ML20009F165
| ML20009F165 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 06/30/1981 |
| From: | Weber D EG&G IDAHO, INC., EG&G, INC. |
| To: | Shemanski P Office of Nuclear Reactor Regulation |
| References | |
| CON-FIN-A-6429 EGG-EA-5476, NUDOCS 8107300002 | |
| Download: ML20009F165 (11) | |
Text
-
EGG-EA-5476 June 1981 DEGRADED GRID PROTECTION FOR CLA.SS lE POWER SYSTEMS, OIw L[/d 3
0YSTER CREEK NUCLEAR STATION UNIT 1, DOCKET NO. 50-21,
5 1
b
['
)MD
-7 JUL 2 71931
- i d O q m.= gi
\\'
.N x
PRELIMINAR1YF
^ **'
Y1C Researcranc ~ecinica Assistance Report U.S. Department of Energy Idaho Operations Office
- Idaho National Engineering Laboratory 8 -
k
~ 1 - fd fy.yd. hen [i 55 3
W Il
- =rr.rurn m.m W,,,,l5L h & l112*?
ll W :
L
"-- < --m -m ~ ~
- - w. eslm e-wan%
r+
m wncm.:
.r mmm?-
x
.l
-k$f Ti
-- NA i
WM3_
--rn.~
^
g--_w _;g.
f f-C.,
DD N
A wwm This is an informal report intended for use as a preliminary or working document Prepared for the U. S. Nuclear Regulatory Commission Under DOE Contract No. DE-AC07-76ID01570 FIN No. A6429 g
E S g G ldaho 9107300002 810630 PDR RES G107300002 PDR
r E Gs G..~. -
f ORM EG40 396 e., n m INTERIM REPORT Accession No.
EGG-EA-S476 Heport No.
Csntract Program er Project
Title:
Selected Operating Reactors Issues Program (III)
' Subject of this Document:
Degraded Grid Protection for Class lE Power Systems, Oyster Creek Nuclear Station Unit 1 Docket No. 50-219 Type of Document:
Technical Evaluation Report Author (s):
I 30SearCa and ' BC'aniCa, i
D. A. Weber Date of Document:
[
June 1981 Responsible NRC Individual and NRC Office or Division:
Paul C. Shemanski, Division of Licensing This document was prepared primarily for preliminary or internal use. it has not received full review and approval. Since there may be substantive changes,itiis document should not be considered final.
EG&G Idaho, Inc.
Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission Washington, D.C.
Under DOE Contract No. DE-AC07 761D01570 NRC FIN No.
A64D INTERIM REPOOT
0430J DEGRADED GRID PROTECTION FOR CLASS lE POWER SYSTEMS OYSTER CREEK NUCLEAR STATION UNIT 1 Docket No. 50-219 D. A. Weber Reliability and Statistics Branch Engineering Analysis Division EG&G Idaho, Inc.
June 1901 Draft 6-20-81 TAC No. 10038
ABSTRACI In June 1977, the NRC sent all operating reactors a letter outlining three positions the staff had taken in regard to the onsite emergency power systems. Jersey Central Power & Light Coapany (JCP&L) was to assess the i
susceptibility of the safety-related electrical equipment at the Oyster l
l Creek Nuclear Station, Unit 1, to a sustained voltage degradation of the l
l off site source and interactic:. of the offsite and onsite emergency power i
systems. This report contains an evaluation of JCP&L's analysis, modifica-tions, and technical specification changes to comply with these NRC posi-tions.
The evaluation has determined that JCP&L does not comply with one of the NRC positions.
FOREWORD This report is supplied as part of the " Selected Operating Reactor Issues Prcgrim (III)" being conducted for the U.S. Nuclear Regulatory Com-mission, Office of Nuclear Reactor Regulation, Division of Licensing, by EG&G Idaho, Inc., Reliability and Statistics Branch.
The U.S. Nuclear Regulatory Commission funded the work under the authorization, C&R 20 19 01 06, FIN No. A6429.
ii
CONTENTS t
1.0 INIRODUCTION.......................................................
1 2.0 DESIGN BASE CRiiERIA...............................................
2 3.0 EVALUATION.........................................................
