USS Enterprise decommissioning, first of its kind
November 4, 2011 · 11:27 AM
The USS Enterprise, which was originally slated for decommissioning in 2014, will now be taken out of the fleet a year earlier. The Department of the Navy and Puget Sound Naval Shipyard are evaluating this large-scale, unprecedented project and its impact on workers and the surrounding community.
The Puget Sound Naval Shipyard has experience in disposing reactor plants from the 114 nuclear-powered ships already helped decommission under their watch.
However, of those decommissioned ships, 106 were nuclear submarines, not carriers. The remaining eight vessels were nuclear-powered cruisers with only two reactor compartments a piece.
The Enterprise houses quadruple the number of reactor compartments as a cruiser. It is the first of its size and scope, which, according to PSNS, requires special consideration and handling.
“The Draft EA is necessary for the disposal of USS Enterprise reactor plants because the 1996 Environmental Impact Statement [for Ohio class and Los Angeles class cruisers] did not include carriers within its scope,” said Darcy Jenne, PSNS spokesperson.
What is known for sure, is that the Enterprise will be defueled and deactivated in an East Coast shipyard. Inactive, the Enterprise will be towed to Bremerton and PSNS.
Once at PSNS, there are two options for consideration – the Navy preferred alternative and the no-action alternative.
The Navy preferred alternative suggests that once PSNS receives the Enterprise, it immediately take apart and dispose of the reactor compartments. Shipyard workers would also take apart the hull of the ship and recycle the remnant sections.
This job is estimated to last up to eight years.
The extracted reactor compartments would still be radioactive, but, according to the EA, self-contained.
“After defueling, about 99.9 percent of the remaining radioactivity in the reactor plant is within the corrosion resistant structural alloys forming the plant,” states the September. EA.
PSNS is discouraged from attempting to drain compartments further.
“Removal of the small quantity of liquid remaining within the reactor compartment package would not be warranted because the increase in radiation exposure to the workers would be in conflict with ALARA guidelines, and would not result in any measurable benefit to the quality of the environment,” states the EA.
Instead, under the Navy’s preferred method, the shipyard will transport all extracted reactor compartments from the USS Enterprise to a designated Navy trench (trench 94) at the DOE Hanford site. Ship parts from 114 previously decommissioned ships are also buried here and will be the final resting place of the USS Enterprise.
The preferred method, also called “cradle to grave,” is estimated to cost between $300 million to $500 million and require 850,000 man-days of work.
No new jobs
The cost to originally build the Enterprise back in 1957 was approximately $450 million.
Though the work for this alternative is intensive, PSNS does not anticipate more hires as a result.
“This work would represent less than historic peak work loads at PSNS & IMF, when up to ten submarines per year underwent reactor compartment disposal and remnant hull recycl.This work is expected to be performed within the shipyard’s available resources,” states the EA.
A second option, called the no-action option, involves receiving the defueled Enterprise from Newport News and storing it indefinitely and intact at PSNS. Waterborne storage would call for mooring the Enterprise on the west side of Mooring Alpha.
Permanent mooring would require less work to start, but indefinite maintenance to ensure public safety. Some of these maintenance tasks include installing fire and flooding alarm systems, a dehumidification system, cathodic protection and lighting. Outside maintenance of the hull and repainting would have to be done every 15 years.
Maintenance workers would be exposed to some radiation, generally below one millirem per hour. “However, localized spots of elevated rates (less than 10 millirem per hour) could exist,” according to the EA.
“Exposure would be similar to work conducted on other inactive nuclear ships at Mooring Alpha and would be less than on active ships undergoing maintenance at the shipyard,” said Jenne.
The real difference for the community with the no-action alternative is in how it would affect the job force. The study estimates that the shipyard’s workload will decrease under the no-action alternative. Waterborne storage rather than a six to eight year disassembly process may cost Kitsap workers jobs.
“It is also possible for the decrease [in workload] to be great enough that redistribution of work is not sufficient and jobs are lost. In this case, there could be socioeconomic impact to the local population, housing, school districts, other employment, and local governments,” states the EA.
At the time, both the DON and PSNS are hoping for the preferred alternative to pass.
“PSNS & IMF and the Navy would prefer to prepare the reactor compartments and ship them to Hanford for burial,” said Jenne.
The Draft Environmental Assessment of the USS Enterprise Decommissioning is open for public comment until Nov. 30. Find the entire DEA document at http://www.hanford.gov/files.cfm/Enterprise_EA_for_public.pdf