ML20076J496
| ML20076J496 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 06/09/1983 |
| From: | Mooney J CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harrison J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| CSC-6735, NUDOCS 8309070214 | |
| Download: ML20076J496 (4) | |
Text
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CORSum813' POW 8r
- C0mpanY Executive Manager -
Midland hvject Office.
General offices: 1945 West Pomall Road, Jackson, MI 49201 + (517) 788 0774 June 9, 1983 PRINCIPAL STAFF RA kNF 1 -
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PAO Mr'J J Harrison 22L SLO Midland Project Section EdO-RC U S Nuclear Regulatory Commission MM Region III N
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' H' Glen Ellyn, IL 60137 s
MIDLAND. ENERGY CENTER CWO 7020 LOAD TEST FOR PIER Wil File: 0485.16 UFI: 42*05*22*04 Serial: CSC-6735 70*01 During the NRC visit of May 11 and 12 at the Midland Site, data for the load test at Pier W11 was presented. The applicant believed that based on the data from Pier Wil as well as other prototype piers that the apparent' soil modulus, E, value shown was consistent with the design assumptions for the permanent underpinning design. However, the NRC believed that an E value of 1500 ksf and a differential settlement of " between the electrical penetration area / control tower and the main auxiliary building was appropriate.
H.'nce the NRC asked Consumers to look at the following options:
A.
Review the building capacity for an E of 1500 ksf or differential settlement of h" and provide results of shear strength from unconsolidated undrained triaxial tests on representative samples taken within 1 feet of the bearing stratum of some piers (to confirm the design ultimate bearing capacity of 44 ksf).
B.
Increase the jacking load so that the remaining differential settlement after lock off is k" and provide results of triaxial tests as discussed in option (A).
C.
Hold the jacking load an the permanent wall long enough so that the Fremaining differential settlement after lock off is " and provide results of triaxial tests as discussed in option (A).
D.
Perform another pier load test. One of the requirements is that friction between the pier and surrounding soil is eliminated. The NRC may provide additional requirements if the applicant chooses this option. One of the additional requirements may be to hold the duration of each 1 cad increment longer.
In this case provide results of triaxial tests as discussed in option (A).
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s E.. Perform a' plate' load test for a plate.of'18" minimum size.l he plate 1 T
should be loaded so as to reach failure load (or the assumed ultimate bearing capacity) of the' soil. 'The results of this. test should demonstrate that a minimum E1value:on the order of 3000 ksf is achieved. If.this test is per-formed to ASTM standards, NRR Washington need not review the~ test procedure further. - Region III.can give approval directly before the test-is performed.
Consumers Power Co. was to indicate to the NRC which option they would adopt.
~ Based on CPCo review of the options we wish to adopt option (A).. We have conducted a parametric study for the auxiliary building with reduced spring values in order to achieve the suggested differential settlement of ". The reduced spring constants correspond to apparent modulus values less than 1500 kaf. These reduced springs induced differential settlements of 0.47" for the EPA (relative to the Main Auxiliary Building) and 0.44" for the control tower (relative to the Main Auxiliary Building).
Our review of the analysis, based on the structural design criteria, has indicated that:
1.
The existing structure south of column row G is adequate.
2.
The permanent underpinning wall reinforcement as designed remains unchanged.
3.
All control towers Piers including CT1, CT3, CT11 and CT12 also remain unchanged.
4.
The connection between the EPA and the Main Auxiliary Building and the Control Tower underpinning and the building may have some minor effect.
The final design of these connections is underway.
5.
Based on review of the most critical settlement loading combination of the main building north of column row G, there are a couple of localized areas at elevation 634' and 659' which are slightly overstressed. We believe that a more detailed evaluation will demonstrate these areas to be adequate.
In case these areas can not be shown to be adequate, the appropriate repairs will be made.
The calculations performed for the above study are available for review. We have also reviewed option (C) 1.e. holding the jacking load longer.
Since the parametric study shows that the structure can take a larger differential settlement than originally assumed, we believe the present acceptance criteria for final lock-off of the permanent foundation should be redefined. The present acceptance criteria for lock off, referenced in SSER section 3.8.3.1 page 3-9, is as follows:
1.
Reaching secondary consolidation on the semi-log plot.
2.
Settlement increment of.05" in last 30 days.
3.
Settlement increment of.01" in last 10 days.
The second criteria translates to \\" additional total settlement for 40 years after lock off. The differential settlements corresponding to these criteria
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would be even smaller since the Main Auxiliary Building will also be settling during this time.
Since a study has been performed per option (A), items 2 and 3 of the accep-tance criterian should be redefined as follows:
2.
.05" in last 15 days.
(This translates to " additional total settlement for 40 years af ter lock off.)
3.
.01" in last 5 days.
Based on the above, Consumers Power Company believes that the structure is satisfactory for the lower E value for control tower and EPA and we have therefore decided not to perform a new load test.
Based on the capacity of the structure, we would also redefine the acceptance criteria for the lock off of the persanent wall. We also commit to provide NRC with resulte of the triexial tests.
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- ACTION INFORMATION J W Cook, P26-336B R A Wells, HPQAD A J Boos, Bechtel Ann Arbor J A Mooney, P14-115A J E Brunner, M-1079 J R Schaub, P14-305 I
R C Bauman, P14-312B W R Bird, P14-418A J K Meisenheimer, Midland A R Mallenkapf, P14-408A D B Miller, Midland F W Buckman, P24-624A D B Budzik, P24-517A N J Saari, Midland D F Lewis, Bechtel Ann Arbor R W Huston, Consumers Power Company 7910 Woodmont Avenue Suite #220 Bethesda, Maryland 20014 R L Tueteberg,' P24-505 NRC Correspondence File, P24-517 Mr. Mike Miller l
Isham, Lincoln & Beale l
3 First National Plaza, Suite #5100 l
Chicago, IL 60602 Isham, Lincoln & Beale 1120. Connecticut Avenue N.W.
Washington, D.C.
20036 l
R M Wheeler, Midland A E Blocher, Midland l
T R Thiruvengadam, P14-400 Ucil Swanberg, Bechtel Ann Arbor Mr. Ron Callen l
Michigan Public Service Commission I
6545 Mercantile Way l
Lansing, MI 48909 l
l File: 0485.16 UFI:
42*05*22*04 i
l