ML19275J746
| ML19275J746 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 06/05/1970 |
| From: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Hendrie J Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML19275J747 | List: |
| References | |
| NUDOCS 8111240311 | |
| Download: ML19275J746 (6) | |
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OfflCIAi. USE ONLY JUN - 5 1910 Docket No. 50-247 Dr. dct?cph :f. Ile adric Chairma1, Adytr ey Cumittee on Reactor Safegraards U.
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Dear Dr. Hendrie:
Ei,;bteen copics of a report. prepared cy t!
Division of Reactor Licensing are enclosed for review by the Com-mittoa.
T: is report relates to two unresolved items concerning renctor protection and engineered safoty mc*ure instru nentation and controls for the Consclidated Edison Company of New York, Inc.'s application for an operating license for 1.ts proposea Indian Point Nuclear Generating Unit No. 2.
Sincerely, CrtgM1 tigwd by Peter * " arr:s Peter A. Morris, Director Division of Reactor Licensing
Enclosure:
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unresolved ite.ms concernir.g rt uctor protection cnd erigir.eereci safety fenttue instrtmentation and contralr.
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JUN a 190 Docket No. 50-247 Special neport to the ACRS, INDIAN POINT NUCLEAR GENERATING UNIT NO. 2 Operatine License Peview U. S. Atomic Energy Commission Division of Reactor Licensing OFFECHAL USE ONLY
v5FECHAL UE ONUf 1.
INTRODUCTION This special report to the ACRS concerns two issues which have arisen in the course of our review of the instrumentation and controls for the Indian Poirt 2 protection system and engineered safety features.
Since ne are in disagreement with the applicant o.' these issues and since :he final rr.so'.etica nay affect the sebe du? e for r'_ ant comp: e tio:- and startup, we have requested an opportunity to discuss these matters with the Commit *ae at the June ACfc meeting in order to obtain Committee comments and facilitate early resolution.
The two.ssues invalve:
(1) operation ~_th less than fcur coolant Ic> ops in service, and (2) the design of the engineered safety feature ca. al actuation panel. Our positions and those of the applicant ate summardred in the following sections.
2.
OpEPjtTION k'ITH LESS THAN FOUR LOOPS IN SERVICE Thermal protection of the core is normally provided by the over-pa er and overtempercture AT circuits which vary the AT trip set pcInts automatically as a function of average temperature, pres. ire,
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n' hen the plant is operatec with one loop out of service, adequate core protection requires that the 4 T set-peints te reduced.
The applicant proposes to make these adjustments to the OT setpoints nanually and states that c,aly f our adj us tments are required.
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,u-ke have evaluated the applicant's proposal and have concluded that because more restrictive setpcints are required for safety, the proposal for manual adjustnnnt does not comply with Section 4.15 of the IEEE-279 cr* teria which requires a positive means of assuring that the nore restrictive setpoints are used.
Section 4.15 furt'-
requires that the cevices used to prevent improper use of less restrictive set points shall be considered a part of the protectici.
system and shall be designed in accordance with the single failure c rit e ri on. Thus, we would approve t.he applicant's plan to reset the 4.T setpoints only if the protection system were designed such that the removc1 of a pump from service would place the nore restrictive setpoints in force automatica_1y. We have discussed this matter with the appliccnt and we understand that Con Ed and Westinghouse are evaluating an alternate proposal involving setting the permissive circuit which allows reactor operation with less than four loops in operation at a power level sufficiently low that the full power AT trip settings provide adequate protection for steady state and desir.n transient conditions. Pending receipt, review and approval of t his preposal, we plan to require e Technica Specification rhich would net permit plant nperntion with fewer than four pumps in service.
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ENGINEERED SAEETY EEATURE MANUAL ACTUATIOS PA'TL,S_
Panels SB-1 and SB-2, located in the control room, include the necessary controls (switches, lights) to manual actuation of the engincared safety features. Our visit to t e site disclosed chat tl.: ccLles entering this par.el, the wiring '. side the pane) and the location of the controls on the front of the panel do r.'t comply with our l'ccrpretaticn of the IEEE-279 criteria for separation and indepet.dence of redundant systems. Cables for reduninnt cys* ems enter the panel through co=on openings in the control roam floor, and teminate on adjacent terminal boards.
Ccunecting wires f rom the terminal boards to the centrols f o redundant systeir.s are bundles together, and the location of the controls on the panel provides little separation.
We hLve discussed these pancis at a nutber of meetings vith Westinghouse and Censolidated Edison. They discussed a number of possible modifications which would prov.i de seme additional separation but have made too firm proposal. Among the possible modifications diccussed were:
a.
The additien of isolation devices to preclude faults in the panels f rom disabling automatic actuation of engineered safety features.
In this case, no physical separatien would be provided to prevent f aults f rom disabling the capability to transfer from the injection to the recirculation mode of emergency core cooling.
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The addition of physical protection features to prevent equipment used in the area (e.g., floor polishers and hand tools) from causing faults.
The installation of separate ccnnection boxes for each of tne re dundae safety feature chains near the cable trays. Wires and cables for the redundant chains would be brough t from the connection boxes through separate floor openings to the controls on the panel, maintaining physical separation. The applicant fel:. that the remaining lack of physical separation at several multi-function switches would defeat the purpose of the added physical separation in the cables and wiring.
Modification (c) above if combined with i=provement in the des:1gn of the multifunction switches, would resolve the cencerns we have expressed to the applicant. Ganged switches are available which provide better separation between ctages or wafers. Another possible modification vould be the addition of slave re2_ys to reduce the wiring
.cncestion in the vi cinity of the switches.
The applicant does not plan to modify the panels unless we require it. and has requested an opportunity to discuss this matter with the s.C M -
he have reviewed our position on this matter. We have concluded that al thcugh modification of the panel to reduce the probability that ir.ults resulting, from localized mechanical damage, overheating O m m cgL A L gd e s gU Np <n t-nm res
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n-in bundles, or localized fires, would provide increased margins of saf ety, and although compliance with the IEEE-279 criteria should be required for plants currently in design and construction, we are not convinced that the requirement of such modifications of the already-built Indian Point 2 system would provide sufficient
" substantial, additional protection which is required for the public health and safety" to justify the requirement.
OFFECHAL USE O!FCI