4.215. To provide defence in depth and to enhance the general reliability of the containment systems, instrumentation should be provided for the purposes of:

(a) Detecting deviations from normal operation,

(b) Monitoring the stability of the containment structure,

(c) Leakage testing and integrity testing,

(d) Monitoring the availability of the containment systems,

(e) Providing actuation signals for containment systems,

(f) Post-accident monitoring.

Detection of deviations from normal operation

4.216. Specific design recommendations regarding instrumentation for monitoring the containment for the early detection of deviations from normal operation are provided in Appendix I. See also Section 6 on instrumentation for the detection and monitoring of severe accident conditions.

Control of the containment structure

4.217. Appropriate instrumentation should be incorporated inside the containment in order to monitor closely any deformation (radial, vertical or circumferential) or movement of the containment structures or the containment walls.

4.218. For prestressed concrete walls, means to detect loss of the prestressing should be provided. The concrete compression and rigidity parameters (such as Young’s modulus) should be defined, and they should be verified by such means as acoustic measurements. The temperature in concrete singularities should also be measured to aid the interpretation of the results of pressure proofing tests.

4.219. Appropriate instrumentation for measurements relating to earthquakes should be provided on the basemat of the containment or on a suitable floor.