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Resolution of Generic Safety Issues: Issue 33: Correcting Atmospheric Dump Valve Opening upon Loss of Integrated Control System Power ( NUREG-0933, Main Report with Supplements 1–35 )

DESCRIPTION

This issue was identified in an AEOD memorandum106 to NRR in May 1980. The concern is related to a feature on some B&W reactors in which the failure of the Non-Nuclear Instrumentation and Integrated Control System (NNI/ICS) power supply results in automatic opening of the steam generator atmospheric dump valve to the fifty percent open position. Therefore, on the loss of NNI/ICS power, an overcooling transient could ensue.

CONCLUSION

This issue is covered in Task Item 2 of USI A-47, "Safety Implications of Control Systems."

REFERENCES

0106.Memorandum for H. Denton from C. Michelson, "Lessons Learned from the Crystal River Transient of February 26, 1980—Correcting Atmospheric Dump Valve Opening upon Loss of Integrated Control System Power," May 23, 1980. [8009150079]