ML19340E200
| ML19340E200 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 11/07/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Linder F DAIRYLAND POWER COOPERATIVE |
| References | |
| NUDOCS 8101060631 | |
| Download: ML19340E200 (2) | |
Text
-_
- y ua o
UNITED STATES E"
7, NUCLEAR REGULATORY COMMISSION REGION lli
{
o,
[
799 ROOSEVELT ROAD gv j cLEN ELLYN. ILLINOLS Go137 November 7, 1980 l
i i
l Those on Attached Address Listing:
i This IE Information Notice No. 80-40 is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible apolicability to their facilities.
No specific action or response is requested at this time.
If further NRC l
evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact this office.
Sincerely, LO.
James G. Keppler l
Director l
l
Enclosure:
IE Information
(
Notice No. 80-40 l
cc w/ enc 1:
Mr. D. W. Kane, Sargent & Lundy Mr. Gary N. Wright, Chief y
Division of Nuclear Safety i
Reproduction Unit NRC 20b l
l p
8101060(,3g
1 1
RIII's CORPORATE ADDRESSES FOR OPERATING LICENSEES AND CONSTRUCTION PERMIT HOLDERS (BWR's and PWR's)
Docket No. 50-329 Docket No. 50-330 Its Consumers Power Company Tj ATTN:
Mr. James W. Cook
[;
Vice President
)
Midland Project ad 1945 West Parnall Road
=.:
pq Jackson, MI 49201 3
- 3 g,
N 6
'a "3
cc w/ encl-Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC l
Public Service Commission Myron M. Cherry, Chicago Docket No. 50-409 Dairyland Power Cooperative ATTN:
Mr. F. W. Linder General Manager 2615 East Avenue - South La Crosse, WI 54601 cc w/ enc 1:
Mr. R. E. Shimshak, P ant Superintendent ral Files Irector, NRR/DPM Director, NRR/ DOR AEOD Resident Inspector, RIII l
PDR i
Local PDR l
NSIC TIC Mr. John Duffy, Chief Boiler Inspector I
SSlNS No.:
6835 UNITED STATES Accession No.:
NUCLEAR REGULATORY COMMISSION 8008220269 IN 80 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 November 7, 1980 IE Information Notice No.: 80-40:
EXCESSIVE NID0 GEN SUPPLY PRESSURE ACTUA SAFETY-RELIEF VALVE OPERATION TO CAUSE REACTOR DEPRESSURIZATION Descriptic f Circumstances:
On October 7 and 31, 1980, surized at Boston Edison Company's Pilgrim Nuclear Power Stati The Pilgrim Station Unit 1 uses a GE BWR. The depressurizations resulted whe excessive. pressure in the nitrogen supply system caused the "A" Target Rock (TR) safety relief valve to open and remain open until the excessive supply pressure could be isolated, pneumatic operator pressure vented and the main steam system depressurized sufficiently to allow the main disk to reseat.
These two events involved a failure in the pressure regulation of the supply nitrogen and not a failure of the TR safety relief valve to function as design The safety relief valves at Pilgrim are designed to be supplied, with other drywell instrumentation, from either the compressed air system or containment atmosphere control system (CACS).
The CACS uses nitrogen for containment inerting.
The supply fcr the safety relief valves is provided from the CACS through an ambient air vaporizer and then through one of two parallel pressure regulators or a parallel bypass line.
new supply of liquid nitrogen had been added to the storage tanks. Shortly b time of the events the two pressure regulators were in service with the bypass At the closed.
Nitrogen pressure supplying the valves increased to This may have been caused by liquid nitrogen reaching the pressura regulators 160 - 165 psi.
or by a failure in a pressure regulator.
which was sufficient to leak through the solenoid actuator and initiate theThe pneumatic operator of the safety relief valve.
The design normal operating pressure of the compressed air or nitrogen systems supplying the safety-relief valves is90-110 psi. At a pressure of 145 psi the solenoid valve may begin to leak since excessive pressure acts to unseat the disk.
solenoid disk to reseat.The supply pressure must then decrease to 135 psi or less for t In addition the design of the safety-relief valve is such that as the main steam pressur,e increases, less instrument pressure is necessary to initiate the pneumatic cperator.
Approximately 3 to 5 psi at the pneumatic operator is sufficient to initiate the safety-relief valve opening.
Such a pressure begins to build with leakage through the solenoid actuator and was reached in the "A" valve at 160 psi supply pressure.
from GE and TRC, approximately 180 psi pressure is necessary for all of theAccording to safety relief valves to open as result of supply overpressure.
It would appear that under such conditions of overpressure that safety-relief valve openings would be sequential rather than s' The particular solenoid actuator valves ust valves are manufactured by TRC.
Their des-DUPLICATE DOCUMENT pressure tends to unseat the solenoid valvt valves use e sther AVC0 (Automat 1c Valve Cor Entire document previously Company) solenoid valves according to infoi entered into system under:
~
ANO $00%2.2 0 2.@
No. of pages:
30
-