Three Mile Island Unit 2 Overview and Management Issues. THE 5TH MEETING OF THE INTERNATIONAL DECOMMISSIONING NETWORK. 1 through 3 November, 2011 Chuck Negin, Project Enhancement Corp. Subjects & Framework. Subjects TMI-2 Cleanup Description
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Three Mile Island Unit 2 Overview and Management Issues
THE 5TH MEETING OF THE INTERNATIONAL DECOMMISSIONING NETWORK
1 through 3 November, 2011
Chuck Negin, Project Enhancement Corp.
Fuel & Debris Storage
Idaho National Laboratory
Three Mile Island
Commercial Low Level
Barnwell, South Carolina
Reactor Pressure Vessel Cutaway View
Some Manual Tools
Low Tech but Effective
Tungsten Carbide Teeth with Synthetic Diamond
1.5 minute Core Bore & Cavity after Core Bore
1986 to 1990
341 canisters of fuel & debris in 46 shipments by rail cask to the Idaho National Laboratory
1990 to 2000
Wet Storage in Spent Fuel Storage Pool
2000 – 2001
Removed from pool, dewatered, dried, and placed in dry storage
Defueling Options Evaluations
First Video of Core
Sonar Mapping &
Defueling Method Decision
Dry Canal & Mostly Manual
Vessel Head Lift
Lost Water Clarity
* GPU Nuclear Defueling Completion Report, pages ES-9 and ES-10
** EPRI NP-7156 Section 3.2.3
Assessment Required a Combination of**:
300,000 lbs = 13,600 kg
From EPRI TR-100640, Page 10-4
“Accident” Water (in Containment and Reactor Systems)
Defueling Water Cleanup System
Final Water Disposal
Accident vs. Non-Accident Decommissioning Comparisons
No similarity to normal decommissioning
TMI-2 Example; 1 to 2 years
Many activities similar to normal decommissioning but with conditions an order of magnitude more severe
TMI-2 Example; 8 to 9 years
Activities are similar to long term care and maintenance followed by removal and/or entombment
TMI-2 example; 40 years or more
Phase 1 end state is one for which conditions are that parameters such as pressure, temperature, water movements, gas release, and radioactive material migration are under human operational control.
As a project this phase is in no way similar to normal decommissioning
Establishing control requires specific activities that require decommissioning skills and methods; such as localized decontamination and system flushing
Phase 2 end state is one for which conditions have been established to place the facility in a monitored storage and maintenance configuration while waiting final decommissioning.
Elements of this phase will likely begin while the accident stabilization activities are being conducted.
Capturing and storing the damaged fuel and fuel debris, removal from the site if a destination is available.
Processing of highly radioactive water and gas.
Storing and disposing of the concentrated process media.
On-site decontamination is primarily as needed for worker protection and area accessibility.
Final decommissioning begins with the establishment of the storage and maintenance configuration
The end state is either:
complete demolition and removal of all facilities, or
partial demolition of facilities with entombment of what remains.
Removal of materials fuel and fuel debris and processing media in storage
Removal of all radioactive materials. A partial exception to this would be when the end state includes entombment.
Demolition to the degree decided and removal of the demolition debris for disposal or recycle.
Decontamination to meet established criteria.
Functionally similar to a Normal Decommissioning Project in that Management Challenges Include
Financing and cash flow.
Assembling the personnel with some degree of skill in the many technical and operational areas, recognizing that many activities do not have a large base from which to draw.
Organization; creating an efficient on-site organization that interfaces well with the parallel operational organization. Need to ensure the many contractors work as one organization.
Working pro-actively with regulators. Regulations are generally not created with post-accident cleanup considerations; which is not surprising because regulations are standards and these situations are one-of-a-kind.
Working pro-actively with the responsible local community leaders to keep the public informed of the status of hazards and risks.
The need for on-site facilities for management and support staff, labs for radiochemical analysis, machine shop for quickly fabricating tools and repairing equipment, etc.
Water management and accident water processing, selection of systems and how to store the processing media.
Large volumes of processed water; its storage, use for cleanup, and eventual release
A critical goal is to obtain characterization data and information regarding the true physical conditions of fuel, contamination, equipment function, and structural integrity. Without such information when needed, decision making is tentative.
Adapting robotic and video technology to the physical constraints
How to capture fuel and debris including methods, equipment, safety issues. Should a highly automated system be developed or can mostly-manually controlled operations be used?
For both the highly radioactive processing concentrates and damaged fuel, selecting on-site staging and storage locations and designing their features.
Questions for IAEA Consideration
Based on Windscale, TMI-2, A2
Two reports that provide detail are:
IAEA Technical Reports Series No. 321, “management of Severely Damaged Nuclear Fuel and Related Waste”
IAEA-TECDOC-935, “Issues and decisions for nuclear power plant management after fuel damage events.”
TECDOC-935 also addresses fuel damage events less serious than the Fukushima/TMI-2 accidents.
How does post-accident cleanup ramp down?
At what point does the accident cleanup phase end with:
The facility is in a monitored storage mode; or
The project proceeds to dismantling the facility and achieving final cleanup criteria.
What are the criteria for completing final decommissioning?
What is to be the ultimate end state and conditions for the site and facility, including residual radioactivity?
Should part of the facility be permanently entombed or must all be removed and transported elsewhere?
Who will own it?
In an accident situation, there will be several decisions for which many factors are not within the authority and control of the power plant owner and operator.
Examples that relate to ultimate destination of highly radioactive materials; which are:
Ion exchange and filtration media resulting from processing accident contaminated water, particularly with high levels of Cs-137. The concentrations may be too high for acceptance within low or intermediate level disposal facilities.
Damaged fuel and fuel debris.
What to do will likely involve government leaders and regulators.
How to store, package, and transport this material can all be affected by where it will be sent; or whether it will be on-site indefinitely.
Does it make sense to address these questions now? Is there a role for the IAEA in this?