IE Circular No. 77-02A February 18, 1977 DESCRIPTION OF CIRCUMSTANCES: The purpose of this circular is to inform you that the National Weather Service has predicted that heavy spring flooding in the area from the Missouri River eastward is likely to occur. Ice covers most of the major river and lake systems in this area and the accumulation of ice and snow in the eastern portion has further increased the flooding potential. In some areas the potential spring flooding may equal or exceed floods of record. The degree of flooding is dependent upon the rate of warming trends, ice breakup rates and the occurrence of spring rains. The two enclosed figures from the National Weather Service indicate the principal frozen rivers and areas of greatest flood potential in the northeast and upper midwest. There will also be the possibility of flooding on the Mississippi River below Cairo, Illinois dependent upon runoff in its tributaries. The enclosed maps do not address the potential of the associated effects of ice impact and blockage or additional precipitation on flood related concerns. ACTION TO BE TAKEN BY LICENSEE: It is recommended at this time that licensees receiving this circular consider the following items in preparation for potential flooding and the associated effects at facilities under construction. Such conditions could affect safety related structures, systems and components as a result of: 1. Safety related items already in-place and not fully protected. 2. Safety related items in site storage including record vaults containing documentation of safety related items. 3. Effects of and interconnection to operating units. At this early date, it is not possible to predict the specific time of occurrence, location, or extent of ,flooding or associated effects. Forecasts regarding flooding or icing can be obtained from the public service forecasters of the U. S. Weather Service Forecast Center in your state. These offices are generally open 24 hours per day. The offices (in the subject area) are advised of river conditions by River Forecast Centers located in Cincinnati, OH: Harrisburg PA: Hartford, CT; and Kansas City, MO. . IE Circular No. 77-02A - 2 - February 18, 1977 This circular is provided for your information and requires no written reply. Approval of NRC requirements for reports concerning possible generic problems has been obtained under 44 U.S.C. 3152 from the U. S. General Accounting Office. (GAO Approval B-180255 (R0072), expires 7/31/77).
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