United States Nuclear Regulatory Commission - Protecting People and the Environment

IE Circular No. 77-02a, Potential Heavy Spring Flooding

IE Circular No. 77-02A                               February 18, 1977


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.  


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

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).

Page Last Reviewed/Updated Tuesday, September 01, 2015