ML20032E285
| ML20032E285 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 11/11/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20032E286 | List: |
| References | |
| TAC-47142, NUDOCS 8111200281 | |
| Download: ML20032E285 (2) | |
Text
of a
DUKE POWER COMPANY power 131:n. DING 422 Sorris Curuct Srnrer. CiutunrTE. N. C. 20242 wiway o. am p u a. a m.
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November 11, 1981
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hk. Harold R. Denton, Director Office of Nuclear Reactor Regulation to j
U. S. Nuclear Regulatory Commission A
Washington, D. C.
20555 4
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S Attention:
Ms. E. G. Adensam, Chief NOVJ. b 19 % j Licensing Branch No. 4
" %~*** p 2
Re: McGuire Nuclear Station Docket Nos. 50-369 3
Dear Mr. Denton:
Attached is a proposed change to the McGuire - Unit 1 Technical Specifications concerning the minimum measured Reactor Coolant System flowrate.
This item has been reviewed and it has been determined that there are no adverse safety or en-vironmental impacts associated with the proposed change.
The proposed amendment is considered to be a Class III amendment pursuant to 10CFR 170.22.
Therefore, enclosed is a check in the amount of $12,300.
Ve truly yours, n
O.
William O. Parker, Jr.
GAC/smh Attachment cc:
M. J. Graham Mr. James P. O'Reilly, Director Resident Inspector U. S. Nuclear Regulatory Conmission McGuire Nuclear Station Region II 101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 i
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8111200281 811111 l
DR ADOCK 050006y d
Mr. Harold R. Denton, Director Page 2 November 11, 1981 WILLIAM 0. PARKER, JR., being duly sworn, states that he is Vice President of Duke Power Company; that he is authorized on the part of said Company to sign and file with the Nuclear Regulatory Commission this revision to the McGuire Nuclear Station Technical Specifications, Appendix A to License No. NPF-9; and that all statements and matters set forth therein are true and correct to the f
best of his knowl ge.
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William O. Parker, Jr., @ e President Subscribed and sworn to before me this lith day of November, 1981 Ya 0-liotary Public' My Commission Expires:
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1 Technical Specification 3/4.2.3 - RCS Flowrate and Nuclear Enthalpy Rise-Hot Channel Factor Proposed Change Revise Figure 3.2-3 to lower the minimum Reactor Coolant System flowrate to 383,500 gpm for operation at or below 90% Rated Thermal Power. This value corresponds to 95% of thermal design flow plus measurement uncer cainties of 3.5%.
Justification and Safety Analysis Preliminary measurements of total RCS flow at McGuire Unit 1 indicate that the measured flow may be less than the Thermal Design Flow used in the plant acci-dent analyses. The Technical Specifications allow a finite time period in which to restore RCS flow to above the minimum required value; however the time period is based on the assumption that the low. flow is due to time limited local effects, e.g. grid voltage / frequency dips. The indications at McGuire are not believed to be due to grid or flow fluctuations, but rather the re-sults of actions taken to increase core bypass flow to lower upper head tempera-ture to T.
c In the event the RCS flow is actually verified to be less than Thermal Design Flow, the plant Technical Specifications are quite specific in action to be taken. However the Technical Specifications do not recognize the possibility of a long term reduction in flow, nor the relationships between flow and DNB or flow and core power which allow various trade-offs. These trade offs allow continued operation at some reduced flow and a corresponding reduction in allowed maximum power.
It is widely recognized that there are relationships between core power, flow, and DNS as noted below:
3 Flow 1][
(Eq. 1) 3 DNB 1%
3 Power 1%
3 DNB 1.8%
(Eq. 2) thus the relationship between Power and Flow is:
l 3 Power 1%
(Eq. 3) 3 Flow 1.8%
As a result of the above noted relationships and a conservative assumption (based on current indications) that the verified RCS flow will be no lower than 0.95 of Thermal Design Flow it is proposed that McGuire Unit 1 be op-erated at a maximum power level of 90% of Rated Thermal Power (3070 MWeh core power) in the event that measured flow is less than Thermal Design Flow (plus measurement uncertainty).
This reduction in core power is the equivalent of an RCS flow increase of ap-8111200284 811111 PDR ADOCK 05000369 P
pg o
.)
proximately 18% in terms of margin to DNB. Since the expected flow deficit is 5% or less, the actual result in the power reduction is an increase of ap-proximately 13% in terms of margin to DNB.
Operation of the plant within this power restriction results in no increase in T
thus there is no temperature impact in terms of margin to DNB.
avg McGuire Unit l's Technical Specification limits -and accident analyses results have been evaluated to determine the impact of the RCS flow and power reduc-tions. In all cases sufficient margin exists to allow plant operation at the reduced power level. No Technical Specification limits require modification, including core limits, OTAT, OPAT, and Power Range Neutron Flux - High, High setpoint.
The core limits re=ain the same due to the increased margin to DNB afforded by the power reduction and interpretation that they are now valid for 3070 MWth instead of 3411 Mhun. This implies that 3070 MWth should be considered to be 1.0 in fraction of Rated Thermal Power for Figure 2.1-1.
With no change in the core limits the OTAT and OPAT trip setpoints remain unchanged. Utilizing the latest Westinghouse data, the uncertainty in the instrumentation for the Power Range Neutron Flux - High trip function is 4.7% span (or 3.6% RTP). With a normal assumption of reactor trip at 109% RTP the uncertainty analysis veri-fies that a trip will take place at 109% RTP plus 5.6% RIP, or 114.6% RTP. A
{
5% reduction in RCS flow requires a trip at 115.2% RTP, thus adequate margin exists in the instrumentation such that no change in the nominal setpoint is necessary.
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