The Primary evaluation of the impacts of naturaI phenomena on the safety functions of the geological disposal system; An Example study on site generic phase

Makino, Hitoshi; ; Miyahara, Kaname

JNC TN8400 2000-033, 74 Pages, 2000/11

JNC-TN8400-2000-033.pdf:9.19MB

Natural phenomena is one of the potential factors perturbing the long-term stability of the geological environment, and for natural phenomena, it is necessary to consider uncertainties relevant to time, frequency and effect. Therefore it will be important to have information about the potential impacts of natural phenomena on the safety functions of geological disposal system in the future by assuming that natural phenomena perturbs the safety functions of the geological disposal system. In this report, we have considered 4 natural phenomena, 'uplift, subsidence and denudation', 'climatic and sea-level changes', 'earthquakes and fault movement' and 'volcanism', which had been extracted by investigation in foreign countries and by considering the characteristics of Japan as natural phenomena which may perturb the long-term stability of the geological environment. And we have considered mainly typical effects of naturaI phenomena on geological environment and investigated the typical impacts of those natural phenomena on the safety functions of the geological disposal system. On perturbation scenarios, the maximum of total doses have been less than regulatory guidelines in foreign countries in all situations except the cases assuming that a new fault, which causes significant pathway of groundwater flow and nuclide migration, intersects the waste packages. In the case, the maximum of total doses may reach the same level as regulatory guidelines in foreign countries or natural radiation exposure in Japan depending on fault generation time or grandwater flow rate through the fault. And, on isolation failure scenarios, it has been implied that nuclide mass/flux originated from geological disposal is comparable level with nuclide mass/flux in natural environment. These results could give useful information about the potential impacts of natural phenomena on the safety functions of geological disposal system, and also could show the potential importance of ...

None

*; Fuse, Keisuke*; *; Yasuda, Kenya*

PNC TJ7454 97-001, 536 Pages, 1997/03

PNC-TJ7454-97-001.pdf:13.9MB

no abstracts in English

None

Takase, Hiroyasu*; Nakayasu, Akio*

PNC TJ1281 95-005, 68 Pages, 1995/02

PNC-TJ1281-95-005.pdf:1.76MB

None

A Study on the evaluation of topographic change due to uplift, denudation and eustasy affecting to nuclide migration for disposal of radioactive wastes

Shimada, Taro; Uchikoshi, Emiko*; Takai, Shizuka; Takeda, Seiji

no journal, , 

Long-term topographic change due to uplift, denudation and eustasy may change the field of groundwater flow and nuclide migration when radioactive wastes are disposed at the repository near the sea. In this report, we constructed the frame work for evaluating uncertainties of future topograophic changes. Using the evaluation code under developing at JAEA, we tried evaluating the future topographic change until 0.125k years after for catchment basin near the sea.

Numerical study on the impact of long-term landscape evolution and sea-level change on groundwater flow

Takai, Shizuka; Shimada, Taro; Uchikoshi, Emiko*; Takeda, Seiji

no journal, , 

In geological disposal, landscape evolution by uplift, denudation, and sea-level change will change geological environment and decrease the depth of disposal. This may lower safety functions of disposal system: therefore, the effect needs to be evaluated properly. In the assessment, landscape evolution needs to be evaluated considering topography, material properties, and environmental factors. In addition, uncertainty should be considered for future sea-level change, which will significantly different from previous glacial cycles due to anthropogenic greenhouse-gas emissions. In this study, we evaluated future landscape evolution for a glacial-interglacial cycle (125 ka) by numerical simulation. Then, we conducted groundwater simulation considering transient topography and sea-level change. The uncertainty of future global sea-level change was considered based on previous studies by glacial isostatic adjustment simulation. The impact on groundwater flow was evaluated at the typical basin consisting of mountain, river, plain, and sea in Japan.

Modeling of coastal landscape evolution during the last glacial-interglacial cycle; A Case study on the Kamikita coastal plain, NE Japan

Takai, Shizuka; Sanga, Tomoji*; Shimada, Taro; Takeda, Seiji

no journal, , 

Prediction of long-term future landscape evolution is indispensable for safety assessment for intermediate radioactive waste disposal, whose safety assessment period is ~10 years. To assess the coastal landscape evolution considering the uncertainty of future sea-level change, the numerical simulation based on the landscape evolution models (LEMs) will be valuable. However, the applicability of LEMs over 10 years has not been verified in coastal areas. JAEA has developed a LEMs (JAEAsmtp) coupling hillslope and fluvial transport, tectonics, marine sedimentation, sea-level and climate change, and lithology. In this study, we demonstrate the capabilities of JAEAsmtp in assessing the coastal landscape evolution over the last glacial-interglacial cycle. Our target area (250 km) is located on the Kamikita coastal plain (sedimentary rock), where the marine terraces (MIS5e, 7, 9) are widely distributed. First, based on the marine terraces, borehole, and sonic prospecting data, the spatial distributions of the present and paleo-elevation, uplift rate, and alluvial deposits were estimated. Second, the LEMs parameters for fluvial incision and erodibilities were obtained from the slope-area analysis and soil-test data, respectively. Finally, the landscape evolution from MIS5e (125 ka) to present was simulated. By incorporating the drift sand into JAEAsmtp, the applicability was confirmed via reproducibility of the present coastal line and the distribution of alluvial deposits.