ML18139B727
| ML18139B727 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/26/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18139B726 | List: |
| References | |
| REF-GTECI-B-24, REF-GTECI-ES, TASK-B-24, TASK-OR NUDOCS 8202160217 | |
| Download: ML18139B727 (2) | |
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e SAFETY EVALUATION REPORT SURRY POWER STATION UNITS 1 AND 2 OVERRIDE OF CONTAINMENT PURGE ISOLATION AND OTHER ENGINEERED SAFETY FEATURES ACTUATION SIGNALS Introduction Instances have been reported at nuclear power plants where the intended automatic closure of containment purge/ventilation valves during a postulated accident would not have occurred because the safety actuation signals were inadvertently overridden and/or blocked, due to design deficiencies. These instances were determined to constitute an Abnormal Occurrence {#78-5).
As a followup action, NRR issued a generic letter requesting each licensee to take certain actions.
Evaluation The enclosed report (TER-C5257-185/186) was prepared for us by Franklin Research Center, as part of our technical assistance contract program.
The report provides their technical evaluation of the conformance of the plant design to the NRC criteria established for this review.
The enclosed report concludes that, associated with the basic subatmospheric containment design, there is no containment ventilation isolation system.
Hence the review criteria for containment purge and vent operation do not apply*at this station.
As part of this review, other ESF systems that may have manual override capability included in their design, were audited. *The report concludes that with the single exception of one valve, the ESF systems reviewed satisfy the review criteria.
The exception noted by our technical assistance contractor is a solenoid valve, SV-102, which serves to divert the vent from the air ejector after-condensers from the normal plant ventilation exhaust t9 the containment in the event of high radiation detected in this flow.path. While this circuit configuration is a technical deviation from the review criteria, the NRC had determined this to be a deviation that'is acceptable with regard to the protection of public health and safety. This determinati.on is based upon consideration of the fol lowing factors:
( a20216021'i a2o*i:-26 f
PDR ADOCK *.05000280 p
- PDR*
e l. The changing of this valve SV-102 from the 11emergency 11 state to the 11normal 11 state cannot occur as long as the emergency signals are present, i.e., containment pressure is greater than the CLS-High setpoint.
- 2.
When 11reset 11 of this valve is permitted, the containment pressure must also be subatmospheric and hence the motive forces would cause any air flow to be into the containment, versus outleakage.
- 3. If the valve should inadvertently:open due to an equipment failure, the possibility of backflow (i.e. outleakage) is protected by a check valve VCF 128.
- 4.
In the event that both the solenoid valve SV-102 failed and the check valve VCF-128 failed, the escape routes of this p*otentially contaminated air are protected by another closed valve (SV-103) in the normal plant vent and by water traps in the after-condenser water drain systems.
Summary Based upon our parttcipation in a site visit, our review of the contractor 1s evaluation, and the considerations described above, we conclude that there is reasonable assurance that the design of the containment purge/vent system and the ESF systems satisfy the applicable criteria of this review.
The design is therefore acceptable.
....,