ML16341G356
| ML16341G356 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/04/1991 |
| From: | Rood H Office of Nuclear Reactor Regulation |
| To: | Shiffer J PACIFIC GAS & ELECTRIC CO. |
| References | |
| IEB-88-008, IEB-88-8, TAC-M69623, TAC-M69624, NUDOCS 9111250112 | |
| Download: ML16341G356 (14) | |
Text
Docket Nos.
50-275 and 50-323 November 4, i99i Mr. J.
D. Shiffer Senior Vice President Nuclear Power Generation Pacific Gas and Electric Company 77 Beale Street, Room 1451 San Francisco, California 94106
Dear Mr. Shiffer:
DISTRIBUTION Docket File, NRC 5 LPOR PD5 Reading BBoger MVlrgi1lo TQuay HRood RCesaro JNor berg TChan OGC EJordan ACRS (,10)
PDV p/f CYCheng PMorrill, RV
- H14ong, RV PMorrill, RV RZimmerman, RV
SUBJECT:
NRC BULLETIN 88-08 "THERh%L STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS" (TAC NOS.
69623 AND 69624)
By letters dated September 6, 1988, December 19,
- 1988, and January 4, 1990, the Pacific Gas and Electric Company (PGKE) responded to NRC Bulletin 88-08.
Your response stated that a review was performed of piping connected to the Diablo Canyon Unit Nos.
1 and 2 reactor coolant systems.
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 response is consistent with modification or monitoring alter natives stated in the Bulletin.
Although no response was required related to Supplement 3 of the Bulletin, some licensees have addressed Supplement 3 in response to the Bulletin.
Those who have not will not be required to provide a specific response to Supplement 3.
However, you are reminded that, having been informed of the phenomenon identified in that supplement, you are responsible for adequate review of both its applicability to your plant and any considered actions.
The NRC staff may audit or inspect the implementation of Bulletin 88-08 and its supplements at a later date.
Enclosure 1 contains information that you may use to assess the adequacy of your program with respect to Action 3 of the Bulletin, and Supplement 3.
Therefore, you meet the requirements of NRC Bulletin 88-08, and no further action is required.
This completes our action on TAC Nos.
69623 and 69624.
Sincerely, Original signed by
Enclosure:
As stated cc:
See next page Harry Rood, Senior Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation DRPM/P
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Pocket Nos.
50-275 and 50-323 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 November 4, 1991 Mr. J.
D. Shiffer Senior Vice President Nuclear Power Generation Pacific Gas and Electric Company 77 Beale Street, Room 1451 San Francisco, California 94106
Dear Mr. Shiffer:
SUBJECT:
NRC BULLETIN 88-08 THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEMS" (TAC NOS.
69623 AND 69624)
By letters dated September 6, 1988, December 19,
- 1988, and January 4,
- 1990, the Pacific Gas anId Electric Company (PGSE) responded to NRC Bulletin 88-08.
Your response stated that a review was performed of piping connected to the Diablo Canyon Unit Nos.
1 and 2 reactor coolant systems.
The NRC stai'f 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 response is consistent'ith modification cr monitoring alternatives stated in the Bulletin.
Although no response was required related to Supplement 3 of the Bulletin, some licensees have addressed Supplement 3 in response to the Bulletin.
Those who have not will not be required to provide a specific response to Supplement 3.
However, you are reminded that, having been informed of'he phenomenon identified in that supplement, you are responsible f'r adequate review of both its applicability to your plant and any considered actions.
The NRC staff may audit or inspect the implementation of Bulletin 88-08 and its supplements at a later date.
Enclosure 1 contains information that you ma~
use to assess the adequacy of your program with respect to Action 3 of the Bulletin, and Supplement 3.
Therefore, you meet the requirements of NRC Bulletin 88-08, and no further action is required.
This completes our action on TAC Nos. 69623 and 69624.
Sincerely,
Enclosure:
As stated cc:
See next page Harry Roo, Senior Project Mianager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
~g ffpW
Mr. J.
D. Shiffer Pacific Gas and Electric Company Diablo Canyon CC:
Regional Administrator, Region V
U.S. Nuclear Regulatory Comnission 1450 Maria Lane, Suite 210 Walnut Creek, California 94596 Mr. Peter H. Kaufman Deputy Attorney General State cf California 110 West A Street, Suite 700 San Diego, California 92101 NRC Resident Inspector Diablo Canyon Nuclear Power Plant c/o U.S. Nuclear Regulatory Commission P. 0.
Box 369 Avila Beach, California 93424 Richard F. Locke, Esq.
Pacific Gas 5 Electric Company Post Office Box 7442 San Francisco, California 94120 Mr. John Hickman Senior Health Physicist Environmental Radioactive Mgmt. Unit Environmental Management Branct State Department of Health Services 714 P Street, P.oom 616 Sacramento, Gal iforni a 95814 Michael M. Strumwasser, Esq.
Special Assistant Attorney General State of California Department of Justice 3580 Wilshire Boulevard, Room 800 Los Angeles, California 90010 Managing Editor The Count~
Tele ram Tribune 1321 Johnson Avenue P. 0.
