Low Alkaline Cement Used in the Construction of a Gallery in the Horonobe Underground Research Laboratory

2010 ◽  
Author(s):  
Masashi Nakayama ◽  
Haruo Sato ◽  
Yutaka Sugita ◽  
Seiji Ito ◽  
Masashi Minamide ◽  
...  
Keyword(s):  
Fly Ash ◽  
Research Laboratory ◽  
Concrete Lining ◽  
Energy Agency ◽  
Tunnel Support ◽  
Long Term Stability ◽  
Alkaline Conditions ◽  
High Level ◽  
Underground Research Laboratory

In Japan, any high level radioactive waste (HLW) repository is to be constructed at over 300 m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various admixtures. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly Fly-ash Contained Silicafume Cement), containing over 60 wt% of silica-fume (SF) and fly-ash (FA). HFSC was used experimentally as the shotcrete material in construction of part of the 140m deep gallery in the Horonobe Underground Research Laboratory (URL). The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40 wt% OPC (Ordinary Portland Cement), 20 wt% SF, and 40 wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC. The total length of tunnel using HFSC shotcrete is about 73 m and about 500 m3 of HFSC was used. The workability of HFSC shotcrete was confirmed in this experimental construction.

Dose-Dependence of Pb-Ion Implantation Damage in Zirconolite, Hollandite, and Zircon

1981 ◽  
Vol 11 ◽  
Author(s):  
T. J. Headley ◽  
G. W. Arnold ◽  
C. J. M. Northrup
Keyword(s):  
Radiation Damage ◽  
Structural Damage ◽  
Accelerated Aging ◽  
Dose Dependence ◽  
High Level Waste ◽  
Long Term Stability ◽  
Waste Forms ◽  
Recent Approach ◽  
High Level

The long-term stability of nuclear waste forms is an important consideration in their selection for safe disposal of radioactive waste. Stability against long-term radiation damage is particularly difficult to assess by short-term laboratory experiments. Much of the displacement damage in high-level waste forms will be generated by heavy recoil nuclei emitted during the α-decay process of long-lived actinide elements. Hence, an accelerated aging test which reliably simulates the α-recoil damage accumulated during thousands of years of storage is desirable. One recent approach to this simulation is to implant the waste form with heavy Pb-ions.I- 6 If the validity of this approach is to be fully assessed, two important questions which have not yet been investigated must be answered.(1) Is the structural damage, including cumulative effects, similar for irradiation by Pb-ions and a-recoil nuclei in a given material? (2) Is the dose-dependence of the accumulated damage similar? The purpose of this investigation was to assess the extent of these similarities in selected materials. We utilized transmission electron microscopy (TEM) to characterize the radiation damage and measure its dose-dependence.

Technical Know-How for Modeling of a Geological Environment: Part 2—Geological Modeling

2010 ◽  
Author(s):  
Toshiyuki Matsuoka ◽  
Kenji Amano ◽  
Hideaki Osawa ◽  
Takeshi Semba
Keyword(s):  
Research And Development ◽  
Research Laboratory ◽  
Site Characterization ◽  
Initial Surface ◽  
Geological Environment ◽  
Know How ◽  
Environment Model ◽  
High Level ◽  
Underground Research Laboratory ◽  
The Impact

It is important for site characterization projects to manage the decision-making process with transparency and traceability and to transfer the technical know-how developed and accumulated during the research and development to the implementing phase as well as to future generations. The modeling of a geological environment supports efforts to clarify the degree of understanding regarding that geological environment, including uncertainty. Evaluation of the impact of uncertainties in a geological environment model is important to identify and prioritize key issues for further investigations. Therefore, a plan for site characterization should be made based on the results of the modeling. The aim of this study is to support the planning of initial surface-based site characterization based on the technical know-how accumulated from the Mizunami Underground Research Laboratory Project and the Horonobe Underground Research Laboratory Project. These projects are broad scientific studies of the deep geological environment that are a basis for research and development for the geological disposal of high-level radioactive wastes. In this study, the work-flow followed in developing the geological model, one of the geological environment models, and the related technical know-how acquired from literature data have been summarized.

scholarly journals Application of Bio-Oss in tissue regenerative treatment prior to implant installation: literature review

