Water-extended Polyester Research Articles

Optimizing neutron shielding: A specialised container approach for Disused Sealed Radioactive Sources and orphan neutron emitters

Shielding Disused Sealed Radioactive Sources (DSRSs) and orphan neutron sources, such as 252Cf, pose challenges due to the high penetration of neutrons, induced radioactivity in shielding materials, and the limited availability of compact, effective shielding materials. This study addresses these challenges by proposing a specialized container for the safe transport, conditioning, and disposal of neutron-emitting DSRSs and orphan sources. The computational tool that was used in this study is the Monte Carlo N-Particle (MCNP). The investigation begins with an examination of moderation materials, including high-density polyethylene (HDPE), paraffin, and water-extended polyester (WEP). Subsequently, four concrete types, namely Ordinary, Barite, Portland, and Serpentine Concrete, are scrutinized. Employing a comprehensive methodology, the design of the container is optimized to effectively moderate and absorb neutron emissions. The findings of this study demonstrate that the designed compact container can safely handle activities exceeding those studied, effectively managing up to 10 μg (about 0.2 GBq) 252Cf without exceeding 25 μSv/h at the outer container contact. This suggests a promising solution for the secure management of high-activity neutron-emitting sources.

Shielding for transporting an 241Am-Be source for industrial applications

Paraffin, water and water-extended polyester (WEP) were used as main moderator to design a mobile shielding for a 666 GBq 241Am–Be source used in oil industry. The shielding performance was estimated using Monte Carlo methods where the γ-rays induced by the neutron interaction with the shielding materials were also included. The spectra of neutrons and γ-rays around the shielding were estimated, as well as the total neutron and g-ray total fluences per history. The neutron source strength was used to calculate ambient dose equivalent rates, aiming to satisfy the international recommendation (2 mSv/h at the shielding surface). Moderators modify the neutron spectrum of the source reducing the amount of fast neutrons (0.5–11 MeV) and producing epithermal and thermal neutrons. During neutron transport in the moderator neutron capture and inelastic scattering produce gamma-rays. Paraffin has the best shielding performance however it is not suitable because can be affected by extreme temperatures. WEP and water have similar shielding performance, however water do not satisfy the international recommendations because at one site the neutron and γ-ray doses rates are larger than 2 mSv/h. WEP is the best option because fulfill the international recommendations, it is stable and temperatures where paraffin fails. The WEP-based shielding weights 66 kg.

Water-extended polyester neutron shield for a 252Cf neutron source

A Monte Carlo study to determine the shielding features to neutrons of water-extended polyester was carried out. During calculations, (252)Cf and shielding were modelled and the neutron spectra as well as the H(10) were calculated in four sites. The calculation was extended to include a water shielding, the source in vacuum and in air. Besides neutron shielding characteristics, the Kerma in air due to gammas emitted by (252)Cf and due to capture gamma rays in the shielding were included.

Immobilization of borate waste simulate in cement–water extended polyester composite based on poly(ethylene terephthalate) waste, part 3: Behavior of solid waste form during a scenario of flooding accident in the disposal site

Laboratory scale testing program was conducted to investigate the feasibility of using water extended polyester cement composite (PCC) based on poly- (ethylene terephthalate) waste (PET) as immobilization matrix for borate waste, originated from pressurized water reactors (PWRs), during prolonged term of disposal process and in scenario of flooding accident. Twenty-eight days cured solid blocks prepared as a premix of 3% by weight of the water extended polyester (WEP) and ordinary Portland cement (OPC) past having 40% by weight water were subjected to static immersion in three type of leachants, namely tap, sea, ground water. Weight changes, compressive strength variations, porosity, water absorption, and some other physical properties of the solid PCC waste forms were evaluated during 260 days of the static immersion. X-ray diffraction (XRD), infrared analysis (IR), and electron scanning microscope were performed for the waste forms at the end of immersion prolonged period to follow the internal changes in the solid waste forms that may occur due to the corrosion action of the different leachants. The results obtained from the different measurements confirm the performance of the PCC solidified waste form, based on the mentioned formulation, as an acceptable matrix in the various disposal sites and for extended disposal time even at the worst flooding environment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4113–4120, 2007

Immobilization of Borate Waste Simulate in Cement-Water Extended Polyester Composite Based on Poly(Ethylene Terephthalate) Waste: 2-Frost Resistance of the Polymer Modified Cement Composite

Modified composite from water extended polyester (WEP); based on the recycled poly(ethylene terephthalate), (PET), and ordinary Portland cement (OPC) is a candidate matrix for processing borate waste solutions originating from the primary coolant circuit of pressurized water reactors (PWRs). This part of the work discusses the frost resistance of this polymer-modified cement composite (PCC) during the disposal course. Frost resistance is assessed for the candidate PCC after 115 cycles of freezing and thawing treatment (FTC) by evaluating their durability index, compressive strength, apparent porosity, volume of open pores, water absorption, and bulk density. Infrared (IR) and X-ray diffraction (XRD) as non-destructive analyses were performed for the candidate PCC before and after the freezing/thawing treatment to follow the changes that may take place during the hydration regime. The results obtained indicate that the candidate-modified cement composite exhibits acceptable resistance to freezing and thawing treatment even at very exaggerating conditions (−19°C and +60°C).

