ML20058C445
| ML20058C445 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 07/09/1982 |
| 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, 17542, 80-09-#7, 80-9-#7, MCAR-45A, MCAR-45B, NUDOCS 8207260349 | |
| Download: ML20058C445 (7) | |
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I h, Consumers Power T-C0mp2Hy General Off kes: 212 West Mktugen Avenue, Jackson, MI 49201 *(517) 788-0550 July 9, 1982 80-09 #7 tir J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 FIIDLAND PROJECT - UNITS 1 AND 2 DOCKET NOS 50-329 AND 50-330 LOW ALLOY QUENCHED AND TEMPERED BOLTING l's INCIIES AND GREATER IN SUPPORT OF SAFETY RELATED SYTEMS FILE:
0.4.9.46 SERIAL:
175h2
REFERENCES:
J W Cook letters to J G Keppler, Same
Subject:
(1) Serial 10996, dated January 9, 1981 (2) Serial 11526, dated March 31, 1981 (3) Serial 13690, dated September 29, 1981 1
(4) Serial 14666, dated January 15, 1982 l
(5) Serial 16149, dated April 2, 1932 (6) Serial 17354, dated May 17, 1932 This letter, as were the referenced letters is an interim 50.55(e) report concerning the subject bolting. Attachment 1 to this letter provides a summary of the actions being taken with regard to this item.
Another report, either interim or final, will be sent on or before October 29, 1982.
WRB/1r ;
MCAR 45A and 45B, Interim Report 6, dated July 1,1982 CC RJCool, NRC Resident Inspector Midland Nuclear Plant HRDenton, NRC Office of NRR 8207260349 9g979, jy[ j Q1982
{DRADOCK 05000329 PDR Ob f
CC Document Control Desk, NRC Washington, DC CBechhoefer, ASLB Panei RSDecker, ASLB Panel FPCowan, ASLB Panel JHarbour, ASLB Panel AS&L Appeal Panel MMCherry, Esq, MSinclair BStamiris CRStephens WDPaton FJKelley, Esq, Attorney General SHFreeman, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, TNK&J
Serial 175h2 80-09 #7 Bechtel Associates ProfessionalCorporation i758 g
d76095
SUBJECT:
MCAR 45A and 45B (issued 12/18/80)
INTERIM REPORT 6 DATE:
July 1, 1982 PROJECT:
Consumers Power Company Midland Plant Units 1 and 2 l
Bechtel Job 7220 Introduction The discrepancies discussed in this report concern the hardness values of the anchor and connecting studs for the reactor coolant pump (RCP) snubbers.
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-inch 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 RCis during seismic and/or loss-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 ASTM A 540, Grade B23, Class 3.
They were intended to be tensioned to a preload up to 96 kai to maintain the specified snubber spring rates under all loading conditions. Prior to tensioning, to ascertain that the studs could withstand long-term loads of this magnitude without becoming suscep-tible to stress corrosion cracking, Consumers Power Company requested Teledyne Engineering Services (TES) to conduct hardness tests on the ex-posed end of the embedded and connecting studs. TES conducted these hardness tests from November 21 through November 23, 1980. The test re-sults showed that 207 studs of 384 tested are outside the range of hard-ness specified by the ASTM specifications.
MCAR 45B On November 26, 1980, Consumers Power Company expanded the 10 CRF 50.55(e) report to include, as potentially reportable, all low-alloy quenched and tempered bolting materials 1-1/2 inches in diameter and larger used in support of safety-related systems.
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Bechtel Associates Professional Corporation 6758iG U76095 MCAR 45A and 45B Interim Report 6 July 1, 1982 Page 2 Investigative Action 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 evaluate the effect of the measured hardnesses on the ability of the studs to withstand preload, operating, and accident loadings. Based on preliminary Aptech evaluations, it was decided to lower the required stud preload (to a maximum of 12 ksi) to preclude failure because of stress corrosion cracking. Subsequently, Aptech has provided a report AES-81-08-79 (which was transmitted to the NRC via Consumers Power Company letter, Serial 17354, 5/17/82). In this report, the smallest maximum allowable preload for any of the RCP snubber anchor bolts is 50 ksi. Therefore, the required 12 kai preload is less than the allowables in the Aptech report and is accept-able. Instructions were issued to construction to preload the studs to 9 kai, a value lower than the maximum permissible. A tolerance of +3 kai is allowed.
