However, subsea manifolds and templates can weigh in excess of 1,000 tons and will require heavy lift barges for removal. 

Opportunities for Cost deduction in the Ttecontamination and Decommissioning of the Nation s Uranium Enrichment Facilities,V3.tLoaA Academy Press, Washington, D.C., 1996. 

The facility design must consider decommissioning issues, as discussed in Section 4.6. 

A major consequence of the activities associated with the exploitation of mineral deposits (i.e., exploration, the development of mines and processing facilities, the extraction and concentration, which is also called beneficiation, of ores containing the desired minerals, and the decommissioning or abandonment of mine facilities) is the production of extremely large volumes of unwanted materials. Waste volumes vary from ca. 30% of the mass of the ore in the case of gypsum and other non-metals, to about 50% for base metals to more than 80% for strip-mined... 

Operators planning the decommissioning (temporary disconnect) of transmission facilities shall develop procedures for the decommissioning of facilities from service. The procedures shall include the following ... 

Facilities previously decommissioned shall be tested in the same manner as new facilities before being reinstated. 

The JACADS closure activities will involve the dismantling and destruction of that portion of the facility that cannot be decontaminated to meet the 5R cleanliness standard. An area decommissioning matrix delineates the areas that will be decontaminated and dismantled, decontaminated and abandoned in place, or solely abandoned in place (U.S. Army, 2000c). The remaining systems, structures, and components (SSCs) that are left in place must meet the Resource Conservation and Recovery Act (RCRA) criteria for decontamination as well as the Army standard of 5R. Areas that were kept free of any agent or hazardous materials will be sampled to demonstrate their cleanliness in accordance with the final closure sampling and analysis plan. 

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