An underground explosion in a cavity is said to be fully decoupled if the cavity is large enough for the explosion to produce only elastic motion in the walls; in a smaller cavity where the wall motion is elastoplastic, the explosion is said to be partially alecoupled. In this report, the pressure histories on the walls of cavities in salt of suitable size for alecoupling sources are calculated and used in computing the motions of the walls, including the effect of elastoplastic behavior of salt. From the motion of the cavity walls, seismic displacement potentials are calculated and compared with the measured close-in displacement potentials for the Salmon event (5 kt) and the Gnome event (3.1 kt) scaled to 5 kt, both tamped (tightly coupled) nuclear detonations in salt. The close-in alecoupling ratios for salt thus obtained are 350 for Gnome data and 200 for Salmon data. The reduced displacement potential based on the Gnome measurement at 298 m and scaled to the 5-kt size of Salmon is found to be 40% above the measured Salmon value at 300 m; the Gnome measurement may have been in the inelastic region or it may have been influenced by stronger horizontal propagation due to bedding planes. Reduced displacement potentials are also calculated for shots of 100 tons, 0.5 kt, and 1 kt, all in a cavity volume for 100-ton alecoupling. They are 0.47, 5.0, and 45 m s, respectively, as compared with 80 m 3 for a 100-ton fully tamped shot.

A radiation hardened by design embedded microprocessor is presented. The design uses multiple approaches to minimize the performance reduction from hardening, while simultaneously limiting the power increase. The speculative portions of the pipeline are protected by microarchitecture approaches, i.e., the speculative pipeline is dual redundant, whereby instructions that have errors in one copy cause a pipeline restart-only matching results commit to architectural state. The register file is dual redundant with mechanisms for correction using one copy whose parity is correct. The data cache memory is write-through, allowing protection with parity. The remaining architectural state is protected via hardened circuits. These are implemented with self-correcting triple mode redundant (TMR) flip-flops and TMR logic. The design, implemented here on a 90-nm bulk CMOS process, achieves unprecedented single event effects hardness and 400+ MHz operating frequency at less than 500 mW power consumption. The main constituent circuit hardening approaches have been fabricated and tested separately. Broad beam testing of the constituent circuits has resulted in no uncorrectable soft errors below 100 MeV-cm 2 /mg LET EFF . We describe the CAD flows used to ensure node separation to achieve high immunity to multiple node charge collection and discuss the relative costs of the chosen hardening techniques.Index Terms-Radiation hardening by design (RHBD); microprocessor; cache memory; total ionizing dose; single event transients, soft error mitigation, single-event effects.

An underground explosion in a cavity is said to be fully decoupled if the cavity is large enough for the explosion to produce only elastic motion in the walls; in a smaller cavity where the wall motion is elastoplastic, the explosion is said to be partially decoupled. In this report, the pressure histories on the walls of cavities in salt of suitable size for decoupling sources are calculated and used in computing the motions of the walls, including the effect of elastoplastic behavior of salt. From the motion of the cavity walls, seismic displacement potentials are calculated and compared with the measured close‐in displacement potentials for the Salmon event (5 kt) and the Gnome event (3.1 kt) scaled to 5 kt, both tamped (tightly coupled) nuclear detonations in salt. The close‐in decoupling ratios for salt thus obtained are 350 for Gnome data and 200 for Salmon data. The reduced displacement potential based on the Gnome measurement at 298 m and scaled to the 5‐kt size of Salmon is found to be 40% above the measured Salmon value at 300 m; the Gnome measurement may have been in the inelastic region or it may have been influenced by stronger horizontal propagation due to bedding planes. Reduced displacement potentials are also calculated for shots of 100 tons, 0.5 kt, and 1 kt, all in a cavity volume for 100‐ton decoupling. They are 0.47, 5.0, and 45 m3, respectively, as compared with 80 m3 for a 100‐ton fully tamped shot.

No abstract

No abstract