ML18093B276

Submits Supplemental Response to NRC Bulletin 87-002 Re Test Results for Fasteners Found Out of spec.Safety-related Fasteners That Slightly Exceed Hrb Matl Hardness Spec Requirements May Be Used W/O Compromising Safety

ML18093B276
Person / Time
Site:	Salem, Hope Creek, 05000000
Issue date:	04/27/1988
From:	Miltenberger S Public Service Enterprise Group
To:	Russell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
IEB-87-002, IEB-87-2, NLR-N88061, NUDOCS 8811070299
Download: ML18093B276 (11)

Text

Public Service Electric and Gas Company Steven E.. Miltenberger Public Service Electric and Gas Company P.O. Box 236, Hancocks Bridge, NJ 08038 609 339-4199 Vice President -

Nuciear Operation~

April 27, 1988 NLR-N88061 Mr. W. T. Russell, Administrator United States Nuclear Regulatory Commission Region I

• 475 Allendale Road King of Prussia, PA 19406 Gentlemen:

SUPPLEMENTAL RESPONSE TO NRC COMPLIANCE BULLETIN 87-02 SALEM GENERATING STATION UNIT NOS. l AND 2 HOPE CREEK GENERATING STATION DOCKET NOS. 50-272/50-311/50-354 In our initial response to the subject NRC Compliance Bulletin dated January 22, 1988, Public Service Electric and Gas Company (PSE&G) reported the discovery of six noncompliances from the sample of forty (40) fasteners subjected to chemical, mechanical and hardness testing. PSE&G subsequently requested additional time for response so that the initial test results could be verified by an independent testing laboratory before performing an engineering evaluation relating to the safety significance of the fasteners in question.

A second sample from the initial test lot, which included those items found to be in noncompliance, was sent to the PSE&G Research and Test Laboratory (R&TL) for verification of the test results provided by Lehigh Testing Laboratories, Inc. (LTL). The PSE&G R&TL verification testing confirmed the initial LTL test results.

The test results for those fasteners found out of specification and the related safety significance are presented in the enclosure to this letter. Based on our evaluations, PSE&G feels that those safety-related fasteners that slightly exceed the HRB material hardness specification requirements may be used without compromising safety. While a high hardness test result may 8811070299 ggg6~fu72 PDR ADOCK PNU Q

Mr. w. T. Russell 2 04-27-88 indicate that a fastener could be brittle, the fact that the Reduction in Area and Elongation test results exceeded the ASME/ASTM requirements demonstrates that the material is ductile. Also, the measurement of the greater tensile and yield strengths than the ASME/ASTM minimum requirements further substantiate the use of these fasteners.

Should you have any q~estions with regard to this transmittal, please do not hesitate to contact us.

Sincerely, Enclosure C Mr. G. W. Rivenbark USNRC Licensing Project Manager - Hope Creek Mr. G. w. Meyer USNRC Senior Resident Inspector - Hope Creek Mr. D. C. Fischer USNRC Licensing Project Manager - Salem Mr. R. w. Borchardt USNRC Senior Resident Inspector - Salem Mr. W. T. Russell, Administrator USNRC Region I Mr. D. M. Scott, Chief Bureau of Nuclear Engineering Department of Environmental Protection 380 Scotch Road Trenton, NJ 08628

ENCLOSURE PUBLIC SERVICE ELECTRIC AND GAS COMPANY NRC COMPLIANCE BULLETIN 87-02 TEST RESULTS FOR FASTENERS FOUND OUT OF SPECIFICATION Safety-Related Studs and Nuts Evaluated

- 7/8" X 4" Stud, ASTM Al93 Gr. B8 (Mark: AB-8)

- 7/8" Nut, ASTM Al94 Gr. 8 (Mark: T8 Dul)

- 1 1/4" X 6 1/2" Stud, ASTM Al93 Gr. BB {Mark: BBR NL)

- 1/14" Nut, ASTM Al94 Gr. 8 {Mark: BB CFC H4)

Non-Safety-Related Studs/Bolts and Nuts Evaluated

- 3/8" X 3/4" Bolt, ASTM Al93 Gr. BB (Mark: JBB)

- 3/8" Nut, ASTM Al94 Gr. 2H (Mark: 2H-M)

- 7/8" X 5 1/2" Stud, ASTM Al93 Gr. B7 (Mark: S B7)

- 7/8" Nut, ASTM Al94 Gr. 2H (Mark: N/A)

- l" X 2 1/2" Bolt, ASTM Al93 Gr. BB {Mark: JBS)

- 1 11 Nut, ASTM Al94 Gr. 2H (Mark: N/A)

- l X 6" Stud, ASTM Al93 Gr. B7 (Mark: DE B7)

- l" Nut, ASTM Al94 Gr. 2H (Mark: N/A)

Evaluation Results A. Safety-Related Fasteners

1. 7/8 11 x 4" Stud (Mark: AB-8), ASTM Al93 Gr. BB 0

Chemical Analysis c Mn p s Si Ni Cr Mat'l. .OBx 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.06 0.85 0.028 0.030 0.73 8.28 18.24 Report x - Maximum

0 Mechanical Requirements Tensile Yield Reduction Strength Strength Elongation of Area psi psi  %  %

Mat' 1. 75,000 min 30,000 min. 30 min. 50 min.

