United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9605070110

                                   ABB

                                             April 15, 1996
                                             LD-96-009

Document Control Desk
U.S.  Nuclear Regulatory Commission
Washington, D.C, 20555

Subject: Report of a Deviating Condition in a Reactor Trip Function

Dear Sir:

Combustion Engineering, Inc. (ABB-CE) hereby notifies the Nuclear
Regulatory Commission of a condition or circumstance involving a reactor
protection system trip function which has the potential to contribute to
the exceeding of a safety limit. The deviating condition evaluated
involves nuclear instrumentation decalibration factors, which may not
have been adequately compensated for fully when originally setting the
trip setpoint, and which, therefore, have the potential to adversely
affect the High Logarithmic Power channel trip function.  The
uncompensated decalibration factors are Potentially nonconservative in
nature and could, therefore, cause a trip, if needed, to occur at a power
level higher than that accounted for in safety analyses.

Evaluations were performed by ABB-CE to determine if this situation would
in fact result in exceeding any safety limits, Based on the result of
these evaluations ABB-CE has concluded that because of the discretionary
conservatism built into the input parameters for the one affected safety
analysis, that the original High Logarithmic Power trip setpoint remains
acceptable without creating the potential to exceed a safety limit- ABB-
CE has chosen to report this condition because the situation could
conceivably be applicable to other NSSS vendor designs utilizing a
reactor protection system trip for subcritical events based upon absolute
power if nuclear instrumentation decalibration factors are not accounted
for appropriately.  The Enclosure provided herewith summarizes the
information available to ABB-CE regarding the subject condition.

                ABB Combustion Engineering Nuclear Power

Combustion Engineering.  P.O.  Box 500       Telephone (860) 688-1911
Inc.                     2000 Day Hill Rd.   Fax (860) 285-5202
                         Windsor, CT 06095-0500

Document Control Desk                                           LD-96-009
April 15, 1996                                                     Page 2

[f you have any questions, please feel free to contact me or Mr.  Chuck
Molnar of my staff at (203) 285-5205.

                                        Very truly yours,
                                        COMBUSTION ENGINEERING, INC

                                        J. C. Rickard, Director
                                        Operations Licensing

Enclosure: As stated

cc: R.  S.  Siudek (ABB-CE)

ENCLOSURE

ABB Combustion Engineering Nuclear Operations

Report of a Deviating Condition in a Reactor Trip Function

April 15, 1996

ABB Combustion Engineering Nuclear Operations
Report of a Deviating Condition in a Reactor Trip Function

(i)       Name and address of the individuals informing the Commission:

                    I. C.  Rickard, Director
                    Operations Licensing
                    Combustion Engineering, Inc.
                    2000 Day Hill Road
                    Windsor, CT 06095-0500

(ii)      Identification of the facility, the activity, or the basic
          component supplied or such facility or such activity within the
          United States which fails to comply or contains a defect:

          The condition being reported was initially identified at the
          Waterford Steam Electric Station Unit No.  3 (WSES-3).
          Specifically, the deviating condition involves nuclear
          instrumentation decalibration factors, which may not have been
          adequately compensated for fully when originally setting the
          trip setpoint.  These decalibration factors are related to the
          reactor High Logarithmic Power channel trip function and are
          potentially nonconservative In nature.

(iii)     Identification of the firm constructing the facility or
          supplying the basic component which fails to comply or contains
          a defect:

                    Combustion Engineering, Inc.
                    2000 Day Hill Road
                    Windsor, CT 06095-0500

(iv)      Nature of the defect or failure to comply and the safety hazard
          which is created or could be created by such defect or failure
          to comply.,

          Although the High Logarithmic Power trip function is only
          credited at low power levels (from 







 
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