ML18046A963
| ML18046A963 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 10/14/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| TASK-06-07.C1, TASK-6-7.C1, TASK-RR LSO5-81-10-020, LSO5-81-10-20, NUDOCS 8110200314 | |
| Download: ML18046A963 (19) | |
Text
Docket No. 50-255 LSOS10-020 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Power Company 1945 W Parnall Road Jackson, Michigan 49201
Dear Mr. Hoffman:
October 14, 1981
SUBJECT:
SEP TOPIC VI-7.C.1, INDEPENDENCE OF REDUNDANT ONSITE POWER SOURCES SAFETY EVALUATION REPORT FOR PALISADES The final safety evaluation report on the subject topic is enclosed.
Th~
staff report has been modified to reflect the colTUllents provided bw. your letter of September 23, 1981.
We continue to propose modificattons to the 120 volt ac instrument 6ttss.(VCll) 1n order to satisfy the single failure criterion.
However, we also note that this issue is being pursued as a part of SEP
-Topfc VII-3 (Safe Shutdown) _and, therefore, we conclude that your plant satisfies the criteria for SEP Topic VI-7.C.1 and is acceptable.
Enclosuee:
Final SER on SEP Topic VI-7.C.1 cc w/enclosure:
See next page J
- a11oaoo3:1-t
- ai1014
. PDR ADOCK.05000255 1*
P11 PDR Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branbh No. 5 Dfvision of Licensing SEP" i,fl DS&t t&lf (py)
ADD~
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,., NRG F<?RM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960
Mr. David P. Hoffman r
Ms. Mary P. Sinclair Great Lakes Energy Alliance 5711 Summerset Drive Midland, Michigan 48640 Kalamazoo Public Library 315 South Rose Street Kalamazoo, Michigan 49006 Township Supervisor Covert Township Route l, _Box 10 Van B.uren County, Michigan 49043 Office of the Governor (2)
Room l - Capitol Building Lansing, Michigan 48913 William J. Scanlon, Esquire 2034 Pauline Boulevard Ann Arbor, Michigan 48103 Palisades Plant ATTN:
Mr. Robert Montross Plant Manager Covert, Michigan 49043 U. S. Environmental Protection Agency Federal Activities Branch-Region V Office ATTN:
Regional Radiation Representative 230 South Dearborn Street
- Chicago, Illinois 60604 Charles Bechhoefer, Esq., Chairman Atomic Safety and Licensing Board Panel
- u. s. Nuclear Regulatory Conmission Washington, D. C. 20555
~..
Dr. George C. Anderson Department of Oceanography University of Washington Seattle, Washington 98195 Dr. M. Stanley Livingston 1005 Calle Largo*
Santa Fe, New Mexico 87501.
Resident Inspector c/o U. S. NRC Palisades Plant Route 2, P. O. Box 155 Covert, Michigan 49043
I.* Introduction PSS EVALUATION REPORT OF SEP TOPIC. VI-7.C.1 INDEPENDENCE OF REDUNDANT ONSITE POWER SOURCES
- -*PALISADES DOCKET: NO.*
- 50-255 *. -* **
- ENCLOSURE The purpose of this evaluation is to asc.ertain the independence of.
redundant onsite power sources... : Review criteria,_ review guide) ines, and.
review areas, to be covered in this evaluation, are defined in !ections II and IV.
Review areas that are not covered, but are related and essential to the completion of this* topic, are covered by other SEP topics defined
'fn se*ction III. SEP topics are defined in the Report on the Sys_tematic Evaluation of Operatjng Fadl ities dated November 25, 1977.
This topic evaluation report is limited to identificatfon of compliance to review criteria, identification of deviation' frOm review criteria, and identification of any viable corrective measures for each deviation identified.
An integrated system assessment of the identified deviation's significance and recommendation as to the imposition of corrective measures will be the subject of a subsequent report.
II. Review Criteria Review criteria that govern the subject safety topi.c are identified in section 8.3.1, part II, items 1 and 2 and section '8.3.2, part II, items and 2 of NUREG-75/087, NRC Standard Review Plan.
- *2 -
III. Related Safet.Y Topics The following listed.review areas are not covered in this report, but are related and essential to the completion of this topic. These review areas are covered by other SEP topics.as indicated below.
- 1.
