Application of Polyhexamethyleneguanidine Type Biocides at Cementing the Radioactive Waste

Author(s):  
Andrey P. Varlakov ◽  
Olga A. Gorbunova ◽  
Aleksandr S. Barinov ◽  
Vadim A. Iljin ◽  
Konstantin M. Efimov ◽  
...  

Abstract In order to prevent biological corrosion of cement compound containing radioactive waste, it is proposed to use biocidal additives of polyhexamethyleneguanidines (PHMG), which have a wide range of biocidal activity. It has been shown that inclusion of biocidal additives of polyhexamethyleneguanidines in quantities 0,25–2% wt. into the grout used for the solidification of radioactive waste (RW) or for recovering the integrity of old RW repositories provides the necessary bacteriostatic and biocidal protection of cement compound and improves all the regulated properties — compression strength, Cs-137 leaching rate, frost-resistance, radiation resistance and long term water resistance.

1996 ◽  
Vol 465 ◽  
Author(s):  
J. P. Freidberg ◽  
A. J. Shajii ◽  
K. W. Wenzel ◽  
J. R. Lierzer

ABSTRACTThis paper describes a new concept for a high-temperature, electrodeless melter for vitrifying radioactive wastes. Based on the principles of induction heating, it circumvents a number of difficulties associated with existing technology. The melter can operate at higher temperatures (1500–2000°C vs 1150°C), allowing for a higher quality, more durable glass which reduces the long-term leaching rate. Higher processing temperatures also enable conversion from borosilicate to high-silica glass which can accommodate 2 to 3 times as much radioactive waste, potentially halving the ultimate required long-term disposal space. Finally, with high temperatures, conversion of nuclear waste into ceramics can also be considered. This too leads to higher waste loading and the reduction of repository space. The melter is toroidal, linked by an iron core transformer that allows efficient electrical operation even at 60 Hz. One-dimensional electrical and thermal analyses are presented.


Author(s):  
Brendan Breen ◽  
Elizabeth Atherton ◽  
Steve Barlow

United Kingdom Nirex Limited (Nirex) is responsible for providing the UK with environmentally-sound and publicly-acceptable options for the long-term management of radioactive materials generated by the Nation’s commercial, medical, research and defence activities. An important part of Nirex’s responsibilities in developing these options is to build acceptance of its concepts through effective dialogue and engagement with a wide range of stakeholders. One of the options developed by Nirex for the long-term isolation of intermediate-level and some low-level from the accessible environment is to place these wastes in a deep underground repository, excavated in stable rock formations. The repository would remain accessible to allow future generations to have the choice of continuing to store the waste, or to dispose of the wastes by sealing and closing the repository. In conducting the scientific and technical research on this phased disposal concept, Nirex wanted its work programmes to take account of any public concerns with regard to radioactive waste and its management and proposed to develop its understanding of such concerns through public engagement. In October 2001, Nirex engaged an independent organisation to conduct a series of focus group discussions. Focus group meetings were arranged in 4 locations across the UK, selecting varying groups in terms of age, lifestage and socio-economic circumstances in order to engage a broad cross-section of the UK population. Each group attended two, 2-hour sessions on successive evenings. The first session was a general discussion of the issues of nuclear energy and radioactive waste. The second session focused on the more specific detail of the Nirex Phased Disposal Concept. Explanatory material was given to participants at each session. The work has provided some very useful information on issues, which the focus groups considered significant. The groups were able, in the short time available, to grasp many important issues and to provide their views across a range of technical areas. This work has helped Nirex to better understand ways of engaging the public in technical issues and to appreciate some of the key areas and concerns on the more technical areas associated with phased disposal. Several technical queries were identified, which the facilitators were unable to answer during the focus group discussions — Nirex has subsequently provided answers to these questions and made these available on the Nirex Bibliography. This paper describes the approach taken for the focus groups and outlines key findings from the work and some implications for Nirex in communicating technical issues to the public.


