ML20168A431

Final ASP Analysis - ANO 1 (LER 313-74-013)

ML20168A431
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1974-013-00
Download: ML20168A431 (5)

Text

cember 3, 1974 eactor Coolant Pump Underpower/Overpower Monitoring Relays Fail o Function at Arkansas Nuclear 1 re sequence was:

the reactor at 20% power, RCPs A and D were shutdown for two pump ng. The RFS saw neither pump trip.

A and D were restarted and RC~s B and C were tripped. The RPS either pump trip.

quent testing indicated the RPS failed to see a RCP D trip but ee a RCP A trip.

rrent with a trip of the C RCP, the D pump monitor relay also ed (D pump still running), resulting in a reactor trip.

(See attached page) e action:

relays were correctly readjusted for the pump power monitor on.

rpose of failed system or component:

ump power monitors provide pump operating status indication to The RPS is designed to trip the reactor if more than one pump uring four pump operation or If any pump is lost during less loop operation.

ility of system per WASH 1400: Not considered.

ility of component per WASH 1400: Relay, failure to de-energize:

not specified.

vailabilities are in units of per demand D-1. Failure rates are in per hour H1C 1 .

However, in this application, the relays had to be adjusted to operate at a specific pre-determined power level.

in a Reactor Trip No NSIC 97779 - Actual Occurrence for Reactor Coolant Pump Underpower/Overpower Monitoring Relays to Function at Arkansas 1

• No transient requiring RCP trips existed

Reactor at Reactor Coolant RPS Senses other RPS Trips Potential Power With Pump Fails Pump Failure Provide Protection Severe Three RCPs During Operation to Run and Prior to Core Core Operating Trips Damage Damage

.Yes NSIC 97779 - Sequence of Interest for Reactor Coolant Pump Undervoltage/Overpower Monitoring Relays Fail to Function at Arkansas Nuclear I

CATEGORIZATION OF ACCIDENT SEQUENCE PRECURSORS N NUMBER: 97779 December 3, 1974

November 24, 1974 ED: Reactor Protection System OLVED: Pump Power Monitor Relays ys incorrectly adjusted INTEREST: Reactor coolant pump trip during three loop operation ENCE: Failure of RPS to see trips during testing Arkansas Nuclear 1

50-313 PWR ICAL RATING: 850 MWe

.30 yr INEERS: Bechtel rkansas Power & Light Co.

niles'NW'.of Russelville, Ark.

8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> NG CONDITION: 20% power E TYPE OF FAILURE: (a Inadequate performance; (b) failed to start; 0 made inoperable; (d) ___________

HOD: During testing