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Critical heat flux (CHF) experiments were performed in the Steam Generator Test Facility (SGTF) at Argonne National Laboratory for application to liquid metal fast breeder reactor steam generators. The test section consisted of a single, straight, vertical, full-scale LMFBR steam generator tube with force-circulated water boiling upwards inside the tube heated by sodium flowing countercurrent in a surrounding annulus. The test section tube parameters were as follows: 10.1 mm i.d., 15.9 mm o.d., material = 2 1/4 Cr–1 Mo steel, and 13.1 m heated length. Experiments were performed in the water pressure range of 7.0 to 15.3 MPa and the water mass flux range of 720 to 3200 kg/m2˙s. The data exhibited two trends: heat flux independent and heat flux dependent. Empirical correlation equations were developed from over 400 CHF tests performed in the SGTF. The data and correlation equations were compared to the results of other CHF investigations.

A simple method for determining the lower limit of detection (LLD) for personnel dosimetry systems is described. The method relies on the definition of a critical level and a detection level. The critical level is the signal level above which a result has a small probability of being due to a fluctuation of the background. All results below the critical level should not be reported as an indication of a positive result. The detection level is the net signal level (i.e., dose received) above which there is a high confidence that a true reading will be detected and reported as a qualitatively positive result. The detection level may be identified as the LLD. A simple formula is derived to allow the calculation of the LLD under various conditions. This type of formula is being used by the Department of Energy Laboratory Accreditation Program (DOELAP) for personnel dosimetry. Participants in either the National Voluntary Laboratory Accreditation Program (NVLAP) for personnel dosimetry or DOELAP can use performance test results along with a measurement of background levels to estimate the LLDs for their dosimetry system. As long as they maintain their dosimetry system such that the LLDs are less than half the lower limit of the NVLAP or DOELAP test exposure ranges, dosimetry laboratories can avoid testing failures due to poor performance at very low exposures.

Thermal fluctuations were measured in the tube wall in the transition boiling zone of a full-scale LMFBR sodium-heated steam generator tube. The tube had an inside diameter = 10 mm, wall thickness = 2.90 mm, heated length = 13.1 m, and material = 2 1/4 Cr-1 Mo steel. Water flowed vertically upwards inside the straight tube, and sodium flowed counter-currently in a surrounding annulus. Results of thermal, spectral, and thermal stress analyses are presented for a test within the normal operating range of LMFBR steam generators. Results of other tests are presented that show the effects and sensitivity of sodium temperature and water pressure on the severity of the thermal fluctuations.

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