ML20005F037
| ML20005F037 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/01/1990 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-89-2141, IEB-88-011, IEB-88-11, NUDOCS 9001120211 | |
| Download: ML20005F037 (2) | |
Text
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4 GPU Nuclear Corporation Nuclear-
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Middletown, Pennsylvania 17057 0191 -
717 944 7621:
TELEX BA2386 Writer's Direct Dial Number:
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'r January 1, 1990 C311-89-2141
-t U. S. Nuclear Regulatory Commission
' Attention: ' Document Control Desk i
. Washington, DC 20555-Gentlemen:
Three Mile Island Nuclear Station Unit 1 -(TMI-1)
Operating License No. DPR-50, Docket No. 50-289 NRC Bulletin 88-11 Pressurizer. Surge Line Thermal Stratification and Striping
' Justification for' Continued Operation This.. letter provides the Gpu Nuclear (GPUN) Corporation response to NRC
- bulletin-88-11.- The subject bulletin requires an. inspection to determine-
- any gross
- discernible distress or structural damage'in the entire pressurizer surgeiline. Additionally, the subject bulletin requires that'a-justification for continued operation (JCO) be provided for those plants--
k where a bounding analysisi howed that Code requirements would not-be' met for s
the-full licensed life of the pressurizer surge line, after considering the i
effects of thermal stratification and striping.
Since the issuance of the subject bulletin, the upcom hg refueling outage s(8R)iis the first opportunity for TMI-1-to perform the requested r.
L inspection. The 8R outage is scheduled to begin in January, 1990 and the
' requested inspection will be-completed during the outage.
l Analysis:to demonstrate compliance with the Code for the full licensed life of the plant has not been completed at this time.. Such analysis is expected t o. be completed by the end of 1990 as part of the B&WOG activity. The major
- thormal: stratification fatigue usage is caused by heatup/cooldown cycles.
- The following information and. justification is provided as the JC0 of TMI-1. The basic logic for the JC0 of TMI-1 is its low number of heatup/cooldown cycles compared to the number of such cycles at comparable
.B&W ' lowered loop plants.
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-2i January 1, 1990
=In order,to establish equivalency of TMI-1-to the other B&W lowered loop plants in terms of the pressurizer surge line configuration, plant operation and surge line material properties, GPUN reviewed the B&WOG report BAW-2085, dated May 1989, on this subject and its supporting calculations. The results of.this review are: all of the B&W lowered loop plants have virtually identical pressurizer surge line configurations; and, all of the
- B&W plants 'are basically operated in a similar fashion.
Four B&W plants have more heatup/cooldown cycles than TMI-1. Additionally, two of these plants, which have in excess of eighty (80) heatup/cooldown cycles, have equivalent material properties to TMI-1. One of these plants was instrumented to monitor the pressurizer surge line and other plant i
parameters. GPUN has reviewed the data collected at this plant and finds the major thermal stratification cycles that had occurred during the instrumented plant pre-heatup to have been caused by their HPI check valve IST surveillance testing.
l GPUN's review of its own procedures, operations, and surveillance testing i
-indicates that thermal stratification cycles during the pre-heatup phase are j
not expected.
Fatigue usage for the same number of TMI-1 heatup/cooldown
.i cycles as at the instrumented plant is expected to be lower.
TMI-1 has thus far experienced fewer than 40 heatup/cooldown cycles compared to the 80 cycles at the two comparable plants.
Even if we assume the usage factor per i
heatup/cooldown cycle to be the same at TMI-1 as at the other plants, an additional 40 heatup/cooldown cycles at TMI-1 is justified based on their successful operating experience.
Thus, justification for continued operation of TMI-1 has been demonstrated.
- l. D. Huk 11 Vice President and Director,-TMI-1 HDH/GMC/djk cc: R. Hernan (NRC) y J. Stolz (NRC)
W. Russell (NRC)
F. Young (NRC)