ML19274D068
| ML19274D068 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/29/1978 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Stampley N MISSISSIPPI POWER & LIGHT CO. |
| References | |
| NUDOCS 7901090324 | |
| Download: ML19274D068 (1) | |
Text
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'o NUCLEAR REGULATORY COMMISSION f*
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DEC 2 9 878 In Reply Refer To:
RII:JPO 50-416, 50-417 Mississippi Power and Light Company Attn:
Mr. Norris L. Stacpley Vice President of Production P. O. Box 1640 Jackson, Mississippi 39205 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, p(O tes P. O'Reilly D ector
Enclosures:
1.
IE Circular No. 78-19 2.
List of IE Circulars Issued in 1976 cc w/ enc 1:
W. L. Nail, Plant Superintendent P. O. Box 756 Port Gibson, Mississippi 39150 790109O S 2</
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND DiFORCDC.7 WASHINGTON, D.C.
20555 Dece=ber 29, 1978 IE Circular No. 78-19 MANUAL OVERRIDE (BYPASS) 0F SAFETY 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 belov directly relate to the practice of contain=ent purging during nor=al pisnt operation by manually overriding contain=ent isolation signals.
In these instances the auto =atie isolation function of the purge systec contain=ent isola-tion valves was unintentionally made inoperable, and this condition was neither continuously indicated in the control roo= nor known to the plant operators.
During a review of operating procedures on July 25, 1978, the Northeas t Nuclear Energy Co=pany discovered that since May 1,1978, intermittent containment purge operations had been conducted at Millstone Unit No. 2 with the safety actuation isolation signals to both inlet and outlet redundant containment isolation valves (L8 inch butterfly valves) ir the purge inlet and outlet penetrations manually overridden and inoperable.
The isolation signals which are required to auto =atically close the purge valves for containment intesrity 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 alves. To manually override a safety actuation signal, the operator cycles the valve control svitch to the closed position and then to the open position.
This action energized a relay which blocked the safety signal and allowed =anual operation independent of any safety actuation This circuitry was designed to permit reopening these valves signal.
after an accident to allow canual operation of certain safety equip =ent.
On Septe=ber 8, 1978, the Public Service Electric and Gas Co=pany advised the staff that, as a matter of routine, Sale: Unit Nc. I has been venting the contain=ent through the contain=ent ventilation syste:
In certain instances this venting has occurred valves to reduce pressure.
with the contain=ent high particulat radiation monitor isolation signal reller valves overridden. Override of to the purge and pressure-vacuu:
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IE Circular No. 78-19 December 29, 1978 the containment isolation signal was acco=plished by resetting the train A and B reset buttons. Under these circumstances, six valves in the contain=ent vent and purge syste=s could be opened with a high particulate isolation signal present. This override was performed after verifying that the actual containment particulate levels vere acceptable for venting. The licensee, after further investigation of this practice, determined that the reset of the particulate alert also bypasses the contain=ent isolation signal to the purge valves and that the purge valves vould not have automatically closed in the event of an e=ergency core cooling syste (ECCS) safety injection signal.
These events and information gained fro rect t licensing actions have rair.a a generic concern relative to potential design deficiencies that cou.d per=it mar.ually defeating a protection function.
Since all plants
-C construction permits cust meet the require =ents of IEEE 279, we reco=e -3 that you review the design of all safety actuation signal circuits which incorporate a manual 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 features are provided to facilitate adequate ad=inistrative controls, and that the use of each such manual override is annunciated at the system level for every syste= i=pacted.
Co=pliar.ce with Federal Pegulation 50.55a(h) require =ents vill be verified by NRC through the licensing review process and du. inge.. NEC's regular onsite inspections for plants with construction permis requirements relative to this catter have been conveyed to all c;* rating plar.t licensee's via a generic letter.
No written response to this Circular is required.
If you require additional information regarding this catter, contact the Director of the appropriate NBC Regional Office.
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IE Circular No. 78-19 Dece=ber 26, 1978 LISTING OF IE CIPCULARS ISSUED IN 1978 Circular Subject Date Issued To No.
of Issue 78-01 Loss of Well Logging L/5/78 All Holders of Source Well LogginE Source Licenses 78-02 P.oper Lubricating 011 h/20/78 All Holders of for Terry Turbines Reactor OLs or cps 78-03 Packaging Greater Than 5/12/78 All Holders of Type A Quantities of Reactor OLs, cps, Lov Specific Activity Fuel Cycle, Padioactive Material Priority I Material for Transport and Waste Disposal Licenses 78-OL Insta11atien Error That 5/15/78 All Holders of Could Prevent Closing of Reactor OLs or Fire Doors cps 78-05 Inadvertent safety injection 5/23/78 All Holders of During Cocidown Reactor OLs or cps 78-06 Potential Co==en Mode 5/23/78 All Ec1ders of Flooding of ECCS Equip =ent Reactor OLs er Roo=s at BWR Facilities cps 78-07 Damaged Cc=ponents of a 5/31/78 All Holders of Bergen-Paterson Series Reacter OLs or 25030 Hydraulic Test cps St and 76-08 Environmental Qualification 5/31/78 All holders of of Safety Belated Equip =ent Reactor OLs or at Nuclear Power Plants cps 76-09 Arcing of General Electrie 6/5/78 All Holders of Company Size 2 Contactors cps Ebelosure Pnge 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 o-. sesled 6/14/78 All Medical Cources Used in Licensees in Radiation Therapy Categories G and G1 76-11 Recirculation M-G 6/15/78 All Holders of Set Overspeed Stops BWR OLs or cps 78-12 HPCI Turbine 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 Pucps Reactor Odf 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 Chacber Hold Down Bolting OLs or cps for plants with a HPCI Terry Turbine excepting Duane Arnold and Monticello 76-15 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.
76-18 UL Fire Test 11/6/78 All Holders of Reactor OLs or cps Enclosure Page 2 of 2