2019 ◽  
Vol 22 (2) ◽  
pp. 147-154
Author(s):  
Alessandra De Carvalho Moreira ◽  
Jhenifer Rodrigues Silva ◽  
Renata De Paula Samico ◽  
Gabriela Nogueira de Melo Nishioka ◽  
Renato Sussumu Nishioka
Keyword(s):  
Literature Review ◽  
Bone Graft ◽  
Bone Substitute ◽  
Survival Rates ◽  
Natural Mineral ◽  
Beneficial Effects ◽  
Long Term Stability ◽  
Implant Placement ◽  
High Level

Objetivo: Bio-Oss is a xenogene bone graft in which all organic components are removed while retaining their natural mineral architecture. Therefore, the aim of this study was to evaluate, through a literature review, the benefits of using Bio-Oss for tissue regenerative treatment prior to implant placement. Material and Methods: a search was performed in Pubmed (Medline) in order to identify articles published in English between January 1, 2000 and June 31, 2018, where the Bio-Oss graft was used prior to implantation of implants in humans. A total of 40 studies were selected for detailed analysis. From this analysis, 18 articles were identified for inclusion in this review. Results: the articles analyzed in the review showed several beneficial effects of this xenograft, such as: positive osteoconductive properties, recovery of bone heights at sites with severe atrophies, slow xenograft reabsorption suggesting long term stability, survival rates and success of implants placed in grafted sites ranging from 91 to 100% in several studies. Conclusion: the use of bio-oss as a bone substitute is a viable alternative in the placement before dental implants, being used in clinical practice and with proved efficacy in several studies, due to its similarity with the bone and its high level of osteoconductivity.KeywordsBio-Oss; Bone Graft; Implants.

scholarly journals Underground Research Laboratory in “the Yenisei” Section of the Nizhnekansky Massif of the Krasnoyarsk Region

2019 ◽  
pp. 830-841
Author(s):  
Igor I. Linge ◽  
Sergey S. Utkin ◽  
Tatiana A. Kulagina ◽  
Nikolay N. Trokhov
Keyword(s):  
Life Cycle ◽  
Radioactive Waste ◽  
Research Laboratory ◽  
Radioactive Waste Disposal ◽  
Basic Principles ◽  
Scientific Support ◽  
Disposal Facility ◽  
The Russian Federation ◽  
Underground Research Laboratory

The issues of the construction and operation of an underground research laboratory for the purpose of substantiating the long-term safety of the deep radioactive waste disposal facility in the Russian Federation from the perspective of scientific support are considered. The basic principles are stated and the key directions of a long-term program of scientific research, including in an underground laboratory, are justified for assessing and substantiating the safety of an object at all stages of its life cycle

Properties of Materials from Activated Fly Ash from Fluidized Burning

2014 ◽  
Vol 1000 ◽  
pp. 338-341
Author(s):  
Jaromír Poláček ◽  
Rostislav Šulc
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Accelerated Aging ◽  
Long Term Stability ◽  
Mechanical And Physical Properties ◽  
Properties Of Materials ◽  
Physical And Chemical ◽  
Alkali Activated

This article deals with the basic properties of materials based on alkali-activated fly ash which contains a portion of fly ash produced during fluid burning. The primary task of our research was characterization of physical and chemical properties of each type of fly ash and fly ash mixture. The new materials composed of fly ash mixture and fly ash may have the similar mechanical and physical properties. The work focused on findingan appropriate technological procedure, the optimum composition of mixtures. Long-term stability was simulated by means of accelerated aging of these materials.

Nd-Sr Isotope and REE Evidence for the Long-Term Stability of HLW Glass Products and Trace Metal Migration in a Salt Repository: Corroding Basaltic Dykes in Evaporites as Natural Analogues

1997 ◽  
Vol 506 ◽  
Author(s):  
M. Steinmann ◽  
P. Stille ◽  
K. Mengel ◽  
M. Siemann ◽  
W. Bernotat
Keyword(s):  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Sr Isotope ◽  
Long Term Stability ◽  
Natural Analogues ◽  
Metal Migration ◽  
High Level ◽  
Physical And Chemical ◽  
And Chemical Properties

Basaltic dykes in salt rocks can be used in two different ways as natural analogues for high level radioactive waste (HLW) in a salt repository: In the first approach the basalts serve as analogues for the corrosion behavior of HiLW glass products during millions of years because of many similarities in their physical and chemical properties.

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