ML20140G750

Forwards Rev 0 to Calculation 10040-U30-M01, CR & Offsite Atmospheric Dispersion Factors. Ltr Contains No New Commitments,Nor Does Mod Any Prior Commitments

ML20140G750
Person / Time
Site:	Monticello
Issue date:	05/05/1997
From:	Hill W NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20140G754	List: ML20140G750 ML20140G802
References
TAC-M96256, NUDOCS 9705120116
Download: ML20140G750 (5)

Text

Mr Northem States Power Company ,

Monticello Nuclear Generating Plant  !

2807 West Hwy 75

• Monticello. Minnesota 55362 9637 May 5,1997 ,

10 CFR Pad 50  ;

Section 50.90 US Nuclear Regulatory Commission Attn: Document Control Desk 1 Washington, CC 20555 IVONTICELLO NUCLEAR GENERATING PLANT l Docket No. 54263 License No. DPR-22 Supplementary Information to Revision Ona to License Amendment Req'iest Dated July 26,1996 i Reactor Coolant Equivalent Radiciodine Concentration and )

Control Room Habitability (TAC M96256) I 1

Monticello submittal dated July 26,1996 requested that the Operating License be amended and l propoced changes to the Technical Specifications, Appendix A of the Operating License, for the Monticello Nuclear Generating Plant. The proposed amendment changes Technical l Specification sections 3.6.C, Coolant Chemistry, and 3/4.17.8, Control Room Emergency

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Filtration System. In addition, changes were submitted for the bases for these sections. By i submittal dated April 11,1997, revision one to the July 26,1996 license amendment proposed to revise the reactor coolant radiciodine concentration specified in Technical Specification

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section 3.6.C, Coolant Chemistry, in response to evaluations performed of the radiological l consequences of a postulated line break in the Reactor Water Cleanup (RWCU) system.

As stated in the April 11,1997 submittal, the atmospheric 1persion (X/Q) factors used in the analyses provided in Exhibit D and Exhibit E of the April 11th submittal differ from these previously reviewed by the NRC staff and the methodology used to establish the atmospheric I dispersion factors would be provided if requested by the staff. During a phone conversation  !

conducted between members of the NRC staff and the Monticello plant staff on April 28,1997, l the staff requested that the report on which the atmospheric dispersion factors are based be i provided for staff review as well as the Monticello site meteorological data used to derive the atmospheric dispersion factors. Enclosure 1 to this letter is a copy of the report " Control Room and Offsite Atmospheric Dispersion Factors," Calculation 10040-U30-M01, Revision 0, excluding appendices and attachments. Enclosure 2 to this letter is a hard copy of the Monticello 1991 t

site meteorological data. A computer diskette containing the data provided in Enclosure 2 in an electronic ASCll text femat has been transmitted to the NRC-NRR Monticello Project Manager for use by the NRC staff as requested. ,

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l USNRC NORTHERN STATES POWER COMPANY May 5,1997 Page 2 The atmospheric dispersion factors provided in the April 11th submittal and discussed in Enclosure i to this letter were determined using the 1991 Monticello site meteorological data and the methodology of NUREGICR-5055, Atmospheric Diffusion for ControlRoom Habitability Assessments, by J.V. Ramsdell, Pacific Northwest Laboratory,1988; and Regulatory Guide 1.145, Atmospheric Dispersion Modeis for Potential Accident Consequence Assessments at NuclearPowerPlants, Revision 1, USNRC November 1982. The determination of the control room (X/Q) factors used the methodology of NUREG/CR-5055 for ground release from the Reactor Building plenum and the Turbine Building, and used the elevated stack release model from Regulatory Guide 1.145 for elevated releases from the plant Offgas Stack. The determination of offsite (X/Q) factors used the methodology of Regulatory Guide 1.145 for ground release from the Reactor Building plenum and the Turbine Building, and for the elevated releases from the plant Offgas Stack. The radiological consequence analysis provided in the April 11th submittal using the proposed Technical Specification value of 0.25 Ci/gm dose equivalent radiciodine and the atmospheric dispersion factors established by Enclosure 1 determined that the offsite dose consequences due to the evaluated postulated events to be less than 10% of the guidelines provided in 10 CFR Part 100 and within the guidelines of 10 CFR Part 50, General Design Criterion 19 for the control room operators.

