Papers by kunhiraman devan
Comprehensive Compilations of Computation Results and Validations for Neutronics Start-up Tests at China Experimental Fast Reactor
International Conference on Physics of Reactors 2022 (PHYSOR 2022)
A Method for Online Diagnostics of Electromagnetic Relays Against Contact Welding for Safety Critical Applications
IEEE Transactions on Components, Packaging and Manufacturing Technology, 2015
In a nuclear power plant, electromagnetic (EM) relays are often used to communicate TRIP signal c... more In a nuclear power plant, electromagnetic (EM) relays are often used to communicate TRIP signal configured in fail-safe mode. Online diagnostics is an important part of fault tolerant design. Relay contact welding is a failure mode of concern. Current methods do not allow for reliable online diagnostics of this failure mode without actually opening/closing the relays or without making measurements at contact side. In this paper, a technique for online diagnostics of EM relay without affecting the contact status is proposed. The method uses the differences in characteristic decay of coil current during deenergization process between a healthy and a relay whose contacts got welded. A test circuit is designed to verify the concept of deenergizing, followed by quick reenergization of relay coil. Diagnostic information is extracted, and the method is amenable for online automated execution. Results are satisfactory, and a welded contact is successfully detected and indicated by the circuitry. Reliability improvement achieved by deploying the proposed method is highlighted.
Measurements of the neutron total cross-sections of tantalum by using pulsed neutrons based on an electron linac
The neutron total cross-sections of tantalum (Ta-181) were measured in the neutron energy region ... more The neutron total cross-sections of tantalum (Ta-181) were measured in the neutron energy region from 0.01 eV to 100 eV by using the time-of-flight method at the Pohang Neutron Facility, which consists of an electron linac, a water-cooled tantalum target with a water moderator, and a 12-m-long time-of-flight path. A Li-6-ZnS(Ag) scintillator with a diameter of 12.5 cm and a thickness of 1.6 cm was used as a neutron detector, and a natural tantalum metal plate, 10 x 10 cm 2 in area by 0.45 mm in thickness, was used for the neutron transmission measurement. The background level was determined by using a notch-filter of Co, In, and Cd sheets. The present measurement was compared with the previous ones and the evaluated data in ENDF/B-VI.8. The resonance parameters of Ta-181 isotope were obtained from the transmission ratio by using the SAMMY code, which utilizes both Doppler and resolution broadening effects and Bayes' generalized least squares technique
Nuclear Technology and Radiation Protection, 2015
After the successful operation of the fast breeder test reactor for over two decades, India is no... more After the successful operation of the fast breeder test reactor for over two decades, India is now nearing the completion of a 500 MW (electrical) prototype fast breeder reactor. This commercial scale power reactor is a sodium-cooled, pool-type, mixed-oxide fuelled fast reactor. The stability characteristics of the reactor are an important safety aspect to be studied. In the present work, linear stability of the prototype fast breeder reactor analysis is carried out using the transfer function method, while the stability of the system is checked via the Nyquist criteria. For the completeness of the study, transient analysis with various kinds of reactivity perturbations was carried out. The response of the system in both cases indicated that the system is stable.
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Papers by kunhiraman devan