ML20090E547
| ML20090E547 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 08/19/1976 |
| From: | Rig R FLORIDA POWER & LIGHT CO. |
| To: | Stello V Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20090E542 | List: |
| References | |
| L-76-300, NUDOCS 8304040023 | |
| Download: ML20090E547 (3) | |
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We FLORIDA POWER & LIGHT COMPANY August 19, 1976 L-76-300
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Office of Nuclear Reactor Regulation Attn:
Victor.Stello, Jr., Director Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C.
20555-
Dear Mr. Stello:
Re:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Westinghouse Safety Analyses The Westinghouse ~ Electric Corporation has informed Florida Power & Light Company that'recent developments have affected tha results of' certain safety analyses f6h Westinghouse plants.
The following information regarding this problem is being submitted to you in response to an August 13, 1976 telephone request from your staff.
One development involves the temperature of the fluid. in the upper head.
Past ECCS unalyses assumed that the temperature in the upper head was equal to the vessel inlet temperature (Tcold).
The c6nservative judgment is.to assume that the tem-perature will be equal to the vessel outlet temperature (Thot)-
The consequence is a reduction in maximum allowable Heat Flux Hot Channel Factor (F ) to prevent operation at unacceptablo O
. local power levels.
The resulting Fo limit for Turkey Point-is conservatively c.stimated to be 2.I65.
The new F limit was g
derived as shown below:
[2~.32 -A -B +C] D = 2.165 2.32 = previous limit on F Q
A =.26 = estimated'r(eduction in F due to-increase in-g upper head temperature frcnn T to T B=.04 = esbi(ated, reduction in F,
cold hot
- due to plugged steam g
gene 2 at'or tubes.
r C =.05 = estimated increase in F due to the fact that g
the ECCS analysis peak Clad temperature ^is 50*~
be' low the Final Acceptance. Criteria.
D = 220000 = factor for increasing'F-due to operation 0
100 Mwt below the power 1evel used in the.
ECCS analysis.
Note:
For a 925 ft' accumulator. volume, A =.16 and.Fg = 2.27.
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To:
Victor Stollo, Jr.
' August 19, 1976 Re:
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Page.
l Westinghouse Safety Analyses s
Another _ development involves rod bow.
Recent test results indicate that the rod bow DNB penalty is higher than previously used.
The combination of this penalty with available margins results in an estimated reduction in DNBR on a region-by-region basis.
Increasing the rod br c ONB penalty can be offset by a combination of the followine.
a)
A reduction in the maximum allowable Nuclear Enthalpy Rise Hot Channel Factor (FAH) n a region-by-region basis.
i) 0% to 4% reduction for new first cycle fuel applied linearly from Beginning-of-Cycle to' End-of-Cycle.
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ii) 6% constant reduction for fuel,which has
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received 1 cycle of burnup.
, iii) 7% constant reduction for fuel which has received 2 or,more cycles of burnup.
b)
'A reduction in T and a corresponding change'in ave the Overtemperature AT equation.
(l* F in T and l' F in the constant in the temperature difference ave term in the Overtemperature AT equation = 1% in DNBR.)
c)
An increase in reactor coolant flow.
1% flow, b
, increase = 1% increase in DNBR.)
For the time being, the increased upper head fluid temperature and;the increased rod bow penalty are being offset by opera-1 tionally limitin FO and FA as described above.
In the' future, operational cons derations May cause us to revise the means by which we accommodate the higher rod bow DNB penalty, in which case we may utilize some other combination of available options.
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The revised limits described above represent preliminary esti-mates.
The evaluation.of these developments is continuing in i
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To:
Victor Stello, Jr.
August 19, 1976 Re:
Turkey Point Units 3 and 4 Page ~3-Docket Nos. 50-250 and 50-25.1 Westinghouse safety Analyses an effort to quantf fy the effects on the Turkey Point units more precisely.-
Ve ly yours, J
Robert E. Uhrig Vice President REU/ MAS / hic cc:
Norman C. Moseley, Region II Jack R. Newman, Esq.
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