ENS 49047
ENS Event | |
|---|---|
08:39 May 17, 2013 | |
| Title | Unanalyzed Condition for Reactor Coolant System Temperature Below Required Value |
| Event Description | On May 17, 2013 at 0439 EDT, with the unit in Mode 3, operators identified RCS temperature decreased below 551 deg. F with the reactor trip breakers closed. The condition existed for approximately one hour after which operators identified this was below the procedurally required value identified to support power range nuclear instrumentation trip operability. The condition was then immediately corrected.
The plant remains stable in Mode 3. This condition is reportable pursuant to 10 CFR 50.72(b)(3)(ii)(B) for an unanalyzed condition. The NRC Senior Resident Inspector has been notified. The reactor trip breakers were closed to support rod testing at the time this event occurred. RCS temperature was decreasing due to Terry turbine testing which was being performed at the same time. The reactor trip breakers were opened when the operators identified RCS temperature below 551 degrees. The RCS temperature was returned to above 551 degrees. This temperature limit is specified in Millstone 3 FSAR section 15.4.1, "Uncontrolled rod cluster control assembly bank withdrawal from a subcritical or low power startup condition". The licensee notified state and local authorities.
The purpose of this call is to retract the report made on May 17, 2013, Event Number 49047. Upon further review, the condition in which Reactor Coolant System (RCS) temperature decreased below a procedural limit while in Mode 3 did not result in an unanalyzed condition. Engineers verified that RCS boron concentration was sufficiently high that criticality could not have occurred during any inadvertent control rod withdrawal. The details of the engineering review have been provided to the NRC Senior Resident Inspector. Notified R1DO (Gray). |
| Where | |
|---|---|
Millstone  Connecticut (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
| Time - Person (Reporting Time:+3.43 h0.143 days <br />0.0204 weeks <br />0.0047 months <br />) | |
| Opened: | Gerald Baker 12:05 May 17, 2013 |
| NRC Officer: | Howie Crouch |
| Last Updated: | May 23, 2013 |
| 49047 - NRC Website | |
Unit 3 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 566102023-07-06T16:32:0006 July 2023 16:32:00
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