Author(s):  
Maha Zaghdoudi ◽  
Mike Weber ◽  
Anja Kömmling ◽  
Matthias Jaunich ◽  
Dietmar Wolff

Abstract Elastomer seals are used in many industrial applications due to their excellent mechanical properties at a wide range of temperatures. Their high versatility and recovery potential under several load conditions make them well suitable for the application in containers designed for transport, storage and/or disposal of radioactive materials. In containers for low and intermediate level radioactive waste, elastomer seals are used as barrier seals, and as auxiliary seals in storage and transportation casks (dual purpose casks) for heat generating radioactive waste, such as spent fuel and high-level waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered and prohibit an unnecessary cask handling. An extensive knowledge of the change of the elastomer’s properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the permanent safe enclosure of the radioactive material is mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have been already made and are still planned to scientifically support this task. Compression stress relaxation and compression set were identified as key indicators of elastomer long-term performance and quantitatively investigated in comprehensive test programs. Among other representative types of elastomers, specimens made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the most important of their complex mechanical properties. In the presented study, exemplary results were used to simulate the compression stress relaxation and the compression set of elastomer O-rings during aging. Regarding the influence of temperature, the time-temperature superposition principle is applied in the relaxation analysis of elastomer O-rings. The proposed model is implemented in the commercial finite element software ABAQUS/Standard® [1] with a sequential temperature displacement coupling. Numerical results match the experimental compression stress relaxation measurements well. The prediction of compression set values after long-term aging shows a relatively good agreement with the experimental results. Nevertheless, all input parameters derived from the specimen tests, additional assumptions concerning boundary conditions and modeling strategy are discussed with regard to the identified slight discrepancies. The possibility to extend the finite element model to represent the O-ring seal’s ability to recover after a (fast) partial release is taken into account.


MRS Advances ◽  
2020 ◽  
Vol 5 (3-4) ◽  
pp. 121-129
Author(s):  
Vladimir A. Kashcheev ◽  
Nikolay D. Musatov ◽  
Michael I. Ojovan

AbstractSalt cake radioactive waste is a remnant solid salt concentrate after deep evaporation of radioactive evaporator concentrate at WWER NPP’s. The traditional cementing of borate-containing liquid radioactive waste, to which the salt cake belongs, leads to a significant increase in the volume of the final product. This work describes borosilicate vitreous wasteforms developed to immobilize radioactive salt cake waste and comprises data on both glass synthesis and characterization. The composition of glass selected for the purpose of immobilisation of the salt cake radioactive waste allows to include up to 40 wt. % of the oxides contained in the salt cake and to reduce the volume of the final product by more than 2 times compared with the cement compound. The batches were melted in a cold crucible melter at 1200 °C. The normalized cesium leaching rate of the vitrified wasteform product was within range 3.0·10-5 – 3.7·10-6 g/(cm2·day).


2020 ◽  
pp. 66-73
Author(s):  
A. Simonova ◽  
S. Chudakov ◽  
R. Gorenkov ◽  
V. Egorov ◽  
A. Gostry ◽  
...  

The article summarizes the long-term experience of practical application of domestic breakthrough technologies of preventive personalized medicine for laboratory diagnostics of a wide range of socially significant non-infectious diseases. Conceptual approaches to the formation of an integrated program for early detection and prevention of civilization diseases based on these technologies are given. A vision of the prospects for the development of this area in domestic and foreign medicine has been formed.


Author(s):  
S.V. Borshch ◽  
◽  
R.M. Vil’fand ◽  
D.B. Kiktev ◽  
V.M. Khan ◽  
...  

