A14212, Environ Temps in Vicinity of Rupture Point of Steam Lines for Equipment Qualification. Description of Equipment Location in Facility Encl
| ML19323A824 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/30/1976 |
| From: | Del Bene J GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER |
| To: | |
| Shared Package | |
| ML19323A823 | List: |
| References | |
| GA-A14212, NUDOCS 8005060065 | |
| Download: ML19323A824 (20) | |
Text
_ _
ATTACHMENT D GA-A14212 r
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by J. V. DEL BENE l
NOVEMBER 1976
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CONTENTS.
1 1.
SUMMARY
2 2.
INTRODUCTION...........................
3.
ANALYSIS.............................
3 3.1.
Specification of Worst Steam Leak..
3 3
3.2.
Analytical Model and Assumptions.
9 4.
CALCULATED RESULTS........................
REFERENCES.............................12 FIGURES 1.
Steam blowdown rate and enthalpy for a postulated cold reheat pipe rupture in the reactor building.
4 4
2.
Steam blowdown rate and enthalpy for a postulated hot reheat pipe rupture in the turbine building without scram action.
5 3.
Temperature response of the environment near the rupture for a reactor building cold reheat pipe rupture.
10 4.
Temperature response of the environment near the rupture for a turbine building hot reheat pipe rupture.
11 TABLE 1.
Uniform distribution of heat transfer surface areas.
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1.
SUMMARY
This report presents temperature response curves for the environment within 20 ft of a steam pipe rupture for use in equipment qualification.
Worst case blowdown conditions were taken from the cast and analysis report on the qualification of Fort St. Vrain safe shutdown equipment (Ref. 1).
For distances up to 10 f-t from the rupture, the environment tempera-ture is in the range of 600* to 650*F for the 4-minute steam blowdown period.
Cooldown temperatures to 30 minutes are in the range of 300* to 350'F.
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1
2.
INTRODUCTION For the qualification of ths Fort St. Vrain safe shurdown equipment, the environmental temperature response for the worst case pipe rupture was determined for the reactor building and the turbine building (Ref.1).
Response curves of the environmental temperature were determined at several distances from the steam pipe rupture for distances equal to or greater than 20 ft.
This report presents response curves for distances less than 20 ft.
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3.
ANALYSIS 3.1.
SPECIFICATION OF WORST STEAM LEAK As indicated in Ref. 1, a double-ended rupture of the cold reheat pipe in the reactor building produces the most severe environmental blow-down condition.
With this rupture, the steam line is not immediately isolated and the steam blowdown is postulated to last for 4 min.
The blowdown flow rate and enthalpy for a reactor building cold reheat rupture are taken from Fig. 3.3 of Ref. 1.
They are reproduced in Fig.
1.
The rupture of a main steam pipe or a hot reheat pipe in the reactor building is isolated within several seconds, and the steam blowdown flow rate decays to zero in about 10 to 15 sec.
Thus, initially high main steam or hot reheat temperatures of approximately 900*F would only last 10 to 15 sec
.d.
with a rapidly decreasing steam flow rate during this time period.
Reference 1 indicates that the most severe environmental conditions in the turbine building occur with a double-ended rupture of a hot reheat pipe.
The rupture flow rate is not terminated until 4 min, and the enthalpy of the hot reheat steam is higher than the enthalpy of the main steam.
The blowdown flow rate and enthalpy for a turbine building hot reheat rupture are given in Fig. 2.
These curves were reproduced from Fig. 3.4 of Ref. 1.
3.2.
ANALYTICAL MODEL AND ASSUMPTIONS The analytical model considers a double-ended rupture of a 20-in.-
diameter cold reheat pipe in the lower portion of the reactor building and a double-ended rupture of a 34-in.-diameter hot reheat pipe in the lower portion of the turbine building.
Since the reactor and turbine building are vented, there is no storage of blowdown steam or environmental pressure buildup in the buildings.
Instead, the escaping steam blows past walls, 3
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Fig. 1.
Steam blowdown rate and enthalpy for a postulated cold reheat pipe rupture in the reactor building 1
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TERMINATION OF STEAM LEAK
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Steam blowdown rate and enthalpy for a postulated hot reheat pipe rupture in the turbine building without scram action l
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l structures, and equipment within the buildings.
This scenario is especially true for the conditions near the rupture point.
The scenario is also sup-ported by the fact that both buildings are very crowded with piping, structural steel, walkways, and instrument racks.
