Serial/Series Title

4 Matching Results

Results open in a new window/tab.

Spatial distribution measurements of fission neutrons in water as an oxygen data test (open access)

Spatial distribution measurements of fission neutrons in water as an oxygen data test

The spatial distribution of the total neutron density from a /sup 252/Cf source in pure water was measured to high statistical precision at distances from 11 to 80 cm from the source. Assuming the adequacy of the ENDF/B-IV hydrogen, and reasonable constraints on the fission spectrum mean energy, good agreement between experiment and a one-dimensional transport calculation was obtained for both ENDF/B-III and IV oxygen, with Version III slightly better. However, small residual differences remained that could not be removed by adjustment of the spectrum mean energy alone.
Date: February 1978
Creator: Green, L. & Ullo, J.J.
System: The UNT Digital Library
In-pile temperature dependence of the yield strength and growth of Zircaloy (open access)

In-pile temperature dependence of the yield strength and growth of Zircaloy

A previously reported growth model is modified and low temperature growth predictions in Zircaloy are made to support the proposal that the smaller irradiation damage observed at lower temperature results from the damage sites, or depleted zones, being larger at lower temperatures. This proposal holds that the vacancies making up the zones cannot migrate at the lower temperature and, therefore, cannot condense into small voids or dislocation loops. The larger zones serve as better sinks for interstitials because they have a larger capture radius and, since they contain the same number of vacancies as the smaller, higher temperature zones, they heal faster resulting in less total damage. The resulting theoretical predictions are compared with experimental data and found to be in good agreement.
Date: March 1978
Creator: Dollins, C. C.
System: The UNT Digital Library
Irradiation testing of internally pressurized and/or graphite coated Zircaloy-4 clad fuel rods in the NRX Reactor (AWBA Development Program). [LWBR] (open access)

Irradiation testing of internally pressurized and/or graphite coated Zircaloy-4 clad fuel rods in the NRX Reactor (AWBA Development Program). [LWBR]

Irradiation tests on 0.612 inch O.D. by 117-inch long Zircaloy-4 clad fuel rods were performed to assess the effects on fuel rod performance of (1) internal helium pre-pressurization to 500 psi as fabricated, (2) the presence of a graphite barrier coating on the inside cladding surface, and (3) combined pre-pressurization and graphite coating. Periodic dimensional examinations were performed on the test rods, and the results were compared with data obtained from two previously irradiated test rods--both unpressurized and uncoated and one intentionally defected. These comparisons indicate that both pre-pressurization and graphite coating can substantially improve fuel element performance capability.
Date: November 1, 1978
Creator: Hoffman, R.C. & Sherman, J.
System: The UNT Digital Library
Model to predict swelling, gas release, and densification in oxide fuels (open access)

Model to predict swelling, gas release, and densification in oxide fuels

A model was developed to predict in-pile fission gas swelling, gas release, and densification in oxide fuels. This model considers fission gas behavior at the grain interior, on the grain boundaries, and at grain boundary edges under conditions of total gas bubble destruction by fission fragments and partial gas bubble destruction. When gas bubble swelling on grain edges reaches 5 percent, it is assumed that gas tunnels form along the edges. Gas release takes place by migration of the gas in the grains and on the grain boundaries to the edge tunnels. Intergranular and intragranular densifications are considered. Densification takes place by vacancy boil-off due to thermal excitation and vacancy knockout by the passage of fission fragments through the pores. The migration rates of both vacancies and interstitials to pores are also calculated. Comparisons are made between the model and experimental data for swelling, gas release, and densification and found to be in reasonable agreement in most cases.
Date: June 1, 1978
Creator: Dollins, C. C.
System: The UNT Digital Library