-i i- Acknowledgments The author Lawrence is indebted Livermore suite of computer Grateful of Ekookhaven to Rolf Lange, National programs are also due to Nathaniel thanks National affiliation: for their Lawson, and Hoyt Walker of assistance in developing the used in the calculations. Laboratory rate data for the Castl&Bravo *Present 94’7~o. Laboratory Leonard Lawrence for supplying Greenhouse* and Edward me with meteorological Lessard and dose test. Berkeley National Laboratory, Berkeley, California