The capability of the electrical, instrumentation, and control system components to function during and after design basis events, such as earthquakes and anticipated operational occurrences, is covered by SEP topic III-6 and III-12;
- 2.
The capacity, cap.abilit'y~ and reliability of standby power supplies is*'
co~ered bi SEP topiiVIII-2;
- 3.
The offsite power system is covered by topic VIII-1;
- 4.
Electrical and physical separation between safe shutdown system com-ponents including the shutdown system's vital support system components is covered by topic VII-3. This area includes cables from the Class lE distribution system to the system loads;
- 5.
Technical Specification requirements are covered by topic XVI;
- 6.
System testing and surveillance requirements are covered by topics VIII-3A, VIII-38, and VI-lOA;
- 7.
Capability of heating and ventilation systems to.maintain a controlled environment for safety related instrumentation and electrical equipment located outside containment ts covered by topic IX-5;
- 1.
- 8.
The adequacy of the quality assurance program is covered by topic XVII;
- 9.
Systems required for safe shutdown are identified by topic VII-3; lO.
Shared engineered safety features, onsite emergency power, and service systems for multiple unit facilities are covered by topic VI-108;
- 11.
The ECCS Actuation System is covered by topic VI-7.A. 3 and VII-2;
- 12.
The capacity, capability, and reliability of DC power supply is covered by topfc VIII-3;
- 13.
The effects of connecting nonsafety loads to safety related power sources and routing of non-safety cables with safety related cables is covered by topic VII-4 and VIII-2; and
- 14.
The capacity, capability~ and reliability of the onsite power system to supply connected loads under all modes of plant operation is covered by topic VII I-1 A.
lS.
Protection of the Class lE power system components from design basis events such as flooding, missiles~ pipe breaks, and fires are covered by topics II-3, III-4, III-5, and IX-6.
- 16.
The independence of the onsite power system with respect to the offsite power system is covered by SEP topic VIII-lA.
IV.
Review Guidelines The purpose of this evaluation is to ascertain the degree to which Palisades design complies with review criteria that deal with the onsite electric power
,. distribution system.
The review areas to be covered in this evaluation include (A) the required redundancy of the onsite power system, {b) the electrical interconnection between redundant portions of the system, and (c) the physical separation between redundant components ~f the system.*.
including power, instrument, and.control cables.
ReNiew guidelines that address this topic's defined review areas are delineated in the following 1
sections of NRC Standard Review Plan: Section 8.3.1, part III, items 1 and 2 and Section 8.3.2, part III, items 1 and 2.
Review guidelines that address physical separation of power, instrumentation, and contr.ol cables ar~ defined.in Regulatory Guide 1.75 and IEEE Standard 384.
These physicaJ separation guidelines are~included with this topic review.
Additional review guidelines for cable separation, as well as for the physical separation of redundant distribution system components, are defined in section 9.5.1, Appendix A, "Guidance for Fire Protection for Nuclear Power Plants Docketed Prfor to July 1, 1976," positions 0.1.(a).(2) and D.L(C) of the NRC Standard Review Plan.
(Refer to the Palisades fire hazards analysis the NRC Palisades Fire Protection, Safety Evaluation Report, qnd any supplements thereto for identification of compliance to and deviation from section 9.5.l guideli~es.]
V.
Evaluation A simplified diagram of the onsite Class lE power system for Palisades is presented in figure 1.
The diagram is based on Palisades electrical drawings E-1 tllrough E-17.
The following evaluation is based on the simplified diagram and the Palisades FSAR.
The numbered items on the diagram identify inter-connections between redundant distribution systems.
The letter-number items
- 5 :-
identify distribution ~Y~.tem.components reviewed for physical separation.
Determination of component location and ph:Ysical.separation fromredundant counterparts is based upon Palisades equipment *location drawings M-1 through M-15.. *
- A.
Required Redundancy The Palisades onsite Class lE AC power system consists of two*redundant diesel generator (DG)
~upplied power divisions.. DG 1-1 suppli~s 2400 V
. bus l C, station power. transformer ll, 480 Vol f bus 11 and. 480. V MCC-1.
DG l ~2 supplies 24.00 V bus lD,. station power tran.sformer 12, 480 V bus 12 and 480 *V MCC~2;:~
The Pali sades ons*i te Cl ass l E DC power systein consists of two redundant 125 V DC divisions.
