NRC-90-0093, Submits Clarification of Design for Plant Suppression Pool Temp Monitoring Sys.Design Adequate to Ensure Suppression Pool Water Temp within Allowable Tech Spec Limits

Submits Clarification of Design for Plant Suppression Pool Temp Monitoring Sys.Design Adequate to Ensure Suppression Pool Water Temp within Allowable Tech Spec Limits

ML20055G479
Person / Time
Site:	Fermi
Issue date:	07/18/1990
From:	Orser W DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-90-0093, CON-NRC-90-93 NUDOCS 9007230227
Download: ML20055G479 (3)

Text

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July 18, 1990 NIC-90-0093 U. S. Ricleat moulatory Ccmaission i Attn Dccument Control Desk Washington, D. C, 20555 Pcforences: 1) Ferrol 2  !

NIC Docket No. 50-341

!UC License No. NPF-43 >

~ 2) Detroit D51 son Letter to NIC, IF2-56,942 "Sutnittal of Plant  !

Unigue Analysis Report" dated l AprJ1 30, 1982

3) tWRm-0661, " Safety I: valuation Report, Mark I Containnent Long-Term t Program", dated July,1980 .

Subject:

Clarification of the Design of the Fermi 2  !

Egggggsfon Pool hoerature Monitorina Syntggg The purpose of this letter is to clarify the design description of the Fermi 2 Duppression Pool Tenperature Monitoring (SPIM) system. The design of the SP'IM systm was originally described in the Fermi 2 Long Term Program Plant Unique Analysis Report (LTP-PLUiR) that was submittal to NIC in Refererce 2. During a recent Irdependent Safety .  ;

I:ngineering Group (ISM) review of the adcquacy of the SP'IM system design, ISM noted a discrepancy between the description of the design provided in Reference 2 and actual plant conditions. The discrepancy

• involves the seismic qualification of the thermocouples ard control room tenperature recorders of the SFIM system. Upon investigation to determine the actual qualification status of this equiruent, Detroit IBison has determined that the existing design is tdequate and r.eets regulatory requirements as discussed telow.

APIendix A to NURD3-0661 (Reference 3) provides the NIC teceptance o criteria for the Mark I containnent long-term program. Section 2.13.8.3 " Suppression Pool Teucersture Monitor System" states that the

• suppression pool temperature monitoring systm is required to encure >

that the suppression pool is within the allowable limits set forth in the plant Technical Specifications. Anong the design requirements .

specified in IURm-0661, Item e of Section 2.13.8.3 statsa:

"All sensors shall be designo3 to scismic Category I, Quality Group D, and energized from onsite emergency supplies."

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, July 18,1990 NIC-90-0093 l Page 2 l 1 1

I In response to NUREG-0661, Item e, Detroit Edison stated: )

i "The supgession pool tarperature sensors (thernocouples) are l seismicar , wiifled. The sensors are a passive element and do l not reg' a e an w r supply. ha sensors are sounted on -l seismic Cly gi ,1ffed channels and supports, and the signal i cables 6 '

4ed in seismically qualifled ard supported trays j and conds 4 to the main control room recorders. %ere are three

-nulti-pen $12 pens) Stripchart Recorders in the main control room  !

and they are powered from onsite energency bus power supplies.  !

Wese recorders are seismically qualifled." ]

Twelve thernocouples that are actually part of two systems provide the function of suppression pool temperature monitoring. Four of these i thernocouples are part of the Primary Containnent Atnosphere Monitoring (T50) .cystem. % ese thermocouples were purchased as Quality Assurance (QA) level 1, Seimnic Category I. W ese TSO system thernocouples are divisionalized, two per division, and each division .

provides indication in the main control room to a recorder (T50R800 l A&B). Each recorder is powered by a divisional Class 1E power supply  ;

that is energized by emergency diesel generators on a loss of offsite i power. We T50 systen portion of the SPIM systen meets the l requirenents of NUREG-0661, Item e.

It should be noted that one of the T50 thernocouples additionally  ;

provides-input to a non-class IE circuit which is used to display supgession pool water tenperature at the remote shutdown panel. '

Because of the non<1 ass 1E interface, the thernocouple has been designated as QAIM and seismic category II/I. Based on the discussion  ;

abwe, Detroit Edison considers the design adequate to neet the acceptance criteria of NUREG-0661. ,

t he remaining eight thermocouples are part of the Containment (T23) system. %ese thermocouples were purchased as non-Q. However, they are designated as QAIM, which neans they are being maintained like a QA Level I couponent, and are seismic category II/I. Seismic category IJ/I is used to indicate that a couponent will maintain its structural .

and nounting integrity. Additionally, the T23 system thernoccuples are the sane manufacture nodel as the thermocouples used for the TSO ,

system discussed above.  ;

The eight T23 system thermocouples provide input to a single tenperature recorder (T23R800) located in the control roosn. The T23 tenperature recorder is also classifled as QAIM and seismic category

• II/I. The recorder is powered from a non Class lE distribution cabinet that 'is fed by a bus that is restored by the emergency diesel generators on a loss of offsite power. All that is required to restore power to the recorder once the bus is autcenatically >

re-energized by the IDGs is for an operator to close a breaker. i

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July 18,1990 10C-90-0093 Page 3  !

l Detroit Edison considers its design of the Suppression Pool Tunperature Monitoring system adequate to meet the requirenents of  ;

NURBG-0661. Although not purchased as Seismic Category I, the sane  !

seismically qualifled nodel thermocouple that was used in the TSO systm was pirchased for the T23 systm. The thermocouples are rugged in design consisting of a dual copper /constantan elenent with  ;

L nagnesium oxide insulation and a stainless steel outer sheath. With L

the exception of the tenperature recorder, which is located in the mild environnent of the control romi, there are no active conponents.

The installation is seismically supported, the instrunentation is naintained like (Al equipent, and the power supply to the recorder can be restored by an energency diesel generator. The design is adequate to ensure su!Tression pool water tenperature is within

• allowable Technical Specification limits. l If you have any questions regarding this netter or require additional >

infornation, please contact Mr. Lewis Bregni at (313) 586-4072. '

Sincerely, i 1

W. S. Orser cc A. B. Davis R. W. DeFayette f W. G. Rogers J. F. Stang 4

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