Spec.

Test 104,000 75,400 40' 68.6 Report 0

Hardness ~equirements Rockwell Hardness HRB Mat'l. Spec. 96 max.

Test Report 98 0

Meets chemical and mechanical requirements.

0 The test result' for hardness marginally exceeds th~ ASTM material requirement. This is not considered as a detriment to safety as all remaining mechanical and chemical requirements are satisfied.

2. 7/8" Nut (Mark: T8 Dul), ASTM Al94 Gr. 8 c Mn p s Si Ni Cr Mat'l. 0.08x 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.07 0.99 0.023 0.007 0.56 8.15 18.37 Report x - Maximum 0

Hardness Requirements Rockwell Hardness HRB Mat'l. Spec.60-105 Test Report 96.7 0

No safety concern.

0 Meets chemical and mechanical requirements.

3. 1 1/4" x 6 1/2" Stud (Mark: B8R NL), ASTM Al93 Gr. BS 0

Chemical Analysis c Mn p s Si Ni Cr Mat'l. 0.08x 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.06 0.91 0.025 0.021 0.65 8.56 18.27 Report x - Maximum 0

Mechanical Requirements Tensile Yield *Reduction Strength Strength Elongation of Area psi psi  %  %

Mat' 1. 75,000 min 30,000 min. 30 min. 50 min.

Spec.

Test 107 ,_500 74,600 38 69 Report 0

Hardness Requirements Rockwell Hardness HRB Mat'l. Spec. 96 max.

Test Report 99.l 0

Meets chemical and mechanical requirements.

0 The test iesult for hardness marginally exceeds the ASTM material requirement. This is not considered as a detriment to safety as all the remaining mechanical and chemical requirements are satisfied.

4. 1 1/4" Nut (Mark: 88 CFC H4), ASTM Al94 Gr. 8 0

Chemical Analysis c Mn p s Si Ni Cr Mat'l. 0.08x 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.06 1. 69 0.030 0.019 0.26 8.14 18.40 Report x - Maximum 0

Hardness Requirements Rockwell Hardness HRB Mat' l. Spec.60-105 Test Report 99 0

No safety concern.

0 Meets chemical and mechanical requirements.

B. Non-Safety-Related Fasteners

1. 3/8" x 3/4" Bolt (Mark JB8), ASTM Al93 Gr. B8 Chemical Analysis c Mn p s - Si Ni Cr Mat' 1. 0.08x 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.04 1.25 0.042 0.005 0.34 8.15 18.31 Report x - Maximum

0 Hardness Requirements Rockwell Hardness HRB Mat'l Spec. 96 max.

Test Report 31 HRC*

0 Does not meet hardness requirements.

0 100 pieces were purchased under P.O. #P2-179396 but none have been issued to _the stations.

• The hardness was reported by HRC number because the material is harder than the upper scale of HRB which ends at approximately 104. Extrapolation of the HRB scale would equate 31 HRC to about 108 HRB.

2. 3/8" Nut (Mark: 2H-M), ASTM Al94 Gr. 2H 0

Chemical Analysis c p s Mat'!. 0.040 min. 0.040 max. O. 050 max.

Spec.

Test 0.44 0.014 0.009 Report 0

Hardness Reg:uirements Rockwell Hardness HRC Mat'!. Spec. 24-38 Test Report 31 0

Meets chemical and hardness requirements.

3. 7/8" x 5 1/2 11 Stud (Mark: S B7), ASTM Al93 Gr. B7 0

Chemical Analysis c Mn p s Si Cr Mo Mat'l. .37-.49

• 6 5*: _.'... 1 0.035x 0.040x .15-.35 .75-1.2 .15-.25 Spec.

Test .42 .90 0.016 0.012 0.23 1. 02 0.16 Report x - Maximum

0 No h~rdne~s requirements.

0 Meet chemical requirements.

4. 7/8" ~ut (Mark: N/A), ASTM Al94 Gr. 2H 0

Chemical Analysis c Mn p s Mat' 1. 0.40 min. 0.040 max. 0.050 max.

Spec.

