Proposed Flexibility to USA Nuclear Waste Management Strategy

USA nuclear waste management program has stalled due to its continued insistence upon using Yucca Mountain for its disposal of DOE （Department of Energy） and commercial power plants NSF （nuclear spent fuel）. Increased flexibility and significant changes in DOE program are proposed. They include a private waste company to manage it; the construction and operation of ICS （interim centralized storage） facilities for NSF; the search for an AGR （alternate geological repository）; the use of a different methodology involving key local and state participants; a new ＂as safe as practical＂ strategy with defined benefits to the involved locations and states. Assured removal of NSF from ICS and providing limited Price Anderson indemnity for the program will enhance its acceptance. Minimum politics, regular information meetings, compromises, good cost projections and meeting schedules will be necessary to increase the chances of the proposed nuclear waste management program.

Numerical Simulation of TWo Different Flexible Bodies Immersed in Moving Flow

The coupled motion of two flexible bodies with different lengths immersed in moving fluid is studied numerically. The flapping frequency, flapping amplitude and average drag coefficient of each body are calculated and the influences of the arranging manner and separation distance are analyzed. In our simulation, when placed in the flow individually, the flexible body with a longer length will flap in period and the shorter one will maintain still straightly in the flow direction. The numerical results show that, two different flexible structures near placed in moving flow would strongly interact. When they are placed side by side, the existence of the stable shorter flexible body will restrain the flapping of the longer one while the existence of the longer flexible body may also induce the shorter one to flap synchronously. When placed in tandem with the shorter flexible body in upstream, the flapping of the longer one in downstream will be obviously enhanced. In the situation for the longer flexible body placed in upstream of the shorter one, the coupled flapping amplitude and average drag coefficients increase and decrease periodically with increasing the arranging space, and peak values appear as a result of the mediate of the tail wakes.

Thermal properties of polyurethane elastomer with different flexible molecular chain based on para-phenylene diisocyanate

This work focuses on the relationship between flexibility of molecular chains and thermal properties of polyurethane elastomer（PUE）, which laid the foundation of further research about how to improve thermal properties of PUE. A series of PUE samples with different flexibility of molecular chains was prepared by using 1,4-butanediol（1,4-BDO）/bisphenol-a（BPA） blends with different mole ratios including9/1, 8/2, 7/3, 6/4 and 5/5. As comparison, PUE extended with pure 1,4-BDO and BPA was also synthesized.These samples were characterized by differential scanning calorimetry（DSC）, thermogravimetric analysis（TGA）, dynamic mechanical analysis（DMA）, etc. The results showed that with the decrease in flexibility of molecular chains the glass transition temperature（Tg） increased and low-temperature properties became worse. Besides, all samples had a certain degree of microphase separation, and soft segments in some samples were crystallized, i.e. the decreasing flexibility of molecular chains led to the impossibility of chains tightly packing and crystalline domains forming so that the degree of microphase separation decreased and the thermal properties became worse.