NEUTRON SPECTRAL CONSIDERATIONS AFFECTING PROJECTED ESTIMATES OF RADIATION EMBRITTLEMENT OF THE ARMY SM-1A REACTOR PRESSURE VESSEL.
NAVAL RESEARCH LAB WASHINGTON D C
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The pressure vessel of the Army SM-1A reactor is located close to the active core in such a manner that the neutron exposure is relatively high consequently, the pressure vessel steel undergoes a relatively rapid rise in the ductile-brittle transition temperature. The maximum permissible delta NDT for the SM-1A is established by the Army as 340F. Since it is physically impossible to irradiate surveillance test specimens at the SM-1A vessel wall, only the neutron flux was measured at the wall, and representative test specimens were irradiated in a test reactor, the Low Intensity Test Reactor LITR. In translating the delta NDT versus neutron exposure data from the LITR to the case of the SM-1A reactor vessel wall, the neutron spectra of the two reactors were used to adjust both the SM-1A reactor vessel flux and the LITR exposure values in terms of nsq cm 1.0, 0.5, and 0.183 Mev. Since the distribution of neutrons by energy groups was different within each reactor at the specific location of interest, that is, the vessel wall of the SM-1A and an in-core location of the LITR, the damaging potential of the SM-1A reactor spectrum location was related to that of the LITR. With damage equivalence established between the two reactors, a critical neutron exposure nsq cm 0.5 Mev may be projected for producing the maximum delta NDT on the SM-1A reactor vessel wall. By relating this critical exposure to SM-1A reactor operations, a critical power output level of 67 Mw-yr was established. Author
- Nuclear Fission Reactors (Power)
- Fission Reactor Materials