Battery No. 1, Charger No. l and Charger No. 3 supply 125 V DC Bus No. 1.
Charger No. 1 is supplied from MCC-: 1 (and utilimately DG 1-1). Charger No. 3 is supplied from MCC 2 (DG 1-2},
Both chargers are not normally connected to 125 V DC Bus No. 1.
The supply arrangement to 125 V DC Bus No. 2 is again, similar, with Charger No. 2 fed from MCC-2 and. Charger No. 4 fed from MCC-1.
By operating procedure SOP-30 Item 6.7 the chargers are operated in pairs ll and 2) or (3 and 4) to assure diverse AC supply.
Based upon the need for a two division Emergency Core Cooling capability and safe shutdown capability,
~e conclude that the two redundant onsite AC and DC power systems described above meet the regulatory requirements.
This meets the review guidelines and criteria defined in Section II and IV of this report.
The Palisades 120 volt AC instrument power is supplied from a single, non-redundant, 120 volt AC instrument bus (YOl).
The instrument bus can receive power from either 480 volt motor control center 1 or 480 volt motor control center 3 via an-automatic transfer switch.
We con-elude that the single instrument bus does not meet the minimum redundancy requirements and is a deviation from the review guidelines and criteria defined in Section II and IV of this report.. Redundant instrument loads supplied from this single bus do not meet the single failure criterion. The requirement that safe shutdown loads meet the single failure criterion is covered by topic VII-3, Systems Required for Safe Shutdown.
Deviations and recommendation for.corrective measures are addressed in topic VII-3.
The Palisad_es 120 volt AC vital power is supplied from four 120 volt preferred AC busses numbered 1 through 4.
Preferred AC buses 1 and 3 comprise one division of preferred AC:
Preferred AC buses 2 and 4 comprise the other.
Buses 1 and 3 are supplied by Inverters 1 and 3
- respectively, or by the Bypass Regulator; the suppll arran~ement for buses 2 and 4 is similar.
The Reactor Protection System and the Engineered Safety Features Actuation System are four channel systems requiring a redundant power
~uppl y for each channel.
We c.oncl ude that the four preferred AC buses described above meet these redundancy requirements. This meets the rev'iew guidelines and criteria defined in Section II and IV of this report.
e-B.
Electrical Interconnections A simplified diagram of the onsite power system is presented in figure 1.
Each of the fo11owi ng paragraph number designations correspond to numbers show~ on figure 1 and to interconnections between redundant Class.lE-..
divisions or between Class lE and. non-Class lE systems.
- 1.
The 2400 V buses lC and 10 (and, therefore, DG 1-l and D 1-2) can be tied together only if either offsite feeder breakers 152-105 and 152-203 (normally closed) or breakers 152-106 and 152-202 (normally open) are closed..
On loss of the offsite source, these breakers ~ach receive an automatic open signal from independent low voltage sensing devices located on bus lC for breakers. 152-105 and 152-106 and on bus 10 for breakers 152-202 and 152-203. Thus, there is no single failure that can cause the interconnection of bus lC and 10 and the paralleling of the standby onsite power sources after loss of offsite power.
This meets the review criteria and guidelines defined in s*ection II and IV of this report.
- 2.
See item 1.
- 3.
The 480 V buses 11 and 12 may be tied together by closing breakers 52-1118 and 52-1217 (normany open).
An interlock prevents the closure of these tie breakers if both breakers connecting the redundant sources to buses 11 and 12 (breakers 52~1102 and 52-1202,
- respectively) are closed; one of these two supply breakers must be open in order to close the tie breakers. This meets the review criteria.
and guidelines defined in Section II and IV of this report~
8 -
A tie breaker auto trip will ~ccur whenever an under-voltage condition exists at the secondary of startup transformer #1-2 coincident with a reactor or turbine trip, and prior to the closure of the diesel generator output breaker.
A tie breaker auto trip will occur whenever an under-~oltage condition exists on 2400 Volt bus lC or lD and the associated diesel generator output breaker is open~
An undei-voltage
- condition on bus lC opens tie breaker 52-1119 and an under-voltage condition on bus lD opens tie breaker 52-1217.*
These trips satisfy_ the review criteria. and guidelines.
