ML20235W895
| ML20235W895 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 10/08/1987 |
| From: | FLORIDA POWER CORP. |
| To: | |
| Shared Package | |
| ML20235W888 | List: |
| References | |
| NUDOCS 8710190084 | |
| Download: ML20235W895 (7) | |
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PLANT SYSTEMS 3'/4.7.5 L ULTIMATE HEAT SI)lE LIMITING CONDITION FOR OPERATION g
I 3.7.5.1 The ultimate heat sink shall be OPERABLE with:
a.
A minimum water level at or above elevation.79 feet Plant Datum at'the Crystal River Unit 3 intake structure and, b '.~.An. inlet water temperature of I 105'F.-
_l APPLICABILITY: MODES.1, 2, 3 and 4.
ACTION:
j 1
With the water level. < 79 feet Plant' Datum or the inlet water temperature ).105'F, be in at least HOT STANDBY within 6-hours and in l COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
SURVEILLANCE REQUIREMENTS' 4. 7. 5.1 ' The ultimate' heat sink shall b'e determined OPERABLE at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> by ' verifying ' the inlet water temperature and water. level to be within their limits.
87101900B4 871008 PDR ADOCK 05000302 P
PDR g lCRYSTALRIVER-UNIT 3 3/4 7-18 I
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4 s-15)7;1 ULTIMATE HEAT SINK g
SUPPLEMENTAL SPECIFICATION Thef: intake. canal (ultimat'e heat sink) characteristics shall be maintained in accordance..with Figures 15-1a and 15-1b.
APPLICABILITY
=At all_'imes2
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t REMEDIAL ACTION 2 with the ' intake canal characteristics not' maintained in '. accordance with. Figures '
.15-1a and 15-1b,- restore the characteristics of the intake canal within 90 days or
' prepareand submit a report.to the Commission'within the next 30 days outlining the L.
' cause for not-maintaining.ithe characteristics and the plans for restoring the
. intake canal.
TESTING REQUIREMENTS At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, visually determine. the surface area of the intake canal
- at the intake structure to be free of floacing transportable materials that would
-impede safety-related flow of' water into the intake structure, At least once per 24 months, the intake canal characteristics shall be' verified to
'be' maintained in accordance with Figures 15-ia and 15-1b.
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M Area A - Contains no irregularities that would cause flow disturbances.
Area B - Bottoa elevation 167.2 feet and a maximum allowed elevation change of 7 inches between horizontal increments of 5 feet.
Area C - Contains no irregularities that would cause flow disturbances.
Area A, B, & C - Surface free of floating transportable materials that would impede safety-related flow of water into the intake structure.
INTAKE CANAL CHARACTERISTICS CANAL BEND AT CR-3 l
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n BASES The Crystal River intake canal serves as the ultimate heat sink for Crystal River Unit 3.
Maintenance of the characteristics of the intake canal ensures that an adequate cooling water supply will be available during a probable Maximum Hurricane (pMH). Minimum water levels will exist during a minimum tide hurricane. A minimum tide hurricane consists of a pMH which occurs at mean low tide and is oriented in a manner which causes high speed, offshore winds along the canal.
These assumptions are consistent with the recommendation of Regulatory Guide 1.27, " Ultimate Heat Sink for Nuclear plants", March, 1974.
The intake canal performs two principal safety functions.
These functions are the dissipation of residual heat after a reactor shutdown and the dissipation of residual heat after an accident.
Maintenance of the intake canal characteristics helps ensure the two safety functions can be performed.
The assumptions of the analysis for the minimum tide hurricane are documented in Reference 1 and assure that the maximum flow rate of 34,900 gpm is available to supply the safety-related sea water pumps for the nuclear services and decay heat systems.
The major assumptions utilized are as follows:
1.
The water level at the Gulf end of the canal is 1.0 foot below hean Low Water (MLW) during this pMH (relative to the Crystal River plant Datum
[CRpD], tha MLW level is at elevation 88.0 feet).
2.
Wind speeds are 110 mph at the plant end and increased to 115 mph at the Gulf end of the canal.
3.
The canal bottom width is 150 to 225 feet and the average bottom elevations are at elevation 73 feet (CRPD).
4.
Data from Lake Okeechobee in Florida is applied to give preliminary water surface slopes along the canal of 1.1 to 2.0 feet / mile caused by the PMH wind stress.
5.
Actual canal water surface slopes caused by wind stress are 0.1 to 1.0 feet / mile less than the preliminary values because of assumed inflow to canal from offshore wave action entering canal.
The resulting analysis indicated that the intake canal water level sloped downward at 1.0 foot / mile from elevation 87 feet at the Gulf end of the canal to elevation 79 feet at the Unit 3 end of the canal.
This minimum water level of 79 feet at the Unit 3 intake structure is acceptable when compared to the minimum required water level of 73.7 feet for operation of the safety-related pumps.
In order to accure that the maximum flow rate required for these pumps (34,900 gpm) is available under these conditions, a cross-section index concept was developed. It should be applied to the portion of the canal extending from the Gulf to the bend at the Unit 3 intake structure.
This index makes no assumptions about cross-sectional shape.
Therefore, it can be applied to various shapes and to sections with bottom irregularities.
The minimum allowable value for this cross-section index derived j
using a flow rate of 34,900 gpm is 600,000.
To assure that the maximum flow rate j
is available under the minimum tide hurricane conditions in the canal bend area at i
the CR-3 intake structure, it is necessary for the flow to enter the full open face of the intake structure.
This area defines the canal bend central portion.
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l To minimize energy losses and provide a smooth approach to the intake, the central portion of canal cross sections immediately upstream should be as uniform as possible.
In this central portion, the bottom should be smooth and no higher than elevation 67.2 feet so that most sediment will be trapped outside the intake chamber (floor elevation 67.0 feet) and canal bed material will not impede flow into the dual 48 inch pipes (entrance inverts at elevation 67.5 feet) that supply the safety-related pumps.
Outside the central portion, the canal bed and curvature of the banks should be free of major irregularities which could cause flow disturbances.
Additionally, from the Gulf to the Unit 3 intake structure, the canal must be kept as free as po3sible of fixed obstacles and transportable material that may impede the safety-related flow (34,900 gpm) of water into the
- intake, Fixed obstacles will be controlled by 10CFR50.59 and the plant modification process.
The need to dissipate residual heat always exists, as a result the commitment to maintain the characteristics of the intake canal (capabilities of the ultimate heat sink) is applicable at all times.
The remedial action of restoring the characteristics of the intake canal in 90 days is based on the qualitative risk associated with the occurrence of the minimum tide hurricane, engineering judgement, and past operational experience (including survey results and dredging operations).
The testing requirement intervals of once per 24 months for the survey and once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for the visual determination are based on engineering judgement and past operational experiences (including survey results and dredging operations).
REFERENCES:
1.
Gilbert / Commonwealth, Inc. Report No. 2669, Crystal River Unit 3 __
Criteria for Maintaining Adeauate Intake Canal Flow Capacity.
March 2.
1981 2.
FSAR Section 2.4.2.3 3.
FSAR Section 9.5.2.1.2