United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #: 9706200162



SIEMENS



June 3, 1997

LJM:97:056



U.S. Nuclear Regulatory Commission, Region IV

Attn: E.W. Merschoff, Administrator

611 Ryan Plaza Drive, Suite 400

Arlington, TX 76011-8064



Dear Mr. Merschoff:



Subject:  30-Day Followup Report on Part 21 Reportable Defect



On May 22, 1997, Siemens Power Corporation (SPC) notified the NRC (HQ

Operations Center and Region IV) of a 10CFR Part 21 - reportable defect

relative to the uncertainties for additive constants used in SPC's ANFB

critical heat flux correlation for the ATRIUM**[Trademark]-9 fuel design

and other 9x9 fuel designs with internal water channels.  Attached please

find a copy of our 30-day written followup report required under 10CFR

21.21 (d) (3) (ii) which is being provided to you per 10CFR 21.5.  If you

have questions, please feel free to contact me on 509-375-8537.



Very truly yours,



L. J. Maas, Manager

Regulatory Compliance



/pg



Enclosures



cc: C. Hooker - Region IV, WCFO



Siemens Power Corporation



Nuclear Division         2101 Horn Rapids Road    Tel: (509) 375-8100

Engineering &

Manufacturing            P.O. Box 130             Fax: (509) 375-8402

                         Richland, WA 99352-0130



SIEMENS



May 22, 1997

HDC:97:046



Document Control Desk

ATTN: Chief, Planning, Program and Management Support Branch

U.S. Nuclear Regulatory Commission

Washington, D.C. 20555



10 CFR 21 Evaluation and Notification of Adequacy of ATRIUM**[Trademark]-

9 CHF Data Base



This letter is written notification of a reportable defect per 10 CFR

Part 21 reported to the NRC Operations Center by facsimile on May 22,

1997.



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

the critical heat flux (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 ANFB CHF correlation.  A statistical

treatment of the existing relevant CHF data was developed by SPC 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 nonconservative safety limits.  Based on these calculations

and a Part 21 evaluation, SPC has concluded the above described situation

represents a defect as defined in 10 CFR 21.3, "A condition ...  that

could contribute to the exceeding of a safety limit..."



The affected BWR utilities have been kept informed, and the actions taken

and to be taken to address the issue are provided in the Attachment.



Very truly yours,



H. Donald Curet, Manager

Product Licensing



/smg



Attachment



cc:  E. Y. Wang (NRR/DRPM/PECB)



-----------------



*_/ ATRIUM is a trademark of Siemens.



Siemens Power Corporation



Nuclear Division         2101 Horn Rapids Road    Tel: (509) 375-8100

Engineering &

Manufacturing            P.O. Box 130             Fax: (509) 375-8402

                         Richland, WA 99352-0130



                               Attachment



                            REPORTABLE DEFECT



(i.)      Name and address of the individual informing the Commission.



          H. D. Curet, Manager, Product Licensing, Siemens Power

          Corporation, 2101 Horn Rapids Road, Richland, WA 99352.



(ii.)     Identification of the facility, the activity, or the basic

          component supplied for such facility or such activity within

          the United States which fails to comply or contains a defect.



          The NRC determined the number of test points and the range of

          conditions for critical heat flux experiments for the SPC

          ATRIUM [Trademark]-9*_/ fuel design and other 9x9 fuel designs

          with an internal water channel are insufficient to justify the

          uncertainty values for the additive constants used in the

          safety limit determination.  The uncertainty in the additive

          constant for these fuel designs may be larger than previously

          estimated.  A larger uncertainty value may affect the safety

          limit for BWRs containing reload quantities of SPC 9x9 fuel

          designs with internal water channels.



(iii.)    Identification of the firm constructing the facility or

          supplying the basic component which fails to comply or contains

          a defect.



          Siemens Power Corporation, Richland, WA.



(iv.)     Nature of the defect or failure to comply and the safety hazard

          which is created or could be created by such a defect or

          failure to comply.



          Statistically estimated additive constant uncertainties, in

          lieu of uncertainties quantifiable with CHF data, are larger

          than previously estimated for SPC 9x9 fuel designs with

          internal water channels.  These increased additive constant

          uncertainties have resulted in the increase in the safety

          limits for some licensees with SPC 9x9 fuel designs with

          internal water channels.



(v.)      The date on which the information of such defect or failure to

          comply was obtained.



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

          informed SPC the number of test points and the range of

          conditions for critical heat flux experiments for SPC 9x9 fuel

          designs with an internal water channel are insufficient to

          justify the uncertainty values for the additive constants used

          in the safety limit determination.  The magnitude of an

          estimated additive constant uncertainty was



------------------

*_/ATRIUM is a trademark of Siemens.



          determined statistically April 17, 1997 using the methodology

          submitted to the NRC and documented in ANF-1125, Supplement 1,

          Appendix D, "ANFB Critical Power Correlation Uncertainty for

          Limited Data Sets," April 1997.  Due to the increase in the

          estimated value of the uncertainty and its probable impact on

          calculated safety limits, a Part 21 evaluation was initiated to

          determine if a safety hazard existed or could be created.



(vi.)     In the case of a basic component which fails to comply, the

          number and the location of all such components in use at,

          supplied for, or being supplied for one or more facilities or

          activities subject to the regulations in this part.



          Safety limit calculations for current reactors (Quad Cities

          Unit 2, Cycle 15; LaSalle Unit 2, Cycle 8 and Dresden Unit 3,

          Cycle 15) that have received but have not yet operated with SPC

          ATRIUM-9 fuel design were performed using the increased

          additive constant uncertainty.  The safety limit for Quad

          Cities increased 0.01.  The safety limits for LaSalle and

          Dresden were unaffected.



          The safety limit previously calculated by SPC for WNP-2, Cycle

          11, which has been completed and included all SPC fuel, was

          nonconservative in comparison to the safety limit calculated

          using the increased additive constant uncertainties.  Safety

          limit calculations for fuel cycles subsequent to WNP-2, Cycle

          11 were not the responsibility of SPC.



          The corrective action which has been, is being, or will be

          taken; the name of the individual or organization responsible

          for the action; and the length of time that has been or will be

          taken to complete the action.



          All affected licensees have been informed of the additive

          constant uncertainty issue.  SPC has submitted to the NRC a

          statistical methodology (see item v. above) to estimate the

          additive constant uncertainty.  Until the NRC approves this

          methodology, the statistically estimated increase in the

          uncertainty is multiplied by two and added to the original

          additive constant uncertainty.  The larger uncertainty (i.e.,

          increase multiplied by 2) is to be used in future safety limit

          calculations until the NRC approves the uncertainty increase

          estimated by the submitted statistical methodology or new CHF

          data are obtained to quantify a new additive constant

          uncertainty.



(viii.)   Any advice related to the defect or failure to comply about the

          facility, activity, or basic component that has been, is being,

          or will be given to purchasers or licensees.



          In addition to providing revised safety limit calculations

          where appropriate, SPC has advised its customers that it

          intends to obtain additional CHF data to quantify the additive

          constant uncertainty.  If the new uncertainty is comparable to

          the original uncertainty or the increase in the new uncertainty

          is less than the presently estimated uncertainty increase

          obtained by the statistical methodology, safety limits may be

          reduced.  Interactions with the NRC will be required to obtain

          approval for the use of a new or reduced additive constant

          uncertainty.



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