Energize to actuate engineered safety features actuation system and testing method therefor

• US 6,462,667 B1
• Filed: 05/26/2000
• Issued: 10/08/2002
• Est. Priority Date: 12/06/1999
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: Menard, Dennis N.
• Primary Examiner(s): Lieu, Julie
• Application Number:
  US09/579,121
• Time in Patent Office: 865 Days
• Field of Search: 340/660, 340/654, 361/1, 361/160, 361/166, 361/210
• US Class Current: 340/660
• CPC Class Codes: G05B 9/02 electric
• CPC Class Codes: G21D 3/04 Safety arrangements emergency protection of reactor G21C9/00
• CPC Class Codes: Y02E 30/00 Energy generation of nuclear origin
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

A component actuation circuit for an engineered safety features actuation system (ESFAS) includes a plurality of coincidence logic contacts, and a plurality of parallel-connected ESFAS component relays. Each of the coincidence logic contacts closes in response to a command signal. The plurality of parallel-connected ESFAS component relays are connected in series between at least two of the plurality of coincidence logic contacts. Closure of at least two of the coincidence logic contacts energizes the parallel-connected ESFAS component relays, thereby energizing a plurality of ESFAS components.

Claims

1. A component actuation circuit for an engineered safety features actuation system (ESFAS), comprising:

a plurality of coincidence logic contacts connected to a power source, each of said coincidence logic contacts closing in response to a command signal;

a plurality of parallel-connected ESFAS component relays connected in parallel with one another, said plurality of parallel-connected EFAS component relays being connected in series between at least two of said plurality of coincidence logic contacts; and

a plurality of first resistance elements connected (1) in series with said plurality of parallel-connected ESFAS component relays and (2) in parallel with at least one of said plurality of coincidence logic contacts;

wherein closure of at least two of said plurality of coincidence logic contacts energizes said plurality of parallel-connected ESFAS component relays, thereby energizing a plurality of ESFAS components, and said resistance elements exhibit an electrical resistance sufficiently high to prevent said plurality of parallel-connected ESFAS component relays from energizing when said plurality of coincidence logic contacts are open.

2. A component actuation circuit for an ESFAS according to claim 1, further comprising:

at least one test relay contact connected (1) in series with each of said plurality of parallel-connected ESFAS component relays and (2) in parallel with at least one of said plurality of coincidence logic contacts.

3. A component actuation circuit for an ESFAS according to claim 2, further comprising:

at least one second resistance element and a diode test contact connected in series with said at least one test relay contact.

4. A component actuation circuit for an ESFAS according to claim 2, further comprising:

a third resistance element connected in series with said at least one test relay contact.

5. A component actuation circuit for an ESFAS according to claim 4, further comprising:

a monitoring circuit connected in parallel with said third resistance element.

6. A component actuation circuit for an ESFAS according to claim 1, further comprising:

at least one fourth resistance element and a load test contact connected in series with at least one of said plurality of first resistance elements.

7. A component actuation circuit for an ESFAS according to claim 1, further comprising:

at least one monitoring circuit connected in parallel with at least one of said plurality of first resistance elements.

8. A component actuation circuit for an ESFAS according to claim 7, further comprising:

an alarm circuit connected to said at least one monitoring circuit, said alarm circuit generating an alarm when said monitoring circuit senses an abnormal condition.

9. A component actuation circuit for an engineered safety features actuation system (ESFAS), comprising:

a plurality of coincidence logic contacts connected to a power source, each of said coincidence logic contacts closing in response to a command signal;

a plurality of parallel-connected ESFAS component relays connected in parallel with one another, said plurality of parallel-connected EFAS component relays being connected in series between at least two of said plurality of coincidence logic contacts; and

at least one diode on both sides of each of said parallel-connected ESFAS component relays, and being connected in series with each of said parallel-connected ESFAS component relays;

wherein closure of at least two of said plurality of coincidence logic contacts energizes said plurality of parallel-connected ESFAS component relays, thereby energizing a plurality of ESFAS components.

