Loviisa nuclear power station, final disposal of reactor waste

Hydraulic pulse tests were done in the Loviisa power plant area in 1984. The aim of the tests was to study the suitability of the area for a disposal of the low and intermediate level waste in rock caverns. The pulse tests were double packer tests in the pump hole with five measuring points in the three nearby holes for hydraulic head. The aim of this study was to simulate the tests to get some knowledge about the hydraulic properties of the rock. The simulation was made by an axisymmetric mathematical model using the computer. The rock was given different homogenous orthothropic properties, some with a special water-leading zone; and the propagation of the pulse, maintained in two different points in the pulse hole, was observed in the three nearby holes. The results were compared with those measured in the real test situation. As a result some ideas about the way, how water spreads into the rock, were got, and the hydraulic parameters were estimated. The flow was found to be spherical. The flow between the pulse hole and the hole Y4 was to be interpreted with an orthothropic hydraulic conductivity, but it could also be interpreted with a fracture zone. The flows to the other directions could be interpreted with a fracture zone only. The results were found to be in a fairly good correspondence with earlier investigations