ML100541840

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Loss of Voltage/Degraded Voltage Relays - NRC Teleconference - February 23, 2010
ML100541840
Person / Time
Site: Brunswick  Duke Energy icon.png
Issue date: 02/23/2010
From:
Progress Energy Co
To:
Office of Nuclear Reactor Regulation
Saba F, NRR/DORL/LPL2-2, 301-415-1447
Shared Package
ML100541895 List:
References
Download: ML100541840 (18)
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Text

Brunswick Nuclear Plant Loss of Voltage/Degraded Voltage Relays NRC Teleconference February 23, 2010

Agenda

  • Background Agenda
  • Actions Taken
  • Design and Licensing Review Design and Licensing Review Loss of Power (LOP) Instrumentation - TS 3.3.8.1 AC Electrical Power Sources TS 3 8 1 AC Electrical Power Sources - TS 3.8.1 Technical Specification (TS) Bases 3.3.8.1 L

i S t

F ti l T t (LSFT)

  • Logic System Functional Test (LSFT)
  • Actions Remaining 02/23/10 2

=

Background===

  • During development of EC 73119 (Vendor E

ti t

D d d V lt R l 27DV

Background

Exceptions to Degraded Voltage Relay 27DV Procurement Specification) discrepancies were discovered with DC control voltage were discovered with DC control voltage values (Nuclear Condition Report (NCR) 369186)

  • As part of the operability review, several questions were raised regarding adequacy of the Loss of Voltage and Degraded Voltage the Loss of Voltage and Degraded Voltage functions (Tech Spec 3.3.8.1) of the Class IE 4KV Emergency Buses g

y 02/23/10 3

Actions Taken Actions Taken

Determined Design and Licensing Basis requirements for Undervoltage Relays and EDG start logic

Reviewed TS and TS Bases for conformance to the Design and Licensing Basis

Performed LSFT review for Undervoltage and Emergency Diesel Generator (EDG) start functions (EDG) start functions

Performed 480V load study on Degraded Voltage condition

Performed review of Protective Relay settings of Degraded and Loss of Voltage Relays

Conducted Third Party Reviews

Constantly reassessed operability and safety, via Operability Concern Review (OCR) process, pending completion of third party reviews

Conducted periodic Plant Nuclear Safety Committee meeting reviews 02/23/10 4

LOP Instrumentation - TS 3.3.8.1

g y

Loss of Voltage Relay 27/59E Degraded Voltage Relay 27DV g

g y

BOP 4.16KV BUS 1D TRIP BKR OPEN POSITION EMERG 4.16KV BUS E1 TRIP TRIP TRIP TRIP POSITION SWITCH AND CLOSE (52b)

EDG #1 27/DV LOAD BKR (TYP)

TIE TO BUS E2 TIE TO BUS E3 27HS 27/59E OR START 02/23/10 5

480V SUB E5

LOP Instrumentation - TS 3.3.8.1

  • TS 3.3.8.1 Loss of Voltage Relay 27/59E LOP Instrumentation TS 3.3.8.1 Electromechanical inverse time delay undervoltage relay One out of One trip function One-out-of-One trip function Function T i E b t

l d b k

Trip E bus motor load breakers Trip E bus tie breakers Provide EDG breaker close permissive Provide EDG breaker close permissive 02/23/10 6

LOP Instrumentation - TS 3.3.8.1

Two out of Three trip function Two-out-of-Three trip function Function I

l t E B f

ff it (t i M

t d Sl Isolate E Bus from offsite source (trip Master and Slave Breakers) 02/23/10 7

AC Electrical Power Sources - TS 3.8.1

lt l

Definite time solid state undervoltage relay One-out-of-One trip function Function Function Start EDG 02/23/10 8

LOP Instrumentation - TS 3.3.8.1

  • Under degraded voltage conditions coincident with a Large Break LOCA, the LOCA Initiation LOP Instrumentation TS 3.3.8.1 with a Large Break LOCA, the LOCA Initiation signal is the credited EDG start signal rather than the 27HS or slave breaker contacts since these devices would not actuate early enough to meet the time to injection requirements of the accident the time to injection requirements of the accident analysis
  • The LOCA initiation function is covered under th i

t t ti other instrumentation specs

  • All instruments associated with the EDG start and EDG output breaker closure have been excluded p

from TS 3.3.8.1

  • The remaining instruments are devices covered under TS 3.8.1 under TS 3.8.1 02/23/10 9

TS Bases 3.3.8.1 The TS Bases for the loss of voltage relays (27/59E) do not match the current plant design or current Licensing Bases (NCR 369409)

TS Bases 3.3.8.1 p

g g

(NCR 369409)

TS Bases Section 3.3.8.1 indicates instrumentation functions for Loss of Voltage 27/59E Relay performs functions that it was not designed to accomplish was not designed to accomplish Transfer the associated bus from offsite power to the EDG Start the EDG Current descriptions for the Loss of Voltage and Degraded Voltage functions in BNP TS Bases are essentially identical to the descriptions provided with the generic Improved Technical Specification (ITS) bases in NUREG 1433 Rev. 1, which was p