2 3.1 Existing Undervoltage Protection.............................. 3 3.2 Modifications.................................................
3 3.3 Discussion.................................................... 4
4.0 CONCLUSION
S........................................................
9
5.0 REFERENCES
9 s
e iii
TECHNICAL EVALUAT10N REPOR f l
DEGRADED GRID PROTECTION FOR CLASS lE POWER SYSTEMS-OYSTER CREEK NUCLEAR STATION UNIT 1 1.0 INTRODUCTIOh On June 2,1977,I the NRC requested the Jersey Central Power & Light Company (JCP&L) to assess the susceptibility of the safety-related electri-cal equipnent at the Oyster Creek Nuclear Station to a sustained voltage degradat. ion of the offsite source and interaction of the offsite and onsite emergency power systems.I The letter contained three positions with which the current design of the plant was to be compared. Af ter comparing the current design to the staff positions, JCP&L was required to either propose modifications to satisfy the positions and criteria or furnish an analysis to substantiate that the existing facility design has equivalent capabilities.
JCP&L responded to the NRC letter of June 3,1977 with a submittal dated September 25, 1979.2 This submittal and submittals of September 16, 1976, October 14, 1976,4 November 5, 1976,b February 1, 1977,6 April 18, 1977, August 15, 1977,0, November 1, 1979,9 January 18, 1980,10 August 11, 1980,II April 30, 1981,12 and the Oyster Creek Final Safety Analysis Report (FSAR)I3 complete the information reviewed f or this report.
1
2.0 DESIGN BASE CRITERIA The design base criteria that were applied in determining the accepta-bility of the system modifications to protect the safety-related equipment
.g f rom a sustained degradation of the offsite grid are:
1.
General Design Criterion 17 (GDC 17), " Electrical Power Systems," of Appendix A, " General Design Criteria for I4 Nuclear Power Plants," of 10 CFR 50 2.
IEEE Standard 279-1971, " Criteria for Protection Systess for Nuclear Power Generating Stations"15 3.
IEEE Standard 308-1974, " Class IE Power Systems for Nuclear Power Generating Stations"16 4.
Staff positions as detailed in a letter sent to the I
licensee, dated June 2, 1977 5.
ANSI Stendard C84.1-1977, " Voltage Ratings for Electri-cal Power Systeins and Equipment (60 Hz)."I 3.0 EVALUATION This section provides, in Subsection 3.1, a brief description of the existing undervoltage protection at Oyster Creek; in Subsection 3.2, a description of the licensee's proposed modifications for the second-level 2
undervoltage protection; and in Subsection 3.3, a discussion of how the proposed modifications meet the design base criteria.
3.1 Existing Undervoltage Protection.
For loss-of-voltage protection, each of the safety-related 4160V buses 1C and 10 has a set of General Elec-tric type 1AV53K under/overvoltage indication relays.
The undervoltage trip setpoint for each relay is 68.8% (2864V).
Each relay will operate in 3 seconds on total loss of power. The 68.8% on the 4160V buses will result in voltage'of 317 (66%) and 297 (61.8%) for the 480V substations and motor control centers (MCC's), respectively. Operation of either relay will initiate isolation of the 4160V buses and loads, initiate load shedding and start of the emergency diesel generators (DG's), energize the emergency buses with permanently connected loads and energize the automatically con-nected emergency loads through a load sequencer.
3.2 Modifications.
As a result of the NRC request, JCPt.L has installed a second-level undervoltage scheme to protect safety-related-equipment from a sustained degraded grid.
The scheme consists of the addi-tion of independent undervoltage relays for buses 1C and 10.
The three relays on each bus are connected in a two-out-of-three coincident logic, with a setpoint of 3671V +1% (36.7V) and a time delay of 10 seconds +1%
(0.1 sec).
Either bus relay log.: will initiate disconnection of the off-site power source whenever the voltage setpoint and time limits have been exceeded. With the offsite power disconnected, the existing loss-of-voltage relays on the emergency buses will operate as described in Section 3.1.
3
The licensee has proposed changes to the plant's technicol specifica-tions including:
relay surveillance requirements, setpoints and limits, and limiting conditions for operation.
