SYMPOSIA PAPER Published: 14 January 2013
STP103980

(U)HMWPE as Neutron Radiation Shielding Materials: Impact of Gamma Radiation on Structure and Properties

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Due to their extreme high hydrogen contents, high molecular weight (HMW-) and ultra-high molecular weight (UHMW-) polyethylene (PE) are a comprehensible choice as neutron radiation shielding material in casks for storage and transport of radioactive materials. But as a direct consequence of inserting radioactive material in such casks, gamma radiation occurs. Hence, the impact of gamma radiation on the molecular structure of polyethylene has to be taken into consideration. Consequently, PE has to withstand any type of gamma radiation induced degradation affecting safety relevant aspects in order to be applicable for long term neutron radiation shielding purposes during the whole storage period (in Germany, for instance, up to 40 years). The scope of our investigation comprises an estimation of the impact of gamma radiation and temperature on the molecular and supra molecular structure of the two types of PE used as neutron radiation shielding cask components. A further point which is worth exploring is to what extent these changes are detectable by conventional analysis methods. Therefore, thermoanalytical measurements were performed such as differential scanning calorimetry (DSC), thermo mechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermo gravimetric analysis (TGA). Additionally optical and weighing methods were applied. With those methods it is possible to detect structural changes in polyethylene induced by exposure to gamma radiation. The observed amounts of changes of the irradiated material are not safety relevant for the application of polyethylene as neutron radiation shielding material; moreover, some properties actually improve via irradiation.

Author Information

Wolff, Dietmar
BAM Federal Inst. f. Materials Research a. Testing, Berlin, DE
von der Ehe, Kerstin
BAM Federal Inst. f. Materials Research a. Testing, Berlin, DE
Jaunich, Matthias
BAM Federal Inst. f. Materials Research a. Testing, Berlin, DE
Böhning, Martin
BAM Federal Inst. f. Materials Research a. Testing, Berlin, DE
Goering, Harald
BAM Federal Inst. f. Materials Research a. Testing, Berlin, DE
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Details
Developed by Committee: E10
Pages: 211–227
DOI: 10.1520/STP103980
ISBN-EB: 978-0-8031-7563-1
ISBN-13: 978-0-8031-7533-4