THE 5TH MEETING OF THE INTERNATIONAL DECOMMISSIONING NETWORK

1 through 3 November, 2011Chuck Negin, Project Enhancement Corp.

Three Mile Island Unit 2 Overview and Management Issues

Subjects & Framework

Subjects TMI-2 Cleanup Description Accident vs. Non-Accident Decommissioning

Comparisons Questions for IAEA Consideration

Framework – This does not address the stabilization time frame that immediately follows emergency response

The TMI-2 Location & System

Unit 2Containment

19 Zeolite VesselsHanford, Washington

Fuel & Debris StorageIdaho National Laboratory

Important Locations for the TMI-2 Cleanup

Three Mile IslandMiddletown, Pennsylvania

Commercial Low LevelWaste Disposal

Barnwell, South Carolina

2100 miles3400 km

2600 miles4200 km

600 miles1000 km

A Few Good Luck /Bad Luck Observations Affecting the TMI-2 Cleanup

Good Reactor had only operated 3 months Accident was terminated before there was serious damage to the reactor

pressure vessel or primary coolant system Spent fuel pool was empty Existing Department of Energy personnel and facilities had experience

with highly radioactive materials Not so good

There were no significant precedents for the TMI-2 accident Robotics and vision technology were not well advanced Did not anticipate biological growth in the defueling water Could not discharge processed “Accident Water”

Some Important Defueling Related Events (1)

Events/Decisions SignificanceQuick Look First idea of what conditions really were; complete assessment

took another year; could not proceed to plan defueling without this knowledge

Decision to not to install in-core shredding equipment in the vessel

• New application for the proposed technology, concern that failure would cause problems, relied mostly on manual manipulation with power assist

• Allowed defueling to start earlier, knowing that overall schedule would not be minimized. This was preferred over a 3 year development before any fuel would be removed.

Decision to leave refueling canal dry

• Less depth for manually operated tools (picture later)• Shielded work platform 2m above the reactor pressure vessel

flange• Reduced need for water processing• Dose rates were low within the refueling canal

Use of Core Boring Machine

• Samples of the fuel and debris that was melted together• Breaking up the crust and molten mass when manual

methods were unsuccessful

Some Important Defueling Related Events (2)

Events/Decisions SignificanceBiological growth in water Caused a year delay; managing water clarity is extremely

importantDOE to take Fuel & DebrisNew cask design and license

Ship Fuel by Rail and not Truck

• Handling and shipping design and fabrication could not take place until destination was determined

• New cask could be designed for the TMI canisters• Fewer shipments

Ship to Idaho Allowed fuel & debris canisters to be removed from TMI

Final Accountability Precision accountability not required; verified that no visible material remained

Transfer to Dry Storage Long term storage stability, also allowed demolition of fuel pool at Idaho

Various Areas for Defueling

Core Cavity Lower Support Grid Flow Distributor Behind and within the Core

Baffle Plates Lower Head Elsewhere in the Reactor

Systems (not shown)

Reactor Pressure Vessel Cutaway View

Damage Examples

Fuel Removal Tools and Equipment

Powered Equipment- Core Boring Machine- Plasma Arc Power Assisted shears- Bulk Removal- Water Vacuum and Air Lift

Some Manual Tools

Work Platform

Remote Technology in the 1980s

Much of what was done was innovation based on the immediate need

The wagon is one example. A toy remote controlled vehicle was used to survey a very radioactive equipment cubicle.

Several robotic devices were created specifically for TMI-2; ROVER is one example. A miniature submarine in the pressurizer is another.

Low Tech but Effective ROVER

Mini Submarine

Core Boring Machine (1)

Adapted from commercial mining drilling equipment One of the most important machines for the project First use with hollow core bits: 10 samples 1.8 m long x

6.4 cm diameter (figure below) Second use with solid face bits to chew through the hard

once-molten mass in the core region Third use was assisting lower grid and instrument tubes

by grinding metal (next viewgraph)

Tungsten Carbide Teeth with Synthetic Diamond

Core Boring Machine (2)

1.5 minute Core Bore & Cavity after Core Bore

Extreme Case – not TMI-2

Packaging, Transport, & Storage of Fuel and Debris at Idaho

1986 to 1990341 canisters of fuel & debris in 46 shipments by rail cask to the

Idaho National Laboratory

1990 to 2000Wet Storage in Spent Fuel

Storage Pool

2000 – 2001Removed from pool, dewatered, dried, and placed in dry storage

Defueling Progress and Key Impacts

1982-1983Defueling Options Evaluations

1982First Video of Core

1983First Sample

1983Sonar Mapping &Improved Video

Mid-1984Vessel Head Lift

1984Defueling Method DecisionDry Canal & Mostly Manual

Vessel Defueling Progress

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Oct-85 Apr-86 Nov-86 May-87 Dec-87 Jun-88 Jan-89 Aug-89

