ML20002C490
| ML20002C490 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/14/1978 |
| From: | Skibitsky W CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8101100367 | |
| Download: ML20002C490 (9) | |
Text
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s CORSUmBIS POVlCT 1
i C0mpany
....., o m... : 2 2...,. c ~,.,... ~.. s........ ~,.,. 20,..,.. c o..,, 7... o.. o June lk, 1978 Director, Nuclear Reactor Regulation Att; I4r Dennis L Zie= ann, Chief Operating Reactors Branch No 2 US Nuclear Regulatory Co=tission Washington, DC 20555 4
DOCKET 50-155 - LICENSE DFR BIG ROCK POINT PIKiT - ON-SITE E G E;CY POWER SOURCES
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Attached is the response to the HRC staff positions cencerning on-site e=ergency power systems for the 31g Rock Point Plant. The design and installation schedules will be forwarded by September 1,1978.
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"k BIG ROCK POINT PLANT RESPONSE TO NRC STAFF POSITIONS CONCERNING ON-SITE EMERGENCY POWER SYSTDIS Position 1:
Second Level of Under-or Overvoltage Protection With a Time Delay We require that a second level of voltage protection for the on-site power system be provided and that this second level of voltage protection shall satisfy the following criteria:
a.
The selection of voltage and time set points shall be determined from an analysis of the voltage requirements of the safety-related loads at all on-site system distribution levels; b.
The voltage protection shall include coincidence logic to preclude spurious trips of the off-site power source; c.
The ttne delay selected shall be based on the following conditions:
(1) The allovable time delay, including margin, shall not exceed the i
i maximum time delay that is assumed in the FSAR accident analyses; (2) The time delay shall minimize the effect of short duration distur-bances from reducing the availability of the off-site power source (s);
and j-(3) The allowable time duration of a degraded voltage condition at all distribution system levels shall not result in failure of safety 1
systems or components; d.
The voltage monitors shall automatically initiate the disconnection of off-site power sources whenever the voltage set points and time delay limits have been exceeded; e.
The voltage monitors shall be designed to satisRf the requirements of IEEE Standard 279-1971, " Criteria for Protection Systems for Nuclear Pover i
Generating Stations"; and f.
The Technical Specifications shall include limiting conditions for operation, surveillance requirements, trip set points with minimum and maximum limits,
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2 Response la
-The following table lists the maximum and minimum voltage parameters that the safeguards bus vill experience during normal grid and generator voltage conditions.
The table.also shows the maximum and minimum voltage ratings for the continueus operation of the safety-related equipment which is supplied from this bus.
A comparison of these values indicates that the maximum bus voltages are within the maximum ratings for the safeguards equipment. However, the minimum bus voltages exceed the minimum ratings for this equipment.
Safeguards Safeguards Equipment Continuous Bus Voltage Operating Voltage Range Level Under Min & Max Grid Conditions Transf Motor MCC Batt Chg Rated h80 V h80 V hh0 V 480 V hh0 V Min 387 N/A 396 408 396 Max 479 528 48h 528 h8h i
In the analysis of the on-site distribution system, it was determined that postulated unexpected minimum voltage levels can only occur when the station generator is off the line and the plant is utilizing one of the off-site power sources.
Protection for safety-related equipment in this postulated condition vill be provided by the installation of undervoltage relays to the 2h00 V bus.
The relays will be set to protect that equipment that has the highest continuously operating minimum voltage level. See Attachments No 1 and 2 - Single Line and Logic Diagrams - Big Rock Point Plant.
The safety-related equipment with the highest minimum voltage rating is the h80 V MCC. The proposed undervoltage relays vill be set to protect the h80 V MCC from voltages belov 85". (h08V).
Resnonse_ l_b_
The undervoltage protection vill consist of an undervoltage relay connected to the secondary of the 2h00 V/120 V potential transformers that will be installed on each phase combination of the 2h00 V bus. This set of three undervoltage relays vill be connected to provide a 2 out of 3 coincidence outpdt.
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_ Response lc(1)
The -allowable time delay to be used for the undervoltage relays has been de-
. termined to be 10 seconds.
This -value is based on the protection of safety-related components or systems and the necessity to minimize the effect of short duration disturbances.
The basis for this is discussed further in the responses to Positions le(3) and le(2), respectively.
Response le(2)
The ~ time delay which will be used is 10 seconds.
In the develop.nent of this value, the short duration voltage reducing effects of prinary and contincency fault clearing on the plant buses were considered.
It is ' desired to allow the primary and contingency fault clearing devices to perform their normal function whenever possible.
Therefore, it has been de-termined that a time delay of 10 seconds will maximize the use of existing fault' clearing devices, while at the same time minimize the effect of short duration disturbances.
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Response le(3)
It is not credible to expect that an undervoltage condition lasting 10 seconds or less could result in the failure of safety-related components or systems.
