A Frozen Soil Barrier to Control Groundwater Inflow into Damaged Reactors at the Fukushima Daiichi Nuclear Power Station - 16613
- Tokyo Electric Power Company (Japan)
- Savannah River National Laboratory (United States)
- Pacific Northwest National Laboratory (United States)
Reactor buildings and support facilities at the Fukushima Daiichi Nuclear Power Station (F1 Site) were damaged by a March 2011 tsunami. In response, the Tokyo Electric Power Company (TEPCO) is implementing a number of countermeasures to limit the releases and impacts of contaminated water to the surrounding environment. The diverse countermeasures work together in an integrated manner to provide different types, and several levels, of environmental protection. In general, the strategy represents an example of a 'defense in depth' concept that is used for nuclear facilities around the world. One of the key countermeasures is a frozen soil barrier encircling the damaged reactor facilities. The frozen barrier is intended to limit the flow of water into the area, reduce the amount of water entering damaged reactors, and reduce the resulting volume of contaminated water that requires treatment and storage. The frozen soil barrier was designed and installed by a team from TEPCO and Kajima Corporation. A group of scientists and engineers from US Department of Energy National Laboratories provided independent evaluation of the frozen barrier design and operational plans along with technical recommendations to the TEPCO team. The frozen soil barrier design extends to about 30 m depth; the bottom of the barrier is in a low permeability interval, and the total barrier length around the reactors is just over 1.5 km. The barrier required 1927 total boreholes: 1568 for freeze pipes plus 359 for temperature monitoring arrays. Drilling of all of the boreholes was completed November 9, 2015. Construction of the refrigeration plant is complete and all of the above ground piping/manifolds are in the final stages of construction. The DOE laboratory independent assessment of the frozen soil barrier concluded that the technical characteristics of a frozen barrier are relatively well suited to Fukushima-specific hydrogeologic conditions and the need for reducing the inflow of water into damaged reactors at the F1 Site. The scale of the Fukushima barrier is bounded by industry experience and the equipment and infrastructure proposed for the ground freezing is well understood. The on-site pilot test at Fukushima indicated predictable ground freezing and supported the full scale design parameters. These factors increase the confidence in the frozen soil barrier project underway at Fukushima. TEPCO is currently working with the Japanese Nuclear Regulatory Authority (NRA), providing operational plans/strategies for the frozen soil barrier and modeling results of the projected performance. Full scale frozen soil barrier operations are to begin after authorization from NRA. (authors)
- Research Organization:
- WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
- OSTI ID:
- 22838358
- Report Number(s):
- INIS-US-19-WM-16613; TRN: US19V1551083713
- Resource Relation:
- Conference: WM2016: 42. Annual Waste Management Symposium, Phoenix, AZ (United States), 6-10 Mar 2016; Other Information: Country of input: France; 5 refs.; available online at: http://archive.wmsym.org/2016/index.html
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BOREHOLES
COMPUTERIZED SIMULATION
DEPTH
ENVIRONMENTAL PROTECTION
FREEZING
FUKUSHIMA DAIICHI NUCLEAR POWER STATION
GROUND WATER
NUCLEAR FACILITIES
NUCLEAR INDUSTRY
REACTOR ACCIDENTS
RECOMMENDATIONS
REFRIGERATION
SOILS
TEMPERATURE MONITORING
TSUNAMIS