ML20039F788

Requests Review & Comments Re Encl Technical Evaluation Rept Concerning Containment Venting & Purging.Response Requested within 60 Days of Receipt of Ltr

ML20039F788
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	12/18/1981
From:	Clark R Office of Nuclear Reactor Regulation
To:	Withers B PORTLAND GENERAL ELECTRIC CO.
References
TAC-08291, TAC-42594, TAC-8291, NUDOCS 8201130365
Download: ML20039F788 (6)

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h DEC 181981 DISTRIBUTION CTrammell Docket File RAClark NRC PDR Gray File L PDR J.T. Beard Docket No. 50-344 NSIC EReeves TERA Mr. Bart D. Withers Vice President Nuclear ORB #3 Rdg DEisenhut Portland General Electric Company 0 ELD 121 S. W. Salmon Street I&E-3 Portland, Oregon 97204 ACRS-10 JHeltemes

Dear Mr. Withers:

PMKreutzer-3 The purpose of this letter is to supplement our. letter to you of December 4 1981 on the sui 2fect of containment purging and venting. In that letter (p.2) we indicated that the sub-issue of Safety Actuation System Signal Override was still under review, but that completion was scheduled for the near future.

Our review of this matter has now progressed to the point where we have reached tentative conclusions regarding the acceptability of the Trojan design.. Based on the currently docketed information on this subject for Trojan, we have determined that, at present, the. plant design does not comply with the majority of the NEC review criteria involved. The background for this issue, our review criteria, and tentative conclusions are enclosed. Also enclosed is a draft Technical Evaluation Report (TER) prepared by our consultant, Franklin Research Center, which provides a more complete discussion of this matter and the bases for our conclusions with respect to the Trojan design.

You are requested to review the TER and related conclusions and respond to the issues raised therein where deviations from our review criteria have been identified. Your response is requested within 60 days of your receipt of this letter.

OMB clearance is not requimd for this request since it is being transmitted to nine or fewer addressees.

Please contact us if you have any questions concerning this matter.

Sincerely.

Origird Pvd by Ro!

c, O' M 8201130365 811218 Robert A. Clark', Chief PDR ADOCK 05000344 Operating Reactors Branch #3 P

PDR Division of Licensing F

Enclosures:

1. Background

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2. Review Criteria E-

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3. Tentative Conclusions 2

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4. Draft TER g,

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NRC FORM 318 00-80) NRCM 0ao OFFICIAL RECORD COPY uscmesi--muo

o-Portland General Electric Company cc: Multnomah Cour.ty Library Social Science and Science Department

- 801 S.W.10th Avenue Portland, Oregon 97205 a

Michael Malmros, Resident Inspector U. S. Nuclear Regulatory Commission Trojan Nuclear Plant P. O. Box 0 Rainier, Oregon 97048 e

Robert M. Hunt, Chairman Board of County Commissioners Columbia County s

St. Helens, Oregon 97501 Donald W. Godard, Supervisor Siting and Regulation Oregon Department of Energy Labor and Industries Building Room 111 Salem, Oegon 97310 l

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f, ENCLOSURE 1 BACKGROUND Several instances have been reported at nuclear power plants where automatic closure of the containment ventilation / purge valves would not have' occurred because the safety actuation signals, were either overridden or blocked during

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normal plant operations. These events resulted from procedural.inadeguacies, design deffcienctes, and lack of proper management controls.These events -

also brought into question the mechanical operability of the containment isolation valves themselves. These events were determined by the U.S.

Nuclear Regulatory Commission (NRC) to be Abnormal Occurrences. (#78-5) and were, accordingly, reported to the U.S. Congress.,

As a followup to this. Abnormal.0ccurrence, the NRC staff is reviewing the electrical. override' aspects and the mechanical operability aspects of.

containment purging for all operating power reactors. On November.28,1978, the NRC issued a letter entttled " Containment Purging During Normal Plant Operation to All Boiling Water Reactor (BWR) and Pressurized Water. Reactor -

(PWR) Licensees." Portland General Electric Company (PGE), licensee for the Trojan Nuclear Plant, responded to this letter in several submittals'which advised the NRC staff of PGE'-s review of purging operations at the Trojan plant. These responses dealt, in general, with the physical aspects of purging, such as system susceptibility to internal missiles or debris and.

the effects of open purge valves on the potential operation 'of the emergency core cooling system (ECCS). On November 19, 1979, the NRC staff provided an interim position concerning containment purge and vent valve operation pending resolution of issues associated with isolationgvalve operability.

PGE responded to this position on January 14, 1980.

In this response, PGE indicated that the containment at the Trojan plant remained isolated to the i

extent possible with purging and venting conducted only when required for personnel or equipment protection, that the 54-in purge and vent isolation L

valve would be maintained closed during plant operation, and that the L

hydrogen vent system 8-in motor-operated valves would be opened no further than 50 degrees to ensure that critical valve parts would not be damaged l

by a design basis accident.

In. addition, PGE reported the results of the review of all engineered safety feature (ESF) actuation 's'ignal circuits incorporating a manual override including the conclusion that there were no instances where the overriding of one ESF actuation signal would bypass any other ESF actuation signal.

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On March 18, 1980, the NRC requested additional information related to the I

electrical, instrumentation, and control aspects of containment purge and other ESF systems at the Trojan plant. PGE responded to this request by letter dated. June 16, 1980, which was received by FRC on October 20, 1980.

This information was insufficient for an independent schematic level l

i review by FRC and was supplemented, in respcnse to FRC's verbal request for i

additional information, by two transmittals dated January 13,1981 and

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March 11,1981 covering valve control circuitry and solid state protection system circuitry, respectively.