(

)

used to prepare BNPs ITS Submittal in November 1996 These generic descriptions do not accurately reflect the BNP design configuration or licensing basis for these functions BNP when transitioning to ITS incorrectly adopted the generic ITS bases 02/23/10 10

Results Design and Licensing Basis Review Design and Licensing Basis Review Current LOP Instrumentation TS 3.3.8.1 reflects existing plant LOP Instrumentation design Design is consistent with Licensing Basis Current Instrumentation TS reflects existing Design Loss of Voltage function accomplished by 27/59E relays Loss of Voltage function accomplished by 27/59E relays Degraded Voltage function accomplished by the 27DV relays DG Start Signal Review determined 2 credited starts 27HS (Loss of Voltage), Loss of Offsite Power coincident with LOCA Degraded Voltage coincident with LOCA 480V load study on Degraded Voltage conditions shows 480V load study on Degraded Voltage conditions shows 480V loads would operate as required The TS Bases for the loss of voltage relays (27/59E) do not match the current plant Design or current Licensing Basis match the current plant Design or current Licensing Basis (NCR 369409) 02/23/10 11

Logic System Functional Test Logic System Functional Test Performed LSFT review for Undervoltage and EDG f

i EDG start functions Performed Detailed Review of the Logic Performed Detailed Review of the Logic Contact by contact review using current drawings and surveillances drawings and surveillances Color coded drawings to document review 02/23/10 12

Logic System Functional Test Logic System Functional Test 27HS is the Class 1E instrument responsible for the credited EDG start during a LOOP coincident with LOCA 27HS is in a parallel channel with the master and slave breaker logic associated with the 27DV Relays The Slave breaker contact initiates the EDG start before the 27HS for Degraded Voltage Slave contact not credited 27HS for Degraded Voltage. Slave contact not credited.

LOCA initiation signal is credited for Degraded Voltage with LOCA Logic required to be tested under TS Surveillance Requirement 3 8 1 14 Requirement 3.8.1.14 27HS contact in the EDG start logic are not functionally verified during the performance of the LSFT (NCR 379456) 27HS had been last functionally tested when installed in 1983 27HS had been last functionally tested when installed in 1983 Proactively performed the following, while still investigating the requirements:

PRA completed on 12/10/09 Testing conducted satisfactorily on 02/06/10 Testing conducted satisfactorily on 02/06/10 Missed surveillance in accordance with SR 3.0.3 02/23/10 13

Logic System Functional Test Logic System Functional Test LOCA initiation EDG start is the credited EDG start during the Degraded Voltage coincident with LOCA during the Degraded Voltage coincident with LOCA Test Relays (8 contacts) in the EDG start logic found not functionally verified during the performance of the LSFT (NCR 379454) 4 of the 8 Test Relay contacts have Plant Information System Data that show these relay contacts perform the required function For the remaining 4 contacts there is no verification of the as

g left configuration of the contacts Logic required to be tested under TS Surveillance Requirement 3.8.1.14 P

ti l

f d C ti it Ch k

01/28/10 Proactively performed Continuity Check on 01/28/10, while still investigating the requirements Identified as a never performed surveillance 02/23/10 14

Results Logic System Functional Test Logic System Functional Test

  • Identified the following not functionally verified during the performance of the LSFT:

during the performance of the LSFT:

27HS contact in the EDG start logic (NCR 379456)

Test Relays (8 contacts) in the EDG start logic (NCR Test Relays (8 contacts) in the EDG start logic (NCR 379454)

Logic required to be tested under TS Surveillance Requirement 3 8 1 14 Requirement 3.8.1.14

  • Loss of Voltage 27/59E and Degraded Voltage 27DV relay settings were determined to be y

g acceptable based on the calculations 02/23/10 15

Actions Remaining Actions Remaining Revise TS Bases 3.3.8.1 to eliminate confusion associated with the LOP Instrumentation functions associated with the LOP Instrumentation functions (NCR 369409)

Revise appropriate surveillance procedures to verify pp p

p y

the as left configuration of contacts for the EDG Test Relays and incorporate required testing for the 27HS (NCR 379454 and 379456)

Implement design change to Undervoltage scheme (NCR 369186)

Unit 2 - 2011 Refuel Outage Unit 1 - 2012 Refuel Outage Unit 1 2012 Refuel Outage 02/23/10 16

Actions Remaining Actions Remaining LSFT 96-01 Extent of Condition Review (NCR 379762)

Risk significant systems selected for review

EDG Load Sequencing Logic

Automatic Depressurization System (ADS) Logic

High Pressure Coolant Injection System Logic

High Pressure Coolant Injection System Logic

Scope of review will be expanded to additional Systems if additional issues are identified

Verify Design Functions are Tested

Reviews to be performed in accordance with Guidance provided in

Reviews to be performed in accordance with Guidance provided in Generic Letter 96-01 Logic System Functional Testing including Lessons Learned from other LSFTs not adequately performed 02/23/10 17

Questions?

Questions?

18 02/23/10

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