Effects of radiation types and dose rates on selected cable-insulating materials

Hanisch, F.; Maier, Patrick; Okada, Soichi; Schönbacher, H.

doi:10.1016/1359-0197(87)90141-x

Cited by 13 publications

(11 citation statements)

References 4 publications

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“…For equation (1), if the change of the "x/y ratio", ∆R, is multiplied, because the ratio change only depends on the "population of radicals", the total change of the "x/y ratio" after irradiation by a mixed field can be written as follows.…”

Section: Resultsmentioning

confidence: 99%

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Application of Alanine/Esr Spectrum Shape Change in Gamma Dosimetry

Choi¹,

Kim²,

Lee³

et al. 2010

Nuclear Engineering and Technology

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Temperature and radiation are two of the major environmental elements exerting aging effects on the incontainment instrumentation and control cables connected to major components. The effect of radiation on cable material is related to the total absorbed dose, which is mainly dependent on gamma rays [1]. For validity of radiation measurement, at least two operation cycles are required for the installation period. Generally used personal dosimeters are not appropriate for this application due to their rapid signal fading feature and relatively poor linearity at a range of high dose. Alanine-electron spin resonance (ESR) dosimetry material, meanwhile, has been proved to be suitable for long term measurement on the basis of the following factors: small signal dependency on temperature ( 0.2%/K), limited signal fading ( 1%/year), and low influence of humidity, which can be easily overcome by hermetic sealing of capsules [2]. Based on the aforementioned advantages as a long term dosimetry material, in the present study dozens of pellet type alanine dosimeters were installed at selected positions in a nuclear power plant (NPP) for two operation cycles. ESR dosimety is known as a retrospective dosimetry method that can be applied in an emergency after an accident and is accepted as a secondary standard and transfer dosimeter for the comparison of dose quantity between laboratories [3][4][5]. Recently, it was found that the peaks of spectra are mainly due to three kinds of radicals induced by radiation [6][7][8].The central resonance peak amplitude of main peaks is used to estimate radiation dose quantity. The weak "satellite line" beside the central resonance peak has been interpreted as the combined effects of "spin flip" of neighboring hydrogen protons of the methyl group of the paramagnetic center and a R2 radical [9][10][11]. The ratio of the "satellite line and main central resonance peak" is frequently expressed as the "x/y ratio". A decrease of this ratio has been explained by less saturation resistance of the main peak amplitude, which is caused by a decrease of the spin-lattice relaxation time T1. Crystallographic defects and plastic deformation in the structure of the alanine lattice by thermal shock of high linear energy transfer (LET) radiation have been reported as the most likely causes of relaxation time change. The "x/y ratio" irradiated with mixed radiation, composed of two radiations with different LET values, was reported to be intermediate and is determined by the absolute population size of each radical produced by radiation with different LET values. In this paper, the "x/y ratio" of alanine dosimeters returned from the containment building of the NPP is lower than that of dosimeters exposed to gamma rays. Furthermore, the ratio constantly decreased in proportion to the dose quantity, which corresponds with the installation period in the NPP. These results showed good accordance with previously reported results. Application of the above features to estimate gamma dose in mixed radiation fields is ...

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Section: Resultsmentioning

confidence: 99%

“…The effect of radiation on cable material is related to the total absorbed dose, which is mainly dependent on gamma rays [1]. For validity of radiation measurement, at least two operation cycles are required for the installation period.…”

mentioning

confidence: 99%

Application of Alanine/Esr Spectrum Shape Change in Gamma Dosimetry

Choi¹,

Kim²,

Lee³

et al. 2010

Nuclear Engineering and Technology

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“…For polyethylene, ethylene‐propylene copolymer, and tetrafluoroethylene‐propylene copolymer, Seguchi et al found no differences in the effects of irradiation in vacuum by fast neutrons or γ‐rays . Using five different radiation sources including a nuclear reactor and a 60 Co source, Hanisch et al reported that damage of halogen‐free cable‐insulating and cable‐sheathing materials was dependent on the total absorbed dose but not on the type of radiation. However, a higher crosslink rate was observed when polystyrene was irradiated in a nuclear reactor than with γ‐rays and the chemical resistance of polycarbonate and poly(ethylene terephthalate) was observed to decrease much more markedly after exposure to neutron radiation than to γ‐rays .…”

