ML20004D298
| ML20004D298 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/04/1981 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.K.3.02, TASK-TM A01379, A1379, NUDOCS 8106090126 | |
| Download: ML20004D298 (3) | |
Text
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d ONNECTICUT YANKEE ATOMIC POWER COMPANY BERLIN. CO N N ECTICU T P. O. 804 2 70 H ARTFORD. CONNECTICUT 06tOI RL]jm o
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June 4, 1981 x
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'f Docket No. 50-2 A013 k, jut 1 0 B N b
,,,,muoj,g**" Oj Mr. Darrell G. Eisenhut, Director S'*
\\{Q Division of Licensing zy/
Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission g /-
Washingten, D.C.
20555
References:
(1)
D. G. Eisenhut letter to All Operating Plants and Applicants for Operating Licenses and Holders of Construction Permits dated October 31, 1980; forwarding NUREG-0737.
(2)
W. G. Counsil letter to D. G. Eisenhut dated December 31, 1980.
(3)
R. W. Jurgensen letter to J. R. Miller dated March 13, 1981.
Gentlemen:
Haddam Neck Plant TMI Action Plan Item ll.K.3.2; PORV Failure Reduction Methods Item 11.Ks3.2 of Reference (1) required Connecticut Yankee Atomic Power Company (CYAPCO) to submit a report documenting the various actions taken at the Haddam Neck Plant to decrease the probability of a small break Loss-of-Coolant Accident caused by a stuck-open power-operated reliefvalve(PORV).
In Reference (2), CYAPC0 informed the Staff that the report on PORV failure reduction methods being prepared by the Westinghouse Owners' Group would be reviewed for applicability to the Haddam Neck Plant and that the Staff would be infonned of CYMC0's conclusions.
CYAPC0 has reviewed the report, WCAP-9804, and determined that it is applicable to the Haddam Neck Plant and is hereby placed on Docket No.
50-213. Copies of WCAP-9804 are not being attached to this document as it has previously been transmitted to the Staff via Reference (3).
In an effort to reduce the probability of a stuck-open PORV, CYAPC0 has taken the following actions on the recomendations summarized in Section 3.4.2 of WCAP-9804, i
PID Controller Modification - WCAP-9804 recomends that the derivative j
time constant in the PID controller for the pressurizer PORV's be set to 0FF. The Haddam Neck Plant does not use a Proportional Integral Derivative circuit for the PORV's, thus this recommendation does not apply to the i
Haddam Neck Plant.
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' w' Setpoint Change on PORY Interlock Bistables - Pressurizer pressure is controlled 5y three independent pressure channels.
One PORV is con-trolled by channel (1) and the other PORV is controlled by channel (3).
There are no interlocks between channels and thus a spurious high pressure signal in~one channel will activate a PORV. CYAPCO intends to modify the existing PORV actuation logic to open on a two-out-of-three high pressure signal. WCAP-9804 has concluded that an order of magnitude decrease in PORV actuations is expected by implementation of coincident logic. CYAPC0 intends to complete this modification before startup from the next refueling outage, currently scheduled for October,1981.
Direct Indication of Relief and Safety Valve Positicn - There is presently installed at the Haddam Neck Plant an acoustic monitor system which provides a direct indication of PORV position. No further modifications are planned.
Changes to Emergency Operating Instructions - The Westinghouse Reference Emergency Operating Instructions have been updated to include notes and specific procedural steps to isolate a stuck-open PORV. CYAPC0 has modified Emergency Operating Procedures E0P 3.1-S, Steam Generator Tube Rupture and E0P 3.1-45, Diagnostic and Imediate Action for Safety Injection and Recovery from Spurious Actuation of Safety Injection, to incorporate these recomendations from Westinghouse.
CYAPC0 intends to modify Emergency Operating Procedures E0P 3.1-4, Loss of Coolant, and E0P 3.1-44, Abnormal Feed Flow, to incorporate the notes and specific steps related to a stuck-open PORV by August 1, 1981.
In addition, an Emergency Operating Procedure for failure of a PORV has been issued to specifically address this event. This procedure is E0P 3.1-30, Pressurizer Relief Valve Failure.
Post-TMI Operator Training / Simulator Exercises - Prior to the accident at Three Mile Island, it was not common practice for simulator training to include a stuck-open PORV during another transient. Since that time, operator training at the Haddam Neck Plant has dealt extensively with a stuck-open PORV. As noted above, a procedure has been issued to specifically address this event.
CYAPC0 has concluded that the actions already implemented, as described above, have reduced the probability of a small-break LOCA caused by a stuck-open PORV such that it is not a significant contributor to the probability of a small-break LOCA due to all causes. WCAP-9804 has detennined the frequency og a small-break LOCA caused by a stuck-open PORV to be about 2.1 x 10 per reactor year for the Haddam Neck Plant desjgn. This frequency is well below the WASH-1400 median frequency of
- for a small-break LOCA.
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i Instrumentation presently installed which can be used to detect a stuck-open PORV includes panel alarms to indicate an open PORV, the acoustic monitor, quench tank pressure, level and temperature and discharge piping tenperature. These indications are both redundant and diverse, and are capable of providing the operator with a positive indication in the event of a stuck-open PORV. Thus, CYAPC0 has concluded that an automatic PORV isolation system is neither a necessary nor advisable modification to the Haddam Neck Plant. This position is supported by the conclusions of WCAP-9804. Therefore, no further action on NUREG-0737 Item ll.K.3.l'is planned.
P We trust you will find this information responsive to your request.
l Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY I
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/7.lITEL']LJL.t W. G. Couns11 Senior Vice President 1
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