ML20040B718
| ML20040B718 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 01/15/1982 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, 14666, 80-09-#4, 80-9-#4, 80-9-4, MCAR-45A, MCAR-45B, NUDOCS 8201260350 | |
| Download: ML20040B718 (6) | |
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and Co struction 80-09 #h General Offices: 1945 West Parnali Road, Jackson, MI 49201 * (517) 788 0453 January 15, 1982 j_LQj 9l's V
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.y Mr J G Keppler, Regional Adminictrator
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US Huclear Regulatory Commiccion tf
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Region III
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Glen Ellyn, IL 60137
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MIDLAIID PROJECT - UNITS 1 AND 2 wi jli' DOCKEP NOS 50-329 AND 50-330 LOW ALLOY QUENCHED AND TEMPERED BOLTING lh IUCHES AUD GREATER IN SUPPORT OF SAFUTY RELATED SYSTEMS FILE:
0.h.9.46 SERIAL:
lh666
References:
J W Cook letters to J G Keppler, Same Sub, ject:
(1) Serial 10996, dated January 9,1981 I
(2) Serial 11526, dated March 31, 1981
( 3) Serial 13690, dated September 29, 1981 Thic letter, as were the referenced letters, is an interim 50.55(e) report concerning the status of the subject bolting. Attachment 1 provides a deceription of the status of the planned corrective actions.
Another report, either interim or final, will be sent on or before April 2, 1982.
h WRB/lr : MCAR 45A and B, Interim Report h, dated December 16, 1981 CC: RJCook, URC Resident Inspector i
Midland nuc1 m P'nnt (1)
Document Cortrol Desk, URC Wachington, DC (1) 1 OSEo$$8fjj, Poa JAN 211982 l
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Serial lh666 2
80-09 #4 CC: CPeel.hoefer, ASLB Panel RSDecker, ASLB Panel q
FPCowan, ASLB Panel l
JHarbour, ASLB Panel i
AS&L Appeal Panel
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IC4 Cherry, Esq l
MSinclair BStamiris CRStephens, USIGC l
WDPaton, Esq, US!aC
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FJKelley, Esq, Attorney General I
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i SliFreeman, Esq, Asst Attorney General l
WHMarshall i
GJMerritt, Esq, TNK&J l
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s Serial 14666
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8-9 Bechtel Associates Professional Corporation O52587 052758
SUBJECT:
MCAR 45A and 45B (issued 12/18/80) 2 INTERIM REPORT 4 1
DATE:
Decembe r 16, 1981 PROJECT:
Consumers Power Company Midland Plant Units 1 and 2 i
Bechtel Job 7220
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Intr oduc t ion i
l The discrepancies discussed in this report concern the hardness values I
of the anchor and connecting studs for the reactor coolant pump (RCP)
I snubbers.
1 Background
MCAR 45A The RCP snubber anchor studs are 2-1/4, 2-1/2, 3, and 3-1/2 inches in diameter and vary in length from 3'-6" to 7 '-1".
They are embedded in the secondary shield wall and the refueling canal wall.
Also included are 2-and 2-1/4-inch diameter connecting studs approximately l'-10" long that connect the snubbers to a structural steel transition piece.
The anchor studs are partially embedded in the concrete and the con-necting studs are in place. The snubbers restrain the RCPs during seismic and/or los s-of-coolant accident (LOCA) events.
The studs were purchased from various vendors during 1977 and 1978 by Bechtel construction in accordance with either ASTM A 354, Grade BD, or j
ASTM A 540, Grade B23, Class 3.
They were intended to be tensioned to a preload up to 96 ksi to maintain the specified snubber spring rates under all loading conditions. To ascertain that the studs could with-i s tand long-term loads of this magnitude without becoming susceptible to s tress corrosion cracking, Consumers Power Company requested Teledyne Engineering Services (TES) to conduct hardness tests on the exposed end of the embedded and connecting studs. TES conducted these hardness tests from November 21 through November 23, 1980. The test results showed that 207 studs of 384 tested are outside the range of hardness specified by the ASTM specifications.
MCAR 45B On November 26, 1980, Consumers Power Company expanded the 10 CFR 50.55(e) report to include, as potentially reportable, all low-alloy quenched and tempered bolting materials 1-1/2 inches in diameter and above used in support of safety-related systems.
