ML19325D414

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Proposed Tech Spec 3/4.7.6, Flood Protection.
ML19325D414
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 10/13/1989
From:
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML19325D413 List:
References
NUDOCS 8910230238
Download: ML19325D414 (6)
v • d • e


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t a i ATTACHMENT ONE l t

i PROPOSED TECHNICAL SPECIFICATION CHANGES 1 l

NORTH ANNA - UNITS 1 AND 2 l

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VIRGINtA ELECTRIC AND POWER COMPANY j 8910230238 891013 PDR ADOCK 05000338 P PNU

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. j PLANT SYSTEMS i

3/4.7.8 FLDOD PROTECTION l l l LIMITING CONDITION FOR OPER ATION  ;

l i 3.7.6.1 Flood protection shall t>e provided for all safety related systems, components and l l l

structures when the water level of the North Anna Reservoir exceeds 256 feet l Mean Sea Level USGS datum, at the main reservoir spillway. j AEP.LlCAR1 Lit.Y.: At all times  !

ACTION: A. With the water level at the main reservoir spillway above elevation 252 feet {

Mean Sea Level USGS datum, close the sluice gate on the east end of the I drain pipe through the flood protection dyke within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

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B. With the water level at the main reservoir spillway above elevation 256 feet Mean Sea LevelUSGS Datum:

1. Be la at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in 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 />, and ,
2. Initiate and complete within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, the following flood protection  !

measures: i a) Stop the circulating water pumps, and b) Close the condenser isolation valves.

b SURVEILLANCE REQUIREMENTS l 4.7.6.1 The Water Level At The Main Reservoir Spillway Shall be determined to be within l the limits by:

A. Measurement at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> when the water levelis below elevation 251 feet Mean Sea Level USGS datum.  :

B. Measurement at least once per 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> when the water levelis equal to or above 251 feet Mean Sea Level USGS datum. i NORTH ANNA UNIT 1 3/4 7-20 Amendment  !

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- l PLANT SYSTEMS i 1

i 3/4.7.8 FLOOD PROTECTION t f

1 l l LIMITING CONDITION FOR OPER ATION l l

f 3.7.6.1 Flood protection shall be provided for all safety related systems, components and i structures when the water level of the North Anna Reservoir exceeds 256 feet  !

l Mean Sea Level USGS datum, al the main reservoir spillway.  ;

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APPLICABILITY: At all times j i  !

ACTION: A. With the water level at the main reservoir spillway above elevation 252 feet i

Mean Sea Level USGS datum, close the sluice gate on the east end of the drain pipe through the flood protection dyke within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

1 B. W4h ins water level at the main reservoir spillway above elevation 256 feet Mean Sea LevelUSGS Datum: i

1. Be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN f

within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />, and -

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2. Initiate and complete within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, the following fic4xl protection measures:

a) Stop the circulating water pumps, and t b) Close the condenser isolation valves. -

1 SURVEILLANCE REQUIREMENTS 4.7.6.1 The Water Level At The Main Reservoir Spillway Shall be determined to be within l the limits by:

A. Measurement at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> when the water levelis below elevation 251 feet Mean Sea Level USGS datum.

B. Measurement at least onoe per 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> when the water level is equal to or above 251 feet Mean Sea Level USGS datum.

i NORTH ANNA UNIT 2 3/4717 Amendment

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ATTACHMENT TWO  !

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i DISCUSSION OF PROPOSED CHANGES l l

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BASIS FOR  !

l NO SIGNIFICANT HAZARDS DETERMINATION

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i l VIRGINIA ELECTRIC AND POWER COMPANY l ,

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PROPOSED TECHNICAL SPECIFICATION CHANGES: j This change will add a requirement to close the isolation valve on the drain pipe through j the flood control dyke being added around the end of the Unit 2 Turbine and Service ,

Buildings within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the Main Reservoir reaching a level of 252 feet above Mean Sea Level.

In add; tion, the trigger level for escalating surveillance of the Main Reservoir Water Level r is being decreased from 255 ft. Mean Sea Level to 251. ft and the surveillance interval is l decreased from once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> when the reservoir level is below 251 ft. ,

l DISCUSSION: l LER 85 003 00 identified a potential flooding situation at North Anna Power Station which  ;

had not been Identified previously. To obviate this situation, a flood control dyke is to be constructed around the end of the Unit 2 Turbine and Service Buildings (Design Change 8814 3). Drainage for the area enclosed by the dyke, will be provided by a valved drain pipe installed through the bottom of the dyke. In the event of flooding, the drain pipe could ,

provide an inflow path for flood water into the area enclosed by the dyke and then into the Turbine and Service Buildings and the Emergency Switchgear and Relay Rooms. This change to the Technical Specifications will add a requirement to isolate the drain pipe prior to the water levelin the Main Reservoir reaching a level where flooding would occur.

Based on an analysis of the worst case flooding condition, the reservoir level would be rising at a rate of 0.8 foot per hour. Flooding of the Turbine and Service Buildings occurs at 257 ft. above Mean Sea Level and at that rate, would occur 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> after the water level had risen to 252 ft. Therefore the requirement to close the drain pipe valve within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after reaching the 252 ft. level, will ensure that the required protective actions will be taken in a timely manner and that the facility flood control measures will provide protection to the safety related equipment. To insure that the drain pipe Isolation valves remain operational, a periodic test will be implemented to operate the valves through a full stroke l movement at least once every three months.

The reduction of the trigger level for escalating surveillance from 255 ft. to 251 ft. and the decrease in the surveillance interval from once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to once every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, with the reservoir level below 251 ft., will ensure that an increasing water level will be detected in sufficient time to perform the actions required to isolate the dyke drain pipe during the maximum postulated lake inflow.

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BASIS FOR NO SIGNIFICANT HAZARDS DETERMINATION j We have reviewed the changes to Technical Specifications 3/4.7.6 and have found that  :

I these changes will not involve a significant hazards consideration because the proposed changes will not:

(1) result in a significant increase in the probability or consequences of an accident f previously evaluated. This change will provide additional controls, not currently in  ;

place, to reduce the probability of floooing and provide more restrictive  ;

surveillance requirements for identifying potential flooding conditions.

(2) create the possibility of a new or different kind of accident. This change reflects l plant modifications that are being implemented to protect the safety related j equipment during postulated worst case flooding conditions. The installation of l the dyke and the proposed technical specification change and surveillance requirements for potential flooding conditions will enhance protection of safety related equipment, during currently analyzed accidents, and will not introduce any j new, or unanalyzed accidents, l

l (3) result in a significant reduction in the margins of safety. The changes provide for l additional limitations and controls, more restrictive than those currently existing in l the Technical Specifications, to be placed on the operation of the North Anna Units.

Therefore, pursuant to 10 CFR 50.92, based on the above consideration, it has been  !

l determined that operation of North Anna Power Station Units 1 and 2,in accordance with these changes, will not involve a significant hazards consideration, in addition, the changes conform to 48 FR 148764 (14870) " Examples of Amendments That Are Considered Not Likely To involve Significant Hazards Considerations...", example li "A change that constitutes an additional limitation, restriction, or control not presently  ;

included in the Technical Specifications: for example a more stringent surveillance requirement."

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