Reactor Decommissioning History
Zion Decommissioning Unit-1 and Unit-2
revised as noted below

Currently Active in RV / RVI Work
Recent Updates
as of 14 January 2016

Reactor related effort is complete:

  • Unit-2 reactor vessel segmentation officially complete 13-July-2015.
  • Unit-1 reactor vessel segmentation complete December 2015.

RV - Both Units
The Unit-1 reactor was completed in December 2015.
Segmentation of Unit-2 RV was announced complete on July 13, 2015.

RVI - Both Units
The segmentation of the Zion reactor vessel internals campaign was announced complete as of December 15, 2014 when the Unit-1 Lower Core Assembly (LCA) was placed into its shipping container. Unit-1 was started after Unit-2 and was the last RVI work performed.

GTCC (Greater Than Class C)
The fourth and last GTCC canister was placed in the Zion ISFSI on March 6, 2015. All fuel was already in ISFSI at that time.

Fuel
All fuel is on the Zion ISFSI pad in 61 dry fuel canisters. Loading of the first can was during Christmas 2014, and the last can moved to the ISFSI on January 10, 2015. Extreme cold prevented the last can going on the pad on the 1-year mark of the campaign. A year and a day for 61 cans to be processed and placed on the ISFSI is a very impressive campaign.


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Overview

Zion 1 & 2 (ZNPS) are Westinghouse commercial PWR power reactors. There are located midway between Chicago, Illinois and Milwaukee, Wisconsin on the beach of Lake Michigan. Unit 1 (DPR-39) & Unit 2 (DPR-48) each had a generating capacity of 1085 MWe and design capacity of 3250 MWt. Commercial operations were achieved for Unit-1 on December 1973 and for Unit-2 on September 1974. Final reactor operation for Unit-1 was February 21, 1997 and Unit-2 was September 19, 1996. Both units are currently being decommissioned at the same time. In March 2014, ZionSolutions' John Sauger noted that 2018 is targeted completion for the Zion Decommissioning project.

Zion's eight upper assembly steam generator sections (Model 51's) are removed (or nearing completion). Lower assemblies will be wire saw cut to remove the U-tubes and provide a weldable surface for transport shield/cover.

The (61) dry fuel storage casks and (4) GTCC casks are stored vertically outdoors at the on-site ISFSI using NAC International MAGNASTOR dry fuel canisters.

Reactor Decommissioning Specifics

Reactor Vessel Internals Removal
Underwater segmentation was done using cold cutting methods (reciprocating saw, rotary saw, milling). There were four primary segmentation tools used. There was one fixed tool (called the VRS) in the shallow end that segmented the upper internals and final size reduced many of the lower internals. Lower internals were initially segmented using three "portable" machines (i.e. the cutting tool was mounted to the piece being cut instead of the piece being mounted on the cutting tool). These machines were named the CHORCE, BMT, and FaST.

The segmentation of the Zion reactor vessel internals (RVI) campaign was announced complete as of December 15, 2014 when the Unit-1 Lower Core Assembly (LCA) was placed into its shipping container. Unit-1 was started after Unit-2 and was the last RVI work performed.

Reactor Vessel Removal
The RV was segmented and packaged in pieces, then shipped to Clive. RV cutting process was Oxy-fuel (thermal cutting) from the outside. Wire saw was also used for secondary cutting such as the nozzles and flange. The RV's were both lifted incrementally as pieces were cut and removed (as was once planned for Humboldt Bay). The original cutting process planned was Wire Saw (AWS), but the Oxy-fuel type of thermal cutting later selected because it would be faster.

Decommissioning of the Zion Unit-2 Reactor Pressure Vessel (RV or RPV) began in November 2014 with the mobilization of segmentation support equipment. On 2/26/15 all 8 nozzles were severed. On 3/5/15 all bottom instrument tubes severed, making the RV stand alone and free. On 3/20/15 the wire saw cuts on the top RV flange were complete, and preparations to lift and torch cut were in process. On 6/8/15 a few of the nozzle area pieces were packaged and remaining were in process of removal. Unit-1 should start in 2015.

The RV Head for Unit 2 was shipped to the EnergySolutions waste facility in Clive as one piece while the Unit-1 was size reduced (hand held torch) before shipping.

Segmentation and Packaging Plan (S&P Plan)
Siempelkamp Nuclear Services (SNS) segmentation plan for the Zion Reactor Vessel and Reactor Vessel Internals. The final packing configuration for the Unit-1 GTCC canisters was changed by ZionSolutions (using staffing from PlantDecommssioning.com) in order to fit more than planned cutting debris and additional radiation shielding.

GTCC Packaging
Cutting debris (cutting chips and small pieces) from both reactors that was GTCC was more than expected. This proved to be a challenge because two of the GTCC TSC canisters were already removed from the containment building, leaving only the last two available. These last two were already packed with RVI pieces leaving few open areas. Another challenge was that the cutting chips could not be simply tossed into the GTCC liners. Regulatory compliance requires that all GTCC debris must be retrievable in case segregation is required at a later date. The orientation of the RVI pieces in the last two GTCC canisters was changed (repackaged) to allow better use of space to allow for retrievable boxes containing the cutting chips. Adding to the space/volume challenge was the fact that half of the cutting chips were "fluffy"; meaning they took a lot of volume even thought they had little mass. In order for all the chips to fit, an underwater chip compactor was proposed and supplied by PlantDecommissioning.

The Greater than Class C (GTCC) material from the reactor will remain on site with the fuel in the ISFSI. There are four canisters. These are the NAC International MAGNASTOR and MAGNATRAN models of TSC (Transportable Storage Canister). While already in use for fuel storage, Zion is the first application for GTCC packaging for this model TSC.

Key People
John Sauger, Nick Williams, Dave Brown, Dan Pryor, Ken Bentley, Ron Richards, Ed Barron, Steve Larson (these are reactor related people only).

Contractors (reactor related)
ZionSolutions - EnergySolutions
TLG Services (for D&D cost estimating in 1999).
Bigge Crane (heavy transport out of containment)
Siempelkamp Nuclear Services, Inc. (SNS - formerly MOTA Corporation)
NAC International (Dry storage for GTCC)
WMG
PlantDecommissioning.com (Equipment design, fabrication, revised GTCC packaging plan, staff augmentation)

Comments
The Zion D&D is considered the largest and the first side-by-side decommissioning of two power producing nuclear units.

Related Publications and Documents (Reactor Relevant)
ZionSolutions 8-24-2011 Weekly Reader Newsletter with RVI Segmentation overview.
ZionSolutions 9-29-2011 Weekly Reader Newsletter with RVI Segmentation update.
ZionSolutions 11-28-2011 Weekly Reader Newsletter on Cavity Fill Milestone.
April 2012 Nuclear Decommissioning Report
20 September 2013 Nuclear Engineering International (relevant to Kontec 2013)
July 2014 Power Magazine
June/July 2015 The Synergist (EHS Trade Magazine)

References
The NRC's web page as of 8/24/06 & 2/22/10.
INSC web page as of 8/22/05.
Exelon Nuclear Operations Communications Department on 8/25/06.
Commonwealth Edison's PSDAR to the NRC dated February 14, 2000, revision 0.
Conversations with site people Feb 2010 through above date.

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