ML20196J281

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Proposed Tech Specs,Deleting Components Replaced During Svc Water Reservoir Improvement Project & Changing Allowable Differential Settlement of Class 1 Structures
ML20196J281
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 03/10/1988
From:
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20196J260 List:
References
NUDOCS 8803140237
Download: ML20196J281 (8)
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O TABLE 3.7-5

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g ALLOWABLE 1DTAL SETTLEMENT OR DIFFERENTIAL SETTLEMENT FOR CLASS 1 STRUCTURES 3

% ALLOWABLE ALLOWABLE TOTAL DIFFERENTIAL

$ SETTLEMENT SETTLEMENT

  • SETTLEMENT *

, SETTLEMENT POINT STRUCTURE POINT STRUCTURE / COMPONENT (FEET) (FEET)

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U 130 Containment Unit 1 223 Fuel Building N/A 0.12 w

130 Containment Unit 1 129 Auxiliary Building N/A 0.12

I43 y .y g Containment Unit 1 142 Unit 1 Safeguards Area N/A 0.04 t3m "

144 "O Containment Unit 1 145 Unit 1 Safeguards Area N/A 0.04 D5 0.12 149 gg Containment Unit 1 239 Unit 1 Main Steam Valve House N/A 09 144 X" Containment Unit 1 243,199,132 Service Building N/A 0.12 II^ O$ Safeguards Area Unit 1 239 Unit 1 Main Steam Valve House N/A 0.07 146 oo Y con 238 Unit 1 Main Steam Valve House N/A 0.08

! 128 gpjo Auxiliary Building CD 129 Auxiliary Buildiag 239 Unit 1 Main Steam Valve House 'N/A 0.08-129 Auxiliary Building 223 Fuel Building N/A 0.05 i 123 f.uxiliary Building 224 Fuel Building N/A. 0.05 122 Auxiliary Building 119 Service Buidling Tunnel' N/A 0.07 7 or 10 Service Water Pump House 17,18 North Side of Expansion Joint. N/A 0.22 from 7/77 Service Water Piping at SWPH 243,132 Service Building (E-5, 238 Unit 1 Main Steam Valve House N/A 0.06 1 E-6) 117 '** Service Building 113 Unit 2 Main Steam Valve House. N/A- 0.047 from 7/77 (E-14) 222 Auxiliary Feedwater Pump 240 Pipe Tunnel N/A 0.12 House - Unit I

O g TABLE 3.7-5 M

x: ALLOWABLE TOTAI. SETTLIGIENT OR DIFFERFNTIAL SETTLEMENT FOR CLASS I STRUCTURES U

x ALLOWABLE AI.LOWABLE TOTA 1. DIFFERENTIAL EE SETTLFMENT SETTLEMENT SETTLEMENT

  • SETTLEMENT
  • POINT STRUCTURE POINT STRUCTURE / COMPONENT (FEET) ___ (FEET) 17,18 North Side of Expansion 0.22 from 8/78 N/A Joint Service Water Piping at SWPil 228 Decontamination Building 250 Pipe Tunnel N/A 0.06 226 Fuel Building 251 Waste Gas Decay Tank N/A 0.06 Enclosure i

114 Service Building (E-17) 0.09 N/A 141 Safeguards Area - Unit 1 253 Unit 1 - Cising N/A 0.12 from 2/79 M

158 *** Turbine Building (B-9 t/2) 0.06 N/A 7

0 245, 246 Fuel Oil Pump flouse 0.03 N/A 206, 207, 208, 209 Boron Recovery Tank Dike 0.03 N/A 204 Circulating Water Intake Structure 0.15 N/A 25,26,27,28 Service Water Valve llouse 0.32 !a- note) N/A 29,30,31,32 Service Water Tie-in Vault 0.12 (see note) N/A i NOTE: From date of Piping Tie-in

  • Unless otherw'se indicated, all"wable settlements are from baseline elevations established in May 1976 or. reference elevations ccrrected to the May 1976 survey. ,
    • Critical differential settlement is downward movement of Point 117 with respect to Pctnt 113. . -
      • Not Class I structure, but settlements affects Class I pipeline.

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TABLE 3.7-5 '

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ALLOWABLE TOTAL SETTLEMENT OR DIFFERENTIAL SETTLEMENT FOR CLASS 1 STkUCTURES

.h M

h5 ALLOWABLE ALLOWABLE TOTAL DIFFERENTIAL g SETTLEMENT SETTLEMENT SETTLEMENT

  • SETTLEMENT
  • 4 POIF CTRUCTURE POINT STRUCTURE / COMPONENT (FEET) (FEET) e --

" 224 Fuel Building N/A 0.12 131 Containment Unit 2 131 Containment Unit 2 123 Auxiliary Building N/A 0.05 i

106 Containment Unit 2 105 Unit 2 Safeguards Area N/A 0.07 107 Containment Unit 2 108 Unit 2 Safeguards Area N/A 0.07 131 Containment Unit 2 124 Unit 2 Main Steam Valve House N/A 0.03 107 Containment Unit 2 116 Service Building (E-15) N/A 0.12 N

111 Safeguards Area Unit 2 124 Unit 2 Main Steam Valve House N/A 0.12

$ 122 Auxiliary Building 120 Unit 2 Main Steam Valve House N/A 0.04 123 Auxiliary Building 124 Unit 2 Main Steam Valve House N/A 0.04 123 Auxiliary Building 224 Fuel Building N/A 0.05 129 Auxiliary Building 223 Fuel Building N/A 0.05 122 Auxiliary Building 119 Service Buidling Tunnel N/A 0.07 243,132 Service Building (E-5, 238 Unit 1 Main Steam Valve Houee N/A 0.04 E-6) 117 ** Service Building 113 Unit 2 Main Steam Valve House N/A 0.047 from 7/77 (E-14) 231 Auxiliary Feedwater Pump 249 Pipe Tunnel N/A 0.12 House - Unit 2 228 Decontamination Building 250 Pipe Tunnel N/A 0.06 d

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TABLE 3.7-5 I.

