Dresden - Unit 1
1.0 Site Identification
|Type of Site:||Power Reactor Facility|
|Project Manager:||John Hickman|
2.0 Site Status Summary
The plant shut down in October 1978 and is currently in SAFSTOR. The Decommissioning Plan was approved in September 1993. No significant dismantlement activities are underway. Isolation of Unit 1 and Units 2 and 3, is complete. All spent fuel from DNPS Unit 1 has now been transferred to the on-site Independent Spent Fuel Storage Installation (ISFSI). During the SAFSTOR period (through 2027), the Unit 1 facility will be subjected to periodic inspection and monitoring. These activities will include condition monitoring of the ISFSI, ongoing environmental surveys, and maintenance of equipment required to support the SAFSTOR condition of the facility. Security will be maintained as part of the site protected area boundary for DNPS Units 1, 2, and 3 during this period. The licensee plans that decontamination and dismantlement of DNPS Unit 1 will take place from 2029 through 2031. Major components, including the nuclear steam supply system and the turbine-generator machinery, will be decontaminated as needed, and removed at this time. Other systems and components will also be removed, packaged and disposed of; the associated buildings will be prepared for demolition. A four-year site restoration delay will follow the major decontamination and dismantlement of DNPS Unit 1 to allow for the decontamination and dismantlement of Units 2 and 3, with completion of these activities tentatively planned for 2035. Site restoration is planned for in 2035 and 2036, with the demolition of the remaining structures and removal of contaminated soil. The licensee plans to conduct a final site survey in late 2036. The licensee will monitor the DNPS ISFSI complex with site security and periodic inspections until final transfer of the spent fuel to the Department of Energy for disposal.
Dresden Unit 1 produced power commercially from 1960 to October 31,1978. The unit had a history of minor steam leaks and erosion in steam piping in the early and mid-1960s. There were also fuel failures during the period of September through December of 1964 and other times which, although not leading to off-gas releases above limits, did cause redistribution of radionuclides from the fuel to other parts of the primary system. Several systems in the plant used admiralty brass (Cu-Ni) heat exchange surfaces, including the Main Condenser. Most of these were taken out of service and replaced with stainless steel tubing. In the sixth partial refueling, the condenser was re-tubed from admiralty brass to 304L stainless steel. The use of Cu-Ni surfaces did lead to translocation and deposition of corrosion products throughout the operating systems. The use of carbon steel in the Secondary Feedwater System may have also contributed to the elevated corrosion radionuclide levels. These foregoing events led to the need to perform a chemical decontamination of the Primary System. The Unit was taken off-line on October 31, 1978, to backfit it with equipment to meet new federal regulations and to perform a chemical decontamination of major piping systems. While it was out of service for retrofitting, additional regulations were issued as a result of the March 1979 incident at Three Mile Island. The estimated cost to bring Dresden Unit 1 into compliance with these regulations was more than $300 million. Commonwealth Edison concluded that the age of the unit and its relatively small size did not warrant the added investment. In 1984, chemical decontamination of the primary system was performed and 753 curies of Cobalt-60 and 12.4 curies of Cesium- 137 were removed. This decontamination was completed and activities began shortly thereafter to prepare the facility for decommissioning. In July of 1986, the NRC revised the Dresden Unit 1 license to possess-but-not-operate status. The United States Nuclear Regulatory Commission (NRC) approved Revision 3 to the Dresden Unit 1 Decommissioning Program Plan on September 3, 1993. In 1998, the Decommissioning Program Plan was revised to the current Defueled Safety Analysis Report (DSAR) format.
3.0 Major Technical or Regulatory Issues
4.0 Estimated Date For Closure