226-CNM : Reinforced concrete in the context of nuclear waste management

Technical Committee 226-CNM

General Information

Chair: Mme Valérie L'HOSTIS
Deputy Chair: Dr. Robert GENS
Activity starting in: 2007
Activity ending in: 2014
Cluster D

Subject matter

Reinforced Concrete (RC) is a major construction material used for many of the facilities and structures involved in the processing, the long-term storage and the disposal of radioactive waste materials generated by the nuclear fuel cycle. RC is used for many purposes, including support, containment, and environmental protection for different types of facilities. These structures are required to function safely and reliably in challenging and varying environments for periods of time that can potentially range up to thousands of years. During their operational life, these structures will in all likelihood be subjected to a number of environmental stresses or ageing factors that may adversely affect their performance and result in shortened service lives. The detection and assessment of the magnitude and rate of occurrence of any environmental factor-related degradation are key factors in maintaining the capability of these structures to meet their operational requirements. As the knowledge base for modern concretes, such as would be used in fuel cycle-related facilities, is relatively short (i.e about, 100 versus the required 200 to 500 or more years), additional input is required in several areas to help ensure that these structures will continue to meet their design requirements throughout their operational life.

Terms of reference

At present the main scope of the TC is studied in several countries where nuclear industry is used (USA, Canada, Japan, and many countries in Europe). Work previously made or underway in RILEM by other TC’s (TC-60-“Corrosion of steel in concrete”, TC-104-DDC, “Damage Classification of Concrete Structures,”, TC-130 “Service life prediction”, and TC 160-MLN, “Life Prediction of Concrete Structures in Nuclear Power Plants”) on the subject of long term performance of reinforced concrete structures will serve as a starting point. At present there are some related RILEM-activities although they are broader and not related to nuclear aspects so specifically ( TC- LTP Prof. Dr. Asko Sarja: Life time performance of materials and structures and TC-MAI Prof. Carmen Andrade: Monitoring assisted integral service life modelinf of steel reinforced concrete structures with respect to corrosion induced damage). Due to the recognized importance of the subject, it seems necessary to provide a review on existing R&D programs on long term prediction for nuclear applications, as well as to identify the gaps in the existing knowledge in order to propose subjects that need further research.

Detailed working programme

Several documents are the basis of the work:

- A status report related to the use of concrete structures in nuclear power plant fuel-cycle facilities has been prepared by the Nuclear Energy Agency of the Organization for Economic Cooperation and Development (NEA/OECD), "Report of the Task Group Reviewing Activities in the Area of Ageing of Concrete Structures Used to Construct Nuclear Power Plant Fuel Cycle Facilities [NEA/CSNI/R(2002)14, July 2002].
- A Workshop have been organised in 2004 in Madrid: 'CSNI/RILEM Workshop on Use and Performance of Concrete in NPP Fuel Cycle Facilities'.
- The NUCPERF 2006 International Workshop (CEA commissariat à l'énergie Atomique , EDF Electricité de France , NEA/OECD, and EFC European Fedeeration of Corrosion event) on 'Corrosion and Long Term Performance of Reinforced Concrete in Nuclear Power Plants and Waste Facilities' (Cadarache, France, 2006).

These meetings allowed to point out several technical areas where additional knowledge was needed:
- Functional and performance requirements for concrete structures in the context of nuclear facilities;
- Degradation processes and their effects, particularly where the degradation phenomena can operate over extended periods of time, or where synergistic effects are present;
- Phenomenological modelling (linked to the previous point) dedicated to the long-term behaviour problematic,
- Field experiences (collection of data during decommissioning, archaeological analogues, etc.),
- Instrumentation and monitoring methods dedicated to performance assessments;
- Service-life models, development and validation that take into account reliability methods and updating as additional data become available (Bayesian);
- Repair techniques to extend the performance period;
- Codes and standards specific to radioactive and hazardous waste facilities.

Technical environment

The proposed working program is following the TC 202 RWD managed by Dan Naus. This technical committee would involve interdisciplinary fields that are linked with the "core business" of RILEM and would utilize developments of several existing RILEM committees.
Work under this committee would also be a logical follow-on to activities sponsored by international organizations such as
- The European Federation of Corrosion (Working Party 4, Nuclear Corrosion)
- The Nuclear Energy Agency of the Organization for Economic Cooperation and Development.
- The International Atomic Energy Agency.

Key input will be provided by researchers selected from countries that are main contributors in the R&D, design, construction, operation, and regulation of waste nuclear reinforced concrete facilities.

There will be also possibilities for interaction/collaboration with other projects dealing with similar topics (see e.g. Workshop on Cementitious Materials Used for radioactive Waste Treatment, Containment, ER and D&D held in Aiken South Carolina, USA in December 2006, or International Workshop on Sulfur Assisted Corrosion in Nuclear Waste Disposal Systems to be held in Belgium in 2008).

Expected achievements

Products of this TC are expected to be:

- An international workshop on 'Corrosion and Long Term Performance of Reinforced Concrete in Nuclear Power Plants and Waste Facilities'(NUCPERF 2009) planned during spring 2009 at Cadarache (France). This event which will have three main objectives:
   - To present the expectations of regulators, licensees, designers and researchers with regards to concrete structures,
   - To discuss R&D progress with regard to corrosion of steel reinforcements and degradation of concrete materials,
   - To reach a consensus on R&D needs to further develop cooperative programmes.
- Edition of proceedings of the Workshop containing also recommendations made during panel discussions planned during the Workshop (end of 2009),
- A state-of-the-art report on actual R&D programs leaded by different countries on the field of long-term durability of reinforced concrete structures used for nuclear facilities (if active members agree on participating, 2009).

Group of users

This TC will address a broad spectrum of activities related to reinforced concrete technology (e.g., material development, performance and degradation, monitoring, service life prediction, repair, and decommissioning). As a result, outputs developed under this TC will be of interest to academia, testing laboratories, architectural/engineering firms, as well as regulatory and national radioactive waste management agencies.

Specific use of the results

Application of the results of this TC can potentially result in reduced costs through use of improved materials and design methods, increased understanding and modelling of degradation parameters, and guidance on performance monitoring, while effecting improved safety and reliability