NEUTRON SPECTRAL CONSIDERATIONS AFFECTING PROJECTED ESTIMATES OF RADIATION EMBRITTLEMENT OF THE ARMY SM-1A REACTOR PRESSURE VESSEL.
Abstract
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 n/sq 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 (n/sq 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)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1966
- Accession Number
- AD0641283
Entities
People
- C. Z. Serpan Jr.
- Lendell E. Steele
Organizations
- United States Naval Research Laboratory