ML20196H177
| ML20196H177 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 07/16/1997 |
| From: | Hosmer J COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9707240152 | |
| Download: ML20196H177 (4) | |
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Commonweahh I:dison Company liyron Generating Station 445o North German Church Road flyron, II. 610149794 i
Tel 815-2365 Hi a
July 16,1997 United States Nuclear Regulatory Commission Washington, D.C. 20555 j
Attention: NRC Document Control Desk
Subject:
Byron Nuclear Power Station, Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66 NRC Docket Numbers: 50-454 and 50-455
" Supplemental Response to Request for Additional Information" l
References:
1.
J. Hosmer letter to the Nuclear Regulatory Commission dated January 31,1997, transmitting Technical Specification Amendment Request for Specific Activity i
2.
D. Lynch letter to I. Johnson dated May 2,1997, transmitting Rcquest for AdditionalInformation Pertaining to the Proposed j
Reduction in the Maximum Allowable Dose Equivalent Iodine-13 I Concentration 3.
J. Hosmer letter to the Nuclear Regulatory Commission dated May 23, 1997, transmitting Response to Request for Information.
Reference I transmitted the Commonwealth Edison Company's (Comed) request to amend the technical specification to allow for the reduction in the allowable dose equivalent iodine concentration in the reactor coolant for Byron Unit 1. Subsequent to that submittal, the Nuclear Regulatory Commission (NRC) issued a Request for Additional Information (RAI) (Reference 2).
Comed provided their response in Reference 3. The attachment supersedes Comed's response to RAI Question 1, which addressed the Murphy-Campe equation that was used in the determination of the maximum X/Q values.
The supplemental response differs from that previously submitted:
The table presented in Reference 3 response to Question I contained effective wind speeds (u-eff), not actual input value of the wind speed (u) as presented in the attached supplement to Question 1. An effective wind speed, "u-eff," is the input value of the wind speed, "u," adjusted to account for the containment diameter and the distance from the containment surface to the control room intake used in the Murphy-Campe Equation 6.
This was done in order to utilize the X/Q equation included in the computer code used at Comed and enable an assessment using the Murphy-Campe methodology.
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NRC Document Control Desk July 16,1997 l
_ Reference 3 states that Comed used an approach detailed in Meteorology and Atomic Energy -1968, Section 3-3.5.2; in actuality the X/Q model applicable to Byron and used in the UFSAR is taken from the Murphy-Campe paper..
j If you have any questions concerning this correspondence, please contact Denise Saccomando at (630) 663-7283.
Sincerely, J
John B Hosmer l
Engineering Vice President L
l Attachment cc:
D. Lynch, Senior Project Manager-NRR G. Dick, Byron /Braidwood Project Manger-NRR l
S. Burgess, Senior Resident inspector Byron A.B. Beach, Regional Administrator-RIII Office of Nuclear Safety-IDNS l
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ATTACHMENT REQUEST FOR ADDITIONAL INFORMATION RELATED TO TI:E PROPOSED REDUCTION IN THE BYRON UNIT 1 DOSE EQUIVA. LENT IODINE-131 NRC Ouestion # 1:
Table 6.4-la of the Byron Station UFSAR provides infoamation regarding the values of the atmospheric dispersion factors, X/Q, which are used in dose assessments when evaluating the control room habitability for design basis accidents. State what additional parameters and assumptions were used in your calculations to determine the various values of X/Q in Table 6.4-la. These parameters should include the wind speeds at the 5, 10, 20, and 40 percentile levels, values of sigma y and sigma z, the period over which the meteorological data was acquired, the wind directions used to calculate the X/Q values and, if appropriate, building measurements (i.e. diameter) and the building cross-sectional area. State which Murphy-Campe equation you used and your basis for the use of the applicable equation. Finally, provide the input parameters and assumptions you used in determining the maximum X/Q value over the time period of 0 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
Byron Response:
All additional parameters and assun.ptions used in determining Table 6.4-la X/Q are documented below.
The 5th percentile wind speed is 0.655 m/s which was obtained from a cumulative probability distribution anahsis using FSAR Table 2.3-25 meteorological data.
This table was compiled from on-site meteorology data collected over a three-year period of record (Jan.1,1974-Dec. 31,1976). The maximum X/Q value was determined to be that for winds blowing from the north containment (unit 2) in en easterly direction (98 degrees east of north) to the control room intake, located inside the Turbine Building, on the auxiliary building / turbine building common wall,100 feet distant (in plan view) from the containment surface. The turbine building structure is assumed to be non-existent.
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j; The percentile levels associated 'with time eriods are in accordance.with the l
Murphy-Campe paper presented at the 13 AEC Air Cleaning Conference in j-August 1974. Orly the data associated with the 5* percentile is used in the steam l
line break analysis. The remaining data is applicable to the control room dose l.
assessment for the Loss of Coolant Accident, which is considered to be an upper l
bound of all accidents postulated to occur per UFSAR Section 6.4.4.1. The wind speeds and associated data for each percentile level are as follows:
l Percentile Level Time Period (hr)
Wind Speed (m/sec) 5 0-8 0.655
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10 8-24 1.18 20 24-96.
'l.97 40 96 720 3.30 The X/Q'model applicable to Byron and used in the UFSAR LOCA assessments is derbed from equation 6 of the Murphy-Campe paper, This equation models the po#ated PWR LOCA single containment model where leakage from the comainment to the environment is assumed to be from a " porous" containment l
(the Murphy-Campe diffuse source) to the atmosphere and then to a point receiver
- [the control room air intake]. The equation below does not include the term wi6 l
values of sigma-y and sigma-z included in the Murphy-Campe Equation 6 because this term is negligible compared to A/(2+K) term. The equation used in the Byron LOCA control room assessment is:
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X/Q = [2+K]/uA, where
.1 K=3/(s/d)"
i s = distance from containment surface to the intake j
d = containment diameter A= the cross sectional area of the building causing the downwind turbulent' 2
wake =2700 m 1
For Byron, d = 147 feet and s = 100 feet. ' assumes turbine building is not in place.)
.Then K = 5.169 2
- X/Q =.[2t5.169]/(0.655 m/sec x 2700 m )
= 4.05E-3 sec/ m' '
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This X/Q model used does not require values of sigma y and sigma z and is considered to provide a conservative estimate of atmcspheric dispersion (X/Q) for the present analysis, given the complexity of multiple structures on site, and the 1
i location of the control room air intakes (within the turbine building).
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