Bare Fiber Bragg Gratings embedded into concrete buffer Supercontainer concept for nuclear waste storage [ANIMMA--2015-IO-337]
- University of Mons, Boulevard Dolez 31, 7000 Mons (Belgium)
- SCK-CEN, Boeretang 200, 2400 Mol (Belgium)
- Department Mechanics of Materials and Constructions - MeMC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels (Belgium)
Nuclear power plants have been generating electricity for more than 50 years. In Belgium, 55% of the current energy supply comes from nuclear power. Providing for the safe storage of nuclear waste, including spent fuel (SF) and vitrified high level radioactive waste (HLW), remains an important challenge in the life cycle of nuclear fuel. In this context, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF/NIRAS) is investigating a reference conceptual design called the Supercontainer (SC) for the packaging of SF and HLW. This conceptual design is based on a multiple-barrier system consisting of a hermetically-sealed carbon steel overpack and a surrounding highly-alkaline concrete buffer. The first one is developed to retain the radionuclides. The two main functions of the buffer are (a) to create a high pH environment around the carbon steel overpack in order to passivate the metal surface and so to slow down the corrosion propagation during the thermal phase and (b) to provide a radiological shielding during the construction and the handling of the Supercontainer. A recent test has been performed to investigate the feasibility to construct the SC. This test incorporated several kinds of sensors including Digital Image Correlation (DIC), Acoustic Emission (AE), corrosion sensing techniques and optical fibers with and without fiber Bragg gratings (FBGs). In particular, several single-mode optical fibers with 4 mm long FBGs with different Bragg wavelengths and distributed along the optical fibers were used. For casting and curing condition monitoring, a number of gratings were incorporated inside the concrete buffer during the first stage of construction. Then other sensors were embedded near a heat source installed in the second stage to simulate the effects of heat generated by radioactive waste. The FBGs were designed to measure both temperature and strain effects in the concrete. To discriminate between these effects special packaging was used for some sensors that were installed very close to the unpackaged ones. Sensors placed in plastic tubes have reduced sensitivity to strain, while the ones inserted in metal tubes are only temperature sensitive and their readings can be directly compared with those obtained from thermocouples located nearby. In addition to monitoring temperature and strain behaviour, embedding also had as objective to determine the impact of the high alkaline environment on the silica fibers over a very long time. This article presents the preliminary results obtained with the different FBGs and provides recommendations for future improvement. (authors)
- Research Organization:
- Institute of Electrical and Electronics Engineers - IEEE, 3 Park Avenue, 17th Floor, New York, N.Y. 10016-5997 (United States)
- OSTI ID:
- 22531384
- Report Number(s):
- ANIMMA-2015-IO-337; TRN: US16V0403102325
- Resource Relation:
- Conference: ANIMMA 2015: 4. International Conference on Advancements in Nuclear Instrumentation Measurement Methods and their Applications, Lisboa (Portugal), 20-24 Apr 2015; Other Information: Country of input: France
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BRAGG REFLECTION
CARBON STEELS
CONCRETES
CORRELATIONS
CORROSION
DIFFRACTION GRATINGS
FISSILE MATERIALS
HIGH-LEVEL RADIOACTIVE WASTES
LIFE CYCLE
NUCLEAR POWER PLANTS
OPTICAL FIBERS
RADIOISOTOPES
SENSITIVITY
SENSORS
SHIELDING
SILICA
SPENT FUELS
THERMOCOUPLES
VITRIFICATION