ML20216B328

Discusses Amend 132 to License DPR-43.Requested Revised Analysis Reflecting Higher Source Term Encl.Results of Analysis Conclude That Potential Thyroid Doses to Public Continue to Be Less than Guideline Values of 10CFR100

ML20216B328
Person / Time
Site:	Kewaunee
Issue date:	04/07/1998
From:	Steinhardt C WISCONSIN PUBLIC SERVICE CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-98-30 NUDOCS 9804130421
Download: ML20216B328 (7)

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NRC-98-30 Public Service Corporation u sotmdia v of Wii resot.eces corr'or abo'il 000 Hwth Adams Snect PO Don 1%02 Green Bay W154307-9002 1 800 450 7260 April 7,1998 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Ladies / Gentlemen:

Docket 50-305 Operating License DPR-43 Kewaunee Nuclear Power Plant Amendment 132 to Kewaunee11 ant Operating. License l

References:

1) Letter from R. J. Laufer (NRC) to M. L. Marchi (WPSC) dated May 7, 1997.

2) Letter from M. L. Marchi (WPSC) to the Document Control Desk (NRC) 1 dated November 25,1997.

l 3) Letter from M. L. Marchi (WPSC) to the Document Control Desk (NRC) l dated March 23,1998. l

4) Letter from M. L. Marchi (WPSC) to the Document Control Desk (NRC) dated September 5,1997.

On May 7,1997, the Nuclear Regulatory Commission (NRC) issued Amendment 132 to the Kewaunee Plant Operating License (Reference 1). In addition to several administrative changes, the amendment provided relaxation of the controls for the containment airlocks during refueling operations. Following the identification of several concerns with the amer.dment, on November 25,1997 (Reference 2), Wisconsin Public Service Corporation (WPSC) committed to not implement the airlock provisions of the amendment until NRC issuance of a revised safety evaluation To resolve the concerns additional information was provided in Reference 3.

Through subsequent telecons with the NRC, WPSC understands that a revised radiological analysis of a postulated fuel handling accident in containment (FHAIC) is required to resolve this issue.

As discussed in Reference 4, WPSC is currently pursuing the use of a modified Siemens Power )

Corporation fuel assembly design, and operation with higher core peaking factors with a resultant higher source term. Implementation of these changes requires a revised radiological analysis for a FIIAIC. Therefore, for expediency, the requested revised analysis (provided in Attachment 1) reflects the higher source term. \

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Document Control Desk April 7,1998 l Page 2 l

l The results of the analysis conclude that potential thyroid doses to the pr,blic continue to be less than the guideline values of 10 CFR Part 100 and the potential th)Nid dose to a control room operator satisfies General Design Criteria 19 of Appendix A to 10 CFR Part 50. Therefore, WPSC has concluded that implementation of the amendment does not significantly challenge safe l ]

l- plant operation, and WPSC awaits NRC concurrence prior to implementation.

If you have any questions concerning this information, please contact me or a member of my staff.

Sincerely, f *\

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C. R. Steinhardt Senior Vice President - Nuclear Power l

RPP Attach.

cc - US NRC Region Ill US NRC Senior Resident Inspector Electric Division, PSCW Subscribed and Sworn to Before Me ' isJM Day of /7A __ 1998 7

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Notary Public, State of Wisconsin My Commission Expires:

Juncl3.3999 1

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1 ATTACHMENT 1 I

Letter from C.R. Steinhardt (WPSC) l l

To Document Control Desk (NRC) 1 Dated ,j April 7,1998 1

1 Radiological Consequences of a Fuel Handling Accident in Containment l l

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Document Control Desk April 7,1998 Attachment 1. Page 1 RADIOLOGICALCONSEQUENCES_OEAEUELliANDLING. ACCIDENT _IN CONTAINMENT (FHAIC)

Introduction For this analysis all the rods of one fuel assembly are assumed to be damaged during fuel handling with full release of the gap fission activity. The fuel assembly is submerged with water scrubbing of the radioiodine. The activity released from the water surface moves directly from the containment to the environment without any additional delay or filtration. The release duration is two hours. Thyroid doses havr ' een determined to be limiting for this accident; thus, only cumulative thyroid doses are deternuned for the control room, site boundary, and low population Zone.

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InputParameters_andAssumptions The fuel assembly gap activity is that of a high power assembly with 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> of decay consistent with the Technical Specification time restriction on fuel handling. The activity was determined using the ORIGEN2 code adjusted for a radial peaking value of 1.70. ORIGEN2 was used to generate the single assembly activities based upon an initial heavy metal loading of 411 kgU, 5 wt% U-235, and a range of burnups up to 60 GWD/MTU. Activity levels corresponding to a burnup of 48 GWD/MTU were identified as limiting and were used in the evaluation. Gap activities for a single assembly are based upon the ORIGEN2 results and the R.G.1.25 &

NUREG/CR-5009 gap fractions. An iodine partition factor of 0.01 is used for the pool scrubbing.

