1. Fuel Cycle Systems Scenario Analysis: Recycling LWR Plutonium in Thorium Fuelled PT-HWRs
Daniel Wojtaszek
3rd Technical Workshop on Fuel Cycle Simulation
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July 11, 2018
UNRESTRICTED

2. Presentation Outline Objective
Pressure Tube Heavy Water Reactor (PT-HWR)
Thorium-Plutonium Fuel Concepts
Two Stage Fuel Cycle Scenario
Implementation
Results
Conclusion
Discussion

3. Objective
To compare the impact of multiple Pu+Th fuel concepts on electricity production in a fuel cycle scenario.
Pu from LWR UOX spent fuel -> Pu+Th PT-HWR fuel.

4. Pressure Tube Heavy Water Reactor
Heavy water moderated and cooled.
High neutron economy.
Current PT-HWRs are fuelled with natural uranium (NU).
Online refuelling.
Fuel is in the form of cylindrical fuel bundles.
(~0.5 m long, ~0.1 m diameter).

5. Thorium-Plutonium Fuel Concepts
Low-PU+Th
3.5% Pu.
BU ~23.6 MWd/kg.
Core Mass ~60 MTHE.
~550 MWe.
Hi-Pu+Th
4.5% Pu.
BU ~36.4 MWd/kg.
~492 MWe.
Central Graphite Rod
To reduce CVR.
Depletion Calculations
WIMS-AECL.
RFSP.

6. Two Stage Fuel Cycle Scenario
Fuel Feed
Material
Nuclear Fuel
Nuclear Power
Plant
Back-end
Storage
Separations Pu
To ST-2
Sep-A
UOX Separation
LEU O2
Stage 1
(ST-1) RU NU
LWR
FP,MA
UOX fuel.
4.1% Enriched.
47 MWd/kg. DU
Pu to Pu+Th fabrication (FIFO).
RU, FPs, and MAs to long-term storage.
1 UOX separations plant.
~3,000 MTHE/year.
25 year lifetime.
Begins operating 24 years. into the scenario.
Spent UOX fuel.
5 years cooling (minimum).
FIFO transfer to separations.
100 LWRs (740 MWe each).
40 year lifetime.
All begin operation 1 year into the scenario.
Pu From ST-1
Stage 2
(ST-2)
Pu + Th O2 Th
PT-HWR
1 (Pu,Th)O2 fabrication plant.
Sufficient throughput to fuel the entire fleet.
25 year lifetime.
Begins operating 1 month after start of separations plant.
Interim Storage
Fleet size depends on fuel availability.
30 year lifetime.
Deployment begins 1 month after start of (Pu,Th)O2 fabrication plant.
Rate of deployment depends on fuel fabrication throughput.
Long-term Storage

7. Implementation Scenario implemented using Cyclus fuel cycle simulator.
Composition of Pu+Th fuel adjusted by Cycamore fuel fabrication plant based on a starting composition.
Size of the PT-HWR fleet was calculated using trial and error simulation runs.
Warning!
Adjusted composition does not take into account any delay in loading fuel into the reactor.
Required calculating the deployment schedule offline based on a guess of the maximum fleet size, and its required fuel fabrication throughput.
Th Mine
Pu+Th Fabrication
Pu+Th Storage
PT-HWRs
Pu from St. 1

8. Results
100 LWRs
1080 TWd
34 PT-HWRs
183 TWd
26 PT-HWRs
156 TWd

9. Results

10. Results
Not FIFO here

11. Conclusions
PT-HWRs are a viable existing technology for utilizing thorium-based fuels with plutonium from LWR spent UOX fuel.
The higher-burnup fuel can result in more power generation than that of the low-burnup fuel.

12. Discussion
Calculation of plutonium fraction in fuel taking into account post-fabrication decay.
Finding the PT-HWR deployment schedules required repeated complete simulation runs.
Improving the ability to couple simulation code with an external facility deployment code.
Option of halting or backtracking a simulation when there is insufficient fuel.