- 4.
480 Volt motor contiol center number 2 (MCC-#2) and MCC-#1 were tied together through instrument AC bus as* shown on figure l. This interconnection was deleted on Palisades drawing E-1, Plant Single Line Diagram, Revision 1, dated March 28, 1978.
The power source to the instrument AC bus was changed from MCC-#2 to MCC-#3.
See item 10 for the evaluation of this new interconnection.
By the deletion of the interconnection between MCC-#2 and MCC-#1, the concern for possible failure of both redundant divisions because of failure of the common instrument AC bus, has* been eliminated.
.. 9 -
- 5.
The batte.ry chargers are adequately.sized:for<the station batteries
- which were originally *installed in the plant~: and are"sdll
- adeq~ate for th~ new batteries ~hich are b~ing in~tallea during
.the current refue.ling outage".. The foilowing discussion pertains to the plant config~tation which.will exist after the current*
refuelirig outage~.**
The two new station. batteries each have a nominal capacity of approximately 1800 A~H. The steady state DC loads will be approxi-mately 86 amps :on.DC *bus No; l,and 84:ampson bus No.* 2.. Thes~,*,..
values' :include presently *.knoWn *loads which are be'i.ng*. added*. by~:**,
planned modifications, *and apply* to b9th. normal and post-accident conditions.
Each of the two battery chargers available for each DC bus has a rated output of 200 a~ps, The.single charger which is normally supplying each DC bus, therefore, has sufficient capacity to carry bus load as well as charge the battery at a rate of approximately 115 amps.
To facilitate CPCo design of the new batteries, a load study was performed to conservatively predict the required battery capacity for a post-accident condition involving a loss of off-site power.
This study predicted that 523 A-H would be consumed by loads on DC bus No. l and 666 A-H on DC bus No. 2 over the two hour period
- 1.
following the off-site power loss.
If the chargers remain avail-able,* they would supply 400 A-H to each bus over the*two-hour.
period (200A capacity X 2 hrs).
The total battery discharge, therefore, would only be. approximately 123 A-H for station battery No. l and 266 A-H for battery No. 2.
The batteries could clearly be recharged rapidly in this post-accident condition w~th the available capacity of the single charger on each bus.
If the chargers remained unavailable throughout the post accident period,
- the new batteries have the capacity to carry DC lo.ads for* a sub-.
stantial period of time beyond the first two hours until an off-site or on-site AC power source can be restored.
The iiew* sfation batteries have a c~pacity more than twice than that of the original batteries, and are obviously very conservatively sized.
Ii must also be noted that the dual charger configuration at Palisades offers a degree of redundancy and increased reliability over the confi-guration normally found at current plants.
In a situation in which off-site power is lost and a diesel generator is not available, the redundant charger powered from the operable diesel can be used to carry DC loads and charge the battery in the opposite division.
The probability that a DC bus will be lost in this situation is therefore greatly reduced.
Palisades DC bus reliability would be expected to be greater than that offered by the more typical current design practice utilizing single chargers on each DC bus. *
- 6.
See item number 5,
- 7.
The bypass regulator output breakars are interlocked to
.. preclude supplii~g more than one preferred A(bus at. a time.
The interlock sche~e has a. key lock o~ each output breaker.
The four breaker locks utilize a single key which is maintained by the Shift Supervisor.
The key must be i<nserted in the desired breaker locking device before that breaker can be closed, and
~
with a breaker closed, the key cannot be removed.
Therefore, only one br~aker can be closed at a tilll2.
- 8. Associated non-Class-lE 480 volt bus 77 is interconne~ted with non-Cl ass l E bus 78 by a single tie breaker.
The supply breakers to
~
bus 77 and 78 are interlocked with the tie breaker suc.h that one of the two suppli break!rs must be open to close the tie breaker.
- Thus, Class 1E bus 1C cannot be paralleled with non-Class 1E bus lE through bus 77 and 78.
Also, th~ load brea~er on btis lC opens on loss of offsite power to prevent diesel generator 1~1 ove~load.
This meets the review guidelines.
- 9.
The interconnection between 480v bus 13 and 48Qv bus 14 is the same as item 8 evaluation.
- 10.
Division l Class lE MCC #1 is interconnected with non-Class lE MCC §3 through an auto transfer switch via the instrument AC bus.
