Concrete hydration, which is part of the chemical process of cement grout curing, has a heat of reaction that could potentially lead to temperature increases in the borehole. However, the period of heat generation is of the order of a few months. Treatment in the GSA Concrete hydration will have ended, and the associated heat dissipated, short after borehole closure. It is considered that the heat production during curing will not have a significant impact on the long-term safety of the borehole. Inclusion of FEP Excluded in all scenarios. 2.1.10.3 Temperature evolution Description A range of processes could potentially generate heat in a closed borehole (see FEPs 2.1.10.1 and 2.1.10.2). These processes could contribute to temperature profiles across the borehole and into the host rock. Although the effect on temperature may only be temporary, it could have a permanent effect on borehole safety if it causes cracking in any backfill, concrete structures and the immediately surrounding host rock. Water flow rates might increase and gas could migrate more easily. Treatment in the GSA It is considered that the temperature rise in the borehole will be limited for Category 3 to 5 sources (see FEPs 2.1.10.1 and 2.1.10.2). Therefore, isothermal conditions are assumed for the GSA for Category 3 to 5 sources. For Category 1 and 2 sources, calculations in Section 3.2 of the current report show that non-isothermal conditions initially exist in the borehole for the highest activity sources with peak temperatures of up to 275 °C in the capsule and slightly over 100 °C in the borehole backfill. Isothermal conditions are established after around 50 years for the Co-60 sources and 200 years for the Cs-137 sources. The impacts of these thermal conditions on other near-field FEPs are discussed under FEPs 2.1.2 to 2.1.9 above. Inclusion of FEP Excluded for Category 3 to 5 sources in all scenarios. Included for Category 1 and 2 sources.
Concrete hydration, which is part of the chemical process of cement grout curing, has a heat of reaction that could potentially lead to temperature increases in the borehole. However, the period of heat generation is of the order of a few months. Treatment in the GSA Concrete hydration will have ended, and the associated heat dissipated, short after borehole closure. It is considered that the heat production during curing will not have a significant impact on the long-term safety of the borehole. Inclusion of FEP Excluded in all scenarios. 2.1.10.3 Temperature evolution Description A range of processes could potentially generate heat in a closed borehole (see FEPs 2.1.10.1 and 2.1.10.2). These processes could contribute to temperature profiles across the borehole and into the host rock. Although the effect on temperature may only be temporary, it could have a permanent effect on borehole safety if it causes cracking in any backfill, concrete structures and the immediately surrounding host rock. Water flow rates might increase and gas could migrate more easily. Treatment in the GSA It is considered that the temperature rise in the borehole will be limited for Category 3 to 5 sources (see FEPs 2.1.10.1 and 2.1.10.2). Therefore, isothermal conditions are assumed for the GSA for Category 3 to 5 sources. For Category 1 and 2 sources, calculations in Section 3.2 of the current report show that non-isothermal conditions initially exist in the borehole for the highest activity sources with peak temperatures of up to 275 °C in the capsule and slightly over 100 °C in the borehole backfill. Isothermal conditions are established after around 50 years for the Co-60 sources and 200 years for the Cs-137 sources. The impacts of these thermal conditions on other near-field FEPs are discussed under FEPs 2.1.2 to 2.1.9 above. Inclusion of FEP Excluded for Category 3 to 5 sources in all scenarios. Included for Category 1 and 2 sources.
final%20report%20QRS-1668A-1v1.0(draft)(8Dec14).docx