ML17056B426
| ML17056B426 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point, Comanche Peak  |
| Issue date: | 10/02/1991 |
| From: | Brinkman D Office of Nuclear Reactor Regulation |
| To: | Sylvia B NIAGARA MOHAWK POWER CORP. |
| References | |
| IEB-88-008, IEB-88-8, TAC-69656, NUDOCS 9110100032 | |
| Download: ML17056B426 (16) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 October 2, 1991 Docket No. 50-410 Mr. B. Ralph Sylvia Executive Vice President, Nuclear Niagara Mohawk Power Corporation 301 P 1 a infie1 d Road
- Syracuse, New York 13211
Dear Mr. Sylvia:
SUBJECT:
NRC BULLETIN 88-08, "THERMAL STRESSES IN PIPING CONNECTEO TO REACTOR COOLANT SYSTEMS," NINE MILE POINT NUCLEAR STATION UNIT NO.
2 (TAC NO. 69656)
By letter dated September 28, 1988, Niagara Mohawk Power Corporation responded to NRC Bulletin 88-08.
Your response stated that a review had been performed of piping connected to the reactor coolant system and that no unisolable piping was identified that could be subject to thermal cycle fatigue from cold water leakage during normal plant operations.
In the cases of systems that have the potential to incur damage from cold water leakage during surveillance testing, you determined that test times are insufficient to cause thermal cycling fatigue stress.
The NRC staff and its consultant, Brookhaven National Laboratories, have completed the review of your response to Bulletin 88-08 and its supplements.
The staff has determined that your resp'onse is consistent with the modification or monitoring alternatives stated in the bulletin.
The NRC staff may audit or inspect the implementation of Bulletin 88-08 and its supplements at a later date.
The enclosure to this letter contains information that you may use to assess the adequacy of your program with respect to Action 3 of the bulletin, and Supplement 3.
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October 2, 1991 In summary, you meet the requirements of Bulletin 88-08 for the Nine Mile Point Nuclear Station Unit flo. 2.
This completes our activity related to TAC Number 69656.
Sincer ely,
Enclosure:
Evaluation Criteria Donald S. Brinkman, Senior Project Manager Project Directot ate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc w/enclosure:.
See next page
Mr. B. Ralph Sylvia Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit 2 CC:
Mr. Hark J. Wetterhahn, Esquire Winston 5 Strawn 1400 L Street, NW.
Washington, D.C. 20005-3502 Hr. Richard Goldsmith Syracuse University College of Law E. I. White Hall Campus
- Syracuse, New York 12223 Resident Inspector Nine Mile Point Nuclear Power Station P. 0.
Box 126
- Lycoming, New York 13093 Mr. Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 Hr. David K. Greene Manager Licensing Niagara Mohawk Power Corporation 301 Plainfield Road
- Syracuse, New York 13212 Ms. Donna Ross New York State Energy Office 2 Empire State Plaza 16th Floor
- Albany, New York 12223 Supervisor Town of Scriba Route 8, Box 382
- Oswego, New York 13126 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, Pennsylvania 19406 Charlie Donaldson, Esquire Assistant Attorney General New York Department of Law 120 Broadway New York, New York 10271 Mr. Richard H. Kessel Chair and Executive Director State Consumer Protection Board 99 Washington Avenue
- Albany, New York,12210 Mr. Hartin J.
McCormick Jr.
Plant Manager, Unit 2 Nine Mile Point Nuclear Station Niagara Mohawk Power Corporation P. 0.
Box 32
- Lycoming, NY 13093 Mr. Joseph F. Firlit Vice President - Nuclear Generation Nine Mile Point Nuclear Station Niagara Mohawk Corporation P. 0.
Box 32
- Lycoming, New York 13093
. ENCLOSURE EVALUATION-CRITERIA FOR RESPONSES TO NRC B
EMENT 3 1.0 OBJECTIVE To provide continuing assurance for the '1ife of the plant that unisolable sections of piping connected to the reactor coolant system (RCS) will not be subjected to thermal stratification and thermal cycling that could cause fatigue failure of the piping.
2.0 PURPOSE To provide guidelines for evaluation of licensee responses, including acceptable procedures and criteria to prevent crack initiation in susceptible unisolable piping.
3.0 IDENTIFICATION OF POTENTIALLY SUSCEPTIBLE PIPING (I)
Sections of injection piping systems, regardless of pipe size, which are normally stagnant and have the following characteristics:
A.
The pressure is higher than the RCS pressure during reactor power operation.
B.
The piping sections contain long horizontal runs.
C.
The piping systems are isolated by one or more check valves and a closed isolation valve in series.
D.
For sections connected to the RCS:
a.
Water injection is top or side entry.
b.
The first upstream check valve is located less than 25 pipe diameters from the RCS nozzle.
Examples of such sections in PWRs are the safety injection lines and charging lines between the reactor coolant loop and the first upstream check valve, and the auxiliary pressurizer spray line between the charging line and the main pressurizer spray line.