O ALLOWABLE TUTAL SETTLEMENT OR DIFFERENTIAL SETTLEMENT FOR CLASS I STRUCTURES ,

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o ALLOWABLE ALLOWABLE N TOTAL DIFFERENTIAL SETTLEMENT SETTLEMENT SETTLEMENT
  • SETTLEMENT *'

3 g POINT STRUCTURE POINT STRUCTURE / COMPONENT (FEET) (FEET) 226 Fuel Building 251 Waste Gas Decay Tank N/A 0.06-h Enclosure a

w 104 Safeguards Area Unit 2 254 Unit 2 Casing Cooling N/A 0.12 Building from 2/79 7, 10 Service Water Pump House 17, 18 Service Water Piping N/A 0.22-at SWPH from 7/77 17, 18 Service Water Piping 0.22 from 8/78 N/A at SWPH North Side of Expansion Joint y 204 Circulating Water Intake 0.15 N/A; A Structure Y

g 158 *** Turbine Building 0.06 N/A (B-9 1/2) 114 Service Building (E-17) 0.09 N/A 245, 246 Fuel Oil Pump House 0.03 N/A.

206, 207, 208, 209 Boron Recovery Tank Dike 0.03 _N/A 25,26,27,28 Service Water Valve House 0.32 (see note) N/A-29,30.31,32 Service Water Tie-in Vault 0.12 (see note) N/A NOTE: From date of piping tie-in

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ATTACHMENT 2 SAFETY EVALUATION l

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Virginia Electric and Power Company l

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, Change to Units 1 and 2 Technical Specification Table 3.7.5, Allowable Total Settlement or Differential Settlement for Class 1 Structure." j l

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DISCUSSION l l

The proposed changes to Technical Specifications Section 3.7.12, Table 3.7.5 deletes the Settlement Monitoring requirements for Service Water lines which were removed from service and replaced with new lines connecting the Service Water System to the new Service Water valve house and spray headers during the Service Water Reservoir Improvement Project in 1987.

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BASIS FOR NO SIGNIFICANT HAZARDS DETERMINATION The proposed change to delete monitoring of settlement points no longer in l service does no* involve a significant hazards consideration because operation of North Anna Units 1 & 2 in accordance with this change would not:

l (1) involve a significant increase in the probability or consequence of an accident previously evaluated, or (2) create the possibility of a new or different kind of accident from any ,

accident previously identified, or (3) involve a significant reduction in a margin of safety, because this  !

change only deletes Settlement Monitoring on equipment previously '

replaced. This replacement was approved by the NRC via license I amendment 91 for Unit 1, and license amendment 76 for Unit 2, both '

dated March 27, 1987. '

Therefore it has been concluded that the proposed change does not involve a  ;

significant safety hazards consideration.

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DISCUSSION The proposed change will also revise the limit for differential settlement between points 117 and 113 of Table 3.7-5. The differential settlement between settlement monitoring points 117, the Service Building, and 113, the Unit 2 Main Steam Valve House (MSVH), has frequently approached 75% of the allowable value in Table 3.7-5 of Technical Specification Section 3.7.12, and the measured value exceeded 75% of the allowable value in June 1987 and in 1980. A report on exceeding 75% of allowable differential settlement between these two points was submitted to the Commission in 1981 and in August 1987 in accordance with Technical Specifications. ~The report of August 1987 is provided in Attachment 3.

The primary concern of the differential settlement between the Service Building and the Unit 2 MSVH is the effect on. the four buried service water lines running between the two structures. The code allowable stress in the service water lines for differential settlement condition is 45,000' psi. As stated in -

the Technical Specifications, critical differential settlement is downward movement of the Service Building with respect to the MSVH. The results of an engineering analysis show that. . disregarding survey inaccuracies, there has been negligible additional settlement of the Service Building since 1981.

The differential settlement limit of 0.03 feet in the Technical Specification was based upon an estimate of future differential settlement between points 117 ,

and 113. The Service Water pipe stress analysis shows that considerable margin exists before code allowable stresses would be exceeded and, therefore, the differential settlement of the Service Building with respect to the Unit - 2 MSVH has had no significant impact on the service water pipes or on plant operability.

The proposed change will revise the allowable value of differential settlement l between the Service Building and the Unit 2 MSVH from 0.03 feet to 0.047 feet.

This value, 0.047 feet, corresponds to a stress of 44,176 psi in the -service water lines, which is still below the code allowable stress of 45,000 psi.

This action would mean that the 75% reportable threshold would increase.

Therefore, additienni review need only be initiated when there is significant concern.  ;

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i BASIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION The proposed change to increase the Allowable Differential Settlement between points 117 and 113 does not involve a significant hazards consideration as defined by 10 CFR 50.92 because operation of North Anna 1 and 2 in accordance with this change would not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated as the stress in the service water lines for the requested value of differential settlement has been verified to be below the code allevable stress. j
2. Create the possibility of a new or different kind of accident from any l accident previously evaluated. The proposed increase in differential i settlement will not place the service water lines in a condition that l

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will. compromise the structural integrity of the piping and therefore will'not. introduce'any new or.' unique operational' modes ar accident-precursors.

3.-. Involve'.a .sigtiificant=' reduction in th'e margin of safety because the resulting pipe stress, while increased, will still be .within the code.

allowable stress and therefore the margin of safety, required by the code is. maintained... '8' -

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