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. ENCLOSURE 2

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REVIEW CRITERIA Criterion 1.

In keeping with the requirements of General Design Criteria (GDC) 55 and 56, the overridding* of one type of safety actuation signal

-(e.g., radiation) should not cause the blocking of any other type of safety actuation signal (e.g., pressure) for those valves that have' nD functf6n besides containnent isolation.

Criterion 2.

Sufficient physical features (e.g., key lock switches) are to be provided to facilitate adequate administrative controls.

Criterion 3.

A system level annunciation of the overridden status should be provided for. every safety system impacted when any override is active.

(See NRC Regulatory Guide 1.47.)

Criterion 4.

Diverse ' signals should be provided 'to initiate isolation _of

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the containment ventilation system. Specifically, containment. high radiation, safety-injection ' actuation, and containment high pressure (where containment high pressure is not a portion of safety injection actuation) should automatically initiate CVI.

Criterion 5.

The instrumentation and control systems provided to initiate tne ESF should be designed and qualified as safety-grade equipment.

Criterion 6.

The overriding or resetting + of the ESF actuation signal should not cause any valve or damper to change position.

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the signal is still present, and it is blocked in order -to perform a function contrary to the signal.

'+Res et: the signal has come and gone,'and the circuit is being cleared in order to return it to the normal condition...

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ENCLOSURE 3-TENTATIVE CONCLUSIONS Criterion 1.

In the case of the Containment Ventilation Isolation system, the " RESET" feature of the Solid State Protection System will cause the overiiding of one type of actuation signal (e.g., safety injection) and the block of a different type of actuation signal (e.g.,' containment high radiation).

This des'ign feature does not comply with Criterion fl. The fact that PGE is currently maintaining containment purgetsupply and exhaust ~

valves shut during plant operation does not eliminate the long-term potential for failing to re-close these valves automatically when a second isolation signal is received.

Other ESF systems with this feature are acceptable only because a single actuation parameter is involved.

Criterion 2..None of the ESF systems at the Trojan plant satisfy Criterion 2.

SSPS " RESET" push buttons act as overiides since their actuation will eliminate an output signal from-their associated SAF-0UT device when an ESF initiating signal is present.

Criterion 3.

ESF systems at the Trojan plant do not satisfy Criterion 3.

The " RESET" of a SAF-0UT device with an input signal present aerforms as-an override of one or more actuating parameters which should 3e annunciated at the system level in order to satisfy Criterion 3.

Criterion 4.

ESF systems at the Trojan plant partially satisfy Criterion 4.

Containment purge and exhaust valves (54-in) are isolated by the CVI system which is actuated by diver'se signals (safety injection actuation and high i

radiation).

Other ventilation valves, however, are not isolated by the CVI j

subsystem.

Those valves (e.g., 8-in hydrogen vent valve) are isolated by i

the containment isolation system. This system.is activated automatically by safety injection actuation which, while providing some signal diversity, does not satisfy the requirement that isolation of ventilation valves be initiated by containment high radiation.

Criterion 5.

ESF systems at the Trojan plant partially satisfy Criterion 5.

No information has been provided concerning the design and qualification of containment high radiation. detectors and associated circuitry.

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Criterion 6.

ESF systems at the Trojan plant do not satisfy Criterion 6. -

Several instances were found where a solenoid operator control scheme is used that will result in valve repositioning upon ESF actuation signal override. Valves observed during this review which must be so categorized have been identified in the attached Table. The licensee has indicated that modifications have been completed for 23 containment isolation valve control circuits at the Trojan plant to preclude valve repositioning upon ESF reset.

No such modifications were evident on the drawings provided by PGE for review to indicate if any of the valves identified.in the Table may have been so modified.

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'. EW valve Number Name.

Initials Remarks SV 566'l RCDT Sample Isolation' Valve

,'CIS SV 5652,

Sampie Isolati'on valve - Accum Common

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s SV 5655 L

RCS Hot Legs' CIS s

SV 5657 PZR L'iquid Space CIS SV 5659

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PZR Vapor Space,

.C15-r SV 4470

. Service Air to Containment Building CIS SV 4471 Service Air to Containment Building CIS

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SV 4006 RCDT N and Outlet Valve CIS 2

SV 4000 RCDT N2,and Outlet. Valve CIS SV 43,01.

Gas Collection Header Valve CIS SV 4181

. Containment Sump Pump D'ischarge Isolation Valve

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G MO 4180, Containment Sump Pump Discharge

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Isolation Valve-CIS

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.CW Return Line Isolation Valve l

SV 10014 -

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CIS SV 10015 CW Supply Line Isolation valve CIS SV 2993A1,'A2 Feedwater Eypass Control Valve Loop 1

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SV 299331,32 Loep 2 FWI SV 2993C1,C2 Loop 3 FWI -

i SV 2993Dl,D2 Loop 4

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- SV 510A,3 Feedwater Flow Control Valve SG A FWI No:e 2, 3 SV 520A,3 SG B FWI Note,2' 3 SV 530A,3 SG C '

FWI Note 2, 3 SV 540A,'S SG D.

FWI Note 2, 3 SV 2971A,B,C,D,Feedwater Isolation Valves WI Note'3 SV2973A,B,b,D Feedwater Bypass Isolation Valves FWI Note 1.

ESF reset will restnre control to an automatic controller. Valve repositioning will oe dependent on ' controller ' signal.

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Notie 2.

This " RESET" restores control air to the valve operator. Valve position will be determined by the pneumatic signal provided by the feedwater centrol system.

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Note 3.

Pushbutton " RESET" is available, for low Ta' g trip only.

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