UHI Ultra Risk, October 3, 1984: EPRI and Duke Followup

This is my fifth consecutive entry that documents the actions and turmoil that were in response to my NSAC memorandum, UHI Ultra High Risk, October 3, 1984.

Sugnet was a trusted expert in PRA studies and Breen assigned him to discuss UHI with Duke Power Company who operated several plants having UHI.  Here is Sugnet's brief memo following his discussions with Duke.  Click on it for enlargement.

It is interesting Sugnet described his contact as an "... informal discussion ... ."
Sugnet does not say that Leyse regarded UHI as Ultra High Risk.  Sugnet focuses on the assertion that UHI was essentially eliminated from the Duke PRA for McGuire. He concludes that, "We can probably obtain more detailed information from Duke Power if it becomes necessary."

NSAC management was satisfied with the Sugnet document.  Now, I believe that Sugnet's discussion with Duke generated some interest in Duke in looking further into the operational aspects of UHI at McGuire as well as its other UHI units.  I infer this because on October 31, 1984, (six days following the Sugnet memo) McGuire Unit 1 was shut down in order to correct a condition of excessive dissolved nitrogen in the UHI accumulator water.  Excessive dissolved nitrogen was also found in the UHI accumulator water at McGuire Unit 2, and the UHI system was isolated from the primary system and the operating power was reduced to 45 percent of the rated power in order to compensate for the loss of UHI capability.  At Unit 1, it was found that all four UHI level transmitters were improperly installed (apparently about 6 months earlier) and that UHI valves would fail to isolate on low level!


Following are three pages that document the above.  The third page is the Duke PNO, November 2, 1984, that reports the problems with UHI.