Station blackout at Browns Ferry Unit One - Oak Ridge National ...

As a portion of their review of the draft of this report, the Elec
trical Engineering Branch at TVA performed a battery capacity calculation
which shows that the unit batteries at the Browns Ferry plant can be ex
pected to provide power for as long as seven hours under station blackout
conditions. Since a battery life of four hours was assumed for the calcu
lations of this work, a new Appendix G has been added in which all of the
possible failure modes other than battery exhaustion that were considered
in Sections 3, 7, and 8 are re-examined for applicability to the period
between four and seven hours after the inception of a Station Blackout.
The magnitude and timing of the release of the fission product noble
gases and various forms of iodine to the atmosphere are discussed in
Volume 2. This includes the development of release rate coefficients for
the escape of these fission products from fuel as a function of tempera
ture, specification of the various chemical forms, determination of the
optimum strategy for the modeling of precursor/daughter exchange, and the
study of the particular auxiliary systems involved to determine the appli
cable fission product release pathways. These results are incorporated
into a vehicle for the calculation of the transport of the individual fis
sion products from the reactor core, through the primary and secondary
containments to the atmosphere, control volume by control volume.
The primary sources of information used in the preparation of this
report were the Browns Ferry Nuclear Plant (BFNP) Final Safety Analysis
Report (FSAR), the Nuclear Regulatory Commission BWR Systems Manual, the
BFNP Hot License Training Program Operator Training Manuals, the BFNP Unit
1 Technical Specifications, the BFNP Emergency Operating Instructions, and
various other specific drawings, documents, and manuals obtained from the
Tennessee Valley Authority*. Additional information was gathered by means
of one visit to the BFNP and several visits to the TVA Power Operations
Training Center at Soddy-Daisy, Tennessee. The excellent cooperation and
assistance of Tennessee Valley Authority personnel in the gathering of in
formation necessary to this study are gratefully acknowledged.
*The setpoints for automatic action used in this study are the
safety limits as given in the FSAR. In many cases these differ slightly
from the actual setpoints used for instrument adjustment at the BFNP be
cause the instrument adjustment setpoints are established so as to provide
margin for known instrument error.