ML20090E718
| ML20090E718 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Browns Ferry |
| Issue date: | 06/13/1983 |
| From: | Berlinger C Office of Nuclear Reactor Regulation |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17139C189 | List:
|
| References | |
| FOIA-84-105 NUDOCS 8306220162 | |
| Download: ML20090E718 (2) | |
Text
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e-JUN 131983 mbt 0RAMDUM FOR:
D. B. Vassallo, Chief Operating Reactors Branch'!2, DL FROM:
C. H. Berlinger, Chief Core Perfomance Branch, DSI Sl!BJECT:
"BROUNS FERRY EXCLUSION FR0ft APPROVAL OF SINGLE LOOP OPERATION AT S0% POWER" i
Reference:
Menorandum from Brian Sheron to D. B. Vassallo "BWR Single Loop Operation at 50% Power," June 3,1983.
The above referenced neno indicates that there is no reason to exclude Browns Ferry from generic SLO approval.
I would like to briefly indicate why it is the CFB position that Browns Ferry be excluded from the generic SLO approval at this time.
First, as a result of a recent review' by ORUL of the Yemont Yankee Stability t::st data, ORHL disacrees with the following three positions previously taken.
by General Electric in their stability submittals.
1.
Core stability at any point in the power / flow o;arating nap is independent of the mode in which the core flow is induced, i.e., no difference between SLO and two-loop operation (TLO).
2.
Core stability increases as core flow increases fo11cwing constant control and position (viz, power / flow ratio) line in the power / flow operating map, regardless of the nodo of cperation, i.e., SLO or TLO.
3.
The least stable condition on the power / flow operating nap ccrrespends to natural circulation operation at the rated rod line or above.
He have discussed these differences with General Electic and it is our under-standing that they now concede that these positions are not suppor'ed by the i
data.
Second, we feel that since Browns Ferry had previously experienced i
i oscillations while in single loop operation that it should be subject to a i
special review.
Specifically with respect to our current review of the Browns Ferry data, we disagree with TVA's position concerning oscillations experienced in SLO operation.
It is the TVA position that the observed increase in neutron noise under certain SLO conditions is not related to changes in core stability.
Contact:
G. Schwenk, CPD:DSI-X-29421.
OFFICE)
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. 1 This position is supported, according to TVA, by two facts:
1.
The flow fluctuations increase due to reverse flow /downconer nixing etc.
therefore the increase in neutron noise is nerely driven by the higher nagnitude of the flow fluctuations.
2.
The neutron noise increases as core flow increases, which accorcing to two-loop operating experience should make the reactor nore stable.
Point I above is not supported by the data.
If stability changes had not occurred, the ratio between normalized power and flow fluctuations should i
have remained constant.
The " magnification" factor for Browns Ferry during SLO is not constant.
i Point 2 would be well taken if SLO and TLO were to have the sane recirculation-loop dynanic characteristics.
It is not so.
Vermont Yankee data clearly shows that SLO was nore unstable than natural circulation in spite of having a higher core flow rate with the sane power / flow ratio.
TVA plans to allow ORNL personrel to take sone noise data during a future planned pump outage. !!e intenc, with study of this data and the conpletion of ORf!L's review of the Browns Ferry noise oscillations, to resolve TVA's SLO sutr11ttal.
Original signed by:
1 C. H. Berlinger, Chief Core Perfomance Branch, DSI cc:
R. J. Mattson L. S. Rubenstein R.11. Houston B. Sheron R. Clark DISTRIBUTION:
J. Mannon CENTRAL FILE CPB r/f C. BERLINGER L. PHILLIPS G. SCHWENK l
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