The paper presents the summary and results of long-term and multi-faceted experience of international scientific and technical cooperation of Hydrometeorological Center of Russia in the field of hydrometeorology and environmental monitoring within the framework of WMO programs, which indicates its high efficiency in performing a wide range of works at a high scientific and technical level. Keywords: World Meteorological Organization, major WMO programs, representatives of Hydrometeorological Center of Russia in WMO


2017 ◽  
Vol 68 (3) ◽  
pp. 599-601
Author(s):  
Dan Paul Stefanescu ◽  
Oana Roxana Chivu ◽  
Claudiu Babis ◽  
Augustin Semenescu ◽  
Alina Gligor

Any economic activity carried out by an organization, can generate a wide range of environmental implications. Particularly important, must be considered the activities that have a significant negative effect on the environment, meaning those which pollute. Being known the harmful effects of pollution on the human health, the paper presents two models of utmost importance, one of the material environment-economy interactions balance and the other of the material flows between environmental factors and socio-economic activities. The study of these models enable specific conditions that must be satisfied for the economic processes friendly coexist to the environment for long term, meaning to have a minimal impact in that the residues resulting from the economic activity of the organization to be as less harmful to the environment.


HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 436E-436
Author(s):  
Martin P.N. Gent

The persistence of effects of paclobutrazol or uniconazol on stem elongation was determined for several years after large-leaf Rhododendron and Kalmia latifolia were treated with a single-spray application of these triazol growth-regulator chemicals. Potted plants were treated in the second year from propagation, and transplanted into the field in the following spring. The elongation of stems was measured in the year of application and in the following 2 to 4 years. Treatments with a wide range of doses were applied in 1991, 1992, or 1995. For all except the most-dilute applications, stem elongation was retarded in the year following application. At the highest doses, stem growth was inhibited 2 years following application. The results could be explained by a model of growth regulator action that assumed stem elongation was inversely related to amount of growth regulator applied. The dose response coefficient for paclobutrazol was less than that for uniconazol. The dose that inhibited stem elongation one-half as much as a saturating dose was about 0.5 and 0.05 mg/plant, for paclobutrazol and uniconazol, respectively. The dose response coefficient decreased exponentially with time after application, with an exponential time constant of about 2/year. The model predicted a dose of growth regulator that inhibited 0.9 of stem elongation immediately after application would continue to inhibit 0.5 of stem elongation in the following year.


2019 ◽  
Vol 20 (3) ◽  
pp. 251-264 ◽  
Author(s):  
Yinlu Feng ◽  
Zifei Yin ◽  
Daniel Zhang ◽  
Arun Srivastava ◽  
Chen Ling

The success of gene and cell therapy in clinic during the past two decades as well as our expanding ability to manipulate these biomaterials are leading to new therapeutic options for a wide range of inherited and acquired diseases. Combining conventional therapies with this emerging field is a promising strategy to treat those previously-thought untreatable diseases. Traditional Chinese medicine (TCM) has evolved for thousands of years in China and still plays an important role in human health. As part of the active ingredients of TCM, proteins and peptides have attracted long-term enthusiasm of researchers. More recently, they have been utilized in gene and cell therapy, resulting in promising novel strategies to treat both cancer and non-cancer diseases. This manuscript presents a critical review on this field, accompanied with perspectives on the challenges and new directions for future research in this emerging frontier.


Author(s):  
Ilana Seager ◽  
Douglas S. Mennin ◽  
Amelia Aldao

Generalized anxiety disorder (GAD) is a debilitating condition characterized by excessive, pervasive, uncontrollable, and paralyzing worries about a wide range of future situations. Individuals with this condition frequently find themselves stuck in worry and tension cycles in futile attempts at reducing uncertainty and increasing control. GAD has been associated with substantial impairments in functioning and reduced quality of life. GAD remains poorly understood, and the long-term efficacy and end-state functioning resulting from treatment are weaker compared to other anxiety disorders. Some treatments (e.g., emotion regulation therapy, acceptance-based behavioral therapy) have improved efficacy, partly by targeting emotional dysfunction. Basic psychopathology research has focused on identifying the role of negative affect in GAD, so little is known about how positive affect is experienced and regulated in this disorder. This is particularly important in light of the overlap of this condition with major depressive disorder, which is characterized by low or suppressed positive emotion. Developing such an understanding is essential to further improve the efficacy of emotion-based treatments. This chapter reviews current and future directions in the study of positive affect in GAD. The chapter reviews the nascent research on positive affect and GAD, then illustrates dimensions of future work.


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