ML20031C028
| ML20031C028 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 09/29/1981 |
| 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, 13690, 80-09-#3, 80-9, 80-9-#3, NUDOCS 8110060440 | |
| Download: ML20031C028 (5) | |
Text
__ _ _ _ _ - - _ _ _
baA/.rs -rG.)
s
~
O CORSumBIS Power m,_
0 00f Vice President - Projects, Engineering and Construction General Offices: 1945 West Parnefl Road, Jackson, MI 49201 e (517) 78&O453 80-09 #3 4
10 September 29, 1981 g
3 q OCT 61984 Mr J G Keppler, Regional Director r
Office of Inspection & Enforcement
$ u.a %
-8 US Nuclear Regulatory Commission
\\,4 80*ssaps Region III 799 Roosevelt Road t
.QT )c -
Glen Ellyn, IL 60137 MIDLAND PROJECT - UNITS 1 AND 2 DOCKET NOS 50-329 AND 50-330 LOW ALLOY QUENCHED AND TEMPERED BOLTING 1 INCHES AND GREATER IN SUPPORT OF SAFETY RELATED SYSTEMS F.TLE:
0.4.9.L6 SERIAL:
13690
References:
(1) J W Cook letter to J G Keppler, Same Subject, Serial 10996, dated January 9,1981 (2) J W Cook letter to J G Keppler, Same Subject, Serial 11526, dated March 31, 1981 This letter, as were the referenced letters, is an interim 50.55(e) report concerning the status of the subject bolting. Attachment 1 provides a description of the status of the planned corrective actions.
Another report, either interim or final, will be sent on or before January 15, 1982.
L 1
WRB/1r
' : MCAR 45A and B, Interim Report 3, dated September 11, 1981 CC:
Director of Office of Inspection & Enforcement Att Mr Victor Stello, USNFL (15)
((
Director, Office of Management Information & Program Control, USNRC (1)
RJCook, USNRC Resident Inspector Midland Nuclear Plant (1) 8110060440 810929 PDR ADOCK 05000329 1 gggb 0g S
Serial 13690 2
80-09 #3 CC: CBechhoefer, ASLB Panel RSDecker, ASLB Panel FPCowan, ASLB Panel AS&L Appeal Panel
!G: Cherry, Esq MSinclair BStauliris CRStephens, USIBC WDPaton, Esq, USIIRC FJKelley, Esq, M Lorney General SHFreeman, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, TNKtcJ W
.Uk2UDd Serial 13690 Bechtel Associates Professional Corporation 80-09 #3 fl42 Cec
$U' JECT:
MCAR 45A and B (issued 12/18/80)
B INTERIM REPORT 3 DATE:
September 11, 1981 PROJECT:
Consumers Power Company Midland Plant Units 1 and 2 Bechtel Job 7220 Introduction The discrepancies disciissed in this report concern the hardness values of the reactor coolant pump snubber studs.
Backg round MCAR 45A The anchor studs in question are 2-1/4, 2-1/2, 3, and 3-1/2 inches in dia-meter and vary in length from 3'-6" to 7'-1".
They are embedded in the secondary shield wall and the refueling canal wall, and serve as anchor studs for the snubbers.
Also included are 2-and 2-1/4-inch diameter con-necting studs approximately l'-10" long that connect the snubbers to a structural steel transition piece.
These snubbers restrain the reactor coolant pumps during seismic and/or loss-of-coolant accident (LOCA) loads.
The anchor studs were purchased from various vendors during 1977 and 1978 by Bechtel construction.
The studs were purchased in accordance with either ASTM A 354, Grade BD, or ASTM A 540, Grade B23, Class 3.
The anchor studs are partially embedded in the concrete and the connecting studs are in place.
These items 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 withstand long-term loads of this magnitude without becoming susceptible to stress corrosion cracking, Consumerr Power Company asked Teledyne Engineering Services (TES) to conduct hardness tests on the exposed end of the embedded studs and the connection bolts. TES carried out these hardness tests from November 21 through i
l 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 10 CFR 50.55(e) l report to include, as potentially reportable, all the low-alloy quenched and tempered bolting materials 1-1/2 inches in diameter and above used in support of safety-related systems.
l l
l l
042653
~
Bechtel Associates Professional Corporation MCAR 45A and B Interim Reoort 3 September 11, 1981 bk2b32 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.
Aptech is evaluating 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 has been decided to lower the preload (to a maximum of 12 ksi) to preclude failure because of stress corrosion cracking. Aptech has confirmed that a maximum preload of 12 ksi is low eneup,h to preclude stress corrosion cracking for the hardness ranges under consideration.
Instructions have been given to construction to preload the studs to 9 1 3 ksi.
'Ihis preload value, when reduced by temperature and relaxation losses, exceeds 3 ksi. A minimum preload of 1.5 ksi is required by Babcock & Wilcox to re-duce vibration 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 in conjunction with the resolution of MCAR 37.
ITT Grinnell, the supplier of the snubbers, has also been informed of the change in the preload to a minimum of 3 ksi. Grinnell has stated that there is no effect on the snubbers or on the spring rate of the snubbers themselves.
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 opera-ting and short duration loading being determined by Aptech.
Procurement documentation packages for these studs are presently being re-viewed to determine whether any additional action is required.
MCAR 45B Consumcrs Power Company is taking the lead in the investigation required by this MCAR.
Commonwealth Associates, Incorporated (cal) of Jackson, Michigan has been retained by Consumers Power Company to review safety-related purchase i
orders and identify those purchase orders including low alloy quenched and tempered steel (LAQTS) bolting and/or component material. CAI is also obtain-ing data that will be utilized in evaluating LAQTS material. This effort is presently scheduled for completion by October 30, 1981.
Aptech Engineering Services of Palo Alto, California has been retained to j
assist in evaluat.tng the LAQTS materials purchased.
l Corrective Action l
MCAR 45A Construction has been instructed to preload the snubber studs to 9 +
r l
3 ksi. A procedure was developed by B&W construction 'o ensure that the studs are tensioned as required. This work has been completed for Unit 2, t
042653 Bechtel Associates Professional Corpoietion i
MCAR 45A and B Interim Report 3 September 11, 1981 042652 Page 3 and is presently in progress for Unit 1.
Upon receipt of the Aptech Report providing the allowable operating and accident stresses, the calculated stresses will be compared to the Aptech allowabic. A final check of stresses will be made upon receipt of B&W Specification 1235.
TES Technical Report TR-4599-3, Hardness Measurements of Anchor and Connection Studs Securing Reactor Coolant Pump Snubbers at Midland Plant Units 1 and 2, January 28, 1981, was submitted by Consumers Power Company to the NRC.
Safety Implications MCAR 45A If the subject studs were tensioned according to the original design re-
,uirements, there may have been a safety deficiency in that some of the studs may 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 j
At this time the existence of any adverse safety implications relative to other safety-related bolting is undetermined.
Reportability MCAR 45A and B This condition relative to the reactor coolant pump snubber bolts was iden-tified as "potentially reportable" by Consumers Power Company to the NRC under 10 CFR 50.55(e) on November 25, 1980 and expanded on November 26, 1980, to include all the low alloy quenched and tempered bolting materials 1-1/2 inches in diameter and above used in support of safety-related systems.
Prepared by: 5.T I t kb8 MCA M40*d A4O R C8 Reviewed by: M, n_
Reviewed by: bd M O 2rts i
y Concurrence by:
f/
/
SS LE js(C)
_