Results of the PBF/LOFT Lead Rod Test Series

The PBF/LOFT Lead Rod (PBF/LLR) Test Series consisted of four sequential, nuclear blowdown experiments (Test LLR-3, LLR-5, LLR-4, and LLR-4A). The primary objective of the test series was to evaluate the extent of mechanical deformation that would be expected to occur to low pressure (0.1 MPa) light water reactor design fuel rods subjected to a series of nuclear blowdown tests, and to determine if subjecting deformed fuel rods to subsequent testing would result in rod failure. The extent of mechanical deformation (buckling, collapse, or waisting of the cladding) was evaluated by comparison of cladding temperatue versus system pressure response with out-of-pile experimental data and by posttest visual examinations and cladding diametral measurements

Examination of H8 and B8 leadscrews from Three Mile Island Unit 2 (TMI-2)

Visual examinations, preliminary temperature estimates, and chemical and radiological analyses were conducted on samples removed from the control rod drive leadscrews. Hardness measurements and microstructure analysis suggest that significant temperature differences existed between the portions of the leadscrews closest to the bottom and top of the plenum assembly. Preliminary analysis indicates that the temperatures ranged from 666 to 1255/sup 0/K (740 to 1800/sup 0/F) for H8 and 723 to 1033/sup 0/K (842 to 1400/sup 0/F) for B8. The uncertainty in the temperature estimates is about +-28 to 56/sup 0/K (+-50 to 100/sup 0/F). Chemical analyses indicate that UO/sub 2/ and zirconium were deposited to a greater extent on surfaces closer to the core. Radiological analyses suggest that a number of the H8 radionuclides are insoluble in strong acid solutions. In contrast, more of the B8 radionuclides are soluble in strong acidic solutions. Also, an axial gradient in surface radionuclide concentrations was observed, with the highest concentration near the top of the plenum assembly. The data indicate changes in chemical composition and gradients in the surface radionuclide concentrations in the plenum assembly. As extrapolated from leadscrew data, the fractions of total core inventory of radionuclides retained on the plenum assembly surfaces are small (<2%)

Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation