ML20052A568
| ML20052A568 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 04/26/1982 |
| From: | Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| Shared Package | |
| ML20052A561 | List: |
| References | |
| NUDOCS 8204280468 | |
| Download: ML20052A568 (2) | |
Text
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APR 2 61982 MEMORANDUM FOR: Victor Stello, Jr., Deputy Executive Director for Regional Operations and Generic Requirements FROM:
Richard C. DeYoung, Director, Office of Inspection and Enforcement
SUBJECT:
REQUEST FOR CRGR REVIEW OF PROPOSED CATEGORY 1 BULLETIN ON INSPECTION OF PWR PRIMARY BOUNDARY BOLTING
REFERENCES:
1.
IE Information Notice 82 Failure of Steam Generator Primary Side Mariway Closure Studs, March 12, 1982 2.
Results of Commission Briefing - Prioritization of Safety Issues This memo is a request for expedited review of a proposed bulletin under provision III.D of the CRGR Charter.
The bulletin is currently under developnent and will be available to CRGR members by COB Tuesday April 27.
Infomation regarding the Maine Yankee manway cover studs was described in the Reference 1 Information Notice.
Since the manway cover studs and other bolting less than 2" in diameter are not subject to ISI, the staff is developing a set of inspection criteria for incorporation in the bulletin.
The need for further action was reinforced by the results of a PRA which was performed as an example for the Reference 2 Commission Briefing.
Although a detailed study of bolting has been underway by the staff, the actions to be derived are too far in the future to satisfy this immediate
- Concern, i
The outline of the bulletin actions as of April 23 is provided for information.
The outline is subject to change during development of the bulletin.
Facilities Affected - PWR Systems
- Primary Pressure Boundary Bolting < 2 in. diameter, not subject to ISI.
Action
- 1.
Report previous experience.
a.
Any failures.
b.
Ss s hich have had leaks in proximity ggQg gg CONTACT:
E. L. Jordan, IE 49-24848
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l APR 2 6 g Victor Stello, Jr.
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c.
Instances of use of Furmentte or other sealant on primary leaks.
d.
Lubricant used.
e.
Torque / tension practices.
2.
Inspect bolting opened at current or next refueling by MT.
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1 3.
Inspect sample of unopened bolting by best UT available.
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ffice of Inspection and Enforcement U
Enclosures
- 1.
IN 82-06 2.
Bolting Failures in PWRs l
cc/w enclosures:
H. R. Denton, NRR D. G. Eisenhut, NRR R. B. Minogue, RES D. F. Ross, RES J. M. Taylor. IE
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IN 82-06 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 12, 1982 IE INFORMATION NOTICE NO. 82-06:
FAILURE OF STEAM GENERATOR PRIMARY SIDE MANWAY CLOSURE STUDS i
Description of Circumstances:
The Nuclear Regulatory Commission (NRC) was notified by Maine Yankee Atomic Power Company and by Combustion Engineering (CE) that during routine disas-sembly of a steam generator primary side manway at Maine Yankee, 6 of the 20 manway closure studs failed and another 5 were found by ultrasonic ta' sting to be cracked.
These are 1 x 10 inch studs of SA 540 grade B 24 alloy steel.
The studs had been exposed to boric acid from a small primary coolant leak and to Furmanite sealing compound (primary grade) applied in an attempt to seal this leak.
The studs exhibited evidence of surface corrosion attack possibly as a result of an interaction associated with stud preload, lubricant, Furmanite and primary coolant leakage environment.
A metallurgical analysis i
to determine the failure mechanism is currently underway at CE.
The entire set of studs on the affected steam generater (SG #2) have been replaced and an ultrasonic examination of all primary manway studs on steam generator units 2 and 3 is being performed.
Further corrective actions are pending stud failure analysis and its applicability to other primary boundary closures, i;
In the last few years there have been a significant number of incidents of failed or severely degraded bolts and studs.
Examples of the latter; primary coolant pump stud-bolts (Calvert Cliffs and Ft Calhoun) and steam generator primary manway closures studs (Oconee and ANO-1).
The failures described were attributed to stress corrosion cracking and corrosion wastage of high strength studs that are difficult to detect.
The NRC has contacted the CE Regulatory Response Group and requested a review of the problem.
f This IE information notice is provided as an early notification of a potentially significant matter that is still under review by the NRC staff.
If NRC evalua-1 tion so indicates, further licensee action may be requested.
In the interim, i
we expect that licensees will review this information for applicability to their facilities.
No written response to this information notice is requested.
If you need addi-tional information, please contact the Regional Administrator of the appropriate 2
NRC Regional Office.
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Attachment.
Recently issued IE Information Notices
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,e 10 ISSUE 29
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BOLTING FAILURES IN PWR$
DESCRIPTIO,N Bolts and other types of threaded fasteners are used estensively to secure flanges, manway covers and other removable components of the reactor coolant pressure boundary.
In recent years,'a number of incidents involving severe corrosion and other degradation of bolts and studs have been reported.
PRIORITY DETERMINATION 23 incidents of corrosion have,been reported in (currently) 350 PWR-years of experience.
If not discovered, all of these would eventually result in at least a small LOCA.
Assuming that 90% would be discovered and
- repaired,
-3 Frequency estimate:
7 x 10 52-LOCAs/PWR-year Using WASH-1400 52 sequences with this frequency, the release per 4
year is:
1.5 x 10 Curies /PWR-year Cost estimate:
4.8 Million PRIORITY SCORE i
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10 Curies / year /$Million S
l Friority is HIGH I
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