96. overview hot bent high temperature field test-birkholzer

1. Used Fuel Disposition Campaign
International Collaboration in
Disposal Research:
Potential HotBENT Collaboration
Jens Birkholzer
Lawrence Berkeley National Laboratory
FCT UFD Working Group Meeting
“International Session”
UNLV, Las Vegas, NV
06/9/2016

2. Used
Fuel
Disposition
HotBENT - Studying the effects of high
temperatures on clay buffers/nearfield
2
A planned collaboration project, led by NAGRA, to conduct a joint GTS
experiment integrated with lab and modeling studies to evaluate buffer
behavior at 150oC to 200oC
Other potential partners: NUMO, RWM, SURAO, GRS (plus SKB?)

3. Used
Fuel
Disposition
 Due to the high temperature it is expected that the following physico-
chemical effects will occur:
– cementation possibly affecting mechanical properties
– illitization (under certain conditions, e.g. high potassium concentrations) affecting
mechanical properties
 Due to the strong thermal gradients:
– complex moisture transport process, including convection of vapor
– delayed saturation
– heterogeneous, time-dependent density distribution (differential swelling)
What to expect in the buffer for
T > 150oC?
 Numerical models developed, or being
under development, can be used to
simulate the thermal period of a
repository, but database for
T > 150 °C limited (laboratory) or non-
existent (large scale)
Pellet- based
buffer

4. Used
Fuel
Disposition
NAGRA’s Interest in the Experiment
 A part of the bentonite buffer is exposed to temperatures higher than 100oC in
the current NAGRA designs
 Higher design temperature can achieve significant cost reductions
 NAGRA’s PA argumentation is that at least half of the bentonite needs to remain
intact. Ensuring that the largest part of the buffer remains intact adds additional
robustness as construction related voids might be present reducing overall
buffer related performance (e.g., overall swelling pressure).
 The higher and the more homogeneous the swelling pressure  the lower the
chance of microbial impacts at the canister surface  the easier the
argumentation related to the canister lifetime.
 NAGRA’s interest in HotBENT is to:
– Increase database of bentonite performance at temperatures higher than 150oC *
– Understand processes that can only be captured at the large scale, address the
up-scaling effects (at scales relevant to the repository design)
* complement/underpin results from lab studies, HE-E, FE

5. Used
Fuel
Disposition
DOE’s Interest in the Experiment:
Direct Disposal of DPCs
5
Hardin, E.L., Repository Engineering
 Largest capacity: Magnastor
DPC system (37-PWR or equiv.)
 Thermal limits: 35.5 kW
storage/24 kW transport
 Fuel cool time >4 yr OoR
depending on burnup
Pictures and data
from NAC
International
website
31Mar2012

6. Used
Fuel
Disposition
Potential Experiment in FEBEX Tunnel
at Grimsel Test Site
 Old/former FEBEX-DP tunnel (70m, well characterized, multiple boreholes,…)
 40 “Big Bags” and 10 pallets of bentonite blocks MX80 (FE-experiment)
 Auger machine (to be adjusted), currently at FMT

7. Used
Fuel
Disposition
FEBEX Tunnel Dismantling

8. Used
Fuel
Disposition
HotBENT Modular Design and Schedule
 Timeline:
– NAGRA/LBNL joint paper on high-temperature field
experiment at IHLRWM conference 2015
– First multi-institutional HotBENT planning meeting in Baden,
Switzerland, February 12, 2016
– Second multi-institutional HotBENT planning meeting in
Ittingen, Switzerland, May 3-4, 2016
– HotBENT concept to be proposed to all GTS partners at 14th
ISCO meeting June 8-9, 2016
– Detailed design planning and cost estimates by Fall 2016
(additional planning meetings September and December?)
– Launch project in 2017/2018