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Title: Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques

Abstract

The liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC) use expanded perlite as thermal insulation. Some of the perlite may have compacted over time, compromising the thermal performance and also the structural integrity of the tanks. Neutrons can readily penetrate through the 1.75 cm outer steel shell and through the entire 120 cm thick perlite zone. Neutrons interactions with materials produce characteristic gamma rays which are then detected. In compacted perlite the count rates in the individual peaks in the gamma ray spectrum will increase. Portable neutron generators can produce neutron simultaneous fluxes in two energy ranges: fast (14 MeV) and thermal (25 meV). Fast neutrons produce gamma rays by inelastic scattering which is sensitive to Si, Al, Fe and O. Thermal neutrons produce gamma rays by radiative capture in prompt gamma neutron activation (PGNA), which is sensitive to Si, Al, Na, K and H among others. The results of computer simulations using the software MCNP and measurements on a test article suggest that the most promising approach would be to operate the system in time-of-flight mode by pulsing the neutron generator and observing the subsequent die away curve in the PGNA signal.

Authors:
 [1];  [2];  [3];  [4]
  1. Materials Science and Engineering Dept., U. of Maryland, College Park, MD (United States)
  2. Physics Dept., U. of Connecticut, Storrs (United States)
  3. Goddard Space Flight Center, Greenbelt (United States)
  4. John F. Kennedy Space Center, FL (United States)
Publication Date:
OSTI Identifier:
22263775
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1581; Journal Issue: 1; Conference: 40. annual review of progress in quantitative nondestructive evaluation, Baltimore, MD (United States), 21-26 Jul 2013, 10. international conference on Barkhausen noise and micromagnetic testing, Baltimore, MD (United States), 21-26 Jul 2013; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPUTER CODES; COMPUTERIZED SIMULATION; FAST NEUTRONS; FEASIBILITY STUDIES; GAMMA RADIATION; GAMMA SPECTRA; HYDROGEN; INELASTIC SCATTERING; INTERACTIONS; NEUTRON GENERATORS; PERLITE; PULSES; SIGNALS; THERMAL INSULATION; THERMAL NEUTRONS; TIME-OF-FLIGHT METHOD

Citation Formats

Livingston, R. A., Schweitzer, J. S., Parsons, A. M., and Arens, E. E. Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques. United States: N. p., 2014. Web. doi:10.1063/1.4865046.
Livingston, R. A., Schweitzer, J. S., Parsons, A. M., & Arens, E. E. Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques. United States. doi:10.1063/1.4865046.
Livingston, R. A., Schweitzer, J. S., Parsons, A. M., and Arens, E. E. Tue . "Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques". United States. doi:10.1063/1.4865046.
@article{osti_22263775,
title = {Feasibility study for measurement of insulation compaction in the cryogenic rocket fuel storage tanks at Kennedy Space Center by fast/thermal neutron techniques},
author = {Livingston, R. A. and Schweitzer, J. S. and Parsons, A. M. and Arens, E. E.},
abstractNote = {The liquid hydrogen and oxygen cryogenic storage tanks at John F. Kennedy Space Center (KSC) use expanded perlite as thermal insulation. Some of the perlite may have compacted over time, compromising the thermal performance and also the structural integrity of the tanks. Neutrons can readily penetrate through the 1.75 cm outer steel shell and through the entire 120 cm thick perlite zone. Neutrons interactions with materials produce characteristic gamma rays which are then detected. In compacted perlite the count rates in the individual peaks in the gamma ray spectrum will increase. Portable neutron generators can produce neutron simultaneous fluxes in two energy ranges: fast (14 MeV) and thermal (25 meV). Fast neutrons produce gamma rays by inelastic scattering which is sensitive to Si, Al, Fe and O. Thermal neutrons produce gamma rays by radiative capture in prompt gamma neutron activation (PGNA), which is sensitive to Si, Al, Na, K and H among others. The results of computer simulations using the software MCNP and measurements on a test article suggest that the most promising approach would be to operate the system in time-of-flight mode by pulsing the neutron generator and observing the subsequent die away curve in the PGNA signal.},
doi = {10.1063/1.4865046},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1581,
place = {United States},
year = {Tue Feb 18 00:00:00 EST 2014},
month = {Tue Feb 18 00:00:00 EST 2014}
}
  • In double-wall LNG storage tanks, the dynamic load on the wall of the outer tank upon sudden failure of the inner tank can be considerably higher than hydrostatic pressure. However, a simplified analytical model has shown that insulation and gas containment in the annular space between the two tanks will dampen this load. Factors influencing this dampening effect are the dimensions of the insulation space, perlite stiffness, and fiberglass elasticity.
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