ML20209B042

Revises 860613 Response to NRC Ltr Re Deviation Noted in Insp Rept 50-312/86-07.Corrective Actions:Study Revealed 32 Plant Circuits & 82 Related Critical Shield Instrument Cables Requiring Review & Walkdown.Nrc Draft Ack Ltr Encl

ML20209B042
Person / Time
Site:	Rancho Seco
Issue date:	04/15/1987
From:	Julie Ward SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
JEW-87-372, NUDOCS 8704280348
Download: ML20209B042 (6)

Text

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O S MUD "Ty2 SACRAMENTO MUNICIPAL UTILITY DISTRICT O P. O. Box 15830, Sacramento CA 958 - 830,(916) 452-3211 APR 15 1987 AN ELECTRIC SYSTEM SERVING TH ffg % C IF R JEW 87-372 Y J. B. Martin, Regional Administrator U.S. Nuclear Regulatory Commission Region V, Office of Inspection & Enforcement 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596 Docket No. 50-312 Rancho Seco Nuclear Generating Station License No. DPR-54 Responseto Notice of Deviation (NRC Inspection Reports No.

50-312/86-07, Revision 1)

Dear Mr. Martin:

By letter dated June 13, 1986, the Sacramento Municipal Utility District transmitted a response to a Notice of Deviation concerning the unterminated cable-shield drain wires. This letter providoc an update of the corrective actions being taken by the District.

This letter acknowledges the violation cited and describes the J District's intended corrective actions for each specific item listed in the Notice of Violation.

Sincerely, d-(John' . Ward Deputy General Manager, Nuclear Attachment cc: A. D'Angelo G. Kalman INPO 8704280348 DR 870415 ADOCK 05000312 PDR ff-6/

RANCHO SECO NUCLEAR GENERATING STATION O 14440 Twin Cities Road Herald, CA 95638-9799;(209) 333-2935

ATTACHMENT 1 DISTRICT RESPONSE TO NRC INSPECTION 86-07

, REVISION 1 NOTICE OF DEVIATION _

_NRC Deviation between February 21 and AprilAs a resultA.ofHon . the inspection condu 11, 1986, the following alleged deviation from accepted standards was identified:

Analysis Report (USAR) Ranch Seco Nuclear Generating Station Chapter 10, Steam and Power Conversion that: System, Paragraph 10.1, Design Bases, states atmospheric dump v"The Steam bypass-valves to the condense used, as necessary,alves and main-steam valves are following loss of external load and subsequent turbine and reactor trip " .

In addition, USAR Chapter 7, Controls, Paragraph 7.2.3, InteInstrumentation and Paragraph 7.2.3.1, Design Bases, grated Control System, states that:

turbine bypass to the condenser, ,and the the"The com rejection without safety valve operation." atmosphe SMUD Construction January 1, 1986, Specification NEPM 5304 8C . ,

Control, Section 5.9.3 _ Instrumentation andeffective which applies to these systems, states that:

Kynar heat shrinkable tubing if the wire can"A ba possibly come in contact with other uninsulated wire, metal components, or metal devices.

" Unterminated shield drain wires (i.e.,

shield) shrinkable end cap."shall be insulated with a Kynar heat" floating"

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Contrary to the above commitments, an unterminated shield drain wire was left uninsulated and in contact with the metal container for the following field terminations:

Turbine Bypass Valves E/P transducers nos. PY-20561, PY-20563, and PY-20566.

Atmospheric Dump Valves E/P transducer no. PY-20571.

This condition, if left uncorrected, could potentially degrade the signal quality for the circuits by introducing multiple group points.

District Response to Deviation

1) Admission or denial of the alleged violation. l The District acknowledges and admits that this item l occurred as stated. l

2) Reasons for the deviation. l This non-conformance is, however, a non-conformance with current wire shielding practices, rather than a l nonconformance with practices which were accepted as l being typical when the plant was being constructed. It l should be noted that for the Atmospheric Dump Valves,

each shield lead was insulated as documented in the 2

disposition of NCR 5507, Revision 0, dated April 14, 1986.

The District recognizes the importance of ensuring the functional capability of the Turbine Bypass and Atmospheric Dump Valves, as described in the Updated Safety Analysis Report. However, the significance of  :

this Notice of Deviation is best understood when l the voltage levels which are used in the control of I these valves are identified. l Specifically, the control signal is -10 volts to +10 l volts, and is significantly larger than normally l encountered noise in similar circuits, even where l ground loops of the shielding are found. There is no l operational history of the shield preparation causing improper valve operation over the life of the plant.

The lack of insulation on the two Turbine Bypass Valve's shielding was reworked during the current shutdown prior to July 31, 1986.

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j 3) Corrective actions which have been taken and results- l achieved. l A study sponsored by the District has identified other l

circuits which may be in the same configuration. l a

Incorrect grounding of instrument cable shields and l

signal conductors creates ground loops that may cause l l degraded analog signals when electrical power system l

! ground faults or lightning occur. Signals may be l j significantly degraded for up to 0.5 seconds. Lesser l s signal degradation may occur for as long as 1.5 l j seconds. l l Because of the brief duration of the degraded signals, l j only circuits that have memory functions to retain the l 4 signal action can cause unacceptable consequences. A l

! total of 32 plant circuits and 82 related critical l j

shield instrument cables'have been identified as l l requiring a detailed review and walkdown. l 1

The District approved an Electrical System upgrade l I procedure (QAIP-15) which addresses all aspects of the l condition of a control / termination panel. l l 4) Corrective steps which will be taken to avoid further l deviations. l i i To develop a higher level of confidence for systems l

! which may use lower voltages and which are, therefore,

more susceptible to shield ground loop interference, the District will perform an inspection program on a l group of circuits in the same configuration selected by l Nuclear Engineering and Nuclear Operations, based on the l

study performed for the District, as described below: l 4 Prior to Restart, critical instrument cables in which a l 1 momentary spurious signal could have a significant l i impact on monitoring and control functions will be l

) inspected for installation configuration and termination l l quality. l 4

1 l

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.,e i Critical panels opened for modification or maintenance l work will be inspected according to QAIP-15 to l determine if their condition is deficient and requires l immediate rework, or if their condition is such that l they may safely be scheduled for upgrade at a later time.l Significant hazards which affect safety-related and l non-safety-related electrical equipment will be l immediately corrected; other questionable conditions l identified will be evaluated according to QAIP-15. l

5) Data full compliance will be achieved. l The review and walkdown of the 32 circuits and 82 l related critical shield insturment cables and rework of l safety-significant instrument-cable shield l terminations will be completed prior to Restart. l l

a

f DRAFT

, Docket Nos(s). d>T' -d/J >

1 (Address): O_ (/ /) .

/Abl' O /4~N0Ea'- ,

&ndn , u' A vszer- 97;y i ATTENTION:( t . u_. [/ )J e -[

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G . V' o. />d (Jitle) 4 Gentlemen: / ' '

Thank you for your letter dated A> / II , informing us of Y

the steps you have taken to correct the items which we brought to your attention in our letter dated .

Your corrective i actions will be verified during a future inspection.

Your cooperation with us is appreciated, i

Sincerely, i

i bec: Sent to DCS w/cy ltr dtd for Distribution Concurrence: RV i

(inspector) (SectionChief) (Branch Chief) (Other) l i

RV

Form 803 i

(2/10/83) i