ML19206B136
| ML19206B136 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/15/1976 |
| From: | Ashe F Office of Nuclear Reactor Regulation |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7905070438 | |
| Download: ML19206B136 (7) | |
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D.; i 5 So Docket No. 50-320 Tho=aA Ippolito, Ehlef, Electrical. Instrurentation &
Ccatrol Syste=s Branch, DSS THRU:
M. Srinivasan, Section Leader, EI&CS Branch, DSS SQ2fARY OF MEETI3G 'Tl"d REPRESENTATIVES FO?. THREZ MII.S ISLAND UNIT 2 Enclosures A and B provide information that relates to the electrical drawing audit for Three Mile Island Unit 2 which was held at the Burns and Roe Office in Pars =us, New Jersey, Fe'oruary 16-10, 1976.
Enclosure A contains general information concentiag the scope and activity for the me d.ngs.
Enclosure B cantains specific areas of concern resulting from the meetings. We note that items A, C, E and F of Enclosure B require response by the applicant in order to complete our input to the Safety Evaluation Raport.
The project = nager vill transmit Fnelnsure B to the' applicant for nace.ssary action.
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DISTRIBUTION NRC PDR Di LOCAL PDR M r FILE Frank Ashe NRR READING Flectr 6 1, Instru=entation EIC READING and Control Syste=s Branch F. ASHE Division of Systems Safety Rnciasures:
As stated cc:
B. C. Ruscha E. G. Case S. Hanauer R. Heineman R. Fraley, AC2S (3)
DP!f/ DSS ads H. Silver I&E G [( }
Meeting Attendees n,
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- 11. Kehnemuyi 4i R. DeYoung R. Tedesco M. Sriolivasan o, ries
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ENCLCSURE A I.
General Infor=ation Concerninc Scoce and Activity for the Meetings The following syste=s and/or selected portions of the syste=s were involved in the discuc sions.
1.
Auxiliary Feedwater Syste=
2.
Decay Heat Re= oval System 3.
Reactor Building Fan Coolers 4.
Nuclear Service Cooled Cooling Water Systen S.
Reactor Protection Systes 6.
Reactor Coolant Pu=p Monitors 7.
Reactor Trip 3reakers 8.
Diesel Generator Controls 9.
Diesel Generator Sequence Timers 10.
Safety Features Actuation Systen 11.
Make-Up Pumps (High Pressure Injection Pumps) Controls 12.
Reactor Building Spray Systra 13.
Nuclear Services River Water System 14.
Control Building River Water Sooster Pumps.
(Support to the Heating, Ventilation and Air Conditioning Systen for the Control Room.)
15.
Reactor Building Energency Cooling Booster Pumps 16.
Reactor Builuing Exhaust Fans 17.
Selected Contain=ent Isolation Valves 18.
Decay Heat Closed Cooling Water Systc=
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Manual Actuation - (Systems and Cceponent Level) 20.
Reset Provisions 21.
Electrical Penetrations for the Containment 22.
Local Control Switches
'4here applicable the piping and instrument diagram was obtained for each ites above. From this diagram the controls for all pu=ps and selected valves were traced through in detail. This trace was per-formed frc= the Engineered Safety (ES) signal to the final actuated equip =ent.
During this trace provision for testing, train assignments, manual actuation, reset provisions, etc., were noted.
Following this trace physical separation between the two electrical trains was verified for selected routings of c.:atrol and power cables.
The pnysical layout, ccaduit and/or cable tray drawings were used for this purpose. For certain ite=s selected routings of power cables were chosen to trace through.
"or other ite=s selected routings of control cables were chosen to trace through. For each case chosen physical separation was verified between the cables associated with redundant electrical trains from origin to destination point.
It was noted that all pcwer cables are in conduit (including 430 V power cables) and all control cables in conduit or cable trays (The only exceptions to this are short routings of cabic).
The above sequence was repeated for each of the applicable items listed above. The physical location (elevation and angular variatica) was established for the safety-related electrical penetrations of the containment.
