EXPERIMENTAL STUDIES OF TRANSIENT EFFECTS IN FAST REACTOR FUELS. SERIES III. PRE-IRRADIATED MIXED OXIDE (PuO$sub 2$--UO$sub 2$) IRRADIATIONS. FINAL REPORT. TRANSIENT IRRADIATIONS.

1000-MWe LMFBR ACCIDENT ANALYSIS AND SAFETY SYSTEM DESIGN STUDY. ACCIDENT- INITIATING CONDITIONS. PART 1. FLOW ABNORMALITIES. Topical Report.

“…As mentioned previously, the two shaded areas on the left of Figure A-22 indicate the limiting rate of fuel temperature rise for (1) fuel expansion being a function of the average fuel temperature rise (lower shaded portion), and (2) exponentially with temperature, it seems reasonable to assume that the net fuel growth will be determined in a transient by something less than the average temperature change.…”

“…The following values of the reactivity coefficients were used in the sensitivity studies with delayed scram: ( 1) nominal values, (2) 0.5 nominal Doppler with all other coefficients nominal, and (3) zero axial expansion coefficient with all other coefficients nominal, and (4) 1.5 times the sodium density coefficient with all other coefficiehts nominal. The calculations were performed for pump inertias of 15,000 and 6000 lb-ft 2 with the nonrestructured fuel pin model.…”

“…Although failure of the protection system is deemed incredible, certain accidents arising from failure of the protection system coupled with flow abnormalities will be investigated under Activity 220, Accident Analysis. One may conclude (tentatively in the case of some failure mechanisms) that the causes of failure are: (1) melting and (2) overstressing and excessive deformation of the cladding due to fuel expansion or gas pressure. Of course overstressing and melting could occur simultan- The mechanism of fuel thermal expansion is examined as a possible cause of cladding rupture during abnormal reactor operating conditions.…”

Transient Overpower Irradiation of Axially-Restrained, Zero-Burnup, Fast Reactor Fuel Specimens.

“…10; see figure [3][4][5][6][7][8][9]. An examination of the radial fuel and cladding temperature histories (see figure [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] indicates that the failure occurred relatively early in the development of the molten fuel core and well before attainment of peak fuel temperatures at ^^3.6 seconds. However, the time of failure does coincide with the maximum radial extent of the fuel-melt boundary and the peak cladding temperature.…”

“…It appears from the response of thermocouple No. 9 (figure [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] that failure occurred at 3.1 to 3.2 seconds into the transient. The response of thermocouple No.…”