ML18143A972
| ML18143A972 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 01/30/1976 |
| From: | Amish K Rochester Gas & Electric Corp |
| To: | Purple R Office of Nuclear Reactor Regulation |
| References | |
| Download: ML18143A972 (8) | |
Text
NRC Di,"-'rRIBUTION I=OR PART i0 DOCKET~IATERIAL
IEft/iPOIIABYFOllM)
Ql CONTROL NO:
1064 F I LE FROM Rochester Gas 8 Elec.
Cor Rochester, N.Y.
K.W. Amish
~ DATE Of= DOC 30-76 2-4-76 XXX DATE R EC'D LTR TWX RPT OTI.IE R TO:
R.A. Pur le ORIG 1 Signed 1/
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SENT I OCALPOR CLASS UNCLASS PROP INFO XXX INPUT NO CYS REC'D DOCI(',ET NO:
50- 244 (1 Copy Received)
.PLANT NAME:
RE Ginna 8
1 DESCRIPTION:
Ltr,. re their ltr. of 10-31-75..
= Information providing additional info regarding-fiaal determination of the changes to be made related to water hammerl....
W/attahced
.Schedule f Installation in 1976...
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RqllulatoT/J Zu)WI uixruZI ROCHESTER GAS AND ELECTRIC CORPORATION o
89 EAST AVENIJ CH N.Y. I r
KEITH W. AMISH eQ-~-
CXECIITIVEVICE PRESIDENT A~OE Tld /+6.270 (5
January 30, 19.
Director of Nuclear Reactor Regulation Attention:
Robert, A. Purple, Chief Branch No.
'1 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Purple:
Cv. ) '.A
'n our letter of October 31,
- 1975, we provided information con-cerning secondary system fluid flow instabilities
("water hammer").
That information was requested in your letter of May 13, 1975.
At the time we submitted our letter, final determination of the specific changes to be made at Ginna Station relative to "water hammer" had not been made.
The purpose of this letter is to pro-vide information concerning these changes.
Various administrative controls, steam generator mechanical modi-fications, and piping support. modifications were evaluated to determine their effectiveness in either preventing the occurrence of "water hammer," or reducing its consequences should it occur.
ln evaluating these
- changes, we considered the effect of other changes to the plant which have been or are being made; and the overall reliability and integrity of the steam generators.
Xt is our determination that the best alternative currently avail-able for precluding "water hammer" is administrative control of auxiliary feedwater flow.
As discussed in our previous letter, "water hammer" has been found to occur during recovery of the steam generator feed rings while feedwater flows are above a
threshold value of approximately 200 gpm per generator.
The applicable operating procedures at Ginna Station have been revised to administratively limit auxiliary feedwater flow during recovery of the steam generator feed rings from normal and abnormal transients.
In these situations, the auxiliary feedwater flow rate to either steam generator will be limited to a maximum of 150 gpm by manual operator action from the main control board.
This limitation will apply when-ever steam generator level is below the low-low level set point, 15%
of narrow 'range, and until the level is recovered to 25%.
The limi-tation will not be applied in the event of safety injection system actuation involving steam generator levels far below the feed zing.
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ROCHESTER GAS AND EIECTRIC COR oATE January 30, 197f To Mr. Robert, R. Purple SHEET NO.
Also, the flow control instrumentation on the motor driven auxiliary feedwater pumps will continue to be set at a minimum of 200 gpm during normal plant operation.
Xt is judged that these limitations will adequately preclude "water hammer" since the low-low level set point.
is approximately 2 inches below the bottom of the feed ring and the 25% level is approximately 1 inch above the top of the ring.
A schematic of the present auxiliary feedwater system at Ginna Station is shown in Attachment A.
The system consists of three
- pumps, two motor driven and one turbine driven; and two separate, interconnected piping systems from the pumps to the main feedwater lines.
The drawing shows the valves in the positions for normal plant operation.
Control of auxiliary feedwater flow rate is achieved either through motor operated valves 4007 and 4008 or pneumatically operated valves CV-54 and CV-55. All of these valves are normally in the full open position.
Upon receipt of a signal for pump start, valves 4007 and 4008 are automatically throttled by the flow control system shown to a flow of 200 gpm or more.
The flow control system can be manu-ally over-ridden to achieve lower flow rates through valves 4007 and 4008 by a switch on the main control board.
The flow rate through valves CV-54 and CV-55 can be varied manually from a control station on the main control board.
The flow from the motor driven auxiliary feedwater pumps can be directed through valves CV-54 and CV-55 by opening valves 4000A or 4000B, and 4359 and 4360; and closing valves 4007 and 4008.
The flow rate through all 4 auxiliary feed-water lines can be monitored by flow indicators on the main control board.
Very t uly yours, eith W. Amish Executive Vice President KWA:af Attachment
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