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October 29. 1997 MEMORAPCUM TO:
Herbert M. Berkow, Director Project Directorate PD 112 DMalon of Reactor Projects 1/H FROM:
Jared S. Warmiel, Chisf lastrumentation and Controls Branch Division of Reactor Control And Human Factcrs
SUBJECT:
TASK INTERFACE AGREEMENT (T!A 9712) EVALUATION OF MONTHLY SURVEILLANCE TESTING OF REACTOR TRIP SYPASS BREAKER AND ITS P 4 INTERLOCK FOR VOGTLE a
. UNITS 1 AND 2 (TAC NOS M98528 AND M98529)
By memorandum (TIA) dated May, 5,1997. Region il klontified their concoms regan5ng Southern Nuclear Operating Company's (SNC) monthly survemance testing of
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reactor trip bypass breaker,s and its P 4 Interlock at Vogtle Electric Generating Plant Units 1 and 2. The Region requested that NRR address the consistency of these tests with the
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requirements of plant Technical Specifications. Attached is the stoff's response to the subject TIA. This comp'letes our effort in response to your request; Docket No.: 50-424 and SD-425 Attechment: As stated l
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Contact:
Iqbal Ahmed, HIC 8 i
415 3252 I
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i DISTRIBUTION:
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NRC RLE CENTER COPY DOCUMENT NAME: VOGTLE 97-113
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4 Octotier 129. 1997 e
MEMORAM)UM TO:
Hertiert M. Berkow. Director Project Directorate PD 112 DMalon of Reactor Projects 1/II FROM:
Jared S. Wermiel. Chisf instrumentation and controls Branch DManon of Reactor Control And Human Factors
SUBJECT:
TASK INTERFACE AGREEMENT (TIA 9712) EVALUATION OF MONTHLY SURVEILLANCE TESTING OF REACTOR TRIP BYPASS BREAKER AND ITS P 4 INTERLOCK FOR VOGTLE UNITS 1 AND 2 (TAC NOS. M98528 AND M98529)
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Sy memorandum (TIA) dated May, 5.1997, Region il identified their concerns regarding Southem Nuclear Operating Company's (SNC) moreth!y surveillance testing of reactor trip bypass breakers and its P-4 interlock at Vogtle Electric Generating Plant Units 1 and 2. The Region requested that NRR address the consistency of these tests with the requirements of plant Technical Specifications. Attached is the staff's response to the subject TIA. This completes our effort in response to your request.'
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Docket No.: 50-424 and 50-425
Attachment:
As stated l
Contact:
Iqbal Ahmed. HIC 8 l
415 3252 DISTRIBUTION:
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HICS RF(2)
L Spessard D. Wheeler
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DOCUMENT NAME: VOGTLE 97113 n
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OFFICE HIC 8/DRCH lE HICB/0RQi,, l E HICB/DRQl.
lE NAME IAhmed324, EMarinos P /.,
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OFFICIAL RECORD COPY
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TASK INTERFACE AGREEMENT (TIA 9712) EVALUATION SY THE OVICE OF NUCtfAR REACTOR REGULATION VOGTLE UNITS 1 AND 2 POCKET 50-424 AND 50-425 1.0 INTRODUCT. TON By memorandum dated May 5,1997, Region il requested NRR's technical assistance to evaluate the Vogtie Resident inspector's d'oncems regarding monthly testing of the Vogtle Reactor Trip System (RTS) bypass circuit bceakers and its P 4 interlock. The memurandum specificaDy requested the staff to address ths fo!!owing two concerns, i
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- 1. Is the Econsee's practice of only testing the auto shunt trip feature of the reactor
. trip bypass breakers prior to pfscing thenin service, consistent with the Trip
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Actuation Device Operational Test (TAD 011 requirement of the plant Technical Specification (TS) surveillance requirement (.!R) 3.3.1.47
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- 2. Is the Econsee's practice of not testing the P 4 signal generated by the bypass breaker and supp0ed to the turt>lne EHC system consistent with the TADOT requirement of TS SR 3.3.2.9?
ia 2.0 EVALUATION 3.
The staff evaluation of the Vogtle licensee's practice of testing the bypass breakers and its P 4 Interlocks was based on the design features of the reactor trip breakers (RTBs), reactor 4
trip bypass breekers and their P-4 interlocks, and the plant TS requirements as follows.
