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ENS 52727
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Category
ENS Notification  and Power Reactor
CFR
10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor +  and 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +
Current power
74  +
Current reactor mode
Power Operation +
Description
On April 30, 2017, at 1818 (EDT), the main … On April 30, 2017, at 1818 (EDT), the main turbine steam bypass valve #1 partially opened. Power was incrementally lowered. While lowering power the bypass valve would shut and then reopen and power would again be lowered. When power was lowered to approximately 74 percent the bypass valve remained closed. During the transient the reactor protection system (RPS) Turbine Stop Valve Closure and Control Valve Fast Closure trip functions were declared inoperable due to the opening of the bypass valve which affects the bypass setpoint for those RPS trip functions. With the loss of these RPS trip functions a loss of safety function existed intermittently for approximately 37 minutes. The manual reactor trip function and other RPS functions remained operable.</br>Both channels of the rod withdrawal limiter (RWL) and the end of cycle reactor recirculation pump trip (EOC-RPT) function were also declared inoperable. These functions are credited in accident analysis, this also resulted in a loss of safety function.</br>Currently the bypass valve is closed and the RWL, EOC-RPT and RPS function are operable. Troubleshooting continues to determine the issue with the main turbine that caused the bypass valve to open.</br>NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
Discovered date
22:18:00, 30 April 2017  +
Emergency class
Non Emergency +
Entered date
12:59:00, 3 May 2017  +
Event date
22:18:00, 30 April 2017  +
Event description
On April 30, 2017, at 1818 (EDT), the main … On April 30, 2017, at 1818 (EDT), the main turbine steam bypass valve #1 partially opened. Power was incrementally lowered. While lowering power the bypass valve would shut and then reopen and power would again be lowered. When power was lowered to approximately 74 percent the bypass valve remained closed. During the transient the reactor protection system (RPS) Turbine Stop Valve Closure and Control Valve Fast Closure trip functions were declared inoperable due to the opening of the bypass valve which affects the bypass setpoint for those RPS trip functions. With the loss of these RPS trip functions a loss of safety function existed intermittently for approximately 37 minutes. The manual reactor trip function and other RPS functions remained operable.</br>Both channels of the rod withdrawal limiter (RWL) and the end of cycle reactor recirculation pump trip (EOC-RPT) function were also declared inoperable. These functions are credited in accident analysis, this also resulted in a loss of safety function.</br>Currently the bypass valve is closed and the RWL, EOC-RPT and RPS function are operable. Troubleshooting continues to determine the issue with the main turbine that caused the bypass valve to open.</br>NRC Resident Inspector has been notified. NRC Resident Inspector has been notified.  +
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ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +, ENS 52727 +  and ENS 52727 +
Initial power
100  +
Initial reactor mode
Power Operation +
LER
05000440/LER-1917-002, Regarding Loss of Safety Function Due to Main Turbine Bypass Valve Opening +  and Regarding Loss of Safety Function Due to Main Turbine Bypass Valve Opening +
Last update date
00:00:00, 3 May 2017  +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
01:42:47, 2 March 2018  +
NRC officer
Steven Vitto +
Notification date
12:59:00, 3 May 2017  +
Originated by
Dave Duesing +
Reactor critical
true  +
Reactor scram
false  +
Reactor type
GE-6 +
Region
NRC Region 3 +
Reporting criterion
10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor +  and 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +
Reporting time
2.612 d (62.68 hours, 0.373 weeks, 0.0859 months)  +
Scram
Manual Scram +
Site
Perry +
Start date
22:18:00, 30 April 2017  +
State
Ohio +
System
Reactor Protection System +, Main Turbine +  and Reactor Recirculation Pump +
Title
Open Bypass Valve Causes Loss of Safety Function  +
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http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2017/20170504en.html#en52727  +
Unit
1  +
 
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