ML20066C174
| ML20066C174 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 10/29/1982 |
| 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, 19085, MCAR-45A, MCAR-45B, NUDOCS 8211090371 | |
| Download: ML20066C174 (8) | |
Text
"
Consumers power James W Cook C0mpBDy m, ~,w., - mjuts c.e.,s.,
a.d Co struction General offices: 1945 West Parnell Road, 'ackson MI 49201 e (517) 78&O453 Octcher 29, 1982 80-09 #8 Mr J G Keppler, Regional Administrator US Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, IL 60137 MIDLAND NUCLEAR C0 GENERATION PLANT -
DOCKET NOS 50-329 AND 50-330 LOW ALLOY QUENCllED AND TEMPERED BOLTING 1 INCHES AND GREATER IN SUPPORT OF SAFETY RELATED SYSTEMS FILE:
0.4.9.46 SERIAL:
19085
REFERENCES:
J W Cook letters to J G Keppler, Same
Subject:
(1) Serial 10996, dated January 9, 1981 r
(2) Serial 11526, dated March 31, 1981 (3) Serial 13690, dated September 29, 1981 (4) Serial 14666, dated January 15, 1982 (5) Serial 16149, dated April 2, 1982 (6) Serial 17354, dated May 17, 1982 (7) Serial 17542, dated July 9, 1982 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.
s-Another report, either interim or final, will be sent on or before February 25, 1983.
k WRB/lr : MCAR 45A and 45B, Interim Report 7, dated October 21,.1982 CC RJCook, NRC Resident Inspector Midland Nuclear Plant llRDenton, NRC Office of NPD 8211090371 ~ 821'029 NOV 3 G82
{DRADOCK 05000329 l
)d I
[
N OC1082-0039A-MP01'
S3 rial 19085 2
80-09 #8 CC Document Control Desk, NRC-Washington, DC CBechhoefer, ASLB Panel RSDecker, ASLB Panel FPCowan, ASLB Panel.
JHarbour, ASLB Panel AS&L Appeal Panel MMCherry, Esq i
MSinclair i
BStamiris CRStephens, USNRC WDPaton, Esq,-USNRC FJKelley, Esq. Attorney General 4
SHFreeman, Esq. Asst Attorney General i
WHMarshall i
GJMerritt, Esq, TNK8J l
4 f
I l
l i
f L
i i
I
.OC1082-0039A-MP01
nqg uov Serial 19085 Bechtel Associates ProfessionalCorporation 80_09 as r; 9 0 8 5 0
,,,es,,e,,enno.s,es,, s, Ann Arbor, Michigan asenseess P.O. Box 1000. Ann Arbor, Michgan 48106
SUBJECT:
MCAR 45A and 458 (issued 12/18/80)
INTERIM REPORT 7 DATE:
October 21, 1982 PROJECT:
Consumers Power Company Midland Plant Units 1 and 2 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
HCAR 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 f rom 3'-5" to 7'-1".
They are embedded in the secondary shield wall and the refueling canal wall. Also included are 2-inch cad 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 connecting studs are in place. The snubbers restrain the RCPs 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 urder all loading conditions. Prior to tensioning, to ascertain that the studs could withstand long-term loads of this magnitude without becoming susceptible to stress corrosion cracking, Consumers Power Company I
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 i
On November 26, 1980, Consumers Power Company expanded the i
10 CFR 50.55(e) report to include, as potentially reportable, all I
low-alloy quenched and tempered bolting materials 1-1/2 inches in diameter and larger used in support of safety-related systems.
~T
~~?. 2 J~'
~
2
r A90850 i
Bechtel Associates Professional Corporation
'O90568 MCAR 45A and 45B Interim Report 7 Page 2 l
l l
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
,,j' preload (to a maximum of 12 kai) to preclude failure because of stress l
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 anubber anchor bolts is 50 l
ksi. Therefore, the required 12 kai preload is less than the allowables in the Aptech report and is acceptable.
