ML20069D442
| ML20069D442 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 03/14/1983 |
| From: | Bayne J POWER AUTHORITY OF THE STATE OF NEW YORK (NEW YORK |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| JPN-83-10, JPN-83-25, NUDOCS 8303180375 | |
| Download: ML20069D442 (5) | |
Text
1 POWER AUTHORITY OF THE STATE OF NEW YORK a
10 CoLUMaus CIRCLE.
N EW YORK. N. Y.10019 (2123 397 6200 LEROY W. SINCLAIR Ers=atiU erYa=
TRUSTEES
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dOHN S. DYSON r ow v am ut va
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ne e acessme vnavsys GEORGE L. ING ALLS March 14, 1983
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JPN-83-25 RICH ARD M. FLYNN NOesRT '. MILLONZE se som vec pa s seos mi
& GENE R AL Coupes.L J AMES L. LAROCC A I
l Director ot Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Attention:
Mr. Domenic B. Vassallo, Chief Operating Reactors Branch No. 2 Division of Licensing
Subject:
James A. FitzPatrick Nuclear Power Plant Docket No. 50-333 Revision to Performance Evaluations of the Reactor Coolant and Main Steam Line Tunnel Leakage Detection Systems
Reference:
PASNY letter, J.
P. Bayne to D.
B.
- Vassallo,
" Performance Evaluations of the Reactor Coolant and Main Steam Line Tunnel Leakage Detection Systems,"
dated February 2, 1983 (JPN-83-10).
Dear Sir:
The enclosure to the referenced letter incorrectly stated that control room annunciator trip points were verified as part of the monthly functional test for the Reactor Coolant Leakage Detection System.
In addition, the letter incorrectly stated that the identified leakage rate at the equipment drain sump is limited to 20 gpm.
Rather, the Technical Specifications place a limit on total leakage (identified plus unidentified) of 25 gpm.
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Lastly, the evaluation of the Main Steam Line Tunnel Leak Detection system stated that.each temperature sensor is set to i
initiate a. Main-Steam Isolation Valve closure.
In actuality, each sensor is connected to a logic' system such that any single failed sensor will not cause a valve closure.
A. revised attachment for the referenced letter, with appropriate corrections, is-enclosed.
If you have any questions, please contact Mr. J. A. Gray, Jr. of my staff.
Very.truly yours, 4
(l' l
2-y,,
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N -8xecutive V e President Uuclear Generation i
ec: Mr. J. Linville Resident Inspector U.S. Nuclear Regulatory Commission P.O.
Box 136 Lycoming, New York 13093
p-1 MARCH 7, 1983 REVISED ENCLOSURE 1X) JPN-83-10, SUBMITTED FEBRUARY 2, 1983 POWER AUTHORITY OF THE STATE OF NEW-YORK JAMES-A. FITZPATRICK NUCLEAR POWER PLANT PERFORMANCE EVALUATIONS OF THE' REACTOR COOLANT'AND MAIN STEAM LINE TUNNEL LEAKAGE DETECTION SYSTEMS Reactor Coolant Leakage Detection System-(RCLDS)
'The RCLDS is designed to detect abnormal leakage from the Reactor Coolant Pressure Boundary.
Limits are established on identifiable and unidentifiable liquid leakage.
Both identified and unidentified leakage'in excess of limits is annunciated in the control room.
Sources of leakage in the drywell are generally classified by the drain sump to which leakage is directed.
Identified liquid leakage is~definad as the sum of leakage from the-recirculation pumps, the. reactor vessel head seal and all major-valve seals.
This leakage is piped to the equipment drain cump.
1 The identified leakage rate at the equipment drain sump, is measured daily and avereges ? to 5 gpn during normal operation.
A monthly functi nel test is pe.rformed for the flow rate instrumentation to verify its or,erability.
The ir.strument is calibrated every quarter.
Unidentified liquid leakage is defined as all Reactor Coolant I
Pressure Boundary' leakage not originating from the identified sources _above.