10. A component actuation circuit for a nuclear power plant engineered safety features actuation system (ESFAS), comprising:

ESFAS component actuation means for selectively actuating a plurality of ESFAS components upon energization thereof;

coincidence logic means for selectively connecting/disconnecting a power source to/from said ESFAS component actuation means in accordance with a minimally 2-of-4 coincidence logic scheme; and

first resistance means for limiting current flow from the power source through said ESFAS component actuation means when said coincidence logic means selectively disconnects said ESFAS component actuation means from the power source.

11. A component actuation circuit for a nuclear power plant ESFAS according to claim 10, further comprising:

component actuation test means for selectively connecting said ESFAS component actuation means to the power source via said first resistance means and second resistance means.

12. A component actuation circuit for a nuclear power plant ESFAS according to claim 11, further comprising:

relay coil simulation resistance means for simulating a resistance of a relay coil; and

diode test means for selectively connecting said coincidence logic means to the power source via said relay coil simulation resistance means.

13. A component actuation circuit for a nuclear power plant ESFAS according to claim 10, further comprising:

load test resistance means for simulating a full load resistance; and

load test means for selectively connecting said coincidence logic means to the power source via said load test resistance means.

14. A component actuation circuit for a nuclear power plant ESFAS according to claim 10, further comprising:

monitoring means for monitoring a voltage drop across said first resistance means.

15. A component actuation circuit for a nuclear power plant ESFAS according to claim 14, further comprising:

alarm generation means for generating an alarm when the monitored voltage drop reaches a predetermined setpoint.

16. A component actuation circuit for an engineered safety features actuation system (ESFAS), comprising:

a plurality of coincidence logic contacts connected to a power source, each of said coincidence logic contacts closing in response to a command signal;

a plurality of ESFAS component relays connected in parallel with one another, said parallel-connected ESFAS component relays being connected in series between at least two of said plurality of coincidence logic contacts;

at least one diode on both sides of each of said plurality of parallel-connected ESFAS component relays, and being connected in series with each of said plurality of parallel-connected ESFAS component relays;

at least one lockout contact connected in series with said plurality of parallel-connected ESFAS component relays, and in parallel with at least one of said plurality of coincidence logic contacts;

a lockout relay connected electrically in parallel with said plurality of parallel-connected ESFAS component relays, said lockout relay closing said at least one lockout contact, thereby maintaining said plurality of parallel-connected ESFAS component relays energized;

a plurality of manually initiated contacts connected in series with said plurality of parallel-connected ESFAS component relays, and in parallel with at least one of said plurality of coincidence logic contacts;

a plurality of resistance elements connected (1) in series with said plurality of parallel-connected ESFAS component relays and (2) in parallel with at least one of said plurality of coincidence logic contacts, said resistance elements exhibiting an electrical resistance sufficiently high to prevent said plurality of parallel-connected ESFAS component relays from energizing when said plurality of coincidence logic contacts are open;

at least one test relay contact connected in series with each of said plurality of parallel-connected ESFAS component relays, and in parallel with at least one of said plurality of coincidence logic contacts;

at least one limiting resistor and a diode test contact connected in series with said at least one test relay contact;

a test resistor connected in series with said at least one test relay contact;

a monitoring circuit connected in parallel with said test resistor;

at least one load test resistor and a load test contact connected in series with at least one of said plurality of resistance elements;

at least one monitoring circuit connected in parallel with at least one of said plurality of resistance elements; and

an alarm circuit connected to said at least one monitoring circuit, said alarm circuit generating an alarm when said monitoring circuit senses an abnormal condition,

wherein closure of at least two of said plurality of contacts, or at least two of said plurality of manually initiated contacts, energizes said plurality of ESFAS component relays, thereby energizing one or more EFSAS components.