ML18096A340
| ML18096A340 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 10/23/1991 |
| From: | Stone J Office of Nuclear Reactor Regulation |
| To: | Miltenberger S Public Service Enterprise Group |
| References | |
| IEB-88-008, IEB-88-8, TAC-M69680, TAC-M69681, NUDOCS 9111120093 | |
| Download: ML18096A340 (7) | |
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u Docket ~os. 50-272
- and 50-311 Mr. Steven E. Miltenberger Vice President and Chief Nuclear Officer Public Service Electric & Gas Company Post Office Box 236 Hancocks Bridge, New Jersey 08038
Dear Mr. Miltenberger:
October 23,
SUBJECT:
REVISED ENCLOSURE TO LETTER REGARDING NRC BULLETIN 88-08, 11 THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS, 11 SALEM NUCLEAR GENERATING STATION, UNITS 1 AND 2 (TAC NOS.P169680 ANDyf'ti9681)
By letter dated September 16, 1991, the staff informed you that your response to Bulletin 88-08 did not provide sufficient assurance that unisolable portions of all piping connected to the reactor coolant system would not be subjected to combined cyclic and static thermal and other stresses that could cause fatigue failure during the remaining life of the units. That letter contained criteria to help you in preparing an acceptable response.
Enclosed is updated criteria that was recently issued by the staff and should be used in preparing your response.
The updated criteria contains primarily editorial changes, therefore, the 90 day response time of the original request is still valid.
9111120093 911023 PDR ADOCK 05000272 Q
Enclosure:
Updated Criteria to Bulletin 88-08 cc w/enclosure:
See next page DISTRIBUTION Docket Fi le NRC & Local PDRs PDI-2 Reading SVarga JCalvo CMi 11 er JS tone MO'Brien(2)
RBlough, RGN-I JWhite, RGN-I Sincerely,
/SI James C. Stone, Senior Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation BMozafari TChan
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 Docket Nos. 50-272 and 50-311 Mr. Steven E. Miltenberger Vice President and Chief Nuclear Officer Public Service Electric & Gas Company Post Office Box 236 Hancocks Bridge, New Jersey 08038
Dear Mr. Miltenberger:
October 23, 1991
SUBJECT:
REVISED ENCLOSURE TO LETTER REGARDING NRC BULLETIN 88-08, "THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS, 11 SALEM NUCLEAR GENERATING STATION, UNITS 1 AND 2 (TAC NOS. 69680 AND 69681)
By letter dated September 16, 1991, the staff informed you that your response to Bulletin 88-08 did not provide sufficient assurance that unisolable portions of all piping connected to the reactor coolant system would not be subjected to combined cyclic and static thermal and other stresses that could cause fatigue failure during the remaining life of the units. That letter contained criteria to tle.. lp you in preparing an acceptable response.
Enclosed is updated criteria that was recently issued by the staff and should be used in preparing your response.
The updated criteria contains primarily editorial changes, therefore, the 90 day response time of the original request is still valid.
Enclosure:
Updated Criteria to Bulletin 88-08 cc w/enclosure:
See next page Sincerely, James C. Stone, Senior Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Mr. Steven E. Miltenberger Public Service Electric & Gas Company cc:
Mark J. Wetterhahn, Esquire Winston & Strawn 1400 L Street NW Washington, DC 20005-3502 Richard Fryling, Jr., Esquire Law Department - Tower 5E 80 Park P 1 ace Newark, NJ 07101 Mr. Calvin A. Vondra
- ~eneral Manager - Salem Operations Salem Generating Station P.O. Box 236 Hancocks Bridge, NJ 08038 Mr. S. LaBruna Vice President - Nuclear Operations Nuclear Department P.O. Box 236 Hancocks Bridge, New Jersey 08038 Mr. Thomas P. Johnson, Senior Resident Inspector Salem Generating Station U.S. Nuclear Regulatory Commission
., Drawer I Hancocks Bridge, NJ 08038 Dr. Jill Lipoti, Asst. Director Radiation Protection Programs NJ Department of Environmental Protection CN 415 Trenton, NJ 08£25-0415 Maryland People's Counsel American Building, 9th Floor 231 East Baltimore Street Baltimore, Maryland 21202 Mr. J. T. Robb, Director Joint Owners Affairs Philadelphia Electric Company 955 Chesterbrook Blvd., 51A-13 Wayne, PA 19087 Salem Nuclear Generating Station Richard B. McGlynn, Commission Department of Public Utilities State of New Jersey 101 Commerce Street Newark, NJ 07102 Regional Administrator, Region I U. S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406 Lower Alloways Creek Township c/o Mary 0. Henderson, Clerk Municipal Building, P.O. Box 157 Hancocks Bridge, NJ 08038 Mr. Frank X. Thomson, Jr., Manager Licensing and Regulation Nuclear Department P.O. Box 236 Hancocks Bridge, NJ 08038 Mr. David Wersan Assistant Consumer Advocate Office of Consumer Advocate 1425 Strawberry Square Harrisburg, PA 17120 Mr. Scott B. Lingerer MGR. - Joint Generation Projects Atlantic Electric Company P.O. Box 1500 1199 Black Horse Pike Pleasantville, NJ 08232 Mr. Jack Urban General Manager, Fuels Department Delmarva Power & Light Company 800 King Street Wilmington, DE 19899 Public Service Commission of Maryland Engineering Division ATTN:
Chief Engineer 231 E. Baltimore Street Baltimore, MD 21202-3486
Enclosure EVALUATION CRITERIA FOR RESPONSES TO NRC BULLETIN 88-08, ACTION 3 AND SUPPLEMENT 3
- 1. 0 OBJECTIVE To provide continuing assurance for the life 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
-~ *"
(1) 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.
- 8.
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 mafo 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 1s lower than RCS pressure during 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.
lGOlllK::~--*
------------------------------ 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 the 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 *ipe 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 sho~ld 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:
- 1.
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 S0°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 temperatur~ bistories are out-of-phase and the bottom peak-to-peak temperature fluctuations exceed S0°F.
- d.
Temperature histories do not correspond to the initially*
recorded baseline histories.
-- - - (4) Installation of pressure monitoring instrumentation for leakage detection in injection lines.
..J.
(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 valve and the check valve.)
- 8.
Monitoring time intervals.
- a.
Monitoring should be performed at the following times:
- b.
- 1.
At the beginning of power operation, after startup from a refueling shutdown
- 2.
At least at six-month intervals thereafter, between refueling outages Pressure readings should be recorded continuously for a 24-hour period.
C.
Exceedance criteria.
Actions should be taken to modify piping sections o~ 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.