ML20072N589
| ML20072N589 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 07/08/1983 |
| From: | Maier J ROCHESTER GAS & ELECTRIC CORP. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 8307150379 | |
| Download: ML20072N589 (3) | |
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.g ROCHESTER GAS AND ELECTRIC CORPORATION
- 89 EAST AVENUE, ROCHESTER, N.Y.14649 JOHN E MNER n apeost v<. a. e m-a =t a c oc., v i a 546 2700
-July 8, 1983 Dr. Thomas E. Murley, Regional Administrator U.
S. Nuclear Regulatory Commiss' ion Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, PA 19406
Subject:
Reactor Overpressure Protection System Operation to Mitigate an RCS Pressure Transient R.
E.
Ginna Nuclear Power Plant, Unit No. 1 Docket No. 50-244
Dear Dr. Murley:
In accordance with Technical Specifications, article 6.9.3.d,
" Reactor Overpressure Protection System Operation" the attached report is hereby submitted.
Very Truly Yours, NN LS d JoMn E. Maier Attachments xc:
Document Control Desk (1) l l
l 8307150379 830708 gDRADOCK 05000244 PDR i
l{
Special Report Reactor Overpressure Protection System Operation at R.
E. Ginna On June 9, 1983 at 2158 the reactor was in cold shutdown with the reactor coolant system in a water solid condition and being maintained at a pressure of approximately 310 psig.
Refueling Shutdown Surveillance Procedure (RSSP-2.1) " Safety Injection Functional Test" was in progress and the "A"
logic train was being tested.
During this test only one safeguard train is operated at a time and the D.C.
control breaker for the train not to be operate 1 is maintained in the open position.
This ensures that required operating equipment (e.g. Residual IIeat Removal) will be continuously in service during the performance of the test.
Prior to simulating a safety injection signal the procedure requires charging and letdown to be secured.
The on-shift operators as well as the test personnel believed that all of the charging pumps as well as other non-safeguard loads would trip when the safety injection signal was initiated.
This would have been the case for a true safety injection signal but with the D.C.
control breaker for the "B" safeguard train open the "B"
train equipment did not trip.
Based on this reasoning the 1C Charging Pump as well as the charging and letdown system were not secured.
When the safety injection signal was initiated by simulating a Ili Containment Pressure the IC charging pump did not trip.
However, letdown was isolated when AOV-371 closed on containment isolation.
This left the reactor coolant system without a letdown path but still approximately a 40 gallon por minute charging flow and resulted in a challenge to the Reactor Overpressure Protection System.
After the operator noticed that the 1C charging pump did not trip corrective steps were taken to reduce the charging pump speed and eventually trip the 1C charging pump.
The operator also noticed that the pressurizer power operated relief valves were momentarily open and he acknowledged annuncir. tors for reactor coolant system overpressure protection - high pressure.
The setpoint for these annunciators is 425 psig.
I
l-t A review of control room charts indicate that the maximum reactor coolant system pressure recorded during the transient was approximately 375 psig.
A review of computer data indicates that approximately 41.5 seconds after the initiating safety injection signal both pressurizer power operated relief valves started to open.
Valve 431C attained the full open position about one-half second later and remained full open for almost one second.
The valve then took about one additiotsi second to cycle to the closed position.
Valve 430 cycled to some mid-position (not full open) and returned to the closed position with a total clapsed time of 1.5 seconds.
Almost one minute after the first sequence of relief valve opening both valves again started to open.
Again valve 431C attained the full open position within one-half second and remained open for two-third of a second before going fully closed about one second later.
Valve 430 cycled to some midposition and returned to the closed l
position with a total elapsed time of 1.3 seconds.
l The relief valve actuation coupled with the operator action of securing the 1C charging pump reduced reactor coolant system l
pressure to about 325 poig and terminated the pressure transient.
A change to procedure RSSp-2,1 will be submitted by July 20, 1983 that will caution operators and test personnel of the importance to secure charging and letdown prior to simulating a safety injection signal as failure to do so could result in a pressure excursion causing operation of the reactor overpressure protection system.
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