ML20094H967
| ML20094H967 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 04/20/1981 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML19258A087 | List:
|
| References | |
| CON-BX16-021, CON-BX16-21, FOIA-84-96 NUDOCS 8408140175 | |
| Download: ML20094H967 (8) | |
Text
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3 MIDLM)D 4 83 The safety factors are defined in the following relationship:
A Factor of Safety = A, red where A, = cross-sectional area of reinforcing steel Iten J: Verify that the reactor pressure vessel upper lateral support is considered in the design analyses.
Status: Due to modifications in the reactor vessel support system, Babcock & Wilcox is currently repeating the analysis for the NSSS. When the loads from that analysis are available, Bechtel will evaluate the supports based on the revised loads. Bechtel meanwhile has included the effects of the modified reactor vessel support system in the containment building seismic analysis to assess the possible change in structural response. Changes in the responses and a description of the new model will be provided in an FSAR revision.
Item k: Provide shear values for all tabulations included in the NRC Structural Technical Audit responses.
Status: The affected pages have been revised to include shear values, where applicable.
4 AUXILIARY BUILDING The modification scheme using caissons (described in the audit response) is being revised. Therefore, some questions are not directly applicable.
The modification schemes adopted will be provided by FSAR revision.
Item a: Check for possible additional loading on the control tower due to the effects of caissons.
Status: The effect of possible. additional loading to the control tower due to caissons will be addressed, if applicable.
Item b: Assess the effect of bending on the wing foundation due to the outer caissons.
Status: If the revised modification scheme uses caissons, the effect of bending will be assessed.
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Item c: Consider concrete and soil in combination to determine caisson j
stiffness.
Status:
If caissons are used in the revised modification, concrete and soil will be considered in combination to determine the stiffness.
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Item d: Determine whether friction between the caissons is required to develop full load.
Status: This question will be addressed, if applicable.
Item e: Ensure that the foundation design will be based on a subgrade modulus calculated from actual tests.
-Status: The soil input will be developed using actual soil persmeters I and/or observed settlements.
Item f: Vendor calculations relative to the fuel racks must be checked.
Determine how the impact factor was applied to the fuel racks. Ensure that the possibility of tipping the fuel racks has been considered.
Status: Documentation provided by the vendor indicates the fuel pool rack calculations were checked prior to-the audit. A request will be
- made that the vendor provide information concerning impact factors and verify through analysis that the fuel racks will not tip over under design conditions.
Item 3: Provide an explanation of the approach used to obtain shear values for shear walls.
Status: A revision of Volume 5, Page 24a of the NRC Structural Tech-nical Audit is attached (Attachment E). The response indicates the method used to obtain the shear values. The calculation pages provided J
with Attachment E are for information only.
Item h: Explain how through-cracks will affect load capacity.
Status: Through-cracks will be considered in accordance with the Mid-land concrete crack position in Attachment J.
Item 1: Assess the effects of long-term settlement on the control tower versus main section of the auxiliary building.
1 Status:' Significant long-term differential settlement between the control tower and the main auxiliary building will be addressed by FSAR revision.
Item j: Ensure that the same asthod used to analyse the through-cracks will be used to verify the capacity of an isolated typical section.
Status: A portion of the diesel generator building will be examined using a finite element cracked section analysis (Refer to Page 4 of Attachment J).
1 DIESEL E NERATOR BUILDING Item as Verify spring constants used in the analysis and design of the diesel generator building.
Status: It has been verified that the spring constants used in structural l
analyses are based upon the information provided by the Bechtel geotechnical group.
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Item b: - Estimate stresses associated with the cracking and consider the widening of cracks.
Status: Cracks will be considered in accordance with the Midland i
concrete crack position in Attachment J. Appendix C.
Item c: Verify that reversal effects of seismic loads are considered relative to cracking.
Status: Cracks will be considered in accordance with the Midland concrete crack position in Attachment J.
(Refer to Pages 1, 3, 5, and 13 and Appendix A of Attachment J).
Item d: Coordinate modifications of the pedestal with the diesel generator vendor providing the pedestal design and the seismic qualifications - for the diesel generators.
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Status: The modified design of the pedestals has been coordinated with the vendor. The vendor was also informed that the pedestals were leveled before setting the diesel generators. A new seismic analysis for the diesel generator building was performed, and the design basis spectra will be incorporated in the revised applicable specification for the seismic qualification of all equipment.
Item a: Evaluate the influence of through-cracks on structural capa-city.
4 Status: Cracks will be considered in accordance with the Midland concrete j
crack position in Attachment J.
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Item f: Evaluate the effects of a tornado missile on a well with cracks.
Status: The offacts of a tornado missile on a well with cracks will be i
evaluated in accordance with the Midland concrete crack position in Attachment J.
(Refer to Appendix B of Attachment J) i SERVICE WATER PtBIP STRUCTURE Item a: Provide for monitoring of cracks in the service water pianp atrueture.
1 Status: Monitoring of cracks in the service water pump structure is an l
ongoing activity.
j Item b: Evaluate the ef fects of hydrodynamic loads on interior walls.
Status: Interior walls have been checked for hydrodynamic loads. The
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method used follows that outlined in the Technical Information Docu-ment TID-7024. The wella satisfy FSAR acceptance criteria.
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Item c: Provide a factor of safety for the bearing capacity of the new i
wall foundation.
Status: The safety factor will meet or exceed the FSAR acceptance criteria. The actual factor of safety will be provided in an FSAR revision when the modification scheme is finalized.
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Item dr Establish a monitoring progra for settlement of the service
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water pipes.