The analytical model is based on the blowdown steam flowing past heat l
transfer surfaces.
The model yields the temperature response of these sur-faces and the response of the steam temperature with respect to distance from the rupture and time.
The assumptions and input for the model are:
1.
The steam expands spherically outward from its rupture.
The volume enclosed as a function of distance r from the rupture is 3
V = 4/3 nr.
2.
The heat transfer surface areas of the steel and concrete are distributed homogeneously throughout the regions in consideration.
Data from Ref.1 are used to calculate these distributions.
The
)
results are given in Table 1.
3.
The decay of the heat transfer coefficient versus distance from the steam leak during the steam blowdown period is the same as 2
used in Ref. 1.
The value at 10 ft (86.9 Beu/hr-ft
- F) is used for all distances less than 10 ft.
The heat transfer coefficient after the termination of the steam leak is taken as 5 Beu/hr-ft
- F.
4.
The initial temperature of all the steel and concrete is taken as 100*F.
i The calculations were performed using the TAC 2D thermal analysis com-puter program (Ref. 2).
Since no collection of blowdown steam in the buildings is considered in the analytical model, it was more convenient and expedient to use a thermal analysis program rather than a containment blowdown program.
The TAC 2D program was modeled to simulate the steam expanding spherically outward and passing over the steel and concrete 6
4 4
TABLE 1 UNIFORM DISTRIBUTION OF HEAT TRANSFER SURFACE AREAS Reactor Building (Ref. 1, Table 3.1)
Volume of lower portion of reactor 3
building 198,000 ft Total surface area of steel in this
- 2 volume 104,000 ft Total surface area of concrete in 9
this volume 33,800 ft' Steel surface area per unit volume 2
3 of reactor building 0.525 ft /ft Concrete surface area per unit volume 2
3 of reactor building 0.171 ft /ft 3
Turbine Building (Ref. 1, Table 3.2)
Volume of lower portion of turbine 3
building 750,000 ft Total surface area of steel in this 2
volume 216,200 ft Total surface area of concrete in 2
this volume 80,800 ft Steel surface area per unit volume of 2
3 turbine building 0.288 f t ff t Concrete surface area per unit volume 2
3 of turbine building 0.108 f t f fg 1
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t surface areas.
The steam blowdown flow rate as a function of time was taken from Figs. 1 and 2.
The steam temperature at the rupture point corresponds to the steam enthalpy from Figs. 1 and 2 and atmospheric pressure.
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4.
CALCULATED RESULTS The calculated temperature response of the steam environment at several distances within 20 ft from the rupture are given in Fig. 3 for the reactor building and Fig. 4 for the turbine building.
The response curves very close to the rupture are approximately the same and are drawn as one curve.
The response curves after the termination of the steam leak are conservative.
They are representative of the cooldown of steam remain-1 ing stagnant and coming to equilibrium with the local surrounding surfaces.
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Temperature response of the environment near the rupture for a reactor building cold reheat pipe rupture i
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Fig. 4.
Temperature response of the environment near the rupture for a turbine building hot reheat pipe rupture l
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REFERENCES 1.
Benham, R. G.,
et al., " Qualification of Fort St. Vrain Safe Shut-down Equipment for Steam Environment Resulting from Pipe Ruptures,"
USAEC Report Gulf-GA-A12045, Gulf General Atomic, May 30, 1972.
2.
Boonstra, R.
H., " TAC 2D - A General Purpose Two-Dimensional Heat Transfer Computer Code," General Atomic Report GA-A14032, July 15, 1976.
ilJ 12
ATTACHMENT E Location of Equipment in the Plant Fort St. Vrain Nuclear Generating Station has been divided into areas for purposes of identifying components and equipment requiring environmental qualification. These areas are:
RX1 -Above the Refueling Floor, Reactor Building RX2 -Beneath the Refueling Floor, Reactor Building RX3 -Process Area, Reactor Building CR
-Control Room AX
-Auxiliary Equipment Room SWR -480 Volt Switchgear and Battery Room TB1 -Turbine Building - All Other Areas TB2 -Below Operating Floor - Turbine Building TB3 -Diesel Generator Room - Turbine Building OPL -Outside the Plant PCRV -Internal to the RCRV Pressure Boundary Figures 1 through 5 depict the area described above.
RX2 and TB2 are the High Energy Line Break Areas.
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Reactor building elevation showing regions that were analyzed
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