ML20207N574
| ML20207N574 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/14/1988 |
| From: | Cockfield D PORTLAND GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 8810190225 | |
| Download: ML20207N574 (3) | |
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- Elll PoftlandGeneralElectricCompany David W Cockfield Vice President, Nuclear October 14, 1988 l
l Trojan Nuclear Plant Docket 50-344 licenso NPF-1 i
U.S. Nuclear Regulatory Commission ATTN Document Control Desk Washington DC 20$$5
Dear Sir:
ltnulatory cuide 1.97 Commitment By letter dated March 3, 1986, the Nuclear Regulatory Commission (NRC) requested additional justifications and/or comments from Portland General Elect ric (PCE) concerning exceptions taken in PCE's submittal for Regula-tory Culde (RC) 1.97, "Instrumentation for Light Water-Cooled Nucinar Power Plants to Assess Plant and Environs Coniitions During and Following an Accident". The March 3, 1986 letter requested in part that PCE provide seismically qualified instrumentation for Condensato Storago Tank (CST) level as this qualification had not been provided and the instrument was designated as a Category 1. Type A variable.
PCE's responso dated May 13, 1986 stated that cetegory 1 instrumentation for CST level indication would be provided by the end of the 1986 Refueling Outage. The NRC issued a Safety Evaluation dated September 29, 1986 based, in part, on this commitment.
During a July 1988 review of commitments associated with RC 1.97, pCE discovered that, although some upgrades to CST-level instrumentation were made during the 1986 Refueling Outage, the indication portion of the instrument loop was not upgraded and does not meet Category I seismic qualification requirements.
Further investigation identified that there was a misunders anding between Engineering and Licensing personnel as to the scopo c'. the commitment.
It was Engineering's intent to upgrade only that portion of the instrument loop that performs an automatic safety-related function as described below.
During the 1986 Trojan Refueling Outage, modifications were made to the Auxiliary Feedwater ( AFW) System to improve system reliability. These modifications included eliminating the AFW pump low suction pressure trip and -oplacing it with an automatic low-level trip from the CST which is the prit ry suction source for the AFW pumps.
The CST-level instrumentation associated with the AFW purp trip circuitry, including the transmitters, was upgraded to meet Class 1E design criteria and as such is seismically qualified.
Isolators were provided between the Class 1E portion and l
non-Class IE indication portion of the instrument loop.
I 8310190225 801014 PDR ADOCK 05000344 p
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M'vid Goriend Bochic Coraxurf 1
j Document Control Desk i
i October 14, 1988 i
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The above design was the intended scope of PGE's commitment to upgrade CST level instrumentation which is supported in part by the self-imposed commit-j ment schedule. The commitment to upgrade CST level indication was made in May 1986 midway through tho 1986 Refueling outage. The completion date for f
the commitment was given as the end of the 1986 Refueling Outage.
It is unreasonable to ascume that the design process, including scope reviews, 9
J design, procurement, and installation could be completed in such a short i
period of time. It can, therefore, be concluded that the intention was to take advantage of AW system modifications already in progress and apply l
l these modifications to the RG 1.97 commitment. Although the commitment in j
i PGE's May 13, 1986 letter was to provide seismically qualified CST-level l
indication, qualification of the indication portion of the instrument wan j
not intended by PCE.
PCE does not believe the indication portion of the instemment loop requires seismic qualification for the reasons discussed q
i below.
The design basis for the CST is Seismic Category II and as such it is not
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relied upon to function following a seismic event. The primary safety function of the CST-level instrumentation is to trip the AW pumps on low I
1 CST level to protect the pumps from cavitation damage.
This function is I
I performed automatically by that portion of the instrumentation that has been upgraded to Class 1E standards.
The design of the control room indicators is such that if they fail during a seismic event, they will indicate zero level. In the event of a loss of the CST as the A W pump st; tion source, the operators are instructed to align pump suction to the Seismic Category I service water system.
Reactor core cooling can then be verified by quali-
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fled reactor coolant system temperature, and steam generator level d
indication.
l Although PCE designated CST-level as a Type A variable which requires i
Category 1 quellfication per Regulatory Guide 1.97, it is not necessary to seismically qualify the CST-level indication to perform the safety function j
of protecting the AW pumps, nor will the non-seismic indicators provide l
I misleading information to the operators.
As stated above, the CST is not i
relied upon to function following a seismic event and the indicators will i
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fail such that they read zero-level. The operators will take the appro-l j
priate manual actions per procedure to align the AW pumps to the service i
j water system based on the zero-level indication.
Since Type A variables are j
those variables that prompt the operator to take manual action, PGE's desig-nation of CST-level as Type A is consistent with RG 1.97.
However, up-l 4
grading the indication to seismically qualified to meet Category I require-1
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ments will not provide additional benefit as the currently installed indica-i tion will perform the required function.
J Based on the above discussion, PCE feels the commitment to upgrade CST level
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indication, as stated in our May 13, 1986 letter, was outside the intended i
modifications to the system.
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I Document Control Desk October 14, 1988 l
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As a result of the NRC's RG 1.97 audit conducted from August 8 to August 12, i
1988, a Notice c; Deviation concerning the CST commitment was issued to PCE by NRC letter dated September 16, 1988.
PCE is currently evaluating the events which led to the misunderstanding of the commitment on CST level via a Nonconforming Activity Report (NCAR) to determine the cause and implement corrective actions to prevent recurrence.
Additional corrective actions will include updating PCE's RG 1.97 submittal. Topical Report PCE-1043 j
"Accident Monitoring Instrumentation Review. to provide a more detailed description of the instrumentation qualification and the as-built design.
an assessment of PCE's commitment tracking system will also be performed.
A more detailed discussion of these corrective actions and the schedules for j
contpletion 10 provided in PCE's response to the Notice of Deviation dated i
i October 14, 1988.
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Sincerely.
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Mr. John B. Martin l
l Regional Administrator. Region V l
U.S. Nuclear Regulatory Commission J
I Mr. William T. Dixon l
i State of Oregon Department of Energy i
Mr. R. C. Barr NRC Resident Inspector
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Trojan Nuclear Plant i
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