Immobilization of Borate Waste Simulate in Cement-Water Extended Polyester Composite Based on Polyethylene Terephthalate Waste 1-Mechanical Properties of the Final Waste Forms

ABSTRACT This paper discusses the suitability of Ordinary Portland Cement (OPC), water-extended polyester (WEP), based on recycled polyethylene terephthalate (PET), composite for stabilization/solidification (S/S) of borate waste solution originating from the primary coolant circuit of pressurized water reactors (PWRs). This treatment is a new and attractive economical process that aims at keeping man and his environment healthy through controlling the dispersion of radioactive wastes (i.e., borate waste solution) and the solid plastic waste materials (i.e., PET). Mechanical integrity of the WEP as well as its polymer composite (PC) with OPC was studied under different experimental conditions. Compressive strength measurements for the final waste forms of PC containing borate waste simulate were also evaluated using various compositions of the PC (e.g., water of hydration, polymer:cement ratio, borate content, etc.) Based on the data obtained so far, it could be concluded that the candidate PC with the formulation of polymer:cement ratio 3%, water:cement ratio 40%, polymer:water of emulsion 80/20, and containing up to 3% by weight borate waste simulate shows compressive strength values acceptable for different transportation, storage, and disposal processes.

Management of Low and Intermediate Level Radioactive Wastes by Incorporation into Water Extended Polyesters

Two water extended polyester (WEP) resins were prepared and used as incorporation media for simulated spent ion exchange resin used at the Inshas Reactor (Egypt). The suitability of the final waste forms to fulfil the re quirements needed for the final disposal has been tested under different ex perimental conditions. Factors affecting the mechanical stability of the end products such as damp ion exchange resin/polymer ratio, styrene content, type and concentration of initiator were investigated. Radiation stability of polymer waste forms incorporating inactive resin was studied. The samples showed a significant increase in compressive strength values with an increase in irradia tion dose, until a maximum is reached at a dose rate of 2.5 x 108 rads. At higher irradiation doses the values decreased, but they were still higher than those of unirradiated ones. The resistance of WEP resins as well as their final waste forms to most chemical environments was excellent. Oxygen index values illustrated the flame retardancy of WEP waste forms. Leaching experi ments on incorporated blocks of active resin labelled with Cs-137 and Co-60 showed that improved leach resistance was obtained by using deionized water as the leaching solution rather than underground water. The leach factors for Cs-137 were always higher than those for Co-60 using either leachants.

Water Composites: Relation Between Percent Water and Emulsifier Concentration to Produce Stable Emulsions

Poly (oxy-diethylene-maleate) was prepared and used with styrene monomer to form stable w/o prepolymers. The emulsion stability of the water-extended polyester, using different water percentages with different emulsifiers, was determined. The most stable emulsions were cured using ben zoyl peroxide as the initiator to produce water composites. The water content and the compressive strength of the cured composities were also studied.

Static multileaf collimator for fast-neutron therapy.

This paper describes a multileaf collimator, designed to obtain irregularly shaped neutron fields, that fits into an existing fixed field-size collimator system. The shape of the desired portal field is obtained by appropriately setting the position of each leaf of the collimator. The collimator consists of 40 polyethylene leaves to produce fields of irregular shape of up to 400 cm2. The leaves are interlaced with grooves to prevent neutron leakage. The measured penumbra defined by the multileaf collimator is similar to that defined by the same length fixed field-size water extended polyester (WEP) collimator. The multileaf collimator has a lower neutron transmission due to its higher hydrogen concentration.

Some Studies on Water-Extended Polyester

Three unsaturated polyester resins were prepared and used with styrene monomer to produce water composites. The emulsion stability of the water- extended polyesters using different concentrations of triethanol amine as an emulsifier was studied. The water content and the mechanical properties of the cured composites were also investigated.

A storage and handling facility for 252Cf medical sources

Physics support for brachytherapy with 252Cf at M.D. Anderson consists of patient dosage calculations, source preparation and inventory, facility design and construction, and radiation safety for physician and nursing personnel. Recently, a shielded facility for storage and handling of up to 300 mu g of 252Cf afterloading cells (for interstitial work) and tubes (for intracavitary work) was designed and constructed for the Department of Radiotherapy. The main shield consists of a centrally located lead pot surrounded by borated water-extended polyester. A built-in, curved personnel barrier with sliding Lucite eye shields enables safe and rapid handling of sources during calibration, inventory, cleaning operations and movement to and from the source storage rods. The design radiation levels for the mixed neutron-gamma field from 252Cf were 3 mrem h-1 at the surface of the shield in the working area, less than 2 mrem h-1 in the corridor and adjacent radiotherapy patient room and less than 0.2 mrem h-1 in the nursing office below. The radiation survey of the completed facility and its environs confirmed the calculations.

Progress report on the development of water-extended polyester composites: Coats, C. E., Perrin, H. E. and Watts, G. F. Reinforced Plastics, Vol 14, No 14, p 412 (October 1970)

Progress report on the development of water-extended polyester composites: Coats, C. E., Perrin, H. E. and Watts, G. F. Reinforced Plastics, Vol 14, No 14, p 412 (October 1970)

Ashland offers water-extended polyester

Ashland offers water-extended polyester