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Sinha N.K.,Indira Gandhi Center for Atomic Research | Mukhopadhyay R.,J. K. Tyre and Industries Ltd. | Raj B.,Indira Gandhi Center for Atomic Research | Raj B.,Ps Govindaswamy Naidu Psg Institutions
Nuclear Engineering and Design | Year: 2015

Stress-elongation behavior of a Viton A-401C based compound established for backup seals of 500 MW(e), Prototype Fast Breeder Reactor is depicted. Stress-softening effects are negligible during room temperature (RT) or 110 °C measurements on unaged samples at strain rates of 50 mm/min and 500 mm/min because of low filler content. Relaxation is observed during RT property determination at lower strain rate. Stiffening of behavior at 50 mm/min and 110 °C is attributed to Joule-Gough effect and absence of relaxation because of increased molecular chain mobility. The two zone stress-elongation behavior (determined by chemical cross-links up to ∼85% strain and by ionic interactions beyond) propounded in the article by combining air-aged specimen data (32 weeks at 140/170/200 °C) provides a behavior map of bisphenol cured, low filler, fluoroelastomers made of vinylidene fluoride and hexafluoropropylene. This could be extended to peroxide cured fluorocarbon rubbers for verifications and providing qualified compounds of better grades for critical nuclear elastomeric sealing applications. © 2012 Elsevier B.V. All rights reserved. Source


Sinha N.K.,Indira Gandhi Center for Atomic Research | Raj B.,Indira Gandhi Center for Atomic Research | Raj B.,Ps Govindaswamy Naidu Psg Institutions
Nuclear Engineering and Design | Year: 2012

The unification of elastomeric sealing applications of Indian nuclear reactors based on a few qualified fluoroelastomer/perfluoroelastomer compounds and standardized approaches for finite element analysis (FEA) based design, manufacturing process and antifriction coatings is discussed. It is shown that the advance polymer architecture based Viton ® formulation developed for inflatable seals of 500 MWe Prototype Fast Breeder Reactor (PFBR) and its four basic variations can encompass other sealing applications of PFBR with minimum additional efforts on development and validation. Changing the blend ratio of Viton ® GBL 200S and 600S in inflatable seal formulation could extend its use to Pressurized Heavy Water Reactors (PHWRs). The higher operating temperature of Advanced Heavy Water Reactor (AHWR) seals expands the choice to perfluoroelastomers. FEA based on plane-strain/ axisymmetric modeling (with Mooney-Rivlin as the basic constitutive model), seal manufacture by cold feed extrusion and injection molding as well as plasma Teflon-like coating belonging to two variations obtained from the development of inflatable seals provide the necessary standardization for unification. The gains in simplification of design, development and operation of seals along with the enhancements of safety and reliability are expected to be substantial. © 2011 Elsevier B.V. All rights reserved. Source


Sinha N.K.,Indira Gandhi Center for Atomic Research | Raj B.,Indira Gandhi Center for Atomic Research | Raj B.,Ps Govindaswamy Naidu Psg Institutions
Nuclear Engineering and Design | Year: 2012

Identification of a set of governing physico-mechanical properties for inflatable seals of Prototype Fast Breeder Reactor (PFBR) and specification of their limits is described based on operating requirements, design practices and results from seal development. The limits of tensile strength, elongation at break, hardness, tear strength, fluid compatibility, compression set and specific gravity defined for the Viton GBL 200S/600S based inflatable seal formulation provide a standardized framework for regular production of reactor seals and a streamlined approach for compounding, design, manufacture and quality control. This assures significant reduction of efforts during the envisaged unification of Fast Breeder Reactor sealing based on four variations of inflatable seal compound which could result in a universal design code apart from significant gains in safety, reliability and life. The property set has potential use in Pressurized Heavy Water Reactor and Advanced Heavy Water Reactor. Inclusion of factors such as batch-to-batch variations of compound properties and their reproducibility during laboratory measurements, hot tensile behavior of fluoroelastomer, long term ageing effects and the margin of safety at the end of seal design life ensures the utility of property set in attaining its intended objective. © 2012 Elsevier B.V. All rights reserved. Source


Sinha N.K.,Indira Gandhi Center for Atomic Research | Raj B.,Indira Gandhi Center for Atomic Research | Raj B.,Ps Govindaswamy Naidu Psg Institutions
Nuclear Engineering and Design | Year: 2014

Estimation and stipulation of allowable leakage for inflatable seals of 500 MWe Prototype Fast Breeder Reactor is depicted. Leakage limits are specified using a conservative approach, which assumes escape of radioactive cover gas with fission products across the seals in bypass and permeation modes and possibility of sodium frost deposition in sealed gaps because of permeation leakage of inflation gas. Procedures to arrive at the allowable leakages of argon cover gas (normal-operation/fuel-handling: 10-3/10-2 scc/s/m length of seal) and argon inflation gas (10-3 scc/s/m length of seal) is described. © 2013 Elsevier Ltd. All rights reserved. Source


Sinha N.K.,Indira Gandhi Center for Atomic Research | Ghosh P.,Hari Shankar Singhania Elastomer and Tyre Research Institute HASETRI | Saha A.,Hari Shankar Singhania Elastomer and Tyre Research Institute HASETRI | Mukhopadhyay R.,Hari Shankar Singhania Elastomer and Tyre Research Institute HASETRI | And 3 more authors.
Materials and Design | Year: 2012

Design optimization of static, fluoroelastomer backup seals for the 500. MWe, Prototype Fast Breeder Reactor (PFBR) is depicted. 14 geometric variations of a solid trapezoidal cross-section were studied by finite element analysis (FEA) to arrive at a design with hollowness and double o-ring contours on the sealing face. The seal design with squeeze of 5 mm assures failsafe operation for at least 10. years under a differential pressure of 25. kPa and ageing influences of fluid (air), temperature (110 °C) and γ radiation (23. mGy/h) in reactor. Hybrid elements of 1 mm length, regular integration, Mooney-Rivlin material model and Poisson's ratio of 0.493 were used in axisymmetric analysis scheme. Possible effects of reduced fluoroelastomer strength at 110 °C, ageing, friction, tolerances in reactor scale, testing conditions during FEA data generation and batch-to-batch/production variations in seal material were considered to ensure adequate safety margin at the end of design life. The safety margin and numerical prediction accuracy could be improved further by using properties of specimens extracted from seal. The approach is applicable to other low pressure, moderate temperature elastomeric sealing applications of PFBR, mostly operating under maximum strain of 50%. © 2011 Elsevier Ltd. Source

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