(2)
Sections of other piping systems connected to the RCS, regardless of pipe size, which are normally stagnant and have the following characteristics:
A.
The downstream pressure is lower than RCS pressure dur ing reactor power operation.
B.
The piping systems are isolated by a closed isolation valve, or a check valve in series with a closed isolation valve.
C.
There is a potential for external leakage from the isolation valve.
Examples of piping containing such unisolable sections in PWRs are the residual heat removal (RHR) lines.
Examples of such piping for BWRs are the RHR lines and the core spray injection lines.
4.0 ACCEPTABLE ACTIONS The following actions are considered as acceptable responses to Bulletin 88-08, Action 3 and Supplement 3,
as applicable, provided that the requirements of Bulletin 88-08, Action 2 have been satisfied.
(1)
Revision of system operating conditions to reduce the pressure of the water upstream of the isolation valve below the RCS pressure during power operation.
(2)
Relocation of the check valves closest to the RCS to be at a distance greater than 25 pipe diameters from the nozzle.
(3)
Installation of temperature monitoring instrumentation for detection of piping thermal cycling due to valve leakage.
A.
Type and location of sensors.
a.
Temperature sensors should preferably be resistance temperature detectors (RTDs).
b.
RTDs should be located between the first elbow elbow closest to the RCS, and the first check valve check valve closest to the RCS C ~
For the auxiliary pressurizer spray line, RTDs should be installed near the "tee" connection to the main pressurizer spray line or on She cold portion (ambient temperature) of the line.
d.
RTDs should be located within six inches of the welds.
e.
At each pipe cross section, one RTD should be positioned on the top of the pipe and another RTD on the bottom of the pipe.
B.
Determination of baseline temperature histories.
After RTD installation, temperature should be recorded during normal plant operation at every location over a period of 24
hours.
The resulting temperature versus time records represent the baseline temperature histories at these locations.
Baseline temperature histories should meet the following criteria:
a.
The maximum top-to-bottom temperature difference should not exceed 50'F.
b.
Top and bottom temperature time histories should be in-phase.
c.
Peak-to-peak temperature fluctuations should not exceed 60'F C.
Monitoring time intervals.
a.
Monitoring should be performed at the following times:
l.
At the beginning of power operation, after startup from a refueling shutdown 2.
At least at six-month intervals thereafter, between refueling outages b.
During each monitoring period, temperature readings should be recorded continuously for a 24-hour period.
D.
Exceedance Criteria.
Actions should be taken to modify piping sections or to correct valve leakage if the following conditions occur:
a.
The maximum temperature difference between the top and the bottom of the pipe exceeds 50'F.
b.
Top and bottom temperature histories are in-phase but the peak-to-peak fluctuations of the top or bottom temperatures exceed 60'F.
c.
Top and bottom temperature histories are out-of-phase and the bottom peak-to-peak temperature fluctuations exceed 50'F.
d.
Temperature histories do not correspond to the initially recorded baseline histories.
- 4 (4)
Installatioq of pressure monitoring instrumentation for leakage detection in injection lines.
(Pressure monitoring is not the preferred method since pressure measurements cannot provide a measurement of thermal cycling in the unisolable pipe sections.)
A.
Type and location of sensors.
a.
Pressure sensors should preferably be pressure transducers.
b.
Pressure transducers should be installed upstream and downstream of the first check valve.
c.
For systems having a pressure higher than the RCS pressure, pressure transducers may be installed upstream and down-stream of the first closed isolation valve.
(The downstream section is the pipe segment between the isolation va1ve and the check valve.)
B.
Monitoring time intervals.
a.
Monitoring should be performed at the following times:
l.
At the beginning of power operation, after startup from a refueling shutdown 2.
At least at six-month intervals ther eafter, between refueling outages b.
Pressure readings should be recorded continuously for a
24-hour period.
Exceedance criteria.
Actions should be taken to modify piping sections or to correct valve leakage if the following conditions occur:
a.
For pressure measurements across a check valve, the downstream pressure (RCS pressure) is equal to or less than the upstream pressure at any time during power operation.
b.
For pressure measurements across a closed isolation valve, the downstream pressure is equal to or greater than the upstream pressure at any time during power operation.
Mr. B. Ralph Sylvia October 2, 1991 In summary, you meet the requirements of Bulletin 88-08 for the Nine Mile Point Nuclear Station Unit No. 2.
This completes our activity related to TAC Number 69656.
S incere ly, Original signed by:
Enclosure:
Evaluation Criteria cc w/enclosure:
See next page DISTRIBUTION:
NRC 8 Local PDRs PDI-I Reading S.
Varga J.
Calvo J.
Menning D. Brinkman C.
Vogan OGC E. Jordan, MNBB 3701 ACRS (10)
Plant File C. Cowgill, RGN-I B. Mazafari, 14/B/20 M. Hartzman, EMEB Donald S. Brinkman, Senior Project Manager Project Directorate I-I Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation NAME
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