Feb-86

Dec-1986

April-1987

Sept-1987

Oct-1985

Dec-1988

May-1989

Feb-1990

Dec-1987

Lower GridCutting

Core FormerDisassembly

Lost Water Clarity

Final Clean-Out Verification

Residual Fuel* RPV: < 900 kg In the Reactor Coolant System: < 133 kg; greatest single location amount is ≈36

kg on the B Steam Generator upper tube sheet Criticality ruled out by analysis

Assessment Required a Combination of**: Video inspection for locations Gamma dose rate and spectroscopy Passive neutron solid state track recorders, activation, BF3 detectors Active neutron interrogation Alpha Detectors Sample Analysis

* GPU Nuclear Defueling Completion Report, pages ES-9 and ES-10** EPRI NP-7156 Section 3.2.3

Measurement & Documentation (Accountability)

300,000 lbs = 13,600 kg

From EPRI TR-100640, Page 10-4 Standard accountability (at the gram level) was impossible NRC granted an exemption to the requirement Required a detailed survey conducted after defueling for what remained Computer code analyses conducted for fissionable nuclides: 1) existing prior to the accident,

2) remaining after the accident, and 3) radioactive decay Therefore the net balance is what was sent to Idaho

Water Management

“Accident” Water (in Containment and Reactor Systems) Zeolite (Submerged Demineralizer System) Resin Demineralizers

Defueling Water Cleanup System Primarily filtration to control suspended solids Included zeolite and sand-charcoal media

Final Water Disposal Not allowed to discharge to the river because of tritium fears Used open cycle low temperature evaporator

Key Resin Demineralizer System

Key Zeolite System

Water Processed and Stored

Waste Management Facilities

Some TMI-2 Conclusions

In addition to the Information Presented• Efficiency improved when all the on-site companies were integrated into a single

organizational for responsibility and reporting• On-site tool development resources and radio-chemistry labs helped considerably• A 6 to 8 member independent senior technical advisory group that met every month or

two was important• Participation by DOE facilities and resources was essential

• From the Presentation• Much planning, methods, equipment development could only be done as real conditions

became known• Manual, less complex methods that meant a long schedule allowed quicker adjustment

for unexpected surprises and to try new approaches• Often several options had to be carried forward until one evolved as preferable

Other than Technical

Early- Governor's Concern about Evacuation Recommendation

Surrounding Area Citizens- Citizens Advisory Panel; Local area representatives to review

plans (this was very important!) and periodically hold public meetings

- Citizens monitoring program Annual protests outside the gate City of Lancaster (down river)

- Concern about tritium in drinking water intake

Accident vs. Non-Accident Decommissioning Comparisons

View Post Accident Decommissioning as Three Phases

1. Stabilization• No similarity to normal decommissioning• TMI-2 Example; 1 to 2 years

2. Post-Accident Cleanup• Many activities similar to normal decommissioning but with

conditions an order of magnitude more severe• TMI-2 Example; 8 to 9 years

3. Final Decommissioning• Activities are similar to long term care and maintenance

followed by removal and/or entombment• TMI-2 example; 40 years or more

Phase 1 - Stabilization

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 - Post-Accident Cleanup

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.

Major Goals 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.

Phase 3 - Final Decommissioning

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. Goals

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.

Management ChallengesPutting Together the Project

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.

Management ChallengesA Few Accident Specific Decisions

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

IAEA Guidance Exists

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.

Special Nuclear Material Accountability

It is impossible to accurately account for the special nuclear material in a core that has been melted. (

Fukushima cleanup will need relief from normal standards just as was the case for TMI-2.

The TMI-2 experience provides an example from which to formulate this relief.

Should the IAEA address this (e.g., for Fukushima Daiichi)?

Fuel Debris

Damaged fuel and fuel debris is unlike any standard waste forms

The form of debris can vary considerably Should the IAEA develop criteria for packaging and

storage of such materials?

Keeping a Record of the Fukushima Daichi Accident Cleanup

The experience of the TMI-2 cleanup was well recorded during and at the end of the cleanup. Focus was on decisions, options, what went wrong and what was

successful, why certain choices were made, etc. IAEA guidance on post-accident cleanup has used this information. Many of these reports and supporting information have been provided to

Japan; provides insights although solutions may be much different Recording the Fukushima recovery and cleanup

Conditions are considerably different than either TMI-2 or Chernobyl Much of the cleanup will provide new lessons An English language record will be useful if ever needed

Is there a role for the IAEA in this?

Management ChallengesOn-Site Long Term Decisions

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?

Mobilization of Cleanup Resources

Japan, Russia , the UK, and the USA where severe accidents have occurred have the resources to deal with the cleanup.

Resources needed for major cleanup include personnel, equipment, and examination facilities that have past use and experience with high radiation materials and damaged fuel.

Is there a need to address this for countries that do have such capabilities?

Management ChallengesHighly Radioactive Materials

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?