Soft Error Research*

The Pennsylvania State University

Accelerated Testing

A picture of the reactor core is shown in Figure 1. A variety of dry tubes and fixtures are available in or near the core. A pneumatic transfer system is also available for irradiation of samples. When the reactor core is placed next to a D₂O tank and the graphite reflector assembly near the beam port locations, thermal neutron beams become available from two of the seven existing beam ports. In steady state operation at 1 MW, the thermal neutron flux is 1x10¹³ n/cm²s at the edge of the core and 3x10¹³ n/cm²s at the central thimble. The PSBR can also pulse with the peak flux for maximum pulse ~ 6x10¹⁶ n/cm²sec with a pulse half width of ~10 msec. The maximum rated power of the reactor is 1 MW in the continuous mode and can be increased to 2000 MW in the pulse mode. The reactor power can also be stepped from 10 W to 1 MW to observe the soft error rate dependence on neutron flux.

 

 

 

 

 

 

 

                                                   

 

 

                                                                                          

 

 

 

 

 

 

 

 

 

 

 

 

 

                                          

 

 

Website maintained by

 

Ramakrishnan Krishnan

Figure 1. Reactor Core

 

 

 

 

 

 

                                                   

 

 

                                                                                          

 

 

 

 

 

 

 

 

 

 

 

 

 

                                          

 

 

 

Facilities

 

           The Radiation Science and Engineering Center (RSEC) at The Pennsylvania State University will serve as our test facility. It includes the Penn State Breazeale Reactor (PSBR), gamma irradiation facilities (In-pool Irradiator, Dry Irradiator and Hot Cells) and various radiation detection and measurement laboratories. The PSBR, which first went critical in 1955, is the nation's longest continuously operating university research reactor. The PSBR is a 1 MW, TRIGA (Training, Research, Isotopes, General Atomics) nuclear reactor with moveable core in a large pool and with pulsing capabilities. The core is located in a 24 ft deep pool with ~71,000 gallons of demineralized water.

 

 

 

 

 

 

 

                                                   

 

 

                                                                                          

 

 

 

 

 

 

 

 

 

 

 

 

 

                                          

 

 

TEST SETUP

 

The facilities available at RSEC namely the ability to operate at multiple power levels, pulse the reactor to get an extremely high power range and isolate the thermal and fast neutron flux, will help us characterize the soft error rate effectively. The fast neutron spectrum is currently being calibrated. The upper energy limit of fast neutron flux from the reactor is less than the atmosphere neutrons spectrum, but it corresponds to the dominant portion of the atmosphere neutron flux.

Two different set of experiments are envisioned. One set of experiments will be performed using the neutron flux obtained at the beam ports after the heavy water tanks. This neutron beam has thermal neutrons as the dominant portion of the flux. Currently, we are testing commercially available SRAM chips at this port. The other set of experiments will be performed using the large flux of fast neutrons available at the reactor core. Picture on the right shows the test setup and the reactor core.

 

 

 

 

 

 

                                                   

 

 

                                                                                          

 

 

 

 

 

 

 

 

 

 

 

 

 

                                          

 

 

Figure 2. Test Setup

The results are given in the Results section.

 

* This work is supported in part by NSF Award # 0454123