ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site
ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site
ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site
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3.4 Reactor Materials<br />
Although special, high-quality materials probably would Re used<br />
throughout in <strong>the</strong> construction of a BMSR, most of <strong>the</strong>m Could be obtained<br />
from cowmerical sources that routinely supply such materials using cur-<br />
rently available technology. Two notable exceptions to this generaliza-<br />
tion are <strong>the</strong> Structural alloy that would have to be used for components<br />
normally exposed to molten salt and <strong>the</strong> graphite for <strong>the</strong> reactor core<br />
moderator and reflector. Both of <strong>the</strong>se materials would require specifi-<br />
cations peculiar to <strong>the</strong> MSW system.<br />
3.4.1.1 Requirements<br />
3.4.1 Structural allov<br />
The metallic structural material used in constructing <strong>the</strong> primary<br />
circuit of a molten-salt reactor will sperate at temperatures up to about<br />
700°C. The inside of <strong>the</strong> circuit will be exposed to salt that contains<br />
fission products and will receive a maximum <strong>the</strong>rmal fluence of about 6 X<br />
neutrons/m2 over <strong>the</strong> operating ldfetime of about 30 years. This<br />
fluence will cause some embrittlement because of helium formed by trans-<br />
mutation but will not cause swelling such as is noted at higher fast flu-<br />
ences. The outside of <strong>the</strong> primary circuit will be exposed to nitrogen<br />
that contains sufficient ajir from inleakage to make it oxidizing to <strong>the</strong><br />
metal. Thus, <strong>the</strong> m etal must (1) have moderate oxidation resistance, (2)<br />
resist corrosion by <strong>the</strong> salt, and (3) resist severe embrittlement by<br />
<strong>the</strong>rmal neutrons.<br />
In <strong>the</strong> secondary circuit, <strong>the</strong> metal will be exposed to <strong>the</strong> coolant<br />
salt under much <strong>the</strong> same conditions described for <strong>the</strong> primary circuit.<br />
The main differences will be <strong>the</strong> lack of fission products and uranium in<br />
<strong>the</strong> coolant salt and much lower neutron fluences. This material must have<br />
moderate oxidation resistance and must resist corrosion by a salt not eon-<br />
taining fission products or uranium.<br />
The primary and secondary circuits involve numerous structural shapes<br />
ranging from several centimeters thick to tubing having wall thicknesses<br />
of only a millimeter or so. These shapes must be fabricated and joined