ML19211B958
| ML19211B958 | |
| Person / Time | |
|---|---|
| Issue date: | 07/27/1979 |
| From: | Parczewski K Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19211B959 | List: |
| References | |
| REF-GTECI-A-03, REF-GTECI-A-04, REF-GTECI-A-05, REF-GTECI-RV, TASK-A-03, TASK-A-04, TASK-A-05, TASK-A-3, TASK-OR NUDOCS 8001070263 | |
| Download: ML19211B958 (9) | |
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INTEROFFICE CORRESPONDENCE I
July 23, 1979
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C. F. Obenchain J. L. Lachance "4"'
STEAM GENERATOR TUBE RUPTURE TASK PRELIMINARY PRO Lac-1-79 TASK:
Determine the number of steam generator tube ruptures during a LOCA which will result in elevated peak cladding temperatures in Westinghouse 2 and 3 loop plants, combustion Engineering, and Babcock and Wilcox plants.
be examined in this window regime.The core thermal response is to ASSUW TIONS:.
The tuba ruptures will be assumed to occur at the beginning of reflood during the worst LOCA - a 200% cold leg break.
The tube ruptures will be assumed to occur at the inlet plenum of the intact loop steam generator (s).
For the Westinghouse 3 loop plant, the tube ruptures will be assumed to occur equally in the 2 intact loop steam generators so as to maximize the time period in which secondary-to-primary flow occurs.
METH005:
1.
Blowdown calculations will be performed for the CE and B&W plants using RELAP4/M006.
No RELAP4 input decks are available for Westinghouse 2 and 3 loop plants.
If no acceptable blowdown calculations can be located, a blowdown calculation for a W 4 loop plan;. could be used.
2.
Refill calculations for the plants will be performed using the FLOOD 4 gode with a heat transfer coefficient of 5 8tu/hr-ft4 oF.
This has been shown to be a realistic heat transfer coefficient during the refill period.
A conservative alternative would be to assume adiabatic heat up by using a heat transfer coefficient of O.
The refill time period will be calculated by hand.
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PRELIMINARY 3.
The FLOOD 4 code will be used to calculate the reflood portion of the transients including simulated staan generator tube ruptures.
The FL0004 code will require some modification in order to calculate transients in the CE 2 by 4 plant.
Several assumptions will be required in setting up the FLOOD 4 models that will significantly affect the calculated results.
They are:
(a)
The number of rods that can be top-down quenched has to be specified.
Recomend allowing the whole core with exception of the hot fuel bundle' to be capable of being top-down quenched if liquid in the upper plenum is available.
This should result in maximum steam production in the system and the highest peak cladding temperature.
(b)
A ministat heat transfer coefficient is required for the input model.
In the window regime (stagnant or near stagnant core flow) thc heat transfer in the core is determined by this parameter.
Reconnend using 5 8tu/hr-ftz 0F since this is considered a reasonable value for a heat transfer coefficient during refill.
(c)
The amount of secondary liquid vaporized in the primary has to be specified in the FL0004 model and drastically affects the calculated results in the negative core flow regime.
Fortunately the calculated results in the positive core flow and stagnant core flow regimes are insenstive to this p arameter.
Recommend using a secondary-to-primary flow quality of 1.0.
This represents the worst case since secondary liquid will not be available for top-down quenching of the core and also since steam binding will be maximized.
PROCEDURE:
The steps required to perform this task and the labor and cost are sumnarized in the following table.
The numbers presented are preliminary and considered conservative.
Better estimates can be made once the task is better defined.
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PRELIMINARY ?%@
Page 3 Computer Total Accumulated Labor Cost Cost Cost Task Step Months / cost (K$)
(K$)
(K$)
(KS) 1.
Run best estimate blow-3/14.5 10 24.5 24.5 down calculations for CE and B&W plants &
2.
Update FLOOD 4 code 0.5/2.8 0.5 3.3 27.8 (Rex Shtsnway) 3.
Create FLOOp4 input decks 1.5/7.2 7.2 35 for plants D 4.
Perform refill calculations
.5/2.4 2.4 37.4 5.
Perform reflood calculations P/9.6 8
17.6 55 with tube ruptures assumed to occurc 6.
Write report 2/9.6 9.6 64.6 TOTAL 9.5/46.1 18.5 64.6 a
Existing EH decks will be modified and blowdown calculations performed.
Plants modeled are:
CE-Calvert Cliffs, B&W-Oconee.
An existing Westinghouse blowdown calculation for Zion plant will be used for W 2 and 3 loop plants.
Modif fcation of EH decks requires 2/3 of the time!~
b FLOOD 4 input data consists primarily of loop resistance values and system volume numbers.
We have loop resistance information for the following plants:
CE - Millstone B&W - Crystal River & Davis-Besse W 2 loop - Kewaunee G 3 loop - Surry Ropefully the CE and B&W plants are similar to those modeled in blowdown calculations.
c One base case (no tube ruptures) and approximately 6 tube rupture transtants for each plant will be run.
jd 1765 155 cc:
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L. J. Ybarrondo Central Files