High frequency temperature measurements were recorded at five heights and surface renewal (SR) analysis was used to estimate sensible heat flux density (H) over 0.1 m tall grass. Traces of the temperature data showed ramp-like structures, and the mean amplitude and duration of these ramps were used to calculate H using structure functions. Data were compared with H values measured with a sonic anemometer. Latent heat flux density (XF) was calculated using an energy balance and the results were compared with XE computed from the sonic anemometer data. SR analysis provided good estimates of H for data recorded at all heights but the canopy top and at the highest measurement level, which was above the fully adjusted boundary layer.

The University of California, Davis (UCD), Advanced Canopy‐Atmosphere‐Soil Algorithm (ACASA) is presented and its output is compared with a comprehensive set of observations at six diverse sites. ACASA is a multi‐layer canopy‐surface‐layer model that solves the steady‐slate Reynolds‐averaged fluid flow equations to the third‐order. These equations include an explicit representation of the steady‐state, horizontally homogeneous, diabatic set of vector and scalar fluxes and flux transports. ACASA includes a fourth‐order, near‐exact technique to calculate leaf, stem, and soil surface temperatures and surface energy fluxes at various levels within the canopy. Plan! physiological response to micro‐environmental conditions is also included using Ball‐Berry/von Caemmerer‐Farquhar formulations. Observed energy fluxes and microenvironmental conditions from a grass field in the Netherlands, deciduous and coniferous forests in Canada, tropical pasture and forest in Brazil, and an ancient temperate rainforest in the USA are compared with simulated values. Results indicate that simulated and observed estimates of monthly to annual means of all surface fluxes agree within 95% confidence thresholds for all six sites. Observed and simulated hourly estimates of net radiation are also in excellent agreement for all sites considered. Observed and simulated hourly sensible‐ and latent‐heat flux estimates are in very good statistical agreement in most cases. Differences that exist between ACASA and observed sensible‐and latent‐heat flux estimates are of the same magnitudes as observational uncertainties. Estimates of observed and simulated hourly values of canopy and ground heal storage are within 95% statistical confidence limits of agreement with observations in most cases. Simulated and measured values of daytime intra‐canopy mean wind speed, temperature, and specific humidity agree with 95% confidence within both a tropical and temperate rainforest at all levels. Results also indicate that, in general, ACASA produces flux estimates closer to observations with significantly less scatter than does the Biosphere‐Atmosphere Transfer Scheme. Sensitivity tests show that reducing the vertical resolution, linearizing surface temperature calculations, and/or simplifying the treatment of surface‐layer turbulence each altered mean sensible‐ and latent‐heat flux estimates by amounts that are statistically significant in many cases. Results show that simplifying the model alters flux predictions in manners not simply related to vegetation character, and that using ACASA at its full complexity for all vegetation regimes is warranted. Increasing the vertical resolution beyond 20 layers improved flux predictions at tropical locations but had little impact elsewhere.

(1964) from MIT and the Rasmussen Report (USAEC, 1974). The three first named authors are noted authorities and were members of the nuclear engineering community and not 'antinuclear' advocates.Mills states: "By causing an especially fast rod ejection, the final BORAX I experiment succeeded in violently disassembling the reactor, but the explosion energy was only 135 Mw-sec, or about that of a few pounds of TNT."T. J. Thompson noted that the BORAX I reactor exploded much more quickly and violently than expected so that many records that could have been collected were lost. A one ton plate on the reactor flew 9 meters into the air, and recognizable fuel fragments were blasted as far as 61 meters from the reactor.A quote from J. R. Dietrich demonstrates that reactor design may reduce the chance of explosive runaways, but not eliminate it:"The conceivable effects of reactivity excursion accidents can vary widely from one reactor type to another, if the normal protection circuits on a reactor fail to operate or are ineffectual, a reactivity excursion can result in local to general core damage, and may even release sufficient nuclear energy to produce a low level explosive effect."The Rasmussen Report, which has been widely hailed by the nuclear industry as reliable and accurate even though recently the NRC has stated that some of the probability estimates could have been off, also notes the possibility of explosions associated with reactors: "There are two transient events in a BWR, the rod ejection and rod drop accident, which have the potential for large enough energy releases to rupture the RCS and perhaps the containment (italics ours)."The report concludes that power plant design has made the chance of such an occurrence "negligibly small" but the report does not anywhere, state that such an explosion CANNOT occur. It only says it is unlikely.Fleischer says that nuclear reactors cannot explode because there is no confinement present. We have documented the fact that nuclear explosions are possible even if very unlikely (as noted in the original article) with current models of reactors. However, Fleischer's rejection of the possibility of chemical explosions is even more unacceptable. Does Fleischer believe that the NRC and the nuclear experts at Three Mile Island who expressed great concern over a possible chemical explosion due to a hydrogen bubble were totally ignorant? TMI did not explode and perhaps could not have exploded but the possibility was not rejected on an apriori basis by the many nuclear experts involved.In an OECD report on water-cooled reactor safety J. Oullion (1970, p. 82) stated that, "In the loss-of-coolant accident due to a sudden rupture of the primary circuit, one has to consider two important phenomena: a) Blast effects which may be due to the sudden release of the primary pressurized liquid;0364-152X/80/0004-0189 $01.00

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