Following the accident at the Fukushima nuclear power plant, the Nuclear Safety Authority (ASN) asked Andra to carry out a Supplementary Safety Assessment (SCE) for the Aube Storage Centre (CSA). This assessment consists of reassessing the safety margins of the Basic Nuclear Installation (INB n°149) with regard to extreme natural events that would lead to a serious accident on the installation. The reassessment shall cover the behaviour of the installation in the face of extreme situations and the effectiveness of measures to prevent and reduce the consequences. The extreme natural aggressions to be taken into account are flooding, lightning, hail, snow, high winds, tornado and earthquake. As part of the investigation of the 2016 safety review file, Andra made several commitments related to the earthquake.
On the basis of the commitments made by Andra, the following studies are to be carried out as follows:
- Study of the overall stability, the resistance of the structural elements and the maintenance of the support function of the ACD EIPs.
- Evaluation of the behaviour of the ACD pump room with regard to the seismic design hazard for the operation phase.
- Earthquake sizing for the operation phase, the overall stability of the handling bridge of the transit vessel, the absence of projectile creation by the same bridge and analyzes the resistance of the assemblies of the transit building framework.
- Verification of the presence of the minimum seismic construction provisions of the service building demonstrating that it does not constitute an aggressor vis-à-vis the ACD.
- Justification of the envelope nature of the seismic accelerations used for the calculation of the stability of the handling bridges of the mobile frameworks in order to guarantee the absence of risk of falling of the bridges on the structures and packages.
Conduct of studies (cf. synoptic of studies):
|| Firm Slice Seismic hazards of exploitation
Step 1: Knowledge of the documentation and on-site readings
Step 2: Writing a report that lists all the assumptions taken into account as well as the methodology
Step 3: Writing calculation notes for the seismic hazard associated with the operation phase. This step is the subject of a stopping point in the form of written notes transmitted to Andra.
Deliverables: For the TF, the holder must provide at least 5 notes of hypotheses and 7 notes of calculations.
Optional tranche 1 || Seismic hazards of exploitation
Step 4: Reinforcement notes including budget estimate of the work
Condition: Depending on the results of the calculations in step 3, optional tranche 1 is strengthened if corrective technical solutions, reinforcements and/or special provisions are to be implemented. Separate reports from the calculation notes are written.
Deliverables: For TO1, the incumbent will be required to provide a maximum of 7 reinforcement notes.
Optional tranche 2 || Seismic monitoring hazards
Step 5: Comparative study of the seismic hazard associated with the monitoring phase and the operation phase
Condition: Depending on the solutions proposed in step 4, optional tranche 2 is strengthened. In any case, step 5 can be started only if step 4 has been retained upstream.
Deliverables: For TO2, the incumbent will be required to provide a maximum of 9 reinforcement notes.