DESCRIPTION
This issue was identified in a 1980 AEOD memorandum[1]and concerned the slow loss of control air pressure in the pneumatic control system of BWR scram systems. Air pressure loss at certain low rates can allow a sufficient discharge of water from the scram outlet valves to fill or almost fill the scram discharge header before a scram can be initiated and the rods inserted either by manual or automatic scram initiation. A full or almost full header would prevent scram of the control rods.
CONCLUSION
The safety concern of this issue was addressed in Issue 25, "Automatic Header Dump on BWR Scram System," which was resolved with requirements. Therefore, consideration of the impact of a license renewal period of 20
years was not necessary.[2]
[1] Memorandum for H. Denton from C. Michelson, "Potential for Unacceptable Interaction between the Control Rod Drive System and Non-Essential Control Air System at the Browns Ferry Nuclear Plant," August 18, 1980. [8210120129]
[2] Memorandum for W. Russell from E. Beckjord, "License Renewal Implications of Generic Safety Issues (GSIs) Prioritized and/or Resolved Between October 1990 and March 1994," May 5, 1994. [9406170365]