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3 For the Reactor Protection System (RPS) the control circuitry for one parameter (reactor coolant system flow) was traced from the sensors to the control rod drive trip circuit breakers. Physical routing of the cables associated with this parareter was traced from the pri=ary systes sensors to the RPS cabinets for two redundant channels of the four R?S channels.
The control circuitry for selected Containment Isolation Valves was traced through in detail. These traces included typical valves which use air accu =ulators with a-c and d-c solenoid operators in addition to typical motor operated contain=ent isolation valves.
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ENCLOSL"4E 3 I.
SPECIFIC M.EAS OF CONCERN RESULTING FRCM THE ELICTRICAL DRAWING AUDIT FOR T*4REE :1ILE ISLAND UNIT 2 A.
Borated Water Storace Tank _(3WST) Level Alargs and Indicators The changeover function from the injection code to the recirculation
= ode following a LOCA is completely manual for Three Mile Island Unit 2.
The re-align =ent of flow paths from the SWST to the contain=ent sump is performed by the operator from the main control room. Accordingly, the alar:s and/or indicators are necessary to perform this function.
Presently, the design includes a BWST that is ecuipped with two alar =s, which are low and low-low level.
It was noted that both alar:s are gewered from a single non-safety power source.
In addition, the low-low level alarm is derived from a single level switch and the low level alarm through 2 out of 2 logic. This arrangement for the alarms does not conform to the single failure criterion.
The SWST is also equipped with continuous level indicators (with readouts in the sain control room). However, qualification doc-u=entation concerning these continuous level indicators was not established. The staff will pursue this subject with the applicant.
3.
Electrical Penetratiens During physical routing traces it was observed that selected elec-trical penetratiens contain both safety and non-safety cables.
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2 was noted that these electrical penetrations will )e required to be viewed during the Site Visit.
C.
Nuclear Service Cooled Coolinz Wa;er Svstem (N3CCWS) Swinz Pu=o Desizn The present design for the NSCCWS pumps include an automatic swing feature of a third pu=p to either of two redundant 430 volt motor control centers. This automatic feature is retained for accident conditions and should occur only if the pu=p which is permanently assigned to a redundant motor control center has failed. This design say result in the compromise of physical independence of redundant safety buses as recon = ended by Regulatory Guide 1.6.
The staff will pursue this item with the applicant.
D.
Reactor Trio Breakers Since the connection diagra:s for the physical routing of the power cables to the Reactor Trip 3reakers vere not complete it was noted that this review phase would be conducted during the Site Visit.
E.
Diesel Generator Controls and Associated Circuitrv The following areas were noted with regard to the Dicsel Generator Controls and/or associated circuitry.
1.
Non-bypass trips (for accident conditions) which could shutdown the diesel generator and are not for ed by coincident logic include the loss of generator field and reverse power relay.
The applicant was advised that the retention of these trips for accident conditions was not consistent with the Branch
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Technical Position EICS3 (Electrical, Instrumentation and Control Syste=s 3 ranch) 17.
It was agreed that a copy of this position would be provided to the tpplicant for necessary action.
2.
Provisions for periodic on-line testing of the undervoltage relays used at the 4160 volt Engineered Safety Featuras Buses was not incorporated. The applicant was advised that this por-tion of the design does act satisfy GDC 18 and requires mod-ification.
3.
Testability of the diesel generator sequence tiners which are used to apply loads to the diesel generator at different steps was not established. However, the applicant has agreed to prcvide a description of the integrated system test to verify the accuracy of the sequence tiners.
F.
Cross-Connect Between Trains Bv Control Power Connection for the Safetv Feature Actuation System (Normal Mode)
Five.120 volt vital instrument buses are associated with the _
two train battery system. For the three Safety Injection Channels, and the three Reactor Building Isolation and Cooling channels the present design associates one system level initiation _ train with both of the two battery power trains by the way of control power for this initiation train. This design is not in accordance with the reco==endations contained in Regulatory Guide 1.6.
The staff will pursue dhis issue with the applicant.
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