ML20066L358
| ML20066L358 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 01/23/1991 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-91-009, CON-NRC-91-9 IEB-88-008, IEB-88-8, VPNPD-91-043, VPNPD-91-43, NUDOCS 9102070008 | |
| Download: ML20066L358 (3) | |
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. Wisconsin Electnc FCWER COMPANY 231 W McNgon, Po Box 2046. Mdwoukee, wi 53201 (414)221-2345
- VPNPD 0 43 NRC 009 January 23, 1991 Document Control Desk U.
S.. NUCLEAR REGULATORY COMMISSION
' Mail' Station P1-137 Washington, DC 20555 Gentlemen:
'QQCKET NOS. 50-266 AND 50-301
-ADDITIONAL RESPONSE TO BULLETIN 88-08 THERMAL STRESSES IN PIPING CONNECTED TO REACTOR CQQLANT SYSTEMS POINT BEACH NUCLEAR PLANT UNITS 1 AND 2
References:
1)
WE letter VPNPD-88-480/NRC-88-089 to NRC dated
- September 27, 1988 2)
WE letter ~VPNPD-88-616/NRC-88-128 to NPC dated December 21, 1988 3)
WL letter VPNPD-89-340/NRC-89-074 to NRC dated June 16, 1989 4)
WE letter VPNPD-89-689/NRC-89-169 to_NRC dated December 29, 1989 5)
WE letter VPNPD-90-313/NRC-90-066 to NRC' dated June 29,_1990 Reference 1 identified-piping which-had-thetpotential to be subjected to stresses from temperature stratification!or temperature oscillations which could-be induced by leaking
. isolation or check valves.- Wisconsin Electric (WE) evaluated the pipingcin accordance with the criteria presented in NRC Bulletin i 08, " Thermal Stresses in Piping Connected to Reactor Coolant Systems,"
The lines identified were the-two-inch diameter auxiliary charging piping and the two-inch diameter auxiliary spray piping-for Point Beach Nuclear Plant (PBNP) Units 1 and-2.
. Reference 2 provided results of the Unit 2 inspections and described the temperature monitoring equipment installed, data collection ~ system, and. preliminary information regarding temperature distributions in these-lines.
Refe'rence 3 provided results of inspections and actions taken on
'these two piping systems during the Unit 1 outage completed in April 1989.
Further, the letter documented that WE had removed the 9102070008 910123 h
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'4 Document Control Desk January 23, 1991 Pago 2 auxiliary charging line from the monitoring program and p:
'ided a description of our plans and schedules regarding evaluatio:
of the data being collected for the auxiliary spray piping.
Reference 4 identified that inspection of the in-place thermocouples (TCs) on Unit 2 indicated that several TCs were not in contact with the pipe, and therefore the temperature data previously.:ollected may not have been representative of the actual pipe temperatures.
The TCs were subsequently replaced with direct clamp-on thermocouples to insure contact with the pipe surface.
The letter concluded by stating that WE intended to perform an engineering evaluation of the effects of the recorded thermal stratification on the spray line header piping by June 30, 1990.
Reference 5 described the engineering evaluations performed to assure code compliance due to the unanalyzed condition of thermal
! stratification in the spray line header piping for PBNP Units 1 and 2,
results of the analysis, and resulting actions required to close out the bulletin:
The analyses demonstrated code compliance for Ethe spray and auxiliary-spray line piping and supports with the exception of small-bore piping support AXS206 on the Unit 2 auxiliary spray line in the regenerative heat exchanger room.
The loads causing this support to exceed code allowables were due to the normal design loads generated in the piping reanalysis and were not related'to thermal stratification.- The support did, however, satisfy the cperability criteria established for PBNP.
WE committed to modifying this support to bring the design within code compliance during the Pall 1990 Unit 2 refueling outage.
This letter describes the actions performed to assure code compliance for the Unit 2 support (AXS206) that required modification.
Evaluation of the support design determined that the as-built support configuration could not be modified without affecting another piping system on the gang support.
Therefore, we decided to design a new support to replace AXS206.
During removal of the piping insulation to install the new support design for AXS206, it was discovered that a U-bolt was missing from an adjacent support (AXS207).
Evaluation of the existing support showed that, while the structural hardware for support AXS207 was adequate for the design loads, the system could be improved by replacing AXS207 with a new support-in a different location. -With these changes, the spray and auxiliary spray lines for Unit 2 were reanalyzed for thermal stratification and normal design loading conditions.
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Document Control-Desk January 23, 1991 Page 3 The new support designs were installed during the recently completed fall 1990 refueling outage for PBNP Unit 2.
The analysis results demonstrate code compliance for both design basis loadings and thermal stratification effects for piping and supports on the spray and auxiliary spray lines.
WE believes that all necessary actions required by Bulletin 88-08 are now complete for both units at PBNP.
However, we will inspect the auxiliary spray line pipe supports in the Unit i regenerative heat exchanger room to assure that there aro no support hardware problems similar to those experienced in Unit 2.
We will advise the NRC if this inspection discloses any significant as-built problems.
Please contact us if you have any questions concerning our actions in this matter.
Very-tru,1y yours, W
(lc C.
W.
F6y Vice President Nuclear Power Copy to:
NRC Resident Inspector NRC Regional Administrator, Region III