This preload value, when reduced by temperature and relaxation losses, exceeds 3 kai, a value in excess of the minimum preload of 1.5 kai re-quired by Babcock & Wilcox during operation. New spring rates have been submitted by Bechtel to B&W. B&W 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.
The above noted Aptech report contains an assessment of the reactor coolant I
pump snubber anchor bolts. Based on this report, the allowable stress limits for operation and short duration loading are available. Calcu-lations are now being prepared to determine if the actual bolt stresses, based upon the capacity of the snubbers, are acceptable when compared to the Aptech allowables. Upon completion of the calculation, a final MCAR 45A report will be issued.
Procurement documentation packages for these studs have been reviewed.
All necessary corrective action was completed and a report was issued.
No additional action is required.
MCAR 45B Consumers Power Company is leading the investigation required by this MCAR. Commonwealth Associates, Incorporated (CA1) of Jackson, Fuchigan, has been retained by Consumers Power Company to review safety-related
75816 Bechtel Associates ProfessionalCorporation 076095 MCAR 45A and 45B Interim Report 6 July 1, 1982 Page 3 purchase orders and identify those purchase orders including low-alloy quenched and tempered steel (LAQTS) bolting and/or component material.
The initial effort has been completed; however, additional purchase orders and LAQTS materials have been identified. CAI returned to the site to gather additional data that will be used in evaluating the LAQTS materials.
This activity was completed June 11, 1982. CAI is currently processing data and will possibly identify areas requiring additional data gathering.
Most of the review being conducted on the LAQTS bolting and component support materials consists of field hardness testing. This testing is being per-formed by Consumers Power Company and CAI. This activity began in December 1981 and is estimated to be completed by September 1982.
Science Applications Incorporated (SAI) of Palo Alto, California, has been retained and has developed a sampling plan to determine the quantity of items to be tested. SAI is also providing statistical services in preparing i
the hardness data for evaluation.
Aptech Engineering Services of Palo Alto, California, has been retained to assist in evaluating the LAQTS materials purchased by identifying which materials are LAQTS and require testing. Aptech is also assisting in the analysis of the hardness test results.
Engineering has started a case-by-case evaluation of bolts as bearing connections with a 12 ksi maximum preload.
Corrective 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 studs are tensioned as required. This work has been completed for Unit 2, and is presently in progress for Unit 1.
Engineering has made a preliminary com-parison of the calculated anchor bolt stresses with the Aptech allowable stresses. These stresses, based on the capacity of the snubber, are within the Aptech allowable limits. A final check of stresses will be made upon receipt of B&W Specification 1235, Reactor Coolant System Foundation and Nozzle Loadings, scheduled for issue December 1982. At that time, the need for further corrective action will be determined.
MCAR 45B Quality control receipt inspection includes hardness testing of LAQTS bolting / component support materials to preclude utilization of defective materials.
'075816 Bechtel Associates ProfessionalCorporation 076095 MCAR 45A and 45B Interim Report 6 July 1, 1982 Page 4 Safety Implications MCAR 45A If the subject studs were tensioned according to the original design re-quirements, there may have been a safety deficiency in that some of the 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 Submitted by: TI.
S.L. Sobkowski Civil Group Supervisor M ~$
x_ _ s Approved by:
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L.H. Curtis Q
N Project Engineering Manager Concurrence by:
D. J660 son ChiefCivilEnkineer Concurrence by:
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Ad E.H. Smith Engineering Manager r---
( )N Concurrence by:
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A1GA.Diftrich Project Quali y Assurance 7
Engineer
Bechtel Associates Professional Corporation
- 758I6 076095 MCAR 45A and 45B Interim Report 6 July 1, 1982 Page 5 l
MCAR 45B Submitted by:
bio L.A. Dreisbach Approved by:
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// d L.H. CQrtis Project Engineering Manager tt EL b (
Concurrence by:
E.H. Smith Engineering Manager Concurrence by:
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O p/bfl.A/ ject Diet ich Pro ality Assurance Engineer S
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