Abstract
The concrete structure of a reactor containment is pre-stressed with tendons
placed in ducts. In some reactor containments, these ducts are injected with
cement grout after pre-stressing. The cement grout protects the tendons
against corrosion and has the potential to redistribute the stresses in a tendon in the case of wire failure. The disadvantage of injected ducts is that the tendons pre-stressing level cannot be directly assessed and that the cable cannot be re-stressed if necessary.
In order to assess the of the pre-stressed cables, the US Regulatory Guide
1.90 provides two methods (Alternative A and B) for assessing the prestressing level of cables: Alternative A) Monitoring the pre-stressing level of the reactor containment by means of instrumentation and pressure tests, Alternative B) Monitoring of the reactor containments deformation under pressure tests.
This project has simulated different pressure tests by means of numerical
modelling, which included development of defects such as wire and cable
failure both before and during the pressure tests. The intention was to verify
Alternative B by determining whether a tendon failure would cause any detectable deformations in the structure or not. To carry out this, a case study was analysed based on a typical PWR (Pressurized Water Reactor) containment that physically and mechanically was similar to typical Swedish PWR containment.
Two different structural models were used: 1) A global 3D model that included all the essential components of the reactor containment to study the influence of major defects such as a complete tendon failure, 2) a ring model to study the effect of local defects on the pre-stressing tendons and to determine the extent of the irreversible deformations.
The simulations show that extensive damages on the wires/tendons are required in order to be possible to detect any measurable changes during the pressure tests. In order to be possible to detect any damages, very sensitive sensors are required, and they must be placed directly adjacent to the damaged wire/tendon and within a few meters from the damaged area.
placed in ducts. In some reactor containments, these ducts are injected with
cement grout after pre-stressing. The cement grout protects the tendons
against corrosion and has the potential to redistribute the stresses in a tendon in the case of wire failure. The disadvantage of injected ducts is that the tendons pre-stressing level cannot be directly assessed and that the cable cannot be re-stressed if necessary.
In order to assess the of the pre-stressed cables, the US Regulatory Guide
1.90 provides two methods (Alternative A and B) for assessing the prestressing level of cables: Alternative A) Monitoring the pre-stressing level of the reactor containment by means of instrumentation and pressure tests, Alternative B) Monitoring of the reactor containments deformation under pressure tests.
This project has simulated different pressure tests by means of numerical
modelling, which included development of defects such as wire and cable
failure both before and during the pressure tests. The intention was to verify
Alternative B by determining whether a tendon failure would cause any detectable deformations in the structure or not. To carry out this, a case study was analysed based on a typical PWR (Pressurized Water Reactor) containment that physically and mechanically was similar to typical Swedish PWR containment.
Two different structural models were used: 1) A global 3D model that included all the essential components of the reactor containment to study the influence of major defects such as a complete tendon failure, 2) a ring model to study the effect of local defects on the pre-stressing tendons and to determine the extent of the irreversible deformations.
The simulations show that extensive damages on the wires/tendons are required in order to be possible to detect any measurable changes during the pressure tests. In order to be possible to detect any damages, very sensitive sensors are required, and they must be placed directly adjacent to the damaged wire/tendon and within a few meters from the damaged area.
| Original language | Swedish |
|---|---|
| Place of Publication | Solna |
| Publisher | Swedish Radiation Safety Authority |
| Commissioning body | Swedish Radiation Safety Authority |
| Publication status | Published - 2018 Dec 19 |
Publication series
| Name | |
|---|---|
| Publisher | Swedish Radiation Safety Authority |
| No. | 26 |
| Volume | 2018 |
| ISSN (Print) | 2000-0456 |
| ISSN (Electronic) | 2000-0456 |
Subject classification (UKÄ)
- Other Materials Engineering