ML20153A975
| ML20153A975 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 09/15/1998 |
| From: | Barron H DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-M97262, TAC-M97263, NUDOCS 9809220254 | |
| Download: ML20153A975 (4) | |
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g Duk) Energy C rpor; tion Vy]< g I
McGuire Nuclear Station 12700 Hagers Ferry Road l
Huntersville, NC 28078-9340 (704) 875-4800 omCE
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(704) 875-4809 MX I
September 15, 1998 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.
20555
Subject:
McGuire Nuclear Station Docket Nos. 50-369, 370 Supplemental Information TAC Nos. M97262 and M97263 This letter transmits information related to a proposed technical specification amendment for McGuire Units 1 and 2 that.would allow continued unit operation at elevated lower containment temperatures for a period not to exceed 72 cumulative hours. Submittal of this information was requested by the NRC during a teleconference discussing the subject amendment.
There are no regulatory commitments contained in this submittal. Any questions related to this matter should be directed to Julius Bryant, McGuire Regulatory Compliance at (704) 875-4162.
Skm H.B.
Barron, Vice President McGuire Nuclear Station 1
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9309220254 990915 PDR ADOCK O 369 s
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U'.S. Nuclear Regulatory Commission I:
l Document Control! Desk r
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-_L.A.,Reyes,:. Regional: Administrator' U.S.1 Nuclear Regulatory Commission T Region.!II1
. Atlanta" Federal Center 151: Forsyth St., ) SW, Suite 23T85'
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. Atlanta, GA-30323' i
Frank Rinaldi, Project. Manager U.S. Nuclear RegulatoryLCommiss' ion--
Office:of Nuclear Power Regulation.
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Washington, D.C. 20555 1
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Scott Shaeffer Senior Resident Inspector McGuire' Nuclear: Station.
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' Attachment j
~Page 1 of 2 Supplemental Information Related To TAC Nos. M97262 and M97263 l
Modeling Structure For Containment Temperature Analysis The GOTHIC model used in the steam line break analysis to l
justify an initial lower containment temperature (LCT) of 135 F is identical to that utilized in Chapter 6 of the DPC-NE-3004-PA topical report.
A three-dimensional lower containment mesh is used in both instances.
Nodalization (RETRAN, GOTHIC)
The same nodalization detail is used in the GOTHIC model for the 135 F LCT as in the earlier DPC-NE-3004-PA steam line break analysis. The mass and energy release data for the GOTHIC analyses is generated by the RETRAN code.
The same mass and energy release data was used in the 1350F LCT case as was used in the topical report case (It was unnecessary to re-run the RETRAN analysis as a result of the increased LCT assumption).
Initial Conditions The initial conditions assumed in the GOTHIC steam line break analyses'are the maximum allowable values per McGuire Tech Specs.
They are:
Upper Containment Temperature =
100oF, Lower Containment Temp = 135oF(proposed), Ice condenser temp = 30 F.
(Note:
the actual ice bed maximum temperature allowed per Tech Specs is 27 F, so the assumed ice bed temperature in the analysis is conservatively higher j
by 3 F.)
The containment pressure is assumed to be 0.3 psig j
throughout the containment building (This is also equal to the maximum allowable Tech Spec value).
Pressure / Temperature Response The effect of an increased LCT initial value of 135 F on the containment response to a main steam line break is very slight compared with the case of an initial LCT of 120 F.
The peak break compartment temperature increase is less than 1 degree oF higher for the 13SoF case (from 316oF to 317oF).
The maximum average lower containment temperature remains at about 302oF for both cases. These peaks occur about 22 seconds into the transient. Since the peak temperature is driven by superheat, the higher initial LCT has a limited impact on the temperature response.
a Attachment Page 2 of.2
- The' peak pressure following a steam line break actually-
' decreases slightly for the case with an initial LCT of.
135'F.
This.is due to the lower air mass in lower containment for the higher initial LCT (assuming the same initial pressure and relative humidity level from the' case with.an' initial LCT of 120 F).
The value of the peak pressure decreases from 6.9 psig (for 120oF LCT case) to 6.6 psig (for 135 F initial LCT. case).
Relative' Humidity Assumption The assumed initial relative humidity in all cases analyz'ed' is 100%.
This maximizes the initial water vapor present-in the containment atmosphere and increases all temperatures later in the transient. There is no' Tech Spec requirement on humidity levels in~ containment. Actual humidity levels inside the containment building are generally much lower than this. The containment response following a LOCA/SLB is relatively insensitiveft-o changes in this parameter.
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