ML20203L183
| ML20203L183 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 08/21/1986 |
| From: | Devincentis J PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| SBN-1180, NUDOCS 8608250166 | |
| Download: ML20203L183 (3) | |
Text
_ _ _.
7' SEABROOK STATION c-Engintsring Office a
August 21, 1986 PubNc Service of New Hampshire SBN-1180 T.F.
B7.1.2 NEW HAMPSHIRE YANKEE DIVISION United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Mr. Vincent S. Noonan, Project Director PWR Project Directorate No. 5
References:
(a) Construction Permits CPPR-135 and CPPR-136, Docket Nos. 50-443 and 50-444 (b) Meeting Summary by V. Nerses, Project Manager, Licensing Branch No. 3, Division of Licensing dated October 28, 1985
Subject:
Conformance of Isolation Valve SI-V-93 to Branch Technical Position 18
Dear Sir:
Reference (b) describes a Staff concern with conformance of the control circuitry of an active valve (SI-V-93) to Branch Technical Position 18 (BTP-18).
SI-V-93 is the combined recirculation isolation valve from both safety injection pumps and is a normally open, motor-operated valve. This valve is closed by the operator from the control room, during the switchover to the recirculation mode of safety injection.
To prevent a single failure from causing an undesirable mechanical motion of this valve and thus satisfy the concerns of BTP-18, the control circuitry of SI-V-93 incorporates dual contactors (refer to FSAR Figure 8.3-45).
l l
This circuit requires two separate operator actions, involving the normal valve control switch plus a separate key operated switch to re-position the valve. Furthermore, because of the dual contactor arrange-ment, it takes two electrical circuit failures for a spurious valve operation.
We believe that the special design of the circuit satisfies the BTP-18 concerns and at the same time does not remove power from the valve circuit. Power is always available and the operator can operate the valve from the control room any time by taking the two distinct separate actions described above.
OY ON o\\
l 0 Seabrook Station Construction Field Office. P.O. Box 700 Seabrook, NH O3874
~f United States Nuclear Regu? atory Commission SBN-1180 Attention:
Mr. Vincent S. Noonan Page 2 The above control circuit design was reviewed by the Staf f and was discussed at various meetings and telephone conversations. The Staff disagreed with the philosophy of our design and considered that the duel contactor arrangement ' constituted in effect removal of power from the valve and, therefore, redundant position indication meeting the single failure criterion should be provided for the valve as required by BTP-18.
At the time of the review all indications and alarms for this valve were provided from the same valve position limit switch; therefore to satisfy the Staff's concern with redundant position indication meeting the single failure criterion we made modifications to the existing indications / alarms utilizing a diverse device (i.e., a stem-mounted position switch).
As a result, Valve SI-V-93 is presently provided with the following indications / alarms :
o Red / green valve position indications utilizing the valve position limit switch.
o Valve fully closed status monitor light utilizing the valve position limit switch.
o Specific alarm in the Video Alarm System (VAS) indicating valve not fully open utilizing the stem-mounted position switch.
o Alarm for both "SI Train A Inoperable" and "SI Train B Inoperable" any time SI-V-93 leaves the full open position utilizing the stem-mounted position switch.
We believe the multiplicity of indications and alarms from diverse devices, satisfies the Staff's concerns with BTP-18 and request that this be reflected in the next supplement to Seabrook Station's SER.
Very truly yours,
.s j 2
John Devincentis Director of Engineering cc Atomic Safety and Licensing Board Service List
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