ML19263G068
| ML19263G068 | |
| Person / Time | |
|---|---|
| Site: | Oconee, Crane  |
| Issue date: | 02/27/1980 |
| From: | Newberry S Office of Nuclear Reactor Regulation |
| To: | Vollmer R NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| Shared Package | |
| ML111090060 | List:
|
| References | |
| FOIA-80-515, FOIA-80-555 NUDOCS 8003190150 | |
| Download: ML19263G068 (3) | |
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Docket No. 50-289 S.Newberry Newbcrry chron 7g MEMRANDUM FOR:
R. H. Vollmer, Director, TMI Support THRt!:
G. R. Mazetis, Section Leader, Reactor Systems Branch, DSS FROM:
S. F. Newberry, Reactor Systems Branch, DSS l
SUBJECT:
TMI-1 RESTART REVIEW: ANTICIPATORY REACTOR TRIP l
REFERENCE:
- 1. Memorandum from S. Newberry to R. Vollmer, TMI-1. Restart Review:
Emergency Feedwater System Capacity and Anticipatory Reactor Trip, dated January 25, 1980.
i
- 2. Reactor Trip Summary for TMI-I submitted informally by Met Ed I
during TMI-1 restart review as part of their review of operating
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experience in accordance with IE Bulletin 79-05A.
l
- 3. Letter from G. C. Moore (Florida Power Corp.) to R. A. Reid l
(NRC) dated November 14, 1979.
l My first memorandum to you (reference) recommended a position on the proposed safety-grade anticipatory reactor trip (ART) modification at TMI-1. This j
position was, in summary, that the safety-grade ART inputs proposed by the licensee are acceptable for restart; however. the need for a longer tenn generic study should be determined for all B&W plants concerning an alternate or additional diverse reactor trip. Part of the basis for this position was the similarity of the TMI-1 and Oconee units feed and condensate systems.
While our position remains the same, additional discussions with the licensee necessitated reconsideration due to certain system dissimilarities. The enclosure, in addition to reference 1, documents our basis for recomending i
acceptance of the proposed ART parameters considering the feed and condensate I
design at TMI-1.
,0RIGINAL SIGNED BY:
l Scott F. Newberry Reactor Systems Branch Division of Systems Safety i
Enclosure:
As Stated cc:
D. Ross H. Silver P. Morian l
T. Novak J. Wersiel D. Thatcher S. Israel R. Fitzpatrick D. Dilanni l
P. Matthews M. Rubin E **T!
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Ohtact: Scott Neuberry,'NRR SNewber GMa is SURNA T 49494e7 0
02/%/80 occ=
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NRC Form 318 A (4 79) NRCM O2040
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ENCLOSURE Earlier review and ccceptance of the ART input parameters for loss of feedwater was based upon similarity of the Oconee units to TMI-1 and the assumption that Met Ed would install main feedwater and condensate booster pump low suction pressure trips similar to those at the Oconee plants. Met Ed considered this installation further and, in a conference call February 13, 1980, provided additional information with their position that the addition of these trips was not necessary or desirable considering another difference between Oconee and THI-1 feed and condensate systems.
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During normal operation (full power) at TMI-1, two of the three condensate and condensate booster pumps are operating.
The spare third pumps are kept in standby. One condensate pump and one condensate booster pump are " dedicated" to one of the two feedwater pumps. Should a condensate or condensate booster pump trip, the remaining spare pump will automatically start.
Should the spare pump fail to start, the " dedicated" feedwater pump is tripped. The TMI-1 design does not include, as do Oconee units, low suction pressure trips of the condensate booster pumps or feedwater pumps. The licensee stated that the feedwater pumps are designed with wide impeller-to-casing clearances, permitting continued feedwater pump ope-ation under cavitating or flashing conditions which could be caused by condensate system malfunctions (demineralizers, etc.).
This allows the condensate and feedwater system at THI-1 to continue delivery of water to the steam generators, despite degraded pump suction conditions which, if continued uncorrected, could result in feedwater pump damage. Any changes in feedwater flow are sensed by ICS and a corresponding runback in reactor power is made. Therefore, low suction pressure situations do not result in a trip of the main feedwater pumps (and generation of ART) at TMI-1.
The operating history of TMI-1 bears this out-(references 2 and 3).
Since starting comercial operation in September 1975, there have been no reactor trips caused by a loss of feedwater.
In light of this dissi.r.ilarity, the Ocor'2 and TMI-1 l oss c' 'x.:a ter event data were reviewed again (see reference 1 for discussion of these data). Of those events at Oconee units that would have initiated ART for less of feedwater, all but one would either initiate ART at TMI-1 or are considered to be not relevant due to the difference in design and operating history described above.
Therefore, we concur with the licensee that the pump suction trips are not necessary and that the operating data, in addition to consideration of system differences, support acceptance (see reference 1) of the loss of feedwater ARTS parameter as proposed by the licensee.
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