ML17306B409
| ML17306B409 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 04/20/1993 |
| From: | Trammell C Office of Nuclear Reactor Regulation |
| To: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| References | |
| IEB-88-008, IEB-88-8, TAC-M69664, TAC-M69665, TAC-M69666, NUDOCS 9304260297 | |
| Download: ML17306B409 (10) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 205554001 April 20, 19'3042e0a97 9aoeao PDR ADOCK 05000528 8
PDR Docket Nos. 50-528, 50-529 and 50-530 Hr. William F.
Conway Executive Vice President, Nuclear Arizona Public Service Company P.O.
Box 53999
- Phoenix, Arizona 85072-3999
Dear Hr. Conway:
SUBJECT:
EVALUATION OF THE RESPONSE BY ARIZONA PUBLIC SERVICE COMPANY TO NRC BULLETIN 88-08, "THERMAL STRESSES IN PIPING CONNECTED TO REACTOR COOLANT SYSTEHS" (TAC NOS. H69664, H69665 AND H69666)
In your letter of January 15, 1992, Arizona Public Service Company (APS) provided a response to a request for additional information from the NRC dated October 18,
- 1991, and an updated status of the APS response to Bulletin 88-08, for the Palo Verde Nuclear Generating Station, Units 1, 2 and 3.
APS indicated in the January 15 response that the Auxiliary Pressurizer Spray System (APSS) is the only system susceptible to the phenomena described in the Bulletin.
In response to Action 3 of the Bulletin, APS instituted a
temperature monitoring program of the APSS piping in Unit 3 by installing thermocouples adjacent to the APSS pipe tee and the first upstream check valve.
Temperature data was recorded in one-minute intervals over the Unit 3 second operating cycle including the entire reactor coolant system heatup and
- cooldown, as well as during normal steady state operation.
The data revealed large diametral temperature differences, in the range of 60'F to 115'F, in the APSS 2" diameter piping.
These temperature differences occurred during heatup and cooldown, with the reactor coolant pumps secured.
The data did not reveal large fluctuations in temperature which would represent a leaking control valve or an oscillating control valve.
The licensee stated that it is not clear from the data whether the observed temperature differences represent thermal stratification due to in-leakage, thermocouple bias, insulation effects, or a pressurizer steam convective cooling phenomenon.
An assessment of this data, as well as normal operating
- data, was scheduled for completion by July 31,
- 1992, and would serve as the basis for a bounding ASME Code stress analysis to determine the long-term effects of the observed temperature differences.
No information has been provided on this assessment.
APS has adopted the position that the monitoring results of the APSS do not clearly indicate the existence of valve in-leakage from the charging
- system, and therefore that the implementation of a permanent APSS temperature or pressure monitoring system is not required.
APS has discontinued temperature monitoring at six-month intervals, and it is unclear from the submittal if any
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,I
Hr. William F.
Conway monitoring is being performed.
APS has therefore proposed to evaluate alternative procedures such as valve internal inspections, leak rate testing or portable temperature monitoring.
Since selection of additional monitoring programs to provide continuing assurance of APSS operability are largely dependent on knowledge of the process conditions, APS stated that it anticipated that a decision on the impl'ementation of additional long-term surveillance activities will be completed by December 31, 1992.
The licensee has not provided any information on this decision or the nature of these long-term activities.
APS has concluded that to determine the actual effects of thermal stratification and thermal cycling it needs to redefine the transients associated with the APSS piping.
APS stated that it will perform a bounding thermal stratification analysis assuming worst case bending moments associated with the top-to-bottom temperature differences observed in the Unit 3 monitoring program and an assumed hydraulic condition, to serve as a baseline in determining the need for future corrective actions.
This analysis was scheduled for completion by October 30, 1992.
The licensee has not provided any information regarding this analysis.
Based on our review of the APS submittal, we conclude that adequate assurance has not been provided for continued operation of the APSS for the life of the
- plant, as requested by Action 3 of the Bulletin. The licensee has as yet not determined the cause of the high thermal gradients observed in the APSS piping, nor determined its effect on the fatigue life of the APSS system.
The licensee has stated that the operability of the APSS will be assured by performing inservice inspections of the check and isolation valves.
Inservice inspection as a means of providing assurance of continuing operation is not listed as an acceptable option of Action 3.
We request that until the issues associated with the Bulletin are satisfactorily resolved, the licensee provide this assurance in accordance with the guidelines provided in our letter of October 18, 1991.
Based on the foregoing, it is clear that NRC needs an update on where APS stands with respect to this issue, as well as responses to the commitments contained in the APS letter of January 15, 1992.
.We request that you provide at least a partial response within 60 days of your receipt of this letter, and a schedule for the submittal of any remaining information.
0 t)
~ Mr William F.
Conway This request for information affects fewer than 10 respondents.
Therefore, it is 'not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact us should you have any questions regarding this request.
Sincerely, cc:
See next page Charles M. Trammell, Senior Project Manager Project Directorate V
Division of Reactor Projects III/IV/V Office of Nuclear Reactor Regulation
r Hr. William F.
Conway Arizona Public Service Company Palo Verde CC:
Hr. Steve Olea Arizona Corporation Commission 1200 M. Washington Street
- Phoenix, Arizona 85007 James A. Beoletto, Esq.
Southern California Edison Company P. 0.
Box 800
- Rosemead, California 91770 Senior Resident Inspector U.S. Nuclear Regulatory Commission HC-03 Box 293-NR Buckeye, Arizona 85326 Regional Administrator, Region V
U. S. Nuclear Regulatory Commission 1450 Haria Lane Suite 210 Walnut Creek, California 94596 Hr. Charles B. Brinkman, Hanager Washington Nuclear Operations ABB Combustion Engineering Nuclear Power 12300 Twinbrook Parkway, Suite 330 Rockville, Haryland 20852 Hr. William A. Wright, Acting Director Arizona Radiation Regulatory Agency 4814 South 40 Street
- Phoenix, Arizona 85040 Chairman Haricopa County Board of Supervisors ill South Third Avenue
- Phoenix, Arizona 85003 Jack R.
- Newman, Esq.
Newman 5 Holtzinger, P.C.
1615 L Street, N.M., Suite 1000 Washington, D.C.
20036 Hr. Curtis Hoskins Executive Vice President and Chief Operating Officer Palo Verde Services 2025 N. 3rd Street, Suite 220
- Phoenix, Arizona 85004 Roy P.
Lessey, Jr.,
Esq.
Bradley M. Jones, Esq.
Akin, Gump, Strauss, Hauer and Feld El Paso Electric Company 1333 New Hampshire Ave., Suite 400 Washington, D.C.
20036
il
Hr. William F.
Conway April 20, 1993 This request for information affects fewer than 10 respond'ents.
Therefore, it is not subject to Office of Management and Budget review under Pub.
L.96-511.
Please contact us should you 'have any questions regarding this request.
Sincerely, cc:
See next page DISTRIBUTION:
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