United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:  9705300006



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NRC Operations Center

U.  S.  Nuclear Regulatory Commission

Washington, D.  C.



Attachment to Siemens Power Corporation 10 CFR Part 21 Report (Fuel Cycle

and Event Notification Worksheet) of May 22, 1997



10 CFR 21 Notification of Defect in Critical Heat Flux (CHF) Data Base

Range



During NRC Engineering Inspection 9990081/97-01, the NRC determined that

the CHF data base for the ATRIUM [Trademark] -9 fuel design and other 9x9

fuel designs with internal water channels was not extensive enough to

adequately estimate the uncertainties for the additive constants used in

SPC's CHF correlation.  A statistical treatment of the existing relevant

CHF data was developed to estimate the uncertainties beyond the original

CHF data ranges.  These estimated uncertainties are larger than the

original additive constant uncertainties.  Revised safety limit

calculations with the larger additive constant uncertainties indicate

that certain plants may have operated with incorrect safety limits.



The affected licensees have been informed of the increase in additive

constant uncertainties and of the possibility that previously calculated

safety limits may have been impacted by the larger uncertainties.  Safety

limit calculations for current reactors with ATRIUM [Trademark] -9 fuel

design and other 9x9 fuel designs with internal water channels have been

performed with the inclusion of projected higher additive constant

uncertainties.



FUEL CYCLE FACILITY                     EVENT NUMBER: 32379



FACILITY: SIEMENS POWER CORPORATION     NOTIFICATION DATE: 05/22/97

  RXTYPE: URANIUM FUEL FABRICATION      NOTIFICATION TIME: 17:13 [ET]

COMMENTS: LEU CONVERSION (UF6 to UO2)   EVENT DATE:         05/22/97

          FABRICATION & SCRAP RECOVERY  EVENT TIME:         00:00[PDT]

          COMMERICAL LWR FUEL           LAST UPDATE DATE:   05/22/97

    CITY: RICHLAND            REGION: 4

  COUNTY: BENTON               STATE: WA          NOTIFICATIONS

LICENSE#: SNM-1227         AGREEMENT: Y

  DOCKET: 07001257



NRC NOTIFIED BY: L.  MAAS               RAMSEY              NMSS

HQ OPS OFFICER: BOB STRANSKY            HODGE               NRR



EMERGENCY CLASS: NOT APPLICABLE

10 CFR SECTION:

CDEG 21.21(c)(3)(i)      DEFECTS/NONCOMPLIANCE



                               EVENT TEXT



CRITICAL HEAT FLUX DATABASE USED FOR 9x9 FUEL DESIGNS DOES NOT

ADEQUATELY

ESTIMATE UNCERTAINTIES.



THE FOLLOWING IS TEXT OF A FACSIMILE SUBMITTED BY THE VENDOR:



"DURING NRC ENGINEERING INSPECTION 9990081/97-01, THE NRC DETERMINED

THAT

THE CHF [CRITICAL HEAT FLUX] DATA BASE FOR THE ATRIUM-9 (TM) FUEL

DESIGN

AND OTHER 9x9 FUEL DESIGNS WITH INTERNAL WATER CHANNELS WAS NOT

EXTENSIVE

ENOUGH TO ADEQUATELY ESTIMATE THE UNCERTAINTIES FOR THE ADDITIVE

CONSTANTS USED IN SPC's CHF CORRELATION.  A STATISTICAL TREATMENT OF

THE

EXISTING RELEVANT CHF DATA WAS DEVELOPED TO ESTIMATE THE

UNCERTAINTIES

BEYOND THE ORIGINAL CHF DATA RANGES.  THESE ESTIMATED UNCERTAINTIES

ARE

LARGER THAN THE ORIGINAL ADDITIVE CONSTANT UNCERTAINTIES.  REVISED

SAFETY

LIMIT CALCULATIONS WITH THE LARGER ADDITIVE CONSTANT UNCERTAINTIES

INDICATE THAT CERTAIN PLANTS MAY HAVE OPERATED WITH INCORRECT

SAFETY

LIMITS.



THE AFFECTED LICENSEES HAVE BEEN INFORMED OF THE INCREASE IN

ADDITIVE

CONSTANT UNCERTAINTIES AND OF THE POSSIBLITY THAT PREVIOUSLY

CALCULATED

SAFETY LIMITS MAY HAVE BEEN IMPACTED BY THE LARGER UNCERTAINTIES. 

SAFETY

LIMIT CALCULATIONS FOR CURRENT REACTORS WITH ATRIUM-9 FUEL DESIGN

AND

OTHER 9x9 FUEL DESIGNS WITH INTERNAL WATER CHANNELS HAVE BEEN

PERFORMED

WITH THE INCLUSION OF PROJECTED HIGHER ADDITIVE CONSTANT

UNCERTAINTIES."



A LIST OF AFFECTED FACILITIES WAS NOT PROVIDED.  THE VENDOR WILL

CONTACT

NRC REGION IV REGARDING THIS ISSUE.



Attachment "NRC FORM 361A U.S.NUCLEAR REGULATORY COMMISSION LICENSE

NUMBER: SNM-1227 (NRC Docket No. 70-1257) FUEL CYCLE AND MATERIALS EVENT

NOTIFICATION WORKSHEET" omitted.



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