ML19323G739
| ML19323G739 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/09/1980 |
| From: | Herbein J METROPOLITAN EDISON CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| IEB-80-04, IEB-80-4, TLL-228, NUDOCS 8006060574 | |
| Download: ML19323G739 (2) | |
Text
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7:fe, Metropolitan Edison Company M
Post Office Box 480 Middletown, Pennsylvania 17057 717 944-4041 Writer's Direct Dial Number May 9, 1980 TLL 228 Office of Inspection and Enforcement Attn:
B. H. Grier, Director U. S. Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, Pa.
19406
Dear Sir:
Three Mile Island Nuclear Station, Unit I (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 IE Bulletin 80-04 Attached please find the response to IE Bulletin 80-04, " Analysis of a PWR Main Steam Line Break With Continued Feedwater Addition".
Based on the results of our review, we conclude that the items raised by the subject bulletin are not a concern for IMI-I.
Sincerely, A
s J. G. Herbein Vice President i
TMI-I JGII:DGM: hah Attachment cc: Office of Inspection and Enforcement Division of Reactor Operations Inspection Washington, D.C.
20555 J. T. Collins B. J. Snyder l
8006060 $ )C/
Metropohtan Ed son Company is a Member of the General Pubhc Utiht:es System TLL 228 RESPONSE TO IE BULLETIN 80-04 The response of TMI-I to a steam line break is addressed to FSAR Section 14.
1.2.9.4.
The TMI-I facility was designed with a steam line detection system, which automatically isolates both main and emergency feedwater CEFW) to the steam generator that has sustained a broken steam line.
Isolation of main and emergency feedwater to a steam generator with a broken steam line would occur at 600 psig.
The analysis in the FSAR did not account for EFW supplied to the steam gene-rator with the broken steam line between the time that EFW is automatical;.7 initiated until the EFW flow to the impaired steam generator is isolated.
Following a steam line break, the pressure in the steam generator with a broken steam line would quickly fall below 600 psig.
If EFW were to automati-cally be initiated, the mechanical delays associated with EFW system (approxi-mately 10 seconds) world reduce EFW injection prior to the 600 psig feedwater isolation signal.
Peak containment pressure for the steam line break accident is 28 psig.
Design containment pressure is 60 psig, and ti.s the limited EFW addition to the steam generator with a broken steam line would not significantly increase peak containment pressure following a steam line break.
Based upon a previous commitment contained in our response to Restart Report Question 4, Supplement 1, Part 3, cavitating venturis will be installed in the EFW discharge lines.
If EFW is initiated following a steam line break, EFW flow to the depressurized steam generator would be limited to no more than 625 gpm.
With the addition of the venturis in the EFW discharge line, the TMI-I response is bounded by the TMI-II steam line break analysis (refer to TMI-II FSAR Appendix 15B).
This analysis assumed failure of the feedwater regulating valve to close, causing additional inventory until the feedwater block valve closed.
]
The TMI-II analysis further assumed that an EFW flow of 625 gpm was initiated 1
at 2 see following the steam line break and continued throughout the accident.
The peak containment pressure for this case was less than TMI-I containment design pressure of 60 psig.
With regard to concerns relating to return to power following a steam line break, Section 14.1.2.9.4 of the TMI-I FSAR addresses the reactivity increase following a steam line break.
For this event, feedwater is assumed to be isolated by the steam line rupture detection system.
Even with the blowdown of both steam generators following a steam line break, there is no return to criticality.
As indicated in Section 8.3.9 of the TMI-I Restart Report, the issue of core return to power was evaluated in the GPUSC Safety Evaluation for Cycle 5 operation of TMI-I (the present cycle).
Based on analyses performed for TMI-II (refer to Appendix 15B and References 6 and 7 of the Restart Report, Section 8), it was verified that the TMI-II analyses bounded the TNE-I core design for Cycle 5.
The assumptions used in the TMI-II analysis are more severe than the licensing basis for TMI-I Cycle 5, since it assumes a failure of two steam lines and the failure of both feedwater trains to isolate flow.
The TMI-II analyses demonstrated that as long as a 2% shutdown margin is available, a core does not return to criticality nor does it generate substantial power due to subericical multiplication.
The design of the TMI-I core for Cycle 5 operation maintains at least a 2%
shutdown margin throughout its cycle.