Feasibility of using neutron radiography to inspect the Space Shuttle solid rocket booster aft skirt, forward skirt and frustum. Part 1: Summary report

The space shuttle's solid rocket boosters (SRB) include components made primarily of aluminum that are parachuted back for retrieval from the ocean and refurbished for repeated usage. Nondestructive inspection methods used on these aging parts to reduce the risk of unforeseen problems include x-ray, ultrasonics, and eddy current. Neutron radiography tests on segments of an SRB component show that entrapped moisture and naturally occurring aluminum corrosion can be revealed by neutron radiography even if present in only small amounts. Voids in sealant can also be evaluated. Three alternatives are suggested to follow-up this study: (1) take an SRB component to an existing neutron radiography system; (2) take an existing mobile neutron radiography system to the NASA site; or (3) plan a dedicated system custom designed for NASA applications

Neutron Radioscopic Measurement of Water Adsorption Coefficients in Aerogels

Abstract. In this work, neutron radioscopy was utilized to investigate water vapor uptake by a hydrophilic silica aerogel. Aerogel is an unusual porous material, produced by a sol-gel process that results in a solid material with a unique microstructure composed of nanometer-size particles and pores. Aerogels have an extraordinarily large internal surface area which is accessible via open pores, making them candidates for filters and gas adsorption media. The water vapor deposition was modeled both analytically and computationally, and an estimate for adsorption coefficients for water vapor in aerogel yielded 1.08 × 10 −3 ± 2.58 × 10 −4 cm 2 /s. Initial tests to measure water vapor uptake from moist air were very successful. Dry air was bubbled through water and then flowed past an aerogel. The aerogel was shown to uptake the water vapor readily from moist air. After uptake, the aerogel dried out rapidly in dry air. This phenomenon was repeatable, indicating that the aerogel could be reused with little change in its sorption properties. Neutron radiography was shown to be an effective nondestructive method for evaluating the realtime movement of water vapor in aerogel, as deposition patterns can be analyzed quantitatively as a function of time and penetration distance into the aerogel

FUELCELL2005-74051 THE NATURE OF FLOODING AND DRYING IN POLYMER ELECTROLYTE FUEL CELLS

ABSTRACT Two different 50 cm 2 fuel cells operated at high current density (1.3A/cm 2 -1.5A/cm 2 ) were visualized using neutron imaging, and the liquid water content in the flow channels and diffusion media under the lands and channels was calculated and compared. At high current density with fully humidified inlet flow, a direct comparison between flooded and nonflooded conditions was achieved by increasing the fuel cell temperature over a small range, until voltage loss from flooding was alleviated. Results indicate that a surprisingly small mass of liquid water is responsible for a significant voltage loss. The deleterious effects of flooding are therefore more easily explained with a locally segregated flooded pore model, rather than a homogeneously flooded pore and blockage phenomenon. Anode dryout was similarly observed and quantified, and results indicate that an exceedingly small mass of water is responsible for significant voltage loss, which is consistent with expectations. The results presented help to form a more complete vision of the flooding loss and anode dryout phenomena in PEFCs