The bases for the Technical Specifications state that radioiodine concentration can change rapidly in the reactor coolant during transient reactor operations such as reactor shutdown, reactor power changes and reactor startup if failed fuelis present. This phenomena is referred to as iodine spiking. The Monticello Technical Specification requirements established in specification 3.8/4.8.B " Gaseous Effluents" provide conservative licnits on gaseous effluents consistent with the guidelines established in 10 CFR 50, Appendix 1,

• Numerical Guides for Design Objectives and Limiting Conditions for Operation to Meet the Criterion 'As Low as Reasonably Achievable' for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents." The gaseous effluents subject to the requirements of specification 3.8/4.8.B are directly related to the reactor coolant radiciodine concentration. Maintaining off-gas releases to within acceptable values provides adequate operating constraints such that it is unlikely for transient reactor operations to result in radiciodine concentrations greater than the proposed Technical Specification value. Based upon Monticello's engineering judgment it is unlikely that l the postulated line break in the RWCU system will result in a reactor transient leading to a rapid l increase in reactor coolant radioiodine concentration. l While Monticello feels that a iodine spike is unlikely, a preliminary evaluation of the radiological I consequences of the postulated RWCU line break coincident with a postulated spike in the reactor coolant dose equivalent radiciodine concentration has been performed. This additional evaluation determined that the offsite dose consequences due to the evaluated postulated event to be less than the guidelines provided in 10 CFR Part 100 and within the guidelines of 10 CFR Part 50, General Design Criterion 19 for the control room operators. The evaluation of the postulated radiciodine spike used the radioiodine spike concentration provided in item II.B of Table 15.6-16 provided in the "ABWR Standard Safety Analysis Report," GE Report No.

23A6100, Revision 4, March 1994 (PDR ADOCK Accession No. 9404110236), with the postulated release corrected to account for steam flashing of the liquid release, radiciodine J

USNRC NORTHERN STATES POWER COMPANY May 5,1997 Page 3 plateout on Reactor Building surfaces, dilution of the reactor coolant radiciodine concentration due to continued reactor vesselinventory make-up, and dilution of the airborne radioiodine in the Reactor Building.

The information contained herein does not alter the Monticello finding of no significant hazards considerations provided in the submittal dated April 11,1997 performed in accordance with 10 CFR 50.91 using the standards of 10 CFR 50.92, nor does it alter the environmental assessment provided in the April 11,1997 submittal. This letter contains no new NRC commitments, nor does it modify any prior commitments.

Please contact Mary Engen at (612) 295-1291 if you require further information.

Jh William J Hill Plant Manager Monticello Nuclear Generating Plant c: Regional Administrator-lil, NRC NRR Project Manager, NRC Sr Resident inspector, NRC State of Minnesota, Attn: Kris Sanda Attachments: Affidavit to the US Nuclear Regulatory Commission l

Enclosures:

(1) " Control Room and Offsite Atmospheric Dispersion Factors," Calculation 10040-U30-M01, Revision 0, excluding appendices and attachments.

(2) Monticello Nuclear Generating Plant 1991 Meteorological Data )

UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 SUPPLEMENTARY INFORMATION TO REVISION ONE TO LICENSE AMENDMEN T REQUEST DATED JULY 26,1996 i REACTOR COOLANT EQUIVALENT RADIOlODINE CONCENTRATION AND I 1

CONTROL ROOM HABITABILITY (TAC M96256)  ;

Northern States Power Company, a Minnesota corporation, hereby provides supplementary l 4

information related to submittal dated April 11,1997, " Revision One To License Amendment j Request Dated July 26,1996, Reactor Coolant Equivalent Radioiodine Concentration and '

Control Room Habitability." This letter contains no restricted or other defense information. l NORTHERN STATES POWER COMPANY By /drN, 4 William JHitf' ~

Plant Manager

. Monticello Nuclear Generating Plant )

On this 5 day of M M i 9 97 before me a notary public in and for said County, personally appear 6d William J Hill, Plant Manager, Monticello Nuclear Generating Plant, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.

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Marvin R Engen / mo w yruaus.naa=saam Notary Public - Minnesota  ; .

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Sherburne County

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My Commission Expires January 31,2000

Enclosure 1 " Control Room and Offsite Atmospheric Dispersion Factors,"

Calculation 10040-U30-M01, Revision 0, excluding appendices and attachments.

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