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Decommissioning Nuclear Energy Facilities

After a nuclear energy facility is closed and removed from service, it must be decommissioned. This entails the removal and disposal of radioactive components and materials such as the reactor and associated piping and the cleanup of radioactive or hazardous contamination that may remain in the buildings and on the site. It also includes placing used fuel into robust and shielded dry storage containers. The licensee remains accountable to the U.S. Nuclear Regulatory Commission until decommissioning has been completed and the license terminated.

June 2013
 
Key Facts
 

  • After a nuclear energy facility is closed and removed from service, it must be decommissioned. This entails the removal and disposal of radioactive components and materials such as the reactor and associated piping and the cleanup of radioactive or hazardous contamination that may remain in the buildings and on the site. It also includes placing used fuel into robust and shielded dry storage containers. The licensee remains accountable to the U.S. Nuclear Regulatory Commission until decommissioning has been completed and the license terminated.
     
  • NRC regulations and associated guidance detail the requirements and process for decommissioning. Each licensee for a permanently shutdown facility must file a post-shutdown activities report with the NRC before its operating license expires or within two years after the plant has permanently shut down.
     
  • The NRC requires licensees to put aside funds for eventual decommissioning throughout a facility’s operating lifetime. Companies work with federal and state regulators to ensure that enough money will be available. Decommissioning funds are not under the direct control of the companies and cannot be used for any other purpose.
     
  • Since 1960, more than 70 test, demonstration and power reactors have been retired throughout the United States. These include 10 research and test reactors and 13 commercial and early demonstration nuclear energy facilities currently undergoing decommissioning or in long-term safe storage.


Decommissioning: What's Involved?
Five years before a company plans to terminate reactor operation, it must submit a preliminary decommissioning cost estimate to the NRC. Within two years of shutting down the facility, the company must submit a report on its decommissioning activities to the NRC and the affected states. The report must include a description of the planned decommissioning option (DECON, SAFSTOR or ENTOMB):
 

  • DECON (Decontamination). In DECON, all components and structures that are radioactive are cleaned or dismantled, packaged, and shipped to a low-level waste disposal site or they are stored temporarily on site. Once this task—which takes five or more years—is completed and the NRC terminates the plant’s license, that portion of the site can be reused for other purposes. Facilities using DECON: Fermi 1, Zion 1 and 2.
     
  • SAFSTOR (Safe Storage). In SAFSTOR, the nuclear plant is kept intact and placed in protective storage for up to 60 years. This method, which involves locking the part of the plant that containss radioactive materials and monitoring it with an on-site security force, uses time as a decontaminating agent by allowing the radioactive components to decay to stable elements. For example, if a plant is allowed to sit idle for 30 years, the radioactivity from cobalt 60 will be reduced to 1/50th of its original level; after 50 years, the radioactivity will be about 1/1,000th of its original level. Once radioactivity has decayed to lower levels, the unit is taken apart, similar to DECON. Facilities using SAFSTOR: Dresden 1, Indian Point 1, LaCrosse, Peach Bottom 1, San Onofre 1.
     
  • ENTOMB. This option involves encasing radioactive structures, systems and components in a long-lived substance, such as concrete. The encased plant would be appropriately maintained, and surveillance would continue until the radioactivity decays to a level that permits termination of the plant’s license, with little or no additional decontamination. To date, no NRC licensees have requested this option.

 
The company’s report to the NRC also must include a schedule to complete decommissioning, a discussion of how site-specific decommissioning activities will adhere to previously issued environmental impact statements, and an estimate of expected costs. The NRC reviews the report and holds public meetings to discuss the company’s plans and the regulatory oversight process.
 
While this process is under way, the licensee may perform routine activities, such as maintenance and disposal of small radioactive components. The licensee does not have access to the full amount of the decommissioning funds until the site-specific cost estimate has been accepted by the NRC.
 
At the end of 90 days, if the NRC has no objections, the company may begin major decommissioning activities. These include the permanent removal of large radioactive components—such as the reactor vessel, steam generators or other components that are comparably radioactive—as well as permanent changes to the containment structure. The site must be decommissioned within 60 years.
 
License Termination Plan
The licensee must submit a license termination plan at least two years before the proposed license termination date. The NRC will make the plan available to the public for comment and schedule a public meeting near the facility to discuss its contents. The public also has the opportunity to request adjudicatory hearings. Once public concerns are addressed, the NRC will approve the plan—assuming it demonstrates that the remaining decommissioning activities will be performed according to federal regulations and that they will have no adverse effects on health and safety or the environment.
 
Finally, if the NRC determines that all work has followed the approved license termination plan—and if the final radiation survey demonstrates that the facility and site are suitable for release—the agency will terminate the license, thus completing the decommissioning process.
 
Until the license is terminated, the licensee remains accountable to the NRC.
 
How a Facility Is Decommissioned
Decommissioning a nuclear energy facility has two basic steps.
 
First, the company that operates the plant either decontaminates or removes contaminated equipment and materials. It also places the used nuclear fuel in dry storage until its final disposal. These materials and equipment account for more than 99 percent of the plant’s radioactivity. Their removal lowers the level of radiation and thus reduces the exposure of workers during subsequent decommissioning operations.
 
Second, the company deals with the small amount of radioactivity remaining in the facility, which must be reduced to harmless levels through a cleanup phase called decontamination. Workers remove surface radioactive material that has accumulated inside pipes and heat exchangers or on floors and walls that were not decontaminated during normal plant operations because of inaccessibility or operational considerations. They are aided in decontamination activities by the records that plants are required to keep during operation. Workers use chemical, physical, electrical and ultrasonic processes to decontaminate equipment and surfaces. The removed radioactive material is packaged and transported or stored for disposal at a designated site.
 
Throughout the decommissioning process, regulatory oversight is provided by the NRC and also by the Occupational Safety and Health Administration, the Department of Transportation and the U.S. Environmental Protection Agency. A number of state agencies also play a significant role in the health and safety of the public and decommissioning workers.
 
Funding Requirements for Decommissioning
Every company that operates a nuclear energy facility is required to amass the funds needed to decommission all portions of a nuclear energy facility that have been contaminated by radioactive material.
 
Decommissioning costs include three components: labor, energy, and the transportation and disposal of waste materials. The most reliable estimate of decommissioning costs comes from an engineering study of a specific plant. The company must review annually and report to the NRC every two years on the amount of money required for decommissioning and the adequacy of the fund being used to accumulate it. The size of the fund is adjusted periodically to account for changes in the cost of labor, energy and low-level waste disposal and to take into account technological advancements.
 
The NRC accepts three types of decommissioning funds:
 

  • An external sinking fund that builds up money for decommissioning gradually over the facility’s operating lifetime. Revenues earmarked for decommissioning are collected from customers through rates and invested in a trust fund that is professionally managed.
     
  • A prepayment account in which the company deposits money before the plant begins operation. The account may be a trust, escrow account, government fund, certificate of deposit or government securities. It is kept separate from a company’s other assets and is outside its control.
     
  • A surety bond, letter of credit or insurance, which guarantees that decommissioning costs will be paid if the company defaults on its obligation.

 
Companies typically have set up sinking funds to accumulate money for decommissioning. In the early years of a power reactor’s operating life, decommissioning funds build up slowly, and then accelerate more quickly as the compounded earnings on the trust fund’s investments increase.