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Reactor Trio Bypass Breaker Test in Westinghouse plant designs, a bypass breaker is provided n parallel with each of i
l the two RT8s, only to facilitate at power testing of the RT8s. Westinghouse topical i
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.N report WCAP 7672,
- Solid State Logic Protection System Description" indicated that when an RTB is bypassed for test, the associated solid state protection system (SSPS) l...
train is considered inopertte.
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The RTBs and the bypass breakers are provided with an undervoltage and a shunt trip 2.
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feature. The SSPS provides a signal for automatic trip (de-energize) of the
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- undervoltage coil. However, operating the main control board manual switch v:.
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simultaneously actuates the diverse feature (undervo!! age and shunt trip) of the
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.Jj, reactor trip breakers. In addition, to these features, the bypass breaker can also be tripped by a local manual switch.
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This local shunt trip feature is provided to facilitate at power verification of the bypass breaker trip capability which is pieced in service only during the monthly TADOT of the associated RTB.
The Vogtle plant TS defines TADOT as operating the trip actuating device and verifying the operability of required alarm, interlock, and trip functions. TADOT of an RTB is required on a 31 day staggered test basis and TADOT for the associated bypass breaker is required prior to placing it in service. The plant TS also limits plant operation to two hours when a bypass breaker is racked in for testing the associated RTB. The TS bases for at-power TADOT of the bypass breaker indicates that the bypass breakers are tested only for the shunt trip by operating the local manual switch because the design does not have the capability for separate and independent verification of both shunt and undervoltage trip functions at power. For the bypass s
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breakers, an independent verification of the shunt and undervoltage trip functions operability is performed on an 18-month surveillance test interval TADOT during the
'1 scheduled shutdown of the power plant. As defined, TADOT requires operating the i.i -
trip actuating device (RTB and bypass breaker) without specifying the means to trip 7.
lP, these breakers. Additiona!!y, the associated SSPS train is considered inoperable during 3,
an RTR monthly test which obviates testing the operability of the undervoltage trip l
E-function initiated by an inoperable SSPS train.
.* 3 The staff review of the Vogtle plant design features and TS surveillance requirements found the licensee's monthly TADOT of the reactor trip bypass breakers to be
.1 consistent with TS SR 3.3.1.4.
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Testino Reactor Trio Bypass Breaker P-4 Sional to Turbine EHC System P-4 is an Engineered Safety Feature Actuation System (ESFAS) Interlock enabled when
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an RTS and its associated bypass breaker is open. Norma!!y closed contacts of cell switch'(breaker rock In/out position switch) and that of the auxiliary switch (breaker open/close switch) provide the P-4 s'gnal to trip'the main turbine and initiate other ESFAS functions. The Vogtle design' includes two separate P-4 initiating ircuits one providing trip segnal to the turbine EHC system and the other providing a trip signal to 1
the SSPS for initleting other'ESFAS functions. Each circuit is a parallel combination of one closed contact of the RTS cell switch and one closed contact of the RTS auxiliary switch in series with e similar contact combination of the associated bypass breaker.
As such, the P-4 signalis only generated when either the cell or the auxiliary switch contacts of both the RTB and the associated bypass breaker are closed. It is, therefore, not possible to separately test the P-4 signal contribution by the RTB and the associated bypass breakers.
' The Vogtle plant TS requires TADOs of the reactor trip P-4 interlock on an 18 month surve!!!ance test interval. In an October 10,1997 telecon with the staff, the licenses confittned that the Vogtle test procedures include the bypass breaker auxiliary and cell switch contacts' with those of the RTB as part of the operability verification of the P 4 interlock to the EHC system. In addition, the P 4 interlock operability is verified with the monthly TADOT of the RTBs using a series combination of the RTB auxiliary switch contact and the associated bypass breaker cell switch contact. The licensee further lodicated that the Vogtle plant test procedure requires verifying the proper position.cf the bypass breaker cell switch contacts after racking out the bypass
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The staff. review of the Vogtle plant P-4 signal"desigr[ features and its surveillance test
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procedures 'found the licensee's practice of testing the Pd sig' nel to the EHC system and
. the SSPS to be consistent with the TADOT' requirement of TS SR 3.3.2.9.
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3.0 CONCt.USION 4J Based on its review of the ir. formation provided in the TIA and the October 10,1997
- telecon with the licensee, the staff concludes that the Vogtle licensee's testing of the reactor trip bypass breakers and the P-4 Interlock is consistent with the TADOT requirements of Vogtle Units 1 and 2 TS.
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