ML20211B239
| ML20211B239 | |
| Person / Time | |
|---|---|
| Issue date: | 06/05/1986 |
| From: | Zech G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Bargo G VALCOR ENGINEERING CORP. |
| References | |
| NUDOCS 8606110543 | |
| Download: ML20211B239 (4) | |
Text
June 5, 1986 Valcor Engineering Corporation ATTN:
Mr. G. J. Bargo Director of Quality Assurance 2 Lawrence Road Springfield, New Jersey 07001
Dear Mr. Bargo:
SUBJECT:
DRAFT INFORMATION NOTICE 86-XX, " FAILURE OF DISK GUIDE ASSEMBLY SPRINGS IN VALCOR VALVES" The enclosed draft information notice is being considered for issuance to all nuclear power reactor facilities holding an operating license or construction permit.
Because your company is specifically identified in the notice, we would appreciate your review of the technical facts presented.
If this infor-mation presented is incorrect or there is additional information pertinent to the discussion, we would appreciate your comments.
Any comments received prior to June 20, 1986 will be considered in preparation of the final version.
Thank you, in advance, for your time and efforts in this matter.
Sincerely, Gary G. Zech, Chief Vendor Program Branch Division of Quality Assurance, Vendor and Technical Training Center Programs Office of Inspection and Enforcement
Enclosure:
Draft Information Notice DISTRIBTUION:
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June 5, 1986 Valcor Engineering Corporation ATTN: Mr. G. J. Bargo Director of Quality Assurance 2 Lawrence Road Springfield, New Jersey 07081
Dear Mr. Bargo:
SUBJECT:
DRAFT INFORMATION NOTICE 86-XX, " FAILURE OF DISK GUIDE ASSEMBLY SPRINGS IN VALCOR VALVES" The enclosed draft information notice is being considered for issuance to all nuclear power reactor facilities holding an operating license or construction permit.
Because your company is specifically identified in the notice, we would appreciate your review of the technical facts presented.
If this infor-mation presented is incorrect or there is additional information pertinent to the discussion, we would appreciate your comments.
Any comments received prior to June 20, 1986 will be considered in preparation of the final version.
Thank you, in advance, for your time and efforts in this matter.
Sincerely,
/
/
6tMiary G. Zech, C 'ef Vendor Program Branch Division of Quality Assurance, Vendor and Technical Training Center Programs Office of Inspection and Enforcement
Enclosure:
Draft Information Notice i
SSINS No.: 6835 IM 86-XX UNITED STATES NUCLEAR REGULATORY C0!911SSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 May XX, 1986 IE INFORMATION NOTICE NO. 86-XX:
FAILURE OF DISC GUIDE ASSEMBLY SPRINGS IN VALCOR VALVES Addressees:
All nuclear power reactor facilities holding an
- operating license or a construction permit.
Purpose:
This notice is provided to inform recipients of a potentially significant safety problem that could result from the failure of disc guide assembly springs in solenoid operated globe valves manufactured by Valcor Engineering Corporation.
Under certain service conditions, the spring material is subject to hydrogen embrittlement and subsequent failure that will render the valve inoperative.
It is expected that recipients will review the information for applicability to their facilities and consider action, as appropriate, to preclude a similar problem from occurring at their facilities. However, suggestions contained in this information notice do not constitute NRC requirements; therefore, no spe-cific action or written response is required.
Description of Circumstances:
Difficulties were experienced with the operability of two solenoid-operated globe valves (Model V526-6190A, p/n 454660001) in the charging system at the Fort Calhoun Station, Unit 1 in August 1985. When shut, the valves could not be reopened without securing all charging pumps. During a refueling outage in January 1986, the two valves were disassembled and examined to determine the cause of the valve malfunction.
It was found that disc guide assembly springs in both valves had undergone complete and catastrophic failure. The springs, which initially had 25 coils, were found in sections of only 1-2 coils. Met-allurgical examinations of the failed springs concluded that the cause of fair e was hydrogen embrittlement. The spring material is 17-7 PH stainless steel, which is subject to hydrogen embrittlement when exposed to high-temperature primary coolant containing significant hydrogen levels.
s I
IN 86-XX May XX, 1986 Page 2 of 2 Discussion with the valve manufacturer, Valcor Engineering Corporation, revealed that similar failures had occurred during 1982-83 at the Prairie Island Nuclear Generating Station and the North Anna Nuclear Generating Station. The spring failures for these events also were attributed to hydrogen embrittlement.
Discussion:
Based on analysis and evaluation of the earlier spring failures, the valve manufacturer issued a letter in 1983 to affected licensees recommending that the 17-7 PH stainless steel springs in service subject to reactor water chemistry and above 500 F be replaced with springs made of Elgiloy. With the occurrence of the third similar event, the valve manufacturer is planning to issue a second letter to affected li.censees conservatively reconnending that valves with spring material of 17-7 PH stainless steel used in borated water or reactor chemistry water be closely monitored and evaluated for any change in normal operation such as increased seat leakage or an increase in the time required to change position.
These conditions could be attributed to b:oken springs caused by hydrogen embri ttlement. The manufacturer has concluded that hydrogen embrittlement of the stainless steel springs is a complex function of water temperature, water chemistry, water flow condition, and time of exposure to the service condition; therefore, all such springs are ultimately subject to failure in nuclear power plants with coolant containing significant levels of hydrogen.
The above described events are an indication of a potential licensee / vendor interface problem.
It appears that the vendor may not have been completely
~
informed via the purchase specifications regarding the service condition to which the valve would be exposed.
If the customer had fully informed the vendor of the service conditions, then the vendor could have assisted in making proper material selections.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional Administrator of the appropriate regional office or this office.
j i
Edward L. Jordan, Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical
Contact:
L. D. Vaughan (301) 492-8811
Attachment:
List of Recently Issued IE Information Notices l
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