WP 4.3:Lining stability under thermal load

Workpackage number

WP4.3

Start date or starting event:

Month 6

Activity type

Lining stability under thermal load – RTD

Participant id

11

Person-months per participant:

50

Objectives

The overall objective of this work package is to study the influence of thermal impact on the stability of  linings. This issue is particularly important in terms of operational safety when the retrievability of the radioactive waste is considered. THM laboratory tests and an in-situ test at the Underground Educational Facility - UEF Josef (Mokrsko) are proposed to investigate this issue. The installation and material costs of the laboratory tests and the in-situ test will not be charged to the project.

Description of work

Task 1:  Laboratory tests

In preparation for the in-situ test, long term (up to 6 months) THM laboratory tests will be performed on samples which will simulate the thermal loading of lining materials in the area of the contact zone (concrete lining / compressive material/ host clay rock). The equipment allows the loading of samples by temperature of up to 100 °C during continuous saturation of the samples.

Task 2:  In-situ experiment at Josef UEF (Mokrsko)

During input laboratory tests (first 6 months) a detailed work programme for the in-situ test will be prepared in co-operation with the other partners.

In the UEF Josef facility, a short horizontal gallery will be used. Within this gallery, the impact of  thermal loadings on different types of concrete based lining will be studied. The lining will be heated using different thermal load.

Along the heater, different lining sections will be built consisting of different types: for example with or without compressble materials. The lining thickness will be about 200 mm, the length of loaded lining minimally 1000 mm (depending on the heater used). There will be some free space (gap) between the heater and the lining.

These experiments will be fully instrumented for continuous stress-strain and temperature measurements, especially at the lining interface. It will be very important to control the deformation of the lining especially axially.   The behaviour of the “lining system” and its stability will be studied and the use of compressive material will be tested. During the dismantling of the experiment the rheological alteration of lining materials will be tested.

The experimental procedures will follow these basic steps:

Phase A: gradual increase of temperature

Phase B: long term constant temperature (up to 100oC)

Phase C: gradual decrease of temperature – cooling.

The Josef UEF is presently under construction. The underground area will be devoted to experimental purposes according to the time schedule, in September 2006. The start of the in-situ experiment is planned for the first semester 2007.

Implementation of all the tasks related to WP4.3: in situ test at Mokrsko URL ( the Josef underground facility) in the Czech Republic is subject to official granting of the necessary autorisations by the appropriate authorities as well as the effective entry into operation and transfer of the said facility to the Czech Technical University in Prague. Should these requirements not be fulfilled by 01 /03 /2007 the task would be cancelled. In this instance the test will be performed at the underground silo at the CEG laboratory.

The objectives will remain the same even if it is performed in the underground silo in the laboratory. Only the real soil/structure interaction will not be possible to investigate.

Deliverables

D.9 Thermal impact on the stability of the lining

Milestones and expected result

The proposed in-situ test will allow to assess the thermal impact on the stability of the lining. This constitute important information for the operational safety when retrievability is considered. The results will also give important information about the soil/lining interactions and constitute therefore a milestone for task 3 of WP.5.2

Protocol and objectives of the tests performed  as input for the first end-users group review …………Month 5

Prior approval by the GB of the enduser review reports to proceed with the next related tests - Months 8,26,44

Official granting of the necessary authorisation at UEF………… ……………………………………..Month 6

Soil/lining interactions under thermal load..............................................................................................Month 36