ML19322C023
| ML19322C023 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/23/1970 |
| From: | Ross D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19322C020 | List: |
| References | |
| 700433, NUDOCS 7912200739 | |
| Download: ML19322C023 (11) | |
Text
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April 23,1970 A. Schwencer, PWR Project Branch 2 Division of Reactor Licensing 1
4 RESPONSE TO QUESTIONS 3.6.1 THRCUGE 3.6.9 TO DUKE POWER COMPANY The response of Duke Power in its Amendment No. 11 of April 20, 1970 to Questions 3.6.1-3.6.9 has been analyzed and is enclosed.
4 Denwood F. Ross PWR Project Branch 2 Division of Reactor Licensing Enclosure cc:
C. G. Long K. B. Cady D. F. Ross Docket File (50-269m270,287)
PWR-2 Reading l
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QUESTION:
3.6.1 Describe' the model, computer code, and primary coolant system input variables used to predict core thermal performance during loss-of-flow accidents, including all-pumps-trip, locked-rotor, and sheared-pump-
' shaft events.
ANSWER:
See FSAR page 14 -ll,14-lla.
The codes are not described, or named. No equations are given. Flow coastdown is given for loss of pump power only.
Sheared-shaft accident is not mentioned.
Is sudden decrease in pump pressure used as input to fluid properties? When does W-3 go cut of range?
Should loss of heat removal in steam generator be specified?
4 Disposition:
This question is not yet ' answered fully.
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QUESTION:
3.6.2 Describe the method and indicate the results of the' analysis that predicts core bypass flow during normal operaton, and indicate to what e.: tent this bypass flow rate can be verified during startup and in model tests.
ANSWER:
See FSAR pages 3-43, 3-43a.
The method was described in the answer.
Bypass measurements during startup tests were not described.
B&W calculates 3.6% of system flow rate as -
bypass, and assumes an additional 1.8% (or 50% uncertainty) for a total of 5.4% bypass.
By contrast Westinghouse assumes a flow bypass factor of 4.5%.
l Recommendation:
Since no startup tests were proposed, I suggest that assumed tolcrances be measured during fitting of the -
core internals. Otherwise the answer is satisfactory.
Perhaps the core outlet T/C would provide data also.
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3 QUESTION:
3.6.3 Provide engineering hot spot factors based on measurements from production fuel elements.
ANSWER:
Later Disposition:
Satisfactory to wait; we could accept on Met-Ed, even.
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4 QUESTION:
3.6.4 We understand from our meetings with you that a mixing code named TEMP is used in your core thermal-hydraulic design.
Provide a detailed description of that code, including fundamental assumptions, experimental bases, all input data for normal or design _ calculations, and output results.
The results should include consideration of the various possible modes of operation of the primary pumps.
ANSWER:
To be supplied about May 1,1970.
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5 QUESTION:
3.6.5 Justify the continued use of the W-3 correlation in the computation of DNB ratios for operation with less than four pumps, since the lower' limit for mass flow
.te in the W-3 correlation is 1 x 106 lb/hr-ft2, ANSWER:
See paragraph 3.2.3.1.1j, pages 3-32 of FSAR.
6 The lower limit of the W-3 in terms of mass veloc!cy is 1 x 10 lbm/hr-ft 6
Two-pump operation approaches this value (1.04 to 4.10 x 10 ).
One-pump 6
operaton is definitely below (about 0.5 x 10 lbm/hr-ft ).
The continued use of W-3 was not justified in the amendment.
It was noted that at the maximum design overpower, 30% rated power) for one-pump operation, hot channel DNBR is 4.8 (by W-3) and quality at MDNBR is -8%.
~ Disposition: We should reject the answer, and request a burnout anlaysis based on some correlation that is applicable.
The axial velocity is about 3 ft/sec.
Peak heat flux is about 160,000 Btu /hr-ft.
Bettis data offers the following (see El-Wakil, Chapter 11) q = 0. 28 x 106 (1 00)
(1 +
7) 10 q" = critical heat flux h = enthalpy at b.o.
q G = mass velocity L = length to b.o.,
ft D~=. diameter,_ft o
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' Applicability:
0.25G 58 (x 10 )
. Substitute 6
c = 0.5 x 10 P
1 L = 7 ft.
L/D = 175 and - (0.0012)(175) = 0.21 D = 0.u4 ft i
670 (estimated) h
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c 6
-0.21 q" = (0.28 x 10 ) - (0.67) 2.5 - (1 + 0.05) e 6
q" = (0.28 x 10 )(2.72)(1.1)(0.81) = 680,000 Btu /hr-ft and DNBR = 16,
- 4.2 We-should seek some comment from B&W on this.
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7 QUESTION:
3.6.6 Explain the basis for-your selection of the C-factor correla-tion in the computation of the non-uniform heat flux f actor, F, associated with the'W-3 correlation.
ANSWER:
See FSAR paragraph 3.2.3.1.lb2, pages 3-24, 3-24a (and Figure 3-6k)
B&W has computed the C factor from both correlations. A comparison wa's made (on Figure 3-6K).
The difference is small.
The new correlation may give 1% decrease in DNBR, at most, in ranges of interest.
Disposition:
Answer is satisfactory.
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QUESTION:
3.6.7 We understand that your thermal analysis _ at the design over-power of 114% steady-state power assumes a reactor inlet temperature several degrees cooler than for 100% power.
Explain this assumption by discussing in flow rates and temperatures in the primary and secondary coolant systems for the overpower condition.
ANSWER:
The answer does not provide assurance that feedwater can be supplied in sufficient quantities at 114% power to keep T
= 579' F.
Secondary flow AV i
rates were not given.
A DNBR analysis was performed to show that even if T and T Went up to the T trip Point (620' F) that DNBR was IN OUT OUT L
1.30.
Disposition:
They didn' t answer the ques tion, but the analysis answered the concern.
I would like to know if the analysis on Supplement page 1-13 was done by hand or with TCi?.
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QUESTION:
3.6.8 What is the effect of burnup on the peak linear heat generation rate, maximum fuel temperature,'and UO melting temperature?
2 ANSWER:
See FSAR paragraph 3.2.2.2.3g3, page 3-46 and Figure 3-32a.
B&W reports a decrease in UO melting temperature with burnup from 5080*
3 at EOL to 4800* F at 40,000 mwd /MTU.
The Figure 3-32a shows fuel cen,ter temperature at 20.1 kW/ft (114% P,) vs burnup.
The minimum margin is about 250' F (TMELT MAX, Fuel) and occurs rather uniformly af ter about 20,000
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MWt/MTU.
Disposition:
The thrust of the question was answered in that it appears
-that 114% P is.to be proposed as a safety limit.
I doubt that 114% is "high enough" and expect further dialogue
-during Tech Spec negotiations.
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10 QUESTION:
3.6.9 to 1% plastic strain?What fuel burnup limit is propos d e
to limit the fuel clad f
ANSWER:
See FSAR paragraph 3.2.4.2.lb
, page 3-64 All that is said is that calcul t d ae peak burnup is 42,000 mwd /MTU.
Disposition:
I want B&W fuel growth.to bring in, informally
, their calculations on I found 4-1/2% (not 9-1/2%) AV/VI gav wherein Since I don't know how they tr to correspond to 1% strain concern is for education on my parteat the dished pe this t
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