Test 0 .1 O* 0.36 0.016 0.014 Report 0

Hardness Requirements Rockwell Hardness HRC Mat' 1 Spec. 24-38 Test Report 94.5 HRB*

0 Does not meet chemical and hardness requirements.

• Carbon content and Hardness numbers are relative indicators of material strength. Although the carbon content is below the ASTM minimum requirement, the Hardness number exceeds the ASTM Hardness requirement. Generally, the Hardness number, as a result of a physical test, is a more reliable indicator of material strength than the carbon content. As such, all 7/8" nuts in Item 4 are deemed acceptable.

5. l" x 2 1/2" Bolt (Mark: JBB), ASTM Al93 Gr. BB Gr. B7 0

Chemical Analysis c Mn p s Si Ni Cr Mat'l. O.OBx 2.00x 0.045x 0.030x l.OOx 8-10.5 18-20 Spec.

Test 0.04 1. 24 0.026 0.019 0.40 8.9 18.28 Report x - Maximum

0 Hardness Requirements Rockwell Hardness HRB Mat'l. 96 max.

Spec.

Test 94.3 Report 0

Meets chemical and hardness requirements.

6. l" Nut (Mark: N/A), ASTM Al94 Gr. 2H 0

Chemical Analysis c p s Mat'l. 0. 4 0 min. 0.040 max. 0.050 max.

Spec.

Test 0.15* 0.013 0.019 0

Hardness Requirements Rockwell Hardness HRC Mat' 1. Spec. 24-38 Test Report 75 HRB* (65 ksi tensile strength) 0 Does not meet chemical hardness requirements.

• The nuts in question are utilized on non-safety related components in the plant. PSE&G performs generic calculations to qualify fasteners utilized for pipe supports and other relevant applications for tensile and shear stresses based on code allowables. The selection of nuts is not as critical as the selection of bolts. Frequently, a lower-grade material is suitable for the nuts than is required for the bolts.

Although the nuts are below the ASTM minimum hardness, this is not necessarily considered to be a detriment. Selection of a soft nut ensures plastic yielding of the nut threads which will enable the nut threads to divide the load more evenly. The intent is to ensure failure, if any, of the bolt in tension and to preclude nut stripping failure.

Bolted connections are torqued during installation to a specified value which is higher than the proof strength of the bolt.

Because of this fastner pre-loading, it can be safely assumed that nuts with a lower proof strength than the bolt would fail during this fastener pre-loading procedure. Survivors of the instaliation torque will therefore develop at least the proof strength of the bolt.

Therefore, there is no safety significance involved in the use of these nuts. However, as a conservative approach, all remaining nuts of this type (of those discussed in Items 6. and 8.) shall be returned to the vendor or scrapped.

7. 1 11 x 6 11 Stud (Mark: DE B7), ASTM Al93 Gr. B7 0

. Chemical Analysis c Mn p s Si Cr Mo Mat'l. .37-.49 .65-1.1 0.035x 0.040x .15-.35 .75-1.2 .15-.25 spec.

Test 0.40 0.85 0.011 0.018 0.27 0.94 0.16 Report*

x - Maximum 0

No hardness requirement~.

0 Meets chemical requirements.

8. 1 11 Nut (Mark: N/A), ASTM Al94 Gr. 2H 0

Chemical Analysis c Mn p s Mat'l. 0.40 min. 0.040 max. 0. 05 0 max.

Spec.

Test 0 .14* 0.45 0.018 0.024 Report 0

Hardness Requirements Rockwell Hardness HRC Mat'l. Spec. 24-38 Test Report 77.8 HRB* (69 ksi tensile strength)

0 Does not meet chemical and hardness requirements.

• See explanation delineated in Item 6 above.

c. Recommendations for Future Use of Evaluated Fasteners

1. Use AS-IS Safety Related Studs and Nuts 7/8" x 4" Stud, Al93 Gr. 88 (Mark: AB-8) 7/8" Nut, ASTM Al94 Gr. B (Mark: TB Dul) 1 1/4" x 6 1/2" Stud, ASTM Al93 Gr. BB 1 1/4" Nut, ASTM Al94 Gr. B (Mark: BB CFC H4)

Non-Safety Related Studs and Nuts 3/B" Nut, ASTM Al94 Gr. 2H (Mark: 2H-M) 7/B" x 5 1/2" Stud, ASTM Al93 Gr. 87 (Mark: S B7) l" x 2 1/2" Bolt, ASTM Al93 Gr. BB (Mark: JBB) l" x 6" Stud, ASTM Al93 Gr. 87 (Mark: DE B.7)

2. SCRAPPED or Return to Vendor Non-Safety Related Stud/Bolt and Nuts 3/8" x 3/4~ Bolt, ASTM Al93 Gr. BB (Mark: JBB) 7/8" Nut, ASTM Al94 Gr. 2H (Mark: N/A) l" Nut, ASTM Al94 Gr. 2H (Mark: N/A)