Power to the instrument AC bus is normally supplied by MCC #1.
With loss of MCC #1 the power source is :automa tica 11 y transferred from MCC #1 to MCC #3.
Because MCC 53 is non-Class 1 and is not interconnected with MCC #2 (MCC #l's redundant counterpart), this de~ign meets the review guidelines.
( __
11
- Two a.ssoci ated non-Cl ass 1 E 480 vo 1 t buss es for swi tchyard loads are interconnected by a single tie breaker.
The supply breakers to these busses are interlocked with tie breaker such that one of
- the two supply breakers.must be open to close the tie breaker.
Thus, Class lE bus 1C cannot be paralleled w*ith non-Class lE buses.
The evaluation of item 8 applies to this design.
- c.
Physical Separation A simplified ~iagram of the onsita power system is presented in figure 1.
The letter-number designations on figure l identify distribution system componen.ts *herein evalui1ted for physical* s.eparatio*n.
The *following letter-number designation correspond to* l e.~ter-number des.i gnat ions shown on figure 1.
(A)
Each of the following items are located in a dedicated room.or are separated by the equivalent of a three-hour rated fire barrier from their redundant counterpart or from components assocjated with their redundant counterpart. This meets the review criteria and guidelines defined in Section II and IV of this report.
(1 ) Diesel generator 1-2 (2)
Di es el generator 1-1 (3) 2400 v bus 10
( 4) 2400 V bus l C (5) 125 v batteries (B)
- Each of the 'following* items are located in ~the general* area of their redunda.nt counterparts or *in the area of components assoc-iated with their redundant counterparts.'*. The separation between
- comporients is less than the equivalent of a three-hour rated I
fire barrier. This is a deviation from Section 9.5.1 review guide-1 ines defined in Section IV of this report.
Refer to.the Palisades 1
fire hazards analysis, the NRC Palisades Fire Protection Safety Evaluat1on Report, and any supplements thereto for identification
- of compliance to, deviation from; and corrective *design measures* **
required for deviations from those review guidelines.
(1) Cable between 2400v bus 10 and DG 1-2 (2)
Cable between 2400v bus 1 C and OG 1-1 (3)
Cable between 2400v bus 10 and bus 12
( 4)
Cable between 2400v bus 1 C and bus 11 (5) 480v.bus 12 (6) 480v bus 11 (7)
Cable between bus 12 and MCC i/8 (8)
Cable between bus 11 and MCC #7
{9*}
MCC #8 (10)
MCC #7 (11 } cable between bus 12 and MCC #2 (12}
Cable between bus 11 and MCC #1 (13}
MCC #2
. (14)
MCC #1.
(15). Battery Charger.C-2
- 14
. (16) Battery Charger C-1 (17) 125v DC bus #2 (18) 125v DC bus #1
( 19)
DC-AC inverters I-1, 2 t 3 t and 4 including associated cables (20)
Preferred AC busses 1, 2, 3, and 4 For the above listed cables and for instrumentation and control cables associated with the Class lE power distribution _system
.components, the separ~tion is less than the 5 ft.. vertical 3 ft.'.
horizontal recommended by Regulatory Guide 1.75. This -is a:.
deviation from the review guidelines.
An example of an approach*
that could correct this deviation would be to perform an analysis for the above defined cables to identify the specific deviations from the recorranendations of Regulatory Guide 1.75.
For each specific deviation identified, corrective measures such as installation of barriers, rerouting of redundant cables, or supplemental analyses justifying the existing separation on some other defined basis are acceptable approaches to removing this deviation.
VI.
Conclusion The following list itemizes the deviations from review guidelines that h~ve.
been identified and described in Section V of this report.
- 1.
The single 120 volt AC instrument bus does-net meet the minimum redundancy requirement.
lThe deviation and recommendation for corrective measures are addressed in topic VII-3.)
- 2.
Circuit separation is being addressed in response to_lO CFR 50~48.
By CPCo letters dated March 19, 1981 and May 19, 1981, design infonnation Has submitted for proposed alternate shutdown capability for those instances whe:re separation does not comply with 10 CFR 50 Appe_ndi)'.< R.rl:!quirements.
Th.is infonnation is currently under NRC review, and is no longer a part o~ the SEP review.
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