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On January 11, 2015, at 0024, Unit 2 recei … On January 11, 2015, at 0024, Unit 2 received a plant computer monitoring system (RJ) alarm on point SASB22, indicating the setpoint for the bistable relay that compares pressures between Steam Generators (SGs) was approaching the technical (RK) and went unnoticed until late in the shift. Operators then verified the annunciator for SG differential pressure (DP) was not alarming and SG pressures were normal. The significance of the RJ alarm was not apparent because the value was displayed in units of voltage versus DP.</br></br>On January 24, 2015, further questioning determined the setpoint for the bistable that monitors differential pressure between SGs had exceeded its allowable value. Channel B SG Pressure Difference-High was declared inoperable and SG Level 2-Low was placed in bypass per LCO 3.3.5, Condition A.</br></br>The direct cause of the event was setpoint drift of the SASB22 bistable relay caused by potentiometers that had not recently been wiped clean. The root cause was the lack of an annunciated alarm for SASB22 and associated alarm response procedure to ensure the alarm condition was promptly acknowledged, understood, and correctly addressed within TS time limitations.</br></br>No previous similar events have been reported to the NRC by PVNGS in the prior three years.the NRC by PVNGS in the prior three years. +
January 11, 2015 +
On January 11, 2015, at 0024, Unit 2 recei … On January 11, 2015, at 0024, Unit 2 received a plant computer monitoring system (RJ) alarm on point SASB22, indicating the setpoint for the bistable relay that compares pressures between Steam Generators (SGs) was approaching the technical (RK) and went unnoticed until late in the shift. Operators then verified the annunciator for SG differential pressure (DP) was not alarming and SG pressures were normal. The significance of the RJ alarm was not apparent because the value was displayed in units of voltage versus DP.</br></br>On January 24, 2015, further questioning determined the setpoint for the bistable that monitors differential pressure between SGs had exceeded its allowable value. Channel B SG Pressure Difference-High was declared inoperable and SG Level 2-Low was placed in bypass per LCO 3.3.5, Condition A.</br></br>The direct cause of the event was setpoint drift of the SASB22 bistable relay caused by potentiometers that had not recently been wiped clean. The root cause was the lack of an annunciated alarm for SASB22 and associated alarm response procedure to ensure the alarm condition was promptly acknowledged, understood, and correctly addressed within TS time limitations.</br></br>No previous similar events have been reported to the NRC by PVNGS in the prior three years.the NRC by PVNGS in the prior three years. +
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05000529/LER-2015-001, Condition Prohibited by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5, Engineered Safety Features Actuation System (ESFAS) +, 05000529/LER-2015-001, Condition Prohibited by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5, Engineered Safety Features Actuation System (ESFAS) +, 05000529/LER-2015-001, Condition Prohibited by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5, Engineered Safety Features Actuation System (ESFAS) + and 05000529/LER-2015-001, Condition Prohibited by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5, Engineered Safety Features Actuation System (ESFAS) +
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16:49:04, 19 March 2017 +
March 25, 2015 +
January 11, 2015 +
Condition Prohibited by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.3.5, Engineered Safety Features Actuation System (ESFAS) +
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