ML112430566: Difference between revisions

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{{#Wiki_filter:TVA Heinemann Molded Case Circuit Breakers (MCCBs)()Enclosure 4 Power Board Design:The breakers are clamped between the front cover and the two angle iron supports in the rear.Enclosure 4 Timeline*1974: Initial seismic qualification of 120Vac vital instrument power boards*1992: Replacement Heinemann MCCBs areDedicatedasCommercial Grade are Dedicated as Commercial
-Grade*2008: Heinemann redesigned breakers
*2010: TVA installed breakers at Watts Bar Unit 2Enclosure 4 Regulatory HistoryJanuary 2009: NRC questioned differences in mounting methods between the seismic testing and the installation in Watts Bar Unit
1.August 2010:  Evaluation of historical Corrective Action Program (CAP) resulted in
a violation for not adequately addressing the issue within their CAP.September 2010 -TVA denied the violation.Enclosure 4 Regulatory HistoryOctober 2010 -NRC upheld the violation.November 2010 -TVA accepted the violation.Db2010TVAtdthiD ecem b er 2010 -TVA presen t e d th e i r corrective actions at a public meeting. July 2011 -NRC inspected TVA's corrective actions and concluded that they were not sufficient to close the NOV.Enclosure 4 NRC's Concerns*The MCCBs mounted during testing are not representative of the breaker's clamped
arrangement as installed in the plant.*The test arrangement placed an accelerometer 13 inchesbelowtheupper
-mostrowofbreakers inches below the upper most row of breakers.*The circuit breakers, as viewed on past inspections, did not appear to firmly fit into the
panel.*The licensee used spacer materials, not documented on design drawings, as installation
aids.Enclosure 4 Projected Path Forward*Task Interface Agreement (TIA) has been drafted by Region II and submitted to the office of Nuclear Reactor Regulation (NRR).*After acceptance of the TIA by NRR, a public meetingwillbeheldinRockvilleMD meeting will be held in Rockville , MD.-Opportunity for TVA and NRC technical experts to discuss the issue.*TIA will be finalized with all available information.*TVA will then be able to make their decisions for Corrective Actions with knowledge of NRR's response to the TIA.Enclosure 4 Questions?Enclosure 4}}

Revision as of 08:37, 3 August 2018

08/24/2011 NRC Slides for Watts Bar Nuclear 2 Public Meeting
ML112430566
Person / Time
Site: Watts Bar Tennessee Valley Authority icon.png
Issue date: 09/01/2011
From:
NRC/RGN-II/DCP/CPB2
To:
Tennessee Valley Authority
References
Download: ML112430566 (8)
v • d • e


Text

TVA Heinemann Molded Case Circuit Breakers (MCCBs)()Enclosure 4 Power Board Design:The breakers are clamped between the front cover and the two angle iron supports in the rear.Enclosure 4 Timeline*1974: Initial seismic qualification of 120Vac vital instrument power boards*1992: Replacement Heinemann MCCBs areDedicatedasCommercial Grade are Dedicated as Commercial

-Grade*2008: Heinemann redesigned breakers

  • 2010: TVA installed breakers at Watts Bar Unit 2Enclosure 4 Regulatory HistoryJanuary 2009: NRC questioned differences in mounting methods between the seismic testing and the installation in Watts Bar Unit

1.August 2010: Evaluation of historical Corrective Action Program (CAP) resulted in

a violation for not adequately addressing the issue within their CAP.September 2010 -TVA denied the violation.Enclosure 4 Regulatory HistoryOctober 2010 -NRC upheld the violation.November 2010 -TVA accepted the violation.Db2010TVAtdthiD ecem b er 2010 -TVA presen t e d th e i r corrective actions at a public meeting. July 2011 -NRC inspected TVA's corrective actions and concluded that they were not sufficient to close the NOV.Enclosure 4 NRC's Concerns*The MCCBs mounted during testing are not representative of the breaker's clamped

arrangement as installed in the plant.*The test arrangement placed an accelerometer 13 inchesbelowtheupper

-mostrowofbreakers inches below the upper most row of breakers.*The circuit breakers, as viewed on past inspections, did not appear to firmly fit into the

panel.*The licensee used spacer materials, not documented on design drawings, as installation

aids.Enclosure 4 Projected Path Forward*Task Interface Agreement (TIA) has been drafted by Region II and submitted to the office of Nuclear Reactor Regulation (NRR).*After acceptance of the TIA by NRR, a public meetingwillbeheldinRockvilleMD meeting will be held in Rockville , MD.-Opportunity for TVA and NRC technical experts to discuss the issue.*TIA will be finalized with all available information.*TVA will then be able to make their decisions for Corrective Actions with knowledge of NRR's response to the TIA.Enclosure 4 Questions?Enclosure 4

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