Section: Introductionmentioning

confidence: 99%

Degradation of EPDM and FPM elastomers irradiated at very high dose rates in mixed gamma and neutron fields

Ferrari

Pandini

Zenoni

et al. 2019

Polymer Engineering & Sci

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Elastomers are widely used in radioactive environments, where ionizing radiations induce a deterioration of their properties due to degradative phenomena occurring in the polymer structure. Their radiation resistance is usually assessed using γ‐rays and relatively low dose rates, but in actual applications, they are often exposed to mixed radiation fields and higher dose rates. Ethylene propylene diene monomer (EPDM) is known for its excellent resistance to γ‐rays but absorbs a larger dose by neutron interactions than fluoroelastomer (FPM). In this work, EPDM and FPM were irradiated in mixed neutron and gamma fields, using high dose rates (from 22 to 700 kGy h−1) and total absorbed doses between 0.2 and 3.5 MGy. The effects of irradiation were assessed by swelling tests, differential scanning calorimetry analysis and dynamic mechanical thermal analysis, and tensile tests. The results show that, even if irradiations were carried out in air, degradation took place under nonoxidative conditions owing to the high dose rates employed. Under such conditions, crosslinking is the dominant radiation‐induced reaction in both elastomers. Moreover, material degradation seems to be influenced mostly by the total absorbed dose and not by the type of radiation. Contrary to what observed at the lower dose rates employed with γ‐rays, major dose rate effects are not observed. POLYM. ENG. SCI., 59:2522–2532, 2019. © 2019 Society of Plastics Engineers

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“…Since 1980, there have been more studies on silicone rubber used in the radiation field in the United States, Japan, Germany, England, and other locations. [7][8][9][10][11][12] The focus has been on the effect of different radiation sources and dose rates versus silicone rubber, natural rubber, fluorine rubber, and so on, but they have not touched on the damage to these materials and changes in their microscopic structure. Until now, there has been no detailed study of radiation effects on open-porous silicone rubber foam.…”

Section: Introductionmentioning

confidence: 99%

Radiation effects on methyl vinyl polysilicone foam

Huang

Wang

et al. 2003

J of Applied Polymer Sci

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ABSTRACT:The effects on methyl vinyl polysilicone foam of 60 Co ␥-ray radiation at room temperature was studied in air, in vacuo, and in an inert gas atmosphere. The unirradiated and irradiated samples were analyzed by Fourier transform infrared spectroscopy, scanning electron microscopy, pyrolysis gas chromatography/mass spectroscopy, and thermogravimetric analysis, and the gas products after radiation were analyzed by gas chromatography/mass spectroscopy. The changes of the gel fraction, compression properties, and the stress-relaxation ratio with dose for irradiated samples were observed. The results show that the second crosslinking reaction in the polysilicone after chemical crosslinking took place at a low dose (2 ϫ 10 5 Gy), but radiation degradation was predominant, with the dose increasing step by step. The mechanical properties of polysilicone foam gradually became low grade after it was irradiated by any dose in excess of 2 ϫ 10 5 Gy.

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Effects of radiation types and dose rates on selected cable-insulating materials

Cited by 13 publications

References 4 publications

Application of Alanine/Esr Spectrum Shape Change in Gamma Dosimetry

Application of Alanine/Esr Spectrum Shape Change in Gamma Dosimetry

Degradation of EPDM and FPM elastomers irradiated at very high dose rates in mixed gamma and neutron fields

Radiation effects on methyl vinyl polysilicone foam

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