HELIUM INLEAKAGE THROUGH POROUS-WALLED FUEL ELEMENTS

Technical Report · Tue Nov 21 04:00:00 EST 1961

DOI:https://doi.org/10.2172/4703136· OSTI ID:4703136

Turner, R F

Theoretical and experimental studies indicated that the effective permeability coefficient for graphite is lowered by a helium stream in-sweeping through the graphite pores. This phenomenon was considered in the design of HTGR fuel elements. A portion of the helium gas which is drawn into each fuel element as a purge stream may enter through porous wall sections, supplementing the purge gas entering at the top of each fuel element. The purge stream leaves each fuel element through a header system which carries the purge gas to an external fission product trap. The flow rate through the trapping system determines the upper limit of the average in-leakage through the fuel element walls. In the case of the HTGR, a graphite having a helium permeability of 1.1 cm/sup 2//sec at 350 psia and 700 deg F (approximately 0.1 cm/sup 2//sec at 14.7 psia, 70 deg F) would result in 100% of the purge flow entering through the wall sections of the fuel element. A lower permeability graphite, with most of the purge flow entering at the top of the fuel element appeared to be more desirable for maintaining optimum purge flow conditions. (auth)

• Research Organization: General Atomic Div. General Dynamics Corp., San Diego, Calif.
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-011189
• OSTI ID: 4703136
• Report Number(s): GAMD-2638
• Country of Publication: United States
• Language: English

Related Subjects

CLEANING
FISSION PRODUCTS
FUEL ELEMENTS
GAS FLOW
GRAPHITE
HELIUM
HTGR
LEAKS
METALS, CERAMICS, AND OTHER MATERIALS
PLANNING
POROSITY
QUANTITATIVE ANALYSIS
TEMPERATURE
TRAPS