United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:  9703070020



NOTE:     This text document was processed from a scanned

          version or an electronic submittal and has been

          processed as received.  Some tables, figures,

          strikeouts, redlines, and enclosures may not have

          been included with this submittal, or have been

          omitted due to ASCII text conversion limitations.  In

          order to view this document in its entirety, you may

          wish to use the NUDOCS microfiche in addition to the

          electronic text.



POWER REACTOR                                EVENT NUMBER: 31890



FACILITY: BYRON          REGION: 3      NOTIFICATION DATE: 03/04/97

UNIT:     [1] [2] [ ]    STATE: IL      NOTIFICATION TIME: 16:22 [ET]

RX TYPE: [1] W-4-LP, [2] W-4-LP         EVENT DATE:        03/03/97

                                        EVENT TIME:        00:00[CST]

NRC NOTIFIED BY: PAUL WENC              LAST UPDATE DATE:  03/04/97

HQ OPS OFFICER: HENRY BAILEY



                                             NOTIFICATIONS

EMERGENCY CLASS: NOT APPLICABLE

10 CFR SECTION:

CCCC 21.21     UNSPECIFIED PARAGRAPH

                                        VERNON HODGE, RVIB  NRR



UNIT  SCRAM CODE  RX CRIT  INIT PWR  INIT RX MODE  CURR PWR  CURR RX

MODE



 1        N        N          0       HOT SHUTDOWN    0      HOT SHUTDOWN

 2        N        Y        100       POWER OPERATION 100 POWER OPERATION



                               EVENT TEXT



10 CFR PART 21 NOTIFICATION - CRACKING OF VITEC TRANSFORMER CORES



THESE TRANSFORMERS ARE INSTALLED IN VARIOUS SAFETY-RELATED

CIRCUITS

BOARDS.  TEMPERATURE CHANGES IN THESE CIRCUIT BOARDS COULD CAUSE

ASSOCIATED INSTRUMENTATION TO DRIFT OUT OF RANGE.  THE

SAFETY-RELATED

APPLICATIONS WHERE THIS TRANSFORMER HAS THE MOST POTENTIAL IMPACT

ARE THE

DELTA TEMPERATURE PROTECTION FUNCTIONS (NRA CARDS) IN THE REACTOR

PROTECTION SYSTEM (RPS).  THE DRIFT IN THE RPS COULD CAUSE A CHANNEL

TO

TRIP RESULTING IN A LOSS OF REDUNDANCY IN THE DIVERSE TRIP FUNCTION.



NOTE:     THIS ISSUE ALSO APPLIES TO BRAIDWOOD UNITS 1 AND 2 AND TO ZION

          UNITS 1 AND 2.



Transmittal note omitted.



Commonwealth Edison Company

Byron Generating Station

450 North German Church Road

Byron, IL (illegible)

Tel 815 (illegible)



March 3, 1997                                ComEd



LTR:      BYRON 97-5045

FILE:     2.01.0703



U. S.  Nuclear Regulatory Commission

Washington, DC 20555



Attention:     Document Control Desk



Subject:       Byron Station Units 1 and 2

               Braidwood Station Units 1 and 2

               Zion Station Units 1 and 2



               10 CFR Part 21 Notification

               Cracking of VITEC Transformers

               NRC Dockets 50-454 and 50-455

               NRC Dockets 50-456 and 50-457

               NRC Dockets 50-295 and 50-304



Reference:     "Transformer Cracking", Westinghouse Potential Issue NSAL-

               96-006, dated December 26, 1996.



Applicability



This notification is submitted in accordance with the requirements of 10

CFR Part 21, Section 21.21(a), 21.3a(3), and 21.3d(1).



Identification of Facilities and Components



Byron Nuclear Generating Station Units 1 and 2

Braidwood Nuclear Generating Station Units 1 and 2

Zion Nuclear Generating Station Units 1 and 2



7300 Process Protection System Integrated Circuit Cards (NRA, NLP, NSC,

NLL, NMD, NCH, NVP, and NSA applications)



NRA card model #:  2837A15G01, various date codes supplied by

Westinghouse from October 1991 through 1993.



(illegible)

                                    1



Identification of Component Manufacturer/Supplier



Westinghouse Electric Corporation

Box 355

Pittsburgh, Pennsylvania 15230-0355



Nature of Defect



During installation and testing of the RTD By-Pass modification at

Braidwood Station. a output drift observed with increasing temperature on

several RTD amplifier



Number and Location of All Defective Components



Zion Station has not identified any installations of the suspect circuit

cards at Zion.  The population of potentially affected cards at Byron and

Braidwood Stations is extensive due to the number of circuit card

applications that have been identified by Westinghouse.  The exact number

of potentially defective components is not currently available due to the

uncertainty of which date codes are actually installed in the plants

ComEd has determined that the applications of concern from a 10CFR21

standpoint are the NRA, NLP, and NSC cards.  This is due to the isolated

output function for the applications serviced by these specific cards.



Corrective Actions:



Byron and Braidwood Stations have initiated actions to identify all

circuit cards with the affected date codes.  Once the population of

impacted cards is fully identified, the affected cards will be replaced,

where appropriate.  Westinghouse indicated that it is unlikely that many

transformers with cracked cores exist. In addition, it has been

determined that all installed cards are located in rooms that are

supplied by safety related, redundant HVAC systems that are designed to

maintain appropriate temperatures.  The safety related applications where

this transformer issue has the most potential impact are the [symbol

omitted]T protection functions (NRA cards) because of reactor trip

concerns.  These applications are subjected to periodic channel checks

and it is reasonable to assume that any significant non-conservative

calibration drift would be detectable during channel checking activities.

Both Byron and Braidwood Stations have documented operability assessments

that conclude that there is reasonable assurance of operability for the

potentially affected applications.  Completion of inspection and/or

replacement of the impacted population of circuit cards for both Byron

and Braidwood Stations will be completed prior to the end of the next

refueling outage on each unit.



Byron and Braidwood Stations have inspected all spare circuit cards in

Stores to ensure that no additional potentially affected components are

placed into service.



10 CFR 21 Evaluation



The Safety related applications where this transformer issue has the most

potential impact are the [symbol omitted]T protection functions (NRA

cards).  There is some potential that defective cards would not be

detected during installation and initial calibration.  A negative drift

in the calibration of defective cards could result in non-conservative

calculations for both [symbol omitted]T and the corresponding setpoints.

This could result in a lack of redundant rector trip function.

Therefore, ComEd has determined that the identified defect does represent

a substantial safety hazard per the requirements of 10CFR21 and is

reportable to the NRC.



(illegible)

                                    3



Contacts



Questions pertaining to this notification should be addressed to either:



Bradley J. Adams                   Peter J. Wicyk

Site Engineering                   EI&C Engineering

ComEd Byron Station                ComEd NES, ETW-III

4450 N. German Church Road         1400 Opus Place

Byron, Illinois 61010              Downers Grove, Illinois 60515

(815) 234-5441 x2979               (630) 663-7264



Sincerely,



K. L. Graesser

Site Vice President

Byron Nuclear Station



cc:  H.  Miller, Regional Administrator-RIII

     S.  Burgess, Senior Resident Inspector (Byron)

     C.  Phillips, Senior Resident Inspector (Braidwood)

     A.  Vegel, Senior Resident Inspection (Zion)

     G.  Dick - NRR

     R.  Assa - NRR

     C.  Shiraki - NRR

     Office of Nuclear Facility Safety - IDNS



(illegible)

                                    4



*** END OF DOCUMENT ***



Page Last Reviewed/Updated Thursday, March 29, 2012