Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 84-68
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, DC 20555
August 21, 1984
Information Notice No. 84-68: POTENTIAL DEFICIENCY IN IMPROPERLY RATED
FIELD WIRING TO SOLENOID VALVES
Addressees:
All holders of a nuclear power reactor operating license (OL) or
construction permit (CP).
Purposes:
This notice is provided to inform recipients of a potential deficiency
involving field installed electric cables with low temperature rated
insulation that are terminated inside solenoid valves with high temperature
valve body housing. A cable insulation breakdown may prevent safety-related
solenoid valves from operating properly. It is expected that recipients will
review the information for applicability to their facilities and consider
actions, if appropriate, to preclude a similar problem occurring at their
facilities. However, suggestions contained in this information notice do not
constitute requirements and, therefore, no specific action or written
response is required.
Description of Circumstances:
On March 19, 1984, Bechtel Power Corporation reported under 10 CFR 21 a
design deficiency in field-run cables to Valcor solenoid valves at Callaway
and Wolf Creek Nuclear Plants. A representative of the licensee, the
Standardized Nuclear Unit Power Plant System (SNUPPS) Organization,
investigated the problem as discussed above and issued a report on April 13,
1984, under the provisions of 10 CFR 50.55(e). The details of the report are
summarized below.
The field-run cables are terminated inside a totally enclosed valve body,
housing a large energized solenoid. The configuration is such that the
terminal boards are located within the valve body above the solenoid. No
means is provided to dissipate the heat generated by the solenoid.
Callaway documented the deficiency involving degraded insulation on
field-run cables connected to Valcor solenoid valves. The valve
qualification documents revealed that the ambient temperatures inside the
valve body can approach a maximum of 250-280 F when the valves are
energized for an extended period of time. The field-run cable, used to
connect the valve into the plant control system, has an insulation
temperature rating of 90 C (144 F). Using this lower temperature
insulation cable within a high ambient temperature valve body will cause the
cable insulation to degrade prematurely and may result in cable insulation
failure and ultimately compromise the safety function of the valve.
8408210142
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IN 84-68
August 21, 1984
Page 2 of 2
Wolf Creek and Callaway each have 37 Class 1E Valcor valves that are
affected by this deficiency. An additional 6 non-Class 1E Valcor valves are
also affected. The safety related valves are in the following systems:
Containment hydrogen control
Nuclear sampling
Steam generator blowdown
Residual heat removal
Containment purge
Fuel building HVAC
Other types and makes of valves may be affected at other nuclear sites.
A SNUPPS followup report dated May 10, 1984 indicated that further
investigation identified valves other than Valcor solenoid valves that have
similar deficiencies as described above. These are:
1) Twenty Target Rock solenoid valves furnished under the (NSSS)
scope for use in safety-related systems
2) Two ASCO solenoid valves on each of 12 condenser dump valves (not
safety-related)
3) One ASCO solenoid valve on each of two control room heating,
ventilation, and air conditioning (HVAC) water control valves
Corrective Action:
SNUPPS implemented design changes to replace a portion of the field-run
wiring with qualified high-temperature wiring with 200 C rated
insulation. The high-temperature wire is used as a jumper from the terminal
block inside the valve body to a splice box located approximately 5 to 10
feet from the valve. The field-run cable is spliced into the
high-temperature wire in the splice box, thus, there is no low-temperature
cable inside of the valve body.
No written response to this information notice is required. If you have any
questions about this matter, please contact the Regional Administrator of
the appropriate NRC regional office or this office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: W. Laudan, IE
(301) 492-9759
Attachment: List of Recently Issued IE Information Notices