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l D64 687 Bechtel Associates ProfessionalCorporation 1
MCAR 45A and 45B G52758 Iaterim Report 4 December 16, 1981 Page 2 Investigative Action l
MCAR 45A Aptech Engineering Services of Palo Alto, California, was retained by Consumers Power Company to review the hardness data taken by TES, and to 3
evaluate the effect of the measured hardnesses on the ability of the studs to withstand preload, operating, and accident loadings.
Based on i
preliminary Aptech evaluations, it has been decided to lower the stud preload (to a maximum of 12 ksi) to preclude failure because of stress corrosion cracking. Aptech has confirmed that a maximum preload of i
12 ksi is low enough to preclude stress corrosion cracking for the
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hardness ranges under consideration.
Instructions have been issued to j
construction to preload the stude to 9 ksi, a value lower than the maximum j
permissible. A tolerance of +3 ksi is allowed.
This preload value, when reduced by temperature and relaxation losses, exceeds 3 ksi, a value in excess of the minimum preload of 1.5 ksi re-quired by Babcock 6 Wilcox during operation. New spring rates have been j
submitted by Be..htel to B&W.
B6W is proceeding with the new seismic and LOCA analysis of the reactor coolant system.
ITT Grinnell, supplier of the snubbers, has also been informed of the change in the preload.
Grinnell stated that there is no effect on the snubbers or on the spring rate of the snubbers themselves.
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When the new seismic and LOCA loads are supplied by B&W, the stud stresses will be calculated and compared with the allowable stress limits for oper-j' from Aptech on the allovable short-term loadings is expected by Decem-ating and short duration loading being determined by Aptech. A report ber 31, 1981.
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Procurement documentation packages for these studs have been reviewed to i
determine whether any additioncl action is required. A report on this j
review will be included in the next interim report.
MCAR 45B Consumers Power Company is leading the investigation required by this MCAR.
Commonwealth Associates, Incorporated (CAI) of Jackson, Michigan has been retained by Consumers Power Company to review safety related 4
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052587 Bechtel Associates Professional Corporation
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MCAR 45A and 45B Interim Report 4 December 16, 1981 Page 3 purchase orders and identify those purchase orders including 1cw-alloy quenched and tempered steel (LAQTS) bolting and/or component material.
CAI is also obtaining data that will be used in evaluating LAQTS mate-ri al. This ef fort has been completed, with exception of a few purchase o rde rs.
i Most of the review being conducted on the LAQTS bolting and component support materials consists of field hardness testing. This testing will t
be performed by Consumers Power Company.
Science Applications Incorporated (SAI) of Palo Alto, California has been retained to assist in developing a sampling plan to determine the quan-tity of items to be tested. SAI will also provide statistical services in preparing the hardness data for evaluation.
Aptech Engineering Services of Palo Alto, California has been retained to assist in evaluating the LAQTS materials purchased.
Correct ive Action MCAR 45A Construction has been instructed to preload the snubber studs to 9 +3 ksi.
A procedure was developed by B&W construction to ensure that the st'Eds are tensioned as required. This work has been completed for Unit 2, and is presently in progress for Unit 1.
Upon receipt of the Aptech Report identified above, engineering will compare the calculated stresses with j
the Aptech allowable stress. A final check of stresses will be made upon receipt of B&W Specification 1235, entitled Reactor Coolant System Foun-1 dation and Nozzle Loadings, scheduled for issue December 1982.
TES Technical Report TR-4599-3, Hardness Measurements of Anchor and Con-nection Studs Securing Reactor Coolant Pump Snubbers at Midland Plant Units 1 and 2, dated January 28, 1981, was submitted by Consumers Power Company to the NRC.
I Safety Implications MCAR 45A If the subject studs were tensioned according to the original design re-q ui r eme nt s, there may have been a safety deficiency in that some of the l
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06R587 Bechtel Associates ProfessionalCorporation MCAR 45A and 45B US2758 Interim Report 4 December 16, 1981 Page 4 studs could have failed due to stress corrosion cracking. If uncorrected, this deficiency could adversely affect the safety of Midland plant opera-tions during the expected life of the plant.
MCAR 45B Presently, the existence of adverse safety implications relative to other safety-related bolting is undetermined.
Reportability This condition relative to the reactor coolant pump snubber studs was identified as "potentially reportable" by Consumers Power Company to the NRC under 10 CFR 50.55(e) on November 25, 1980.
MCAR 45A Prepared by:
b / _ M[wu Reviewed by:
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MCAR 45B Prepared by:
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Reviewed by:
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