I 3.3 Discussion. The first position of the NRC staff letter required that a second level of undervoltage protection for the onsite power system be provided.
The letter stipulates other criteria that the undervoltage protection must meet. Each criterion is restated Selow fol-lowed by a discussion regarding the licensee's compliance with that criterion.
1.
"The selection of voltage and time setpoints shall be determined from an analysis of the voltage requirements of the safety-related loads at all onsite system distri-bution levels."
The licensee's proposed setpoint of 3671V (88.5% of 4160V) results in voltages of 89.9% at the 460V rated motor starters.
The motor starters will pickup at 85%
voltage and the control circuitry can withstand a lower voltage. This setpoint allows worst case terminal volt-ages of 91.6%, 85%, 87.4% and 90.4% for the correspond-ing safety-related 4000V, 480V, 460V, and 440 motors.
The minimum rating is 90% for the 4000V motor, and 86.6% for the worst case 480V, 460V, and 440V motors (which consider a 1.15 service factor).
At the pro-posed setpoint all 4000V, 460V, and 440V safety related 4
v.e L
a a
n 4
2 4
equi 9nent will operate at voltages above the minimum required. However the setpoint allows the 480V motors :.0 be operated continuously at voltages below their minimum rating.
Therefore the proposed setpoint i -
is not satisfactory.
12 The licenses submittal of April 30, 1981 points'out that the analysis does not consider the automatic operation of newly installed voltage regulators which will maintain the 4160V bus at 4100V when the grid is at its minimum analyzed value. However, credit cannot be given for the regulators since they have a limited voltage control during degraded grid conditions.
2.
"The voltage protection shall include coincident logic to preclude spurious trips of the offsite power sources."
The proposed modification incorporates a two-out-of-three coincident logic scheme, thereby satisfying this criterion.
3.
"The time delay selected shall be based on the follow-ing conditions:
?
l t
1 l
S
~
a, "The allowable time delay, including margin, shall not exceed the maximum time delay that is assumed 1
in the FSAR accident analysis."
The proposed maximum time delay of 10 seconds (1p.1 seconds)doesnotexceedthismaximumtime delay.
b.
"The time delay shall minimize the effect of short-duration disturbances from reducing the unavaila-bility of the offsite power source (s)."
The licensee's proposed minimum time delay of 10 seconds is long enough to override any short, inconsequential grid disturbances and voltage dips caused from the starting of large motors.
c.
"The allowable time duration of a degraded voltage condition at all distribution system levels shall not result in failure of safety systems or compon-ents."
A review of the licensee's voltage analysis indi-cates that the time delay will not cause any fail-ures of the safety-related equipment.
4.
"The voltage monitors shall automatically initiate the disconnection of offsite power sources whenever the 6
voltage setpoint and time-delay limits have been excecded."
A review of the licensee's submittals confirms that this criterion is met.
5.
The voltage monitors shall be designed to satisfy the requirements of IEEE Standard 279-1971."
The licensee has stated in his proposal that the modi-fications are designed to meet or exceed IEEE Stan-dard 279.
6.
"The technical specifications shall include limiti.ig conditions for operation, surveillance requirements, trip setpoints with minimum and maximum limits, and allowable values for the second-level voltage protec-tion monitors."
The licensee's proposal for technical specification changes includes all the required items.
The second f4RC staff position requires that the system design auto-matically prevent load-shedding of the emergency buses once the onsite sources are supplying power to all sequenced loads.
The load-shedding must also be reinstated if the onsite breakers are tripped.
7
The existing undervoltage relaying scneme for the emergency buses already has these features incorporated.
The second-level undervoltage protection will be blocked automatically when the emergency buses are being fed f rom the onsite sources.
The third NRC staff position requires that certain test requirements be added to the technical specifications.
These tests were to demonstrate the full-functional operability and independence of the onsite power sources, and are to be performed at least once per 18 months during shut-down. The tests are to simulate loss of offsite power in conjunction with a safety-injection actuation signal, and to simulate interruption and sub-sequent reconnection of onsite power sourcas. These tests ver'ry the proper operation of the load-shed system, the load-shed bypass when the emergency diesel generators are supplying power to their respective buses, and that there is no adverse interaction between the onsite and offsite power sources.
