ML15355A390
| ML15355A390 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/21/2015 |
| From: | Anne Defrancisco Reactor Projects Branch 2 |
| To: | Atalla D - No Known Affiliation |
| DeFrancisco A | |
| References | |
| Download: ML15355A390 (1) | |
Text
ML15355A390 From:DeFrancisco,Anne Sent:Monday,December21,201511:36AM To:'DrausioAtalla'
Subject:
ResponsetoQuestionsonIndianPointRodDrop
Drausio Lima Atalla, We received your message regarding the rod drop occurrence at Indian Point Unit 2 on December 5, 2015.
The automatic trips for Unit 2 do not, and did not previously, include a negative flux rate trip (although, as you mention, this was a feature at other plants in the past). Rather, in accordance with the units design basis, a rod drop signal initiates a reduction in turbine load. However, bypass switches have been installed so as to bypass the runback and the bypasses are permanently in defeat. The Westinghouse Owners Group performed a rod drop analysis that supported safely eliminating the turbine runback (or the negative flux rate trip for applicable sites).
Therefore, an anticipated transient without scram did not occur at Indian Point Unit 2 on December 5, 2015. In this instance, operators appropriately initiated a manual trip in accordance with procedures upon observing conditions representative of multiple dropped rods.
Thank you for your interest in nuclear safety and let me know if you have any additional questions.
AnneDeFrancisco ActingSeniorProjectEngineer,ProjectsBranch2 DivisionofReactorProjects,NRCRegionI 6103375078 Anne.defrancisco@nrc.gov
ML15355A390 From:DeFrancisco,Anne Sent:Monday,December21,201511:36AM To:'DrausioAtalla'
Subject:
ResponsetoQuestionsonIndianPointRodDrop
Drausio Lima Atalla, We received your message regarding the rod drop occurrence at Indian Point Unit 2 on December 5, 2015.
The automatic trips for Unit 2 do not, and did not previously, include a negative flux rate trip (although, as you mention, this was a feature at other plants in the past). Rather, in accordance with the units design basis, a rod drop signal initiates a reduction in turbine load. However, bypass switches have been installed so as to bypass the runback and the bypasses are permanently in defeat. The Westinghouse Owners Group performed a rod drop analysis that supported safely eliminating the turbine runback (or the negative flux rate trip for applicable sites).
Therefore, an anticipated transient without scram did not occur at Indian Point Unit 2 on December 5, 2015. In this instance, operators appropriately initiated a manual trip in accordance with procedures upon observing conditions representative of multiple dropped rods.
Thank you for your interest in nuclear safety and let me know if you have any additional questions.
AnneDeFrancisco ActingSeniorProjectEngineer,ProjectsBranch2 DivisionofReactorProjects,NRCRegionI 6103375078 Anne.defrancisco@nrc.gov