ML19274D075
| ML19274D075 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/29/1978 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Proffitt W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 7901090334 | |
| Download: ML19274D075 (1) | |
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ATLANTA. GEORGIA 30303 g,
- v y JEC 2 91978 In Reply Refer To:
RII:JP0 50-339, 50-404 50-405 Virginia Electric and Power Company Attn: M r. k'. L. Proffitt Senior Vice President, Power P. O. Box 26666 Rich =ond, Virginia 23261 Gentlemen:
The enclosed Circular 78-19 is forwarded to you for information.
If there are any questions related to your understanding of the requested
- actions, please contact this office.
Sincerely, g( 0 ames P. O'Reilly D ector
Enclosures:
1.
IE Circular No. 78-19 2.
List of IE Circulars Issued in 1978 790109C'$gy
DEC 2 9 sqg Virginia Electric and Power Company cc v/ encl:
S. V. Lowry, Senior Resident Enginee r P. O. Box 38 Mineral, Virginia 23117 J. A. Ahladas, Station Manager North Anna Power Station Box 402 Mineral, Virginia 23117 T. L. Bauco=, Manager Surry Power Station P. O. Box 315 Surry, Virginia 23883
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON,
'C.
20555 Dece=ber 29, 1978 IE Circular No. 78-19 MAN'JAL OVERRIDE (EYPASS) 0F SAFEIT SYSTEM ACTUATION SIGNALS Description of Circu= stances:
A review of several recent events has raised questions about safety syste= circuit designs which incorporate manual override (bypass) features. The two events described below directly relate to the practice of containment purging during normal plant operation by
=anually overriding containment isolation signals.
In these instances the automatic isclation function of the purge syster contain=ent isola-tion valves was unint entionally =ade inoperable, and this condition was neither continuously indicated in the control roo nor knovr. to the plant operators.
During a review of operating procedures on July 25, 1978, the Northeast Ruclear Energy Company discovered that since May 1,1978, intermittent containment purge operations had been conducted at Millstone Unit No. 2 vith the safety actuation isolation signals to both inlet and outlet redundant containnent isolation valves (h8 inch butterfly valves) in the purge inlet and outlet penetrations manually overridden and inoperable.
The isolation signals which are required to auta=atically close the purge valves for containnent integrity were manually overridden to allow purging of containment with a high radiation signal present. The manual override circuitry designed by the plant's architect / engineer defeated not only the high radiation signal but also all other isolation signals to these v alve s. To manually override a safety actuation signal, t'ae operator then to the cycles the valve control switch to the closed position an open position.
This action energized a relay which blocked the safety signal and allowed manual operation independent of any safety actuation signal. This circuitry was designed to permit reopening these valves after an accident to allov =anual operation of certain safety equip =ent.
On Septe=ber 8,1978, the Public Service Electric and Gas Cocpany advised the staff that, as a matter of routine, Sale: Unit No. I has been venting the containnent through the containment ventilation syste=
In certain instances this venting has occurred valves to reduce pressure.
with the containnent high particulate radiation =enitor isolation signal to the purge and pressure-vacuu: relief valves overridden. Override of 1 of 2
IE Circular No. 78-19 Dece=ber 29. 1978 the contain=ent isolation signal was acco=plished by resetting the train A and B reset buttons. Under these circu= stances, six valves in the containment vent and purge syste=s could be opened with a nigh particulate isolation signal present. This override was perfor=ed after verifying that the actual containment particulate levels were acceptatle for venting. The licensee, after further investigation of this practice, deter =ir-bat the reset of the particulate alar = also bypasses the contain isolation signal to the purge valves and. that the purge valves "%11 not have auto =atically closed in the event of an emergency core ec
.;g syste: (ECCS) safety injection signal.
These events and infor=ation gained from recent licensing actions have reised a generic concern relative to potential design deficiencies that could permit manually defeating a protection function.
Since all plants with construction permits must =eet the require =ents of IEEE 279, ve reco==end that you review the desd gn of all safety actuation signal circuits which incorporate a =anual override feature to ensure that overriding of one safety actuation signal does not also cause the bypass of any other safety actuation signal, that sufficient physical featuras are pt ovided to facilitate adequate ad=inistrative controls, and that the use of each such nanual override is annunciated at the syste= level for every syste= i=pacted.
Co=pliance with Federal Begulation 50.55a(h) require =ents vill be verified by NBC through the licensing review process and during HEC's regular onsite inspections for plants with construction permits.
require =ents relative to this =atter have been conveyed to all operating plant licensee's via a generic letter.
No written response to this Circular is required. If you require additional infor:ation regarding this =atter, contact the Director of the appropriate NBC Begicnal Office.
2 of 2
IE Circular No. 78-19 Dece=ber 28, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date Issued To No.
of Issue 78-01 Loss of Well Logging h/5/78 All Holders of Source Well Logging Source Licenses 78-02 Proper Lubricating 011 h/20/78 All Holders of for Terry Turbines Bea: tor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Low Specific Activity Fuel Cycle, Radioactive Material Priority I Material for Transport and Waste Disposal Licenses 78-OL Installation Error That 5/15/78 All Holders of Could Prevent Closing of Peactor OLs or Fire Doors cps 78-05 Inadvertent safety Injection 5/23/78 All Holders of Puring Cooldovr.
Reactor OLs or cps 78-06 Potential Co==en Mode 5/23/78 All Holders of Flooding of ECCS Equip =ent Reactor OLs or Roo=s at BWR Facilities cps 78-C7 Da= aged Ce=ponents of a 5/31/78 All Holders of Bergen-Paterson Series Beactor OLs or 25000 Hydraulic Test cps Stand 76-08 Environmental Qualification 5/31/78 All Holders of of Safety Related Equip =ent Eeactor OLs or at Nuclear Power Plants cps 7B-09 Arcing of General Electric 6/5/78 All Holders of Company Size 2 Contactors cps Ebelosure Page 1 of 2
IE Circular No. 78-19 December 28, 1978 LISTING OF IE CIRCULARS ISSUED IN 1978 Circular Subject Date of Issued to No.
Issue 78-10 Control of Sealed 6/14/78 All Medical Sources Used in Licensees in Radiation Therapy Categories C and Cl 78-11 Recirculation M-G 6/15/78 All Holders af Set Overspeed Stops
- BWR OLs or cps 78-12 HPCI Turbina Control 6/30/78 All Holders of Valve Lift Rod Bending BWR OLs or cps for plants with HPCI Terry Turbine 78-13 Inoperability of Multiple 7/10/78 All Holders of Service Water Pumps Reactor OLs and cps except for plants located in: AL, AK, CA, FL, GA, lA, MS,
SC 78-14 HPCI Turbine Reversing 7/12/78 All Holders of BWR Chamber Hold Down Bolting OLs or cps for plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 78-15 Checkvalves Fail to 7/20/78 All Holders of Close in Vertical Reactor OLs or cps Position 78-16 Limitorque Valve 7/26/78 All Holders of Actuators Reactor OLs or cps 78-17 Inadequate Guard Training /
10/13/78 All Holders of Qualification and Falsified and applicants Training Records for Reacter OLs.
78-18 UL Fire Test 11/6/78 All Holders of Reactor OLs or cps Enclosure Page 2 of 2