Perhaps the most vulnerable component affected by this condition is the k80 V motor starter control fuse which is designed to fail under certain degraded modes of operation. The mode that is applicable to the above position is that in'which the voltage applied to the starter contactor coil is insufficient to pick up the coil, resulting in an increased current load that causes the fuse to fail.
It has been determined that the minimum time for fuse failure in this under-voltage condition is 25 seconds or longer.
The proposed undervoltage relays with a tipe delay of 10 seconds will function long before any control fuses can be expected to fail.
Thus, a very conservative margin exists.
Response ld Refer to Response la.
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~ Response le-The second level of voltage protection system vill be designed to meet the requirements of IEEE Standard 279-1971.
Response lf Appropriate Technical Specifications changes incorporating the applicable cri-teria shall-be developed and submitted:once the final design for the proposed modification is complete.
Position 2:
Interaction of On-Site Power Sources With Load Shed Feature i
Ve require that the current system designs automatically prevent load shedding of the. emergency buses once the on-site sources are supplying power to all sequenced loads on the emergency buses.
The design shall also include the capability of the load shedding feature to be automatically reinstated if the on-site source supply breakers are tripped. The automatic bypass and re-instatement feature shall be verified during the periodic testing identified 3
in^ Position 3 i
Response 2 System design for the Big Rock Point Plant does not have automatic load shedding or sequencing capabilities. Therefore, Position 2 is not applicable for this plant.
Pbsition 3:
on-Site Power Source Testing We require that the Technical Specifications include a test requirement to demon-strate the full functional operability and independence of the on-site power sources at least once per 18 months during shutdown. The Technical Specifications shall include a requirement for tests:
(1) simula+ing loss of off-site power in con-junction with a safety injection actuation signal; and (2) simulating interruption and subsequent reconnection of on-site power sources to their respective buses.
Proper operation shall be determined by:
Verifying that on loss of off-site power the e=ergency buses have been a.
de-energized and that the loads have been shed from the emergency buses in accordance vith design requirements.
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Verifying that on loss of off-site power the diesel generators start from ambient condition on the autostart signal, the emergency buses are energized with permanently connected loads, the auto-connected emergency loads are energized through the load sequencer, and the system operates for five minutes while the generators are loaded with the emergency loads.
c.
Verifying that on interruption of the on-site sources the loads are shed from the emergency buses in accordance with design requirements and that 4
subsequent loading of the on-site sources is through the load sequencer.
Response 3 Appropriate Technicc.1 Specifications changes incorporating the applicable criteria contained within this position shall be developed and submitted once the final design for the proposed modifications is completed.
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-NRC-3031305-010 UNITED-STATES-NUCLEAR-REGULATORY COMMYS DDC MONTHLY ACCESSION LIST
-- ~04/01/78~
04/30/78~
FIL'E-LEVELS DOC. DATE STN-50-528 ARIZONA PUBLIC SERVICE COMPANY PALO VERDE N1 50 02/28/78 ACCESSION NBR: 78090-0074 TASK NBR:
"- 528 DOCUMENT ~ TYPE LETTER
~~ FICHE NBR :
B DOCUMENT SIZE: 200P NOTARIZED:
DOCKET DATE:
LPDR:
Y REPORT NBR.
RECP: STOLZ J F RECP AFFILI ORG:
VAN BRUNT E E ORG AFFILIA
SUBJECT:
QUALIFICATION PLANS FOR SPECIFICATI OUALIFICATION PLANS FOR SPECIFICATI FOR-SPECIFICATION NM-993t-H2-RECOME 50 04/04/78 ACCESSION NBR: 78104-0146 TASK NBR:
528 DOCUMENT ~ TYPE - LETTER FICHE-NBR :
8 DOCUMENT SIZE: 2P+16P NOTARIZED:
Y DOCKET DATE:
LPDR:
i REPORT ~NBR.
RECP: CASE E G RECP AFFILI ORG:
BRUNT E E ORG AFFILIA
SUBJECT:
FORWARDING REPT ENTITLED: uGUALIFIC PROGRAM FOR AWS D1.le nINCLUDING AF DEMONSTRATE-THAT-THE-MOISTURE CONTF MORE THAN ADEQUATE TO PREVENT HYDF
-50 02/10/78 ACCESSION-NBR:-78088-0143 TASK-NBR:-
528 DOCUMENT TYPE: LETTER FICHE NBR :
C DOCUMENT SIZE: 2P+1P+15P NOTARIZED:
-DOCKET-DATE:
LPDR:-
-1 REPORT NBR:
RECP: VAN BRUNT E E RECP AFFILI ORG :--SPENC ER-G -S-ORG~~AFFILIt
SUBJECT:
ADVISING THAT THERE WAS AN ITEM OF i
50-528/78-01e-50-529/78-01-&-50-530 HERNANDEZ ON 01/16-20/78...W/ATT Ih i
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