ML19206B279
| ML19206B279 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/24/1976 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19206B280 | List: |
| References | |
| NUDOCS 7905080312 | |
| Download: ML19206B279 (5) | |
Text
.
D. B. Vassallo. Assistant Diractor for Light Water a
Reactors, D D FROM:
D. F. Doss, Assistant Director for Ranctor Safety, DSS
SUBJECT:
SER SUFFLI2 CIT FOR T:IRIZ ?:ILE ISLA'C, UUIT 2 Plant Nane:
Three Mile Island, Unit 2 Docket ?*anber:
6 Milestone Nunber:
27-24 Responsible 3 ranch LUR-4 i.nd Project Manager:
H. Silver Systans Safety 3 ranch Involved: Core Performance Branch Description of Revicv:
SER Supplement Requested Completion Date:
NA Review Status:
Complete The Physics Section of The Core Performance 3 ranch has prepared the
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enclosed supplement to the Safety Evaluation Report for Three-Mile M)~
j Island, Unit 2.
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Denwood Y. Ross, Assistant Director for Reactor Safety g.
Division of Systa=3 Safety
Enclosure:
As Stated cc:
S. Hannuer Distribution R. Boyd Docket File A. Heineman NRR Reading File S. Varga CfB Reading File H. Silver oq 7':
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W. Brooks, NRR 27577
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SER Supple =ent - THI-2 The Co==1ttee indicated in its letter of October 22, 1976 that it believes that the proposed power distribution sonitoring methods =ay be acceptable but that an augmented startup program should be employed, and that satisfactory experience at 100% steady state power and during transients at less than full power should be obtained.
Further, this experience should be reviewed and evaluated by the NRC Staff prior to operating at full power in the load following mode.
In our view an augmented startup program is not necessary. Such a program (1,2,3) was conducted at the Rancho-Seco Nuclear Generating Station Unit I reactor which has a core identical to that of TMI-2.
Rancho-Seco Unit I was operated at 2568 Mwt (s92: rated power) for an
. extended peried in order to proof ter.t the bleed and fuel mode of opera-tion prior to operation at full power. A conscious effort was made to exercise the bleed and feed system.
Up-ra=p and down-ra=p power changes were perforced in the turbine-following, reactor-following and integrated modes of the integrated control system.
A " pseudo-design power transient" -as performed in which a rapid reduction in power by 50 FP was performed, power was held at the low value (s307, EP) until the xenon buildup was =aximum, and the power was quickly raised to its original value.
In addition to this pseudo-design transient several actual load following transients were performed in response to dispatcher com= ands. This situation came about due to run-off conditions in the spring of 1975 that dictated the use of hydro-electric LL
9 plants as base loads for the power grids.
The results of the bleed and feed operations were evaluated with respect to the accuracy with which they could be performed. Over 50 transients were perfor=ed, some with boren alone and others with combina-tion of boron and control rod movement. The end point baron concentration was checked against the target value and the deviation in the results was within the measure =ent uncertainty in the boron conce..tration.
Pover distribution =easurements were perfor=ed upon return to full power after ti.a pseude-design transient and showed that thermal =argins
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were met when e >crapolaced to 102% FP.
The ability of the axial imbalance and rod position monitoring to limit power peaking was demon-strated in the tests which were used to calibrate the axial imbalance instrur ntation. These tests showed =argins to DNBR and Fuel Melt limits when extrapolated to design overpower conditions.
an completion of this progra: the licensee requested permission to increase power to 2772 Mwt (the design rated power). This request was reviewed by the staff and the ACRS (
and approval to proceed to 100:
FP was granted. While the request was being reviewed, a broken turbine blade neceseitated the shutdown of the reactor. In December, 1975 the reactor was tgain started up and the rest of the startup tests (those at >92.6" FP) were conducted. Full power was achieved in March 1976 and operation at full power continued into April. At this ci=e insulation failure in the station generr.cor necessitated shutdown of the reactor.
OLL J'
- o. Repairs were completed and full power was again reached in October, 1976.
The ability to calculate power distributions - particularly during transients - is being pursued with R&W on a generic basis. A topical report on the nuclear uncertainty factor is in the final stages of prep-aration at B&W and reports on the methods used to establish operating limits and protection system set points are being prepared. The additional dats that might be generated from an augmented startup program in TMI-2 would have no appreciaole effect on these efforts.
In view of the circumstances described above we conclude that an augmented startup program in TMI-2 is not necessary.
LL J
References 1.
Rancho-Seco Unit 1 Startup Report March, 1975 (Docket 50-312) 2.
Ranch Seco Unit 1 Ferformance Report March, 1975 (Docket 50-31',T 3.
Letter, Mattinoe to Engelken, dated July 30, 1976 4,
Letter, W. Kerr to W. A. Anders, dated Ju13 16. 1975, on proceedings of the 183rd meeting of the ACRS, July 10 -- 12, 1975 h
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