Radiation Resistance of Cable Insulating Materials for Nuclear Power Generating Stations

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymer insulation materials are inevitably exposed to various kinds of environments. As technology advances, increasing demands on the reliable operation under various operating and environmental conditions are made on materials and components. Therefore, it is important to investigate the influence of radiation on polymeric insulating materials used under the combined environments. This paper describes the effects of atmospheric pressure and gammaray irradiation on tracking failure of polybutylene naphthalate (PBN), polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. PBN, PET and PBT were irradiated in air up to 100 kGy and then up to 1000 kGy with a dose rate of 10 kGy/h by using a 60 Co gamma-source. The effects of total dose of irradiation and atmospheric pressure on the time to tracking failure and discharge quantity were discussed. Obtained results show that, with increasing the total dose, the time to tracking failure increased with PBN and PET, but decreased with PBT. With decreasing the atmospheric pressure, the time to tracking failure increased with PBN, PET and PBT. While increasing the total dose, the discharge quantity decreased with PBN and PET, but increased with PBT. With decreasing the atmospheric pressure, the discharge quantity increased with PBN and PET, but decreased with PBT. The experimental results suggest that the chemical structure of the polymeric insulating materials plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of atmospheric pressure on tracking failure of gamma-ray irradiated polymer insulating materials

Liu

2010

“…The actual dose rate which the organic insulating materials receive in practice is almost 1 Gy / h in the primary containment vessel of a typical light water reactor [15,16].Ethylene propylene diene monomer and SR elastometers are frequently used to produce seals, hoses and electrical insulators in nuclear power plants [17]. Investigations have been carried out to study the radiation-induced degradation of mechanical properties of electrical insulating materials used in nuclear environments [17,18,19,20].…”

Section: Introductionmentioning

confidence: 99%

Degradation of Silicone Rubber under AC or DC Voltages in Radiation Environment

Rajini

Udayakumar

2009

The aging of silicone rubber by gamma irradiation has been investigated. Silicone Rubber flat specimens were aged by gamma irradiation with three different doses and the resistance to tracking on applying ac and dc voltages was examined. The results show that the resistance to tracking under dc voltages is less than that of their ac values. This necessitates a separate standard for determination of tracking resistance under dc voltage. Laboratory examination of material changes together with visual observations and leakage current measurements were also made. The dc stressed samples showed a higher surface degradation compared to those stressed by ac voltages. The erosion depth and contact angle affected by radiation have been studied. The aging of the surface was assessed by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy with Energy Dispersive X-ray Analysis.Index Terms -Silicone rubber (SR), Gamma radiation, γ radiation, dc resistance to tracking, contact angle, erosion depth, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy, Energy dispersive X-ray analysis, EDXA, Alumina tri hydrate, ATH.

“…Agarwa [19] has concluded that radiation aging of polymer materials is critical in nuclear systems and spacebased electrical systems. Kuriyama, Hayakawa and Inoue [20] have measured the physical and electrical properties of gamma-ray irradiated PVC jacketed cable and concluded that the electrical receptivity of PVC is reduced greatly. Presently, the researches on irradiation aging are mostly concentrated on electrical performance and mechanical performance, while the radiation reaction, especially the radiation aging theory is rarely studied.…”

Section: Introductionmentioning

confidence: 99%

Effects of gamma-ray irradiation on dielectric surface breakdown of polybutylene polymers

Liu

2007

Polymer materials are required to be used in radiation environments of space and nuclear power stations as insulation materials. For the use of polymer materials in such regions, it must be confirmed whether the electrical performance under radiation environments is different from that without radiation. This paper describes the effects of gamma-ray irradiation on dielectric breakdown of polybutylene naphthalate and terephthalate by applying a dc pulse voltage. Both the polybutylene naphthalate and polybutylene terephthalate were irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy/h by using a 60 Co gamma-source. The total dose of gamma-ray irradiation effects on the time to dielectric breakdown and the discharge quantity of discharge current were discussed. Obtained results show that with increasing the total dose of gamma-ray irradiation, the time to dielectric breakdown increased with polybutylene naphthalate, but decreased with polybutylene terephalate. With increasing the total dose of gamma-ray irradiation, the discharge quantity decreased with polybutylene naphthalate, but increased with polybutylene terephalate. The experimental results suggest that the chemical structure plays a main role in the result of the radiation reaction, which is related to cross-linking and degradation reactions. Dielectric properties are improved by the irradiation for polybutylene polymers which contain more combined phenyls in the main chain.