Unidentitied leakage, limited to 5 gpm,-flows to the drywell floor drain and is surveyed daily.
This leakage generally averages 1-2 9pm during normal operation.
A monthly functional' test i.
His performed for the instrumentation to verify its operability.
The I
' instrumentation is calibrated every quarter.
I Lastly, a Continuous Drywell Atmosphere Sampling System-(which monitors gross particulate,' iodine and noble gas activities) and a continuous drywell pressure detection system further ensure that-
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leakage from the Reactor Coolant Pressure Boundary will not go
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undetected.
Main Steam Line Tunnel Leak Detection System l
The Main Steam Line Tunnel Leak Detection System consists of 16
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temperature sensors.
The sensors are physically grouped into a series of four sensors per steam line, each separated by intervals
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of approximately 20 feet.
Signals for closing the MSIV's are produced at'a temperature of 40*F above the maximum steam tunnel ambient temperature of 160*F.
The 16 detectors are grouped in four l
separate channels (A, B,
C, and D) for a one-out-of-two-twice logic.
All'MSIV's are automatically closed when the main steam isolation logic receives one or more input signals from either I
channel A or C plus one or more input signals ~from either channel B or D.
As. set, the sensors can detect a steam leak on the order of 3500 lbs/hr.
The temperature measurements of each temperature i_
sensor are recorded daily.
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Functional tests for the leak detectors are performed monthly, and each sensor is calibrated once per operating cycle.
For conservatism, trip points are set at 190*F for the detectors, 10*F below the maximum allowed temperature of 200*F.
Forced Shutdowns Due to Leakage Since the initial startup of the FitzPatrick plant, there have been three instances in which Reactor Coolant Pressure Boundary Leakage beyond the established leakage rates occurred.
In all cases the Reactor Coolant Leakage Detection System performed as expected, prompting operatore tc shut down the plant to investigate the cause of the leskege and make appropriate repairs.
'2he first two events occurred in April 1970 and are described in the FitzPatrick Operating Status Feport for that month, sutgitted to the NRC on May 3, 1978 (JAFP-78-216).
On April 18, 1978, operators commenced a nurmci shutdown to investigate unidentified drywell floor drain leakage annunciated by the RCLDS.
The peak reading taken from ficw rate instrumentation was 4.51 gpm on April 17, rhich is below the maximum allowed rate of 5 gpn.
After corrective cetions were taken, the reactor was restarted and the unidentified leakage rate declined to less than 1.5 gpm in subsequent dcily readings.
On April 26, 1978, operators manually scrammed the reactor to investigate leakage into the drywell equipment drain sump.
Reactor Coolant System leaks to the containment were identified and corrective maintenance was performed.
In addition, a leak in the drywell equipment sump cooler was identified as a source of water to the sump and maintenance was performed.
The highest reading taken from the flow rate instrumentation, following annunciation in the control room, was 25.86 gpm, which exceeded the allowable 20 gpm, demanding corrective action.
In the third incident, on April 1, 1981, operators shut down the reactor when the RCLDS indicated a leakage rate limit was being exceeded by about 5 gpm.
The source of leakage was determined to be a failure of the "A" recirculation pump seal.
Within 20 minutes after shutdown, the defective pump was isolated and leakage was brought to within the limits.
The seal was subsequently replaced.
This incident is described in the FitzPatrick Operating Status Report for April 1981, submitted to the NRC on May 7, 1981 (JAFP-81-0464).
These incidents, coupled with monthly functional tests of the Drywell Equipment Drain Sump flow instrumentation and the Drywell Floor Drain Sump flow instrumentation, demonstrate the operability and effectiveness of both the identified and the unidentified leakage detection systems for the Reactor Coolant Pressure Boundary.
3-Main Steam Line Tunnel leakage exceeding allowed limits has never occurred at the FitzPatrick plant.
Hence, the steam tunnel; leakage detectors have never initiated a reactor shutdown.
However, the monthly functional tests, in which instrument trip points are surpassed by heating the local environment around each sensor, ensure that the detectors can indeed function as intended.
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