Status: The service unter pipes will be monitored for differential settlement relative to the structure from inside the building during-f the ederpinning construction activities. The differential settlement will be monitored at points where the pipes cross the exterior unll.
j This monitoring will be conducted on a weekly basis for the duration of the ederpinning activities and will be continued every two useks s'
for 6 months af ter completion of the ederpinning activities.
BORATED WATER STORAGE tansrs Item a: Provide details of the final design, in particular, the con-nection between the inner and outer foundation umils Status: These details will be documented in the FSAR when the design is finalized.
2 Item b Verify vendor acceptance of tank foundation modifications.
j Status: The vendor will perform structural analyses of the tanks under the present foundation condition and the predicted future condition 4
af ter the foundations are modified. Based on the results of these analyses, the acceptance of the tanks will be determined. Acceptability and its basis will be provided in an FSAR revision.
Item c: Establish a monitoring program for pipes in the valve pit.
4 Status: Item c is closed because Seismic Category I piping uns cut out-l side the pit before the load test. A monitoring progree will be established j
if the pipes are reconnected prior to the completion of the modification.
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Item di Monitor bigh stress points for cracks af ter implementation of i
remedial soils actions.
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Status: This item will be considered as a part of the soils remedial actions.
l BURIED PIPES AND TANKS 1
Item at Verify that postulated earthquake loadings will be considered in tank piping connection design.
Status: The analysis for seismically induced forces in buried piping will identify nossle loads. These loads will be added to the values j
already established for thermal and settlement effects. The total will be compared to the acceptance criteria. This is further addressed in 4
the revised responses provided in the NRC structural technical. audit
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(Volume 10) which have been attached (Attachment F).
Item b: Describe the routing of the air supply entering the control room from the control room pressurization tanks.
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Status: Air supply lines are connected to nozzles at the top of both control room pressuriration tanks in the accessway. Lines come out of the accessway wall at el 628'-4-3/4", turn down, and run toward the auxiliary building at el 625'-0".
Both lines from the tanks are con-nected to a common header just outside the auxiliary building. Link seals exclude moisture at both places where lines come out of the accessway and enter the auxiliary building. A line runs through the auxiliary building into the control room area and finally terminates in the heating, ventilating, cad air conditioning duct (see Attachment G).
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Item c: Control room tanks should be monitored for displacements.
Status: The applicable design drawing is being revised to indicate settlement markers for the control room pressurization tank foundations.
GENERAL Item a: Provide a schedule for soils remedial actions.
Status: The schedules of service wat'ar pump structure and auxiliary building remedial actions, as presented during the audit, are shown in Attachment H.
Design of the borated water storage tank modification l
will be completed by July 30, 1981.
l Item b: Provide a copy of the calculation index for the remedial actions.
1 Status: The complete index is included as Attachment I.
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Attachment A
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NRC STRUCTURAL AUDIT PRELIMINARY LIST OF OPEN ITEMS Containment a.
Review thunbers on Page 21. Table 3.8-1 b.
Verify that torsion uns used on components and internal structures.
c.
Membrane shear allouable in equipment hatch area shear allowable (400 psi) needs verification d.
Bijlaard Show that this technique is applicable for contain-asnt shell e.
Check adequacy of baseslab shear reinforcement it's on vertical wide flanges.
f.
Impact effect of 1/32 inch gap stese generator needs to be assessed Allowableasebranetension,3ff' and 6 f'
- which load 3
combination in tension and bendiIg and whefe does it apply h.
Want to know the actual yield stress for reinforcement in the primary shield.
i.
Explain Mu and Vu along with safety factor; Page 57 j.
Peactor pressure vessel upper lateral support is this consi-dared in analysis
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k.
To tabulate shear values in all tables Auxiliary Buildina Check for possible additional loading on control tower due to a.
the effects of caissons i
b.
Bending on foundation of wing due to revised outer caissons must be assessed Stiffness of caissons should consider concrete and soil together c.
d.
Is friction between the caissons required to develop full load e.
Subgrade modulus should be calculated from tests for use in the foundation design f.
Fuel rack celes-unchecked (vendor cale) tapact factor used between fuel racks, and pool unlis from tipping needs to be studied
.Cilesforshearwellshouldbeenplainedshowing (Resolved) 3 approach used h.
How does thru cracks affect load capability l
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Effect of long-term settlement on control tower versus main (4
section of ana111ery building j
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Use some method to analyse the thru cracks, to verify capacity of an isolated typical section.
t Diesel Generster hildina a.
Verify spring coastants b.
Cracks estiaste stress; also consider widentag of cracks c.
Cracks should include reversal offacts of seismic leade d.
Co-ordtaate with vendor on pedestal design and seismic geslification for diesel generators t
e.
Want commitanat to evaluate cracks influence os structurni espacity f.
Present evaluation of tornado missile effects on a us11 with l
cracks 1
l Service Water Fune Structure I
a.
Monitor cracks b.
Eydrodynamic leads on laterior walls i
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Foundation hearing capacity of new dell needs identified 2
factor of safety I
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Ceamit to maattor service water pipes 'for settlement effects.
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l Provide details of final design, especially commeetion between a.
j the two foundation wolle i
b.
Provide Vendor acceptance of taak foundation modifications i
Pipes sl.ould also be monitored in the valve pit I
c.
d.
Comit to esatter high stress points after impleasataties of fin for cracks 1
hried Ploe sad Tasks
' a.
Earthquake should be considered in tank piping connection design b.
Control room tanks should be monitored for displacements c.
Describe air supply lines to control room f rom tanks 4/24/81 i
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West espy of calculation indes for fines l
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