The testing procedures proposed by the licensee comply with the full intent of this position.
Load-shedding on offsite power trip is tested.
Load-sequencing, once the diesel generator is supplying the safety buses, is tested.
The time duration of the tests (equal to or greater than 5 min-utes) will verify that the time delay is sufficient to avoid spurious trips and that the load-shed bypass circuit is functioning properly.
9 8
4.0 CONCLUSION
S i
Based on the information provided by JCP&L, it has bee.1 determined thht the installed modifications do not comply with NRC staff positinn 1.
Certain 480V motors may operate at voltages below their minimum ratings at the present second-level undervoltage relay setpoint, when the offsite grid is at its minimum analyzed value. Credit cannot be given for the installed voltage regulators.
1 i
The existing load-shed circuitry complies with staff position 2 and w;11 prevent adverse interaction of the offsite and onsite emergency power systems.
The proposed changes to the technical specifications adequately test i
the system modifications and comply with staff position 3.
The surveillance requirements, limiting conditions for operation, minimum and maximum limits for the trip setpoint, and allowable values meet the intent'of staff posi-tion 1.
I t
I It is therefore concluded that the setpoint of the installcd seccnd-level undervoltage relays is not acceptable.
The proposed changes to the technical specifications are acceptable, except for the second-level under-I voltage relay setpoint.
5.0 REFERENCES
1.
NRC letter (R. W. Reid) to JCP&L, dated June 2, 1977 9
2.
J'd&L letter (I. R. Finfrock) to the Director, Nuclear Reactor Regu-
)
lation, dated September 25, 1979.
3.
JCP&L letter (I. R. Finfrock) to Mr. George Lear, Cnief, Operating Reactors Branch No. 3, Division of Reactor Licensing, dated September 16, 1976.
4.
JCP&L letter (1. R. Finfrock) to Mr. George Lear, Chief, Operating Reactors Branch No. 3, Division of Rear. tor Licensing, dated Octobo 14, 1976.
5.
JCP&L letter (I. R. Finfrock) to Mr. George Lear, Chief, Operating Reactors Branch No. 3, Division of Reactor Licensing, dated November 5, 1976.
6.
JCP&L letter (I. R. Finfrock) to Mr. George Lear, Chief, Operating Reactors Branch No. 3, Division of Reactor Licensing, dated February, 1977.
7.
JCP&L letter (l. R. Finfrock) to Mr. George Lear, Chief, Operating Reactors Branch No. 3, Division of React'or Licensing, dated April 18, 1977.
8.
JCP&L letter (1. R. Finf rock) to Mr. George Lear, Chief, Operating Reactors Branch No. 3, Division of Reactor Licensing, dated August 15, 1971.
9.
JCP&L letter (I. R. Finfrock) to the Director of Nuclear Reactor Regu-lation, dated November 1, 1979.
- 10. W P&L letter (1. R. Finfrock) to the Director of Nuclear Reactor Regu-lation, dated Jinuary 18, 1980.
- 11. JCP&L letter (I. R. Finfrock) to the Director of Nuclear Reactor Regu-lation, dated August 11, 1980.
10
- 12. JCP&L. letter (1. R. Finfrock) to the Director of Nuclear Reactor Regu-lation, dated April 30, 1981.
- 13. Final Safety Analysis Report (FSAR) for the Oyster Creek Nuclear Station.
{
- 14. General Design Criterion 17, " Electric Power Systems," of Appendix A,
" General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50,
" Domestic Licensing of Production and Utilization Facilities."
i-15.
IEEE Standard 279-1971, " Criteria for Protection Systems for Nuclear
~
l'ower Generating Stations."
16.
IEEE Standard 308-1974, " Standard Criteria for Class lE Power Systems for Nuclear Power Generating Stations."
i
- 17. ANSI C84.1-1977, " Voltage Ratings for Electric Power Systems and E, quip-ment-(60 Hz)."
18.
IEEE Standard 141-1976, "lEEE Recommended Practice for Electric Power Distr ibution for Industrial Plants."
J
e 9
11
-