Instructions were issued to construction to preload the studs to 9 ksi, 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 required 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.
1"T 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 pump snubber anchor bolts. Based on this report, the allowable stress limits for operation and short duration loading are available.
Preliminary calculations have been prepared and the results indicate that the bolt stresses, based upon the capacity of the snubbers, are acceptable when compared to the Apt.ech allowables. Upon completion of the calculation, a final MCAR 45A report will be issued.
l l
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.
69085r Bechtel Associates Professional Corporation 090568 MCAR 45A and 45B Interim Report 7 Page 3 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 purchase orders and identify those purchase orders for low-alloy quenched and tempered steel (LAQTS) bolting and/or component support material.
The initial ef fort has been completed; however, sdditional purchase orders and LAQTS materials have been identified.
CAI returned to the site to gather additional data that will be used in evaluating the LAQIS materials. This activity was completed June 11, 1982. CAI is currently processing data and has identified 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 performed by Consumers Power Company and cal. This activity began in December 1981 and was estimated in July 1982 to be completed by September 1982.
The current estimate is for completion of hardness testing by January 1983.
Based on preliminary hardness test results, we identified several bolting l
material purchases that appeared to contain material considerably sof ter than allowed by ASTM specifications. Further evaluation and testing on a portion of these materials by the Consumers Power Company laboratory, indicated that the bolting materials were actually within the acceptable hardness limits of the ASTM specifications. The differences were determined to be due to the existence of a decarburized layer that had not been completely removed during field testing. We are in the process l
of retesting the remaining portions of this bolting material with the l
decarburized layer removed.
l Science Applications Incorporated (SAI) of Palo Alto, California, has l
been retained and has developed a sampling plan to determine the quantity i
of items to be tested.
SAI is in the process of revising the sacpling plan as a result of the decarburization problem and additional materials identified by cal.
SAI is also providing 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 by identifying which materials are LAQTS and require testing. Aptech is also assisting in the analysis of the hardness test results.
l l......
...........m
d90850 Bechtel Associates Professional Corporation MCAR 45A and 45B Interim Report 7 000568 Page 4 Engineering has started a case-by-case evaluation of bolts as bearing connections with a 12 kai maximum preload.
Corrective Action MCAR 45A Construction has been instructed to preload the snubber studs to 9 i 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 comparison of the calculated anchor bolt stresses with the Aptech allowable stresses. These stresses, based on the capacity of the anubber which limits the loading on the studs, are within the Aptech allowable limits. Upon completion of the calculation, a final MCAR 45A report will be issued.
MCAR 45B Quality control receipt inspection includes hardness testing of LAQTS bolting / component support materials to preclude utilization of defective materials.
Safety Implications MCAR 45A If the subject studs were tensioned according to the original design requirements, 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 operations during the expected life of the plant.
MCAR 45B Presently, the existence of adverse safety implications relative to other safety-related bolting is undetermined.
Y 9 0 8 5 0Bechtel Associates Professional Corporation MCAR 45A and 45B 090568 Interim Report 7 Page 5 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 byy b-FR S.L. Sobkowski Civil Group Supervisor Approved by-L.H. Curtis Project Engineering Manager Concurrence by:
1959tM T.E[fohnson ChiMCivilEq][ deer b[ #
V
-j-
/
Concurrence by:
(~.
E.H. Smith Engineering Manager Concurrence by:
.A. Dietrich Project Quality Assurance Engineer
090850 Bechtel Associates Professional Corporation MCAR 45A and 45B Interin Report 7 080568 Page 6 MCAR 45B Submitted by:
s/ kl I C Ri hards Approved by:
1-L.H. Curtis Project En ineering Manager C
')
Concurrence by:
M N
E.H. Smith Engineering Manager Concurrence by M.A. 'ietrich D
Project Quality Assurance Engineer SLS/ LED /dkj(C) 9/10/1 i
l l
l l
l I
.