ML20155A338
| ML20155A338 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/04/1986 |
| From: | Standerfer F GENERAL PUBLIC UTILITIES CORP. |
| To: | Travers W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20155A341 | List: |
| References | |
| 4410-86-L-0058, 4410-86-L-58, NUDOCS 8604080367 | |
| Download: ML20155A338 (3) | |
Text
s GPU Nuclear Corporation U Nuclear
- '3r,eess48o Middletown, Pennsylvania 17057 717 941-7621 TELEX 84-2386 Writer"s Direct Dial Number:
(717) 948-8461 4410-86-L-0058 Document ID 0411A April 4, 1986 TMI-2 Cleanup Project Directorate Attn: Dr. H. D. Travers Director US Nuclear Regulatory Commission c/o Three Mile Island Nuclear Station Middletown, PA 17057
Dear Dr. Travers:
Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. OPR-73 Docket No. 50-320 Recovery Operations Plan Change Request No. 37 Attached for your review and approval is Recovery Operations Plan Change Request (ROPCR) No. 37.
This proposed change requests the addition of resistance temperature detectors to Table 4.3-7 as an alternate means of measuring reactor vessel water temperature.
Per the requirements of 10 CFR 170, an applicativi fee of $150.00 is enclosed.
Sincerely, hhk NOK l0 g
e R. Standerfer Vice President / Director, THI-2 FRS/RBS/sle Attachment Enclosed:
GPU Nuclear Corp. Check No. 00021998 91 I
GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation kW' OO ke!
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- C4 L
Three Milo Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. OPR-73 Docket No. 50-320 Recovery Operations Plan Change Request No. 37 The Licensee requests that the attached pages 4.3-10 and 4.3-10a of the Recevery Operations Plan (ROP) replace the existing pages.
The purpc,e of this revision is to provide operational flexibility relating to the measurement of in-vessel temperatures.
The change allows the use of either the incore thermocouples or the recently installed in-vessel resistance temperature detectors (RTD) (RC-TI-106, A, B, and C) to satisfy surveillance requirements.
Reason for Change As the defueling operations progress, the possibility of accidently disabling the incore temperature detectors becomes more likely and eventually disallement will become necessary to prevent unacceptable damage to the Reactor Vessel integrity.
In anticipation of this situation, three RTD's were installed in the Internals Indexing Fixture (IIF). Adding the in-vessel RTD's to Table 4.3-7, provides the TMI-2 operators the flexibility and diversity to determine that the RCS temperature is within required limits when the incore thermocouples become inoperable.
Safety Evaluation Justifying Change Addition of the in-vessel RTD's enhances plant safety now and will ensure maintenance of a safe condition during future TMI-2 defueling operations.
The in-vessel RTD's provide a second method of verifying reactor vessel coolant temperatures now. As defueling progresses, the RTD's will become increasingly important since the incores will ultimately be disabled.
In the past, the incore thermocouples have experienced a number of failures Currently, TMI-2 operations uses the average of operational incores as opposed to relying on separate incore readings.
Recent experimental data has indicated that the locations of the incore junctions (sensing region) are undefinable. Junction locations derived from available data range from the bottom of the reactor vessel to well into the active core region where core damage is known to exist.
Based on this information, the accuracy and credibility of individual incores are questionable and usable only to trend RCS temperatures.
The operation of the RTD's has been recorded hourly for approximately two weeks.
During this time period, a minor change (approximately 3*F) was noted in the RCS temperature.
The incore thermocouple average temperature and the average temperature of the 3 RTD's indicated an approximate 6*F difference during the entire 2 week period.
Changes in the RCS temperature were simultaneously reflected by both the incores and the RID's.
This information demonstrates the operability of the newly installed RTD's and serves to confi: m that the incore thermocouple average does trend RCS bulk temperatures.
l
Amendment Class Per the requirements of 10 CFR 170, Licensing fees, an application fee of
$150.00 is enclosed.
r
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