Box 112 San Luis Obispo, California 93406 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, California 93408 Ms. Sandra A. Silver Mothers for Peace 660 Granite Creek Road Santa Cruz, California 95065 Dr.
R.
B. Ferguson, Energy Chair Si erra Club Cali fornia 6715 Rocky Canyon Creston, California 93432 Ms.
Nancy Culver 192 Luneta Street San Luis Obispo, California 93401 Ms. Jacquelyn C. Wheeler 3303 Barranca Court San Luis Obispo, California 93401
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EVALUATION CRITERIA FOR RESPONSES TO NRC B
L LEMENT 3 Enclosure I 1.0 OBJECTIVE To provide continuing assurance for the life of the plant that unisolable sections of reactor coolant system (RCS) will not be subjected to stratification and thermal cycling that cause fatigue failure of the piping.
2.0 PURPOSE l.
To provide guidelines for evaluation of licensee responses.
2.
To provide acceptable procedures and criteria for preventing crack initiation in susceptible unisolable piping.
3.0 IDENTIFICATION OF POTENTIALLY SUSCEPTIBLE PIPING A.
Sections of injection piping systems, regardless of pipe size, which are normally stagnant and have the following characteristics:
1.
The source pressure is normally higher than the reactor coolant loop (RCL) pressure.
2.
Contain long horizontal runs.
3.
Are isolated by one or more check valves and a closed isolation valve in series.
4.
For sections connected to the RCL:
a.
Mater injection is top or side entry.
b.
The first upstream check valve is located less than 25 pipe diameters from the RCL nozzle.
Examples of such sections in PWRs are the safety injection lines and charging lines between the RCL and the first upstream check valve, and the auxiliary pressurizer spray line between the charging line and the main pressurizer spray line.
B.
Sections of.her piping systems connected to the RCL, regardless of pipe size, which are normally stagnant and have the following characteristics:
1.
The downstream pressure is normally lower than RCL pressure.
2.
Are isolated by a closed isolation valve, or a check valve in series with a closed isolation valve.
3.
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 source upstream of the isolation valve below the RCL pressure during normal operation.
2.
Relocation of the check valves closest to the RCL to be at a distance greater than 25 pipe diameters from the nozzle.
3.
Installation of temperature monitoring instrumentation for valve leakage detection.
A.
Section of locations.
a.
Temperature monitoring shou ld be performed by installing resistance temperature detectors (RTDs).
b.
RTDs should be located between first elbow (elbow closest to the RCL), and the first check valve (check valve closest to the RCL).
Co For the auxiliary pressurizer spray line, RTOs should be installed close to the "tee" connection to the main pressurizer spray line or in the cold portion (ambient temperature) of the line.
d.
RTDs should be located within six inches from the welds.
e'.
At each location a
RTD should be positioned on top and bottom of the pipe cross-section.
B.
Determination of baseline temperature histories.
After RTD installation, temperature should be recorded during normal plant operation at every location over a period of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The resulting temperature time-histories represent the baseline histories at these locations subject to the following conditions:
a.
The maximum top-to-bottom temperature difference should not exceed 50'F.
b.
Top and bottom temperature time-histories should be in-phase and not fluctuate by more than ~30'f.
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c.
If top-to-bottom temperature becomes out-of-phase, the bottom temperature should not fluctuate by more than 50'F.
C.
Section of monitoring time intervals.
a.
Monitoring should be performed at the following times:
l.
At the beginning of Mode 1 operation, after startup from a refueling shutdown 2.
At least a six-month intervals between refueling outages b.
During each monitoring period temperature readings should be recorded continuously for a 24-hour period.
c.
Temperature histories should correspond to the initially recorded baseline histories.
4.
Installation of pressure monitoring instrumentation for leakage detection.
A.
Selection of locations.
a.
Pressure monitoring should be performed by installing pressure transducers.
b.
Pressure transducer should be installed upstream and downstream of the first check valve.
B.
Selection of monitoring time intervals.
a.
Monitoring should be performed at the following times:
l.
At the beginning of Mode 1 operation, after startup from a refueling shutdown b.
2.
At least at six-month intervals, thereafter between refueling outages Pressure readings should be recorded continuously for a 24-hour period.
c.
Pressure fluctuation criteria.
No limits on pressure fluctuations are specified.
The only requirement is that the downstream pressure (RCL pressure) should be greater than the upstream pressure at all times.
r
NOTES: 1.
Pressure transducers could also be installed across the first closed isolation valve of injection piping in which case the downstream pressure (the pressure in the pipe segment between the isolation valve and the check valve) should be lower than the upstream pressure.
An equalization of pressure indicates leakage through the valve seat and eventual check valve cycling.
2.
Pressure monitoring is not recommended, since pressure measurements may not provide an accurate indication of events in the unisolable pipe sections.
- 5. 0 CORRECTIVE ACTIONS Corrective actions must be taken if the following conditions arise:
a.
Top-to-bottom temperature differences exceed 50'F.
b.
Top and bottom temperature time-histories become significantly out of phases.
c.
Bottom temperature osci llations exceed 50'F peak-to-peak.
d.
External leakage is detected in closed isolation valves.
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