ML20082T719
| ML20082T719 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 12/08/1983 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8312160105 | |
| Download: ML20082T719 (4) | |
Text
m TENNESSEE VALLEY AUTHORITY If0Y5^esfnut 'SYr5et'ioweEYI December 8,1983 BLRD-50-438/81-64 BLRD-50-439/81-62 U.S. Nuclear Regulatory Commission Region II Attn:
Mr. James P. O'Reilly, Regional Administrator 101 Marietta Street, PW, Suite 2900 Atlanta, Georgia 30303
Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - BOLTS AND NUTS FAIL TO MEET ASTM SPECIFICATIONS - BLRD-50-438/81-64, BLRD-50-439/81 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. V. Crlenjak on September 24, 1981 in accordance with 10 CFR 50.55(e) as NCR's 1597 and 1598. This was followed by our interim reports dated October 22 and December 8,1981; February 19, June 29, and September 27, 1982; and January 7, April 25, and July 14, 1983 Enclosed is our final report. TVA does not now consider the subject nonconforming condition adverse to the safe operation of the plant. Therefore, we will amend our records to delete the sub ject nonconformance as both a 10 CFR 50.55(e) item and a 10 CFR Part 21 item.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Licensing Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 8312160105 831200 BEN O ^
PDR ADOCK 05000438
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1983-TVA SOTH ANNIVERSARY An Equal Opportunity Employer
ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 BOLTS AND NUTS FAIL TO MEET ASTM SPECIFICATIONS NCR'S 1597 AND 1598 BLRD-50-438/81-64, BLRD-50-439/81-62 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency 10,000, 3/4" stainless steel nuts (furnished by Chattanooga Bolt and Screw, Chattanooga, Tennessee) and 10,600, 3/4" x 3-1/2" stainless steel bolts (furnished by Challenge Enterprises, Chattanooga, Tennessee) were received not marked in accordance with ASTM specifications. Subsequent testing of the subject material by Singleton Materials Engineering Laboratory (SME) revealed the material failed to meet ASTM specifications. The associated documentation received with the material erroneously indicated that the nuts and bolts do meet ASTM specifications. Approximately 450 of these bolts and 1300 nuts have been issued to the field for installation.
Nonconformance report (NCH) 1597 pertains to-the bolts and NCR 1598 pertains to the nuts.
Safety Imolications NCR 1597 TVA's Nuclear Engineering Support Branch (NEB) has reviewed laboratory test results on the 3/4" by 3-1/2" A193 Grade B8 bolts identified in NCR 1597 and the ASTM A193 material specification requirements. TVA has evaluated all available information on the bolts which had not been returned to the vendor to determine consequences of their possible use in safety-related applications.
Normally, a straightforward evaluation of this problem would require more material data than those tests and results compiled at SME Laboratory.
Specifically, corrosion tests would have supplied conclusive proof of acceptable material chemical composition, and microhardness readings taken on bolt cross sections along with evaluation of microstructure would have verified acceptable manufacturing practice. These tests could not be accomplished because all bolting material that could be located had already been returned to the vendor. Also, SME performed only those tests that would establish the anticipated ASTM noncompliance of the bolts and subsequently t
destroyed all material samples (SME work was performed in September of 1981).
It is possible, however, from the bolt data compiled to state the following conclusions concerning material properties:
a.
The material is unquestionably austenitic stainless steel.
Chemical analysis indicated both sufficient chromium for corrosion protection and sufficient nickel for austenite formation. Other elements are within the specification limits except for carbon, which is in excess of limits.
For the most part, the excess carbon should impart greater strength to the alloy and, therefore, somewhat less ductility. This ductility decrease is negligible and completely overshadowed by decreased ductility due to cold working (work hardening) of the material.
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4 b.
Material exhibits Rockwell B hardnsss from 11 to 15 points in excass oc A193 Grade B8, Class 1, (B8C1) limits. The observed out-of-specification hardnesses are the result of cold working of the material (forming, 4
sizing, threading, etc.) as evidenced by a spr6ad of just four Rockwell B hardness peints over the ten samples. Those material samples containing excess amounts of carbon (see item a) did not exhibit a measurable hardness effect due to composition.
c.
Approximately 40 percent of the 5olts were fabricated from material that ranges in carbon composition from 0.091 to 0.116 percent. The B8C1 maximum limit for carbon (including allowable product variation) is 0.09 percent. As previously discussed (see items a and b) the effect of the out-of-specification carbon composition is negligible.
d.
All material samples met the minimum tensile and yield strength requirements of the B8C1 specification. The observed maximum yield 2
strength (77,300 lbs/in ) is substantially below the level of strength normally associated with stress corrosion cracking of bolting (the yield strength limit proposed in association with NUREG-0577 is 120,000 2
ibs/in ),
e.
Material exhibits percent elongation from 5.5 to 8.5 percentage points below the minimum limits for B8C1. The observed loss in percentage elongation is another reflection of the work-hardened condition of the material.
In essence, the elongation of this material (as measured by the amount of increased length in a tensile specimen after testing) has been partially expended during working of the material. This condition is recognized by the ASTM material specification; A193 Grade B8 Class 2 (minimum yield strength of 100,000 lbs/in2 in the 3/4" diameter range) allows a minimum elongation of 16 percent.
Reduction in area (as measured by the amount of decreased cross sectional area in a tensile specimen after testing) is another measure of material ductility and is similar to elongation. The percentage reduction in area determinations were within the specification limits on all material samples (see item f).
These results indicate acceptable material ductility.
f.
All material samples met the minimum percent reduction in area requirement of the BSC1 specification (see item e).
In addition, according to existing site construction procedures and practices (including Bellefonte Nuclear Plant Quality Control Procedures (BLN-QCPs) i 6.17 revision 6, " Seismic Support Installation and Inspection" and QCP 6.19 revision 2 " Bolted Flange Connections"), the bolts could not have been used i
in ASME pressure boundary applications or in NF structural application.
j Consequently, 'none of the bolts were used in critical safety-related applications.
From our on review of the A193 testing requirements, we cannot state that the bolts currently meet the A193 specification, nor can we establish that the bolts did not meet the specification requirements (excluding marking requirements) at the time of manufacture. However, as the result of TVA's investigation of this condition as described above, it is our conclusion that this material will adequately-perform under design conditions based on the l
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, ndnumum mechanical property requirements of A193 Grade B8, Class 1.
As such, NCR 1597 was dispositioned "use as is" for the material applications which could not be located in the field. All other material was returned to the a
vendor.
NCR 1598 Testing of the nuts on NCR 1598 by TVA's Singleton Materials Laboratory (SML) showed that they are acceptable under ASTM standards. As a result of this testing, NCR 1598 was closed with the disposition "use as is" for the nuts.
Summary On future contracts where bolting material is being procured more emphasis will be given in stating QA program requirements and for providing access to vendor facilities for inspection and/or QA audits. This will be accomplished by placing a right of access statement in purchase requisitions, and by including the same statement on the standard TVA requisition form 201. This is now a requirement of ELN QCP 10.3, Revision 10, " Preparation and Review of Field Procurement Documentation, which was issued on February 21, 1983 All cencerned personnel have received training in this revision 10 of QCP 10.3.
t Although TVA considers this an isolated incident as BNC-QCP 1.1, " Receiving Inspection" and BNP QCP 10.12, " Material Issue Control" were in effect at the time this condition occurred, inspection personnel have been retrained in the applicable procedures.
Since it has been determined that both the nuts and bolts are acceptable for use, there are no adverse implications to the safe operation of the plant.
TVA, therefore, no longer considers this item reportable under 10 CFR 50.55(e).
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