Term
PRNM
Describe the construction of the LPRMs. |
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Definition
-The LPRM subsystem uses 96 fission chamber detectors that are distributed throughout the core.
-Consists of 24 detector strings with 4 fission chambers at different heights (same plane). |
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Term
PRNM
Describe the spacing of the LPRMs. |
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Definition
-The detectors are spaced 3' apart.
-"A" level detector located 1.5' above the core bottom.
-"D" level detector located 1.5' below the core top. |
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Term
PRNM
Described the function of the LPRM output. |
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Definition
-LPRM and TIP systems combine with Gardel to form core monitoring system.
-the data is combined w/calculated relative nodal power distributions to determine core power distribution. |
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Term
PRNM
Describe the construction and ratings of the LPRMs. |
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Definition
-1.6" long cylinders with .23" diameter.
-Designed for 600F and 2000psig max.
-2 cylinders, separated by a space w/argon gas.
-Inner electrode maintained at 100VDC.
-Inner wall of outer cylinder coated with 90% enriched uranium.
-Fission with uranium coating causes highly charged ions.
-Ions have large flux proportional to Rx power. |
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Term
PRNM
Describe the LPRM Alarms and Rod Blocks. |
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Definition
-LPRM UPSCALE/DOWNSCALE: 3%(downscale) and 100%(upscale). (alarm only)
-Min LPRMs per APRM: 14 (alarm and rod block).
-Min LPRMs per level: 2 (alarm and rod block).
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Term
PRNM
Describe the function and inputs to the APRMs. |
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Definition
-Input from LPRMs to provide averaged output signals that are representative of thermal power.
-4 APRM modules.
-Each APRM module receives input from 24 of the LPRMs (no LPRM shared on an APRM). |
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Term
PRNM
Describe the required number of channels. |
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Definition
| 4 channels, 3 required (1 can be bypassed or fail). |
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Term
PRNM
Describe the output of the APRMs. |
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Definition
-Each APRM calculates the Simulated Thermal Power level of the core by applying a filter with a 6 second time constant tot he Average Neutron Flux level.
-the STP level is representative of the heat rate at the fuel cladding. |
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Term
PRNM
Describe the APRM Trouble and INOP alarms. |
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Definition
-Trouble: Any self test fault <14 LPRMS or <2 LPRMS per level (alarm and rod block).
-INOP: Keylock in INOP, Critical self test fault, Computer "hung up," Loss of input power (alarm, rod block, SCRAM). |
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Term
PRNM
Describe the APRM Flux alarms. |
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Definition
-DOWNSCALE: 3.5% (alarm and rod block).
-UPSCALE: 18% (not in run), 119.5% (RUN) (alarm and SCRAM). |
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Term
PRNM
Describe the APRM STP Upscale alarm. |
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Definition
-13% not in RUN (alarm and rod block).
-.66W+53.6% (alarm and rod block).
-.66(W-7.6%)+53.6% (SLO) (alarm and rodblock).
-108% in RUN (alarm and rod block). |
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Term
PRNM
Describe the APRM STP High Trip. |
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Definition
-.66W+59.6% (alarm and SCRAM).
-.66(W-7.6%)+59.6% (SLO) (alarm and SCRAM).
-114% in RUN (alarm and SCRAM). |
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Term
PRNM
Describe the APRM Recirc Flow alarms. |
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Definition
-10% delta min-max of 4 totals (alarm).
-Upscale 110% (alarm and rod block). |
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Term
PRNM
Describe the function of the OPRMs. |
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Definition
| To monitor the core for thermal hydraulic instabilities and send suppression signals to RPS in time to preserve adequate margin to the MCPR safety limit. |
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Term
PRNM
Describe the channels of the OPRMs. |
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Definition
-4 seperate and redundant channels.
-Each channel receives LPRM signals from the associated APRM.
-Uses 5 algorithms for trips. |
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Term
PRNM
Describe the conditions when OPRM system alarms and trips are enabled. |
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Definition
-Only enabled when power and flow conditions enter the region where thermal hydraulic instabilities may be expected to occur.
-3 conditions:
-Reactor Mode Switch is in RUN.
-Total recirc Flow is low (< or equal to 60%).
-Simulated Thermal Power is high (> or equal to 25%). |
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Term
PRNM
Describe the operability for OPRMs. |
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Definition
-Requires a minimum of 2 operable LPRM inputs.
-OPRM channel operability requires 17 operable cells.
-The number of responsive OPRM cells is the number of operable cells minus 5 minus the number of operable cells with exclusive input from D level LPRM detectors. |
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Term
PRNM
Describe the function of the 2 of 4 Voter. |
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Definition
-Serves as the interface between the APRM/OPRM channels and the RPS.
-Each APRM/OPRM module produces redundant trip output signals to be sent to all four 2 of 4 Voter modules. |
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Term
PRNM
Describe when the 2 of 4 Voter modules will give a trip output. |
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Definition
-Only if 2 or more inputs indicate a trip (of the same function) concurrently.
-An APRM INOP will actuate all 3 trip functions. |
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Term
PRNM
Describe the 2 of 4 Voter module trip functions. |
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Definition
-APRM UPSC/INOP.
-OPRM DIDA/INOP.
-OPRM CDA/INOP. |
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Term
PRNM
Describe the 2 of 4 Voter relationship to RPS. |
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Definition
-Each of the four 2 of 4 Voter modules outputs to a corresponding RPS logic channel.
-The 2 of 4 Voter outputs to the RPS logic are:
-2 of 4 Voter 1: RPS A1.
-2 of 4 Voter 2: RPS B1.
-2 of 4 Voter 3: RPS A2.
-2 of 4 Voter 4: RPS B2. |
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Term
PRNM
Describe the Low Voltage Power Supplies. |
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Definition
-APRM 1/3 powered from 120VAC Vital Bus Y-10.
-APRM 2/4 powered from 120VAC Vital bus Y-30.
-2 of 4 Voter powered directly from RPS (1/3 RPS A, 2/4 RPS B).
-APRM powered from RPS A and/or B through LVPS and auctioneering.
-LVPS powered from RPS A and B DC output PS2 and PS3 not used. |
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