The release is assumed to be immediately at the control room fresh air intake. In less than ten seconds, the control room isolates and enters the 100% recirculation mode of operation with a portion of which is fihered. At the end of the release the control room is purged to remove the remaining radionu . y.

The significant parameters for this analysis are given in Table 1.

Description ofAnalysis. Performed The analysis method follows the guidance of Regulatory Guide 1.25.

Acceptance _ Criteria The NRC has established the offsite dose limits for a FHA as less than 75 rem to the thyroid (reference the Standard Review Plan) which is within the 10 CFR Part 100 guideline value of 300 rem. General Design Criterion 19 of Appendix A to 10 CFR Part 50 specifies an acceptable dose for the control room operator as less than 5 rem whole body or its equivalent to any part of GBNUCI N3GROUPWUCIIARTWPFi1ISilCWRCWA132A.WPD

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Document Control Desk April 7,1998 '

Attachme'nt 1, Page 2 the body. For the thyroid, this has traditionally been considered as 30 rem; however, recent studies have demonstrated that the radiological equivalent to the thyroid of 5 rem whole body is much larger, as high as 170 rem. A non-stochastic, deterministic has been established at 50 rem (10CFR20).

Results The offsite and control room operator thyroid doses due to a fuel handling accident in containment are given in Table 2.

Conclusions i The results demonstrate that potential thyroid doses to members of the public are less than the l

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NRC criteria and 10 CFR Part 100 guidelines. The results for the control room thyroid dose exceed 30 rem but are less than the current knowledge on the equivalent to 5 rem whole body (i.e., 50 rem thyroid). In addition, the analysis uses a number of conservative _ assumptions including:

l The analysis assumes previous operation at 1721 Mwth or 4% higher thac permitted by the licensed plant power level of 1650 Mwth. Operation at the licensed power level results in a reduction in the actual radioactive source term available for release. 1 No credit is taken for activity holdup in the containment or dispersion in the auxiliary building with likely filtration prior to release to the environment.

During refueling operations, as required by the plant Technical Specifications, the containment can be closed within 30 minutes terminating the release before the 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> assumed in the analysis.

Studies have indicated a much smaller iodine partitioning factor (from 0.005 to 0.001) may more realistically characterize the effectiveness of the water scrubbing and the actual release from the water surface.

The analysis assumes all rods of a fuel assembly are at the peak radial power ratio of 1.70. i In reality, there will be a distribution within the assembly with an average several percent below this value, thus reducing the total assembly gap activity. l Therefore based upon this information in total, WPSC concludes that the potential consequences of a fuel handling accident in containment are acceptable. i l

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Document Control Desk  :

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Attachment 1, Page 3 1

TABLEl ASSUMP_TIONS_USED_ EOR _CALCULATINGlADIOLOGICAL. CONSEQUENCES Parameters Quantity Power Level (Mwth) 1721 Number of Fuel Rods Damaged 179 Total Number of Fuel Rods 21659 {

Shutdown Time (hours) 100 Radial Power Peaking Factor 1.70 Fission Product Release Duration (hours) 2 Release Fractions Iodine 12 % i Noble Gases except Krypton-85 10 %

Krypton-85 Gas 30 %

Fuel Assembly Gap Activities (Ci)

I-131 5.60E+04 I-132 4.73E+04 l I-133 5.83E+03 I-134 3.17E-29 I-135 4.20E+00 l

Atmospheric Relative Concentration, X/Q (sec/m')

Control Room (0-8 hr) 2.930E-03 Site Boundary (0-2 hr) 2.232E-04 )

Low Population Zone (0-8 hr) 3.977E-05 Control Room Variables l Emergency Zone Volume (ft') 127600 Normal In/ Outflow (ft'/ min) 2500 l Isolation Delay (sec) 10 Filtered Recirculation Flow (ft'/ min) 2500 Unfiltered Inteakage (ft 2/ min)

! 200 l Charcoal Filter Efficiency 90 Purge Flow (ft'/ min) 6500 Dose Conversion Factors ICRP-30 l

Breathing Rate (m'/sec) 3.47E-04 GBNUCi N WROUP\NUCIIARiWPFIIBd.!ONROPA132A.WPD

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• - Document Control Desk l April 7,1998 i Attachme'nt 1, Page 4 l l

TABLEl

, EHA_OEESITEACONTROL. ROOM. DOSES i

Committed.Doselquivalent Location to_ Thyroid.(Rem)

[ Control Room (0-8 hr) 39.6 i

l Site Boundary (0 2 hr) 48,7 Low Population Zone (0-8 hr) 8.7 l

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