Decommissioning Process

Decommissioning Process

The Diablo Canyon Decommissioning Engagement Panel (DCDEP) recognizes that the decommissioning of the DCPP will be a lengthy and complicated process involving local, state, and federal regulatory agencies. 

When a power company decides to close a nuclear power plant permanently, the facility must be decommissioned by safely removing it from service and reducing residual radioactivity to a level that permits release of the property and termination of the operating license. The NRC has strict rules governing nuclear power plant decommissioning, involving cleanup of radioactively contaminated plant systems and structures and removal of the radioactive fuel. These requirements protect workers and the public during the entire decommissioning process and the public after the license is terminated.

The companies that operate nuclear power plants can use one or both of two options to decommission their facilities.

The first option is known as “DECON,” short for decontamination. With DECON, the first steps of taking the plant apart begin as soon as the fuel is removed from the reactor vessel.  The operator first decontaminates or removes contaminated equipment and materials. The transfer of spent nuclear fuel into dry cask storage and the removal of equipment lowers the radiation level in the facility and significantly reduces the potential exposure to workers during subsequent decommissioning operations.  DECON can take five years or more.

The second option is called “SAFSTOR,” for safe storage.  This process takes much longer. After the fuel is removed from the reactor vessel, the plant is kept intact and placed in protective storage for an extended period of time.  This allows the radioactive elements in components to decay to stable elements. During this time, the main components of the plant remain in place, including the reactor vessel, fuel pools, turbine and other elements. All fuel is removed from the reactor vessel and placed in fuel pools or dry storage on-site. The NRC continues to inspect the site and provides regulatory oversight of maintenance and security appropriate to the low risk profile of the site.  The plant is dismantled in a process similar to the DECON option once radioactivity has decayed to lower levels and the safety risk to workers is substantially reduced.  Generally, sites must spend no longer than 50 years in SAFSTOR to allow up to 10 years for decontamination. The entire process must be completed within 60 years.

According to the NRC website, eighteen commercial reactors in the United States are in the decommissioning process.  Twelve of these reactors are using the SAFSTOR option, six are using the DECON option.

Link to U.S. Nuclear Regulatory Commission Decommissioning Information:

Decommissioning, which includes the issues of the long-term storage and intended future removal from the DCPP site of spent nuclear fuel, could span several decades and will require the community and stakeholders to remain attentive and engaged for many years. 

Example Timeline for Decommissioning
Vision, Goals and Recommendations

Through these vision statements, goals and recommendations, it is the intent of the DCDEP to make health and safety the first consideration throughout the decommissioning process and to establish and maintain working relationships that encourage information sharing and effective dialogue among all persons and entities with an interest in the decommissioning process.

Vision Statements

  • The health, safety and well-being of the local community should be ensured before, during and after decommissioning
  • The decommissioning (decontamination) process should begin immediately upon shutdown with a goal of 10 years for completion of radiological decommissioning and decontamination, thus avoiding SAFSTOR (which allows up to 60-year delay in decontamination)
  • The decommissioning process should be safe, timely, cost effective and efficient
  • The CPUC should continue the DCDEP at a minimum until cessation of operations of the DCPP


  1. Diablo Canyon Decommissioning Engagement Panel
    1. The DCDEP should continue its role of interacting with the public to assure the public’s perspectives are understood and considered by PG&E and regulatory agencies
    2. The DCDEP should continue to assist PG&E in seeking out new ideas/opportunities throughout the decommissioning process
    3. The DCDEP should assist the public in understanding what to expect during the decommissioning process
    4. The DCDEP’s recommendations and guidance during the decommissioning process should be strongly considered by PG&E and regulatory agencies
  2. Safety
    1. The highest level of safety during the decommissioning process should be ensured
    2. The highly radioactive spent nuclear fuel should be stored onsite in the safest and most technologically advanced manner possible and be removed from the site as soon as feasible
    3. The highest level of safety regarding the transport of radioactive contaminated materials and eventual removal of spent fuel from the area should be ensured
    4. The traffic impacts associated with decommissioning activities should be minimized through surrounding communities
  3. Labor
    1. The commitment to the use of a highly skilled and trained local workforce for all decommissioning activities should be continued by PG&E


  1. Diablo Canyon Decommissioning Engagement Panel
    1. Recommend to the CPUC that public meetings and workshops continue to be held and public input received by the DCDEP throughout the decommissioning process
    2. Recommend to the CPUC that a report be prepared each year by the DCDEP reflecting the public input received over that time frame
    3. Recommend that the CPUC consider formally expanding the charter of the Diablo Canyon Independent Safety Committee to include any technical support that may be requested of them by the DCDEP
    4. Recommend that the CPUC consider extending the existence of the Diablo Canyon Independent Safety Committee beyond conclusion of power generation at the DCPP so that their independent and valuable technical and safety expertise would continue to be available to the DCDEP and to the communities in San Luis Obispo County during the decades of decommissioning
  2. Safety
    1. Recommend to PG&E that decommissioning (decontamination) begin immediately upon plant shutdown with a goal of 10 years for completion of radiological decommissioning and decontamination and that SAFSTOR not be considered
    2. Recommend to the CPUC that the spent fuel stored on-site be monitored at all times by PG&E or other entity as appropriate (before and during DECON) using real-time radiation monitoring
    3. Recommend to the CPUC that the implementation of technologically advanced storage methods for spent fuel occur as soon as such methods are identified and determined to be feasible
    4. Recommend to the CPUC that PG&E thoroughly research and investigate the potential for both ship and truck transport of dismantled facilities from the site and the data communicated to the DCDEP
    5. Recommend to PG&E that the transport of demolished facilities (including radiological demolished materials) through surrounding communities be avoided during times of peak traffic
    6. Recommend to PG&E that the possible future transport of spent fuel to an off-site storage facility through surrounding communities be avoided during times of peak traffic
    7. Recommend that PG&E research the safest method of transport and consider any new technological innovation in compliance with all applicable regulations
  3. Labor
    1. Recommend the use of non-discriminatory project labor agreements that incentivize local contractors hire from the local workforce for decommissioning activities, be implemented by PG&E at the earliest possible time
    2. Recommend to PG&E that non-discriminatory project labor agreements incorporate a continued commitment to supporting the local workforce and maintain programs that support the highest level of safety and training
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