ML19350C752

Interim Deficiency Rept Re low-alloy Quenched & Tempered Bolting Matls 1.5 Inch & Greater in Diameter Used in Support of safety-related Sys.Technical Rept Encl.Final Rept by 810929

ML19350C752
Person / Time
Site:	Midland
Issue date:	03/31/1981
From:	Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19350C753	List: ML19350C752 ML19350C756
References
10CFR-050.55E, 10CFR-50.55E, 11526, NUDOCS 8104060661
Download: ML19350C752 (5)

Text

Const!mers 4[

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Vice PressJent - Projects, Engsneenng and Constructson

-%r General offices: 1945 West Parnest Road, Jackson, MI 49201 * (517) 788-0453 80-09 #2 March 31, 1952

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Mr J G Keppler, Regional Director Office of Inspection & Enforcement 9 9 / ,r, -

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MIDLAND PROJECT - UNITS 1 AND 2 DOCKET NOS 50-329 AND 50-330 g ['

LOW ALLOY QUE'ICHED AND TDIPERED BOLTING 1 INCHES AND GREATER' IN SUPPORT OF SAFEIY RELATED SYSTEMS FILE: 0.h.9.h6 UFI: 73*10*01, 023k3(S), 03008(E), 15230(E) SERIAL: 11526

Reference:

(1) J W Cook letter to J G Keppler, Same Subject, Serial No 10996, dated January 9,1981 This repo*t, as was reference (1), is an interim 50 55(e) report concerning the status of the subject bolting. Enclosure 1 provides a description of the status of the planned corrective actions. Enclosure 2 is a Teledyne Engineering Services (TES) report for your revie.r.

Another report, either interin or final, vill be sent on or before September 29, 1981.

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Enclosure:

(1) MCAR h5, Interi= Report #2, March 20,1981 - Lov Alloy, Quenched and Tempered Bolting,1 Inches and Greater, in Support of Safety-Related Systens)

(2) TES Report No IR h599-3, " Hardness Measurements of Anchor and Connection Studs Securing Reaci,or Coolant Pump Snubbers at Midisnd Plants Units 1 and 2, " dated January 28, 1981 CC: Director of Office of Inspection & Enforcement Att Mr Victor Stello, USNRC (15)

Director, Office of Management Infor ation & Program Control, USNRC (1)

RJCook, USNRC Resident Inspector Midland Nuclear Plant (1) 81040604H T

2 Serial 11526 80-09 #2 CC: CBechhoefer, ASLB Panel GALinenberger, ASLB Panel 5'PCowan, ASLB Panel AS&L Appeal Panel M4 Cherry, Esq MSinclair.

CRStephens, USNBC WDPaton, Esq, USNRC FJKelly, Esq, Attorney General SHFreeman, Esq, Asst Attorney General GTTaylor, Esq, Asst Attorney General WHMarshall GJMerritt, Esq, TNK&J

Enclosure 1

' Serial 11526 80-09 #2 Bechtel Associates Professional Corporation 024977

SUBJECT:

MCAR 45A and B (issued 12/18/80)

INTERIM REPORT 2 DATE: March 20,1981 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 reactor coolant pump snubber studs.

Background

MCAR 45A The anchor studs in question 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 as well as the refueling canal wall and serve as anchor studs for the' snubbers. 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. These snubbers restrain' the . reactor coolant pumps during seismic and/or-loss-of-coolant accident i (LOCA) loads. The anchor studs were purchased *from various vendors i _ 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, t

Class 3. The anchor. studs are partially embedded in the concrete and

- the connecting studs are in place. However, none have been tensioned as l of this date. .These items were intended to be tensioned to a preload up to 96 kai to maintain the specified snubber spring rates under all t , loading conditions.- To ascertain that the studs could withstand long-l term loads of this magnitude without becoming susceptible.to stress l corrosion cracking, Consumers Power Company asked Teledyne Engineering l Services (TES).to conduct hardness tests on the exposed end of the i embedded studs and the connection bolts. TES carried out these haedness l

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 fotentially reportable, all the low-alloy quenched cand tempered bolting materials 1-1/2 inches in diameter-and above used in L: .

support of safety-related systems.

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• 4 Bechtel Associates Professional Corporation MCAR 45A and B J Interim Report 2 024977  !

March 20, 1981 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 enough to preclude stress corrosion cracking for the hardness rciges under consideration.

Instructions have been given to construction to preload the studs to 9 ksi. This preload value, when reduced by temperature and relaxa-tion losses, exceeds 3 ksi. A minimum preload of 1.5 ksi is required by Babcock & Wilcox - to reduce 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 conjunc-tion with the resolution of MCAR 37. ITT Grinnell, the supplier o'f 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 en 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 operating and short duration loading being determined by Aptech.

1 Procurement documentation packages for these studs are presently being reviewed to determine whether any additional action is required.

MCAR 45B i A task force has been established' to determine the necessary investi-

- gations required ' to prepare, schedule, and Laplement a program to resolve any identified safety concerns.

Corrective Action

!MCAR 45A' Construction has been instructed to preload the snubber studs to -9 ksi.

A procedure is to-be developed by the subcontractor to ensure that the studs are tensioned'as required.

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Bechtel Associates Professional Corporation MCAR 45A and B 024977 Interim Report 2 March 20, 1981 Page 3 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, will be submitted by Consumers Power Company to the NRC.

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 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 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 identified as "potentially reportable" by Consumers Power Company to the NRC under 10 CFR 50.55(e) on November 25, 1980 and expanded on Nov-ember 26,-1980, to include all the low alloy quenched and tempered bolt-ing materials 1-1/2 inches in diameter and above used in support of safety-related systems.

Prepared by: i M Reviewed by: ,

Concurrence by: 2 4

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