ML20237A866

Provides Addl Info in Response to SER Open Items Re Pressurizer Level,Pressurizer Heater Status & Heat Removal by Containment Fan Heat Removal Sys to Support Previous Position Described in Listed Ltrs (Ref Reg Guide 1.97)

ML20237A866
Person / Time
Site:	Three Mile Island
Issue date:	12/10/1987
From:	Hukill H GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
RTR-REGGD-01.097, RTR-REGGD-1.097 5211-87-2199, TAC-51361, NUDOCS 8712150322
Download: ML20237A866 (6)

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GPU Nuclear Corporation 560 (uolear gems o

=48o Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number: l December 10, 1987 5211-87-2199 (TAC 51361)

U. S. Nuclear Regulatory Commission '

Attn: Docur:ent Control Desk Washington, DC 20555 Gentlemen: I I

Three Mile Island Nuclear Station, Unit 1 (TMI-l)  !

Operating License No. DPP-50  !

Docket No. 50-2'89 Regulatory Guide 1.97 Safety Evaluation Report Open Items l l

NRC Safety Evaluation Report (SER) relating to conformance to Regulatory Guide J 1.97 for TMI-1, dated August 24, 1987, identified open items concerning the following post-accident monitoring variables: a) accumulator tank level and pressure, b) containment sump water temperature, c) pressurizer level, d) pressurizer heater status, and e) heat removal by the containment fan heat removal system.

GPUN considers the accumulator tank level and pressure, and containment sump water temperature variables Category 3 for TMI-l as described in GPUN letter 5211-86-2097, dated June 5,1986. It is our understanding that the need for environmentally qualified Category 2 instrumentation to monitor these variables is undergoing NRC staff generic review and that the NRC will report on the conclusion when the generic review is complete. Therefore, GPUN  ;

assumes that our approach is acceptable and no additional response to the open items regarding accumulator tank level and pressure, and containment sump water temperature is provided at this time.

In response to the SER open items regarding pressurizer level, pressurizer  !

heater status and heat removal by the containment fan heat removal system, the following additional information is provided to support our previous position on these variables as described in GPUN letters 5211-87-2087, dated May 7, 1987; 5211-86-2097, dated June 5,1986; and 5211-84-2252, dated October 1, 1984.

Pressurizer ievel Figure 1, attached, depicts the pressurizer level indications available at TMI-1. Level transmitter LT-777 is a Class IE qualified instrument, while level transmitters RC-LT-1,2,3 are also environmentally' qualified arid are associated with the ICS which utilizes Class IE power sources. This power source is the emergency diesel generator backed vital power electrical oy GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation g 8712150322 871210 PDR ADOCK 050002G9 P PDR

5211-87-2199 'ecember 10, 1987 distribution system. There are two RTD temperature elements located in one the rmowell . Temperature element RC2-TE2 is used to compensate LT-777.

Temperature elements RC2-TEl and RC2-TE2 are selectable, provide an input to ICS, and are used to compensate RC-LT-1,2 or 3. Level transmitter LT-777 is displayed in the control room on a digital indicator. One of the level transmitters RC-LT-1,2, or 3 is selected for display in the control room on a strip chart recorder. Level transmitter LT-777 is not recorded. All four transmitters are environmentally qualified and currently listed on the Equipment Qualification Master List. The RTD elements (RC2-TEl and RC2-TE2) used for temperature compensation for level transmitters LT-777, and RC-LT-1,2 or 3 will be qualified and added to the Equipment Qualification Master List prior to startup following Cycle 7 refueling outage. TMI-l Technical Specification Section 3.5.5 also requires that at least one of the pressurizer level channels be operable during startup/ power operation and hot standby, The TMI-l pressurizer level indication design (as shown on Table 1) in conjunction with environmental qualification of the RTD elements used for temperature compen:.ation, provides a highly reliable source of instrumentation available for post-accident monitoring. Although not in strict compliance with Regulatory Guide 1.97 Category 1 requirements, this set of instruments should be considered an acceptable alternative which satisfies the intent of Regulatory Guide 1.97 for pressurizer level, as allowed by NRC Generic Letter 82-33, Section 6.2.

It should be noted that pressurizer level indication is no longer utilized for HPI throttling which is consistent with the generic B&W emergency operating procedures. l l

Pressurizer Heater Status '

Regulatory Guide 1.97 indicates that pressurizer heater current is a Category 2 variable required to determine the pressurizer heaters operating status.

TMI-l has Category 2 indication of heater breaker status (on/off) displayed in the control room. In addition, qualified pressurizer temperature will be displayed in the control room. The pressurizer temperature RTD elements (RC2-TEl and RC2-TE2) used for temperature compensation will be qualified and added to the Equipment Qualification Master List prior to startup following Cycle 7 refueling outage. Indication of pressurizer temperature provides another indication of heater function in addition to RCS pressure, by indicating that the pressurizer fluid is saturated. At TMI-1, only two banks j of pressurizer heaters can be loaded on the diesel generators. Diesel l generator loading capacity is sufficient to handle these two banks. The I control room operator is aware of the power consumption of the two heater l banks based on rated capacity as well as knowing the actual diesel generator  !

load based on control room indication. Therefore, the number of operating l heater banks is not essential information for the operator to prevent '

overloading a diesel generator.

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5211-87-2199 December 10, 1987 i

The combination of pressurizer temperature, RCS pressure and heater breaker I status gives the operator the information required to determine the effect on f RCS pressure and the determination of whether the heaters are operating. GPUN believes that this instrumentation meets the intent of Regulatory Guide 1.97 in being able to determine pressurizer heater status.

Fan Cooler Heat Removal Regulatory Guide 1.97 requires that fan cooler heat removal capability be determined by a Category 2 variable.

GPUN believes that TMI-l has a sufficient combination of Category 1 and 2 instruments available to the operator to monitor operation of the Containment Fan Heat Removal System. The combination of parameters available are:

Category 1 Indication in Control Room:

1. containment pressure Category 2 Indication in Control Room:

1. fan cooler coil outlet water pressure

2. river water pump motor breaker status .

1

3. reactor building fan motor breaker status l

4. emergency cooling coil leak alarm The operator is directed by procedure to maintain approximately 60 psig outlet pressure on the fan cooler outlet to assure containment integrity post-accident. A pressure of less than 60 psig would be an indication of low flow through the coils due to leakage or flow blockage. A high discharge pressure would be indicative of a flow blockage downstream of the pressure sensor. This would also be an indication of low flow.

In addition, the following indications are available to the operator in an

, accessible area outside the control room: 1) fan cooler flow, 2) fan cooler outlet temperature, and 3) river water temperature. If the control room indications suggested that the fan coolers were not operating, then a more detailed evaluation of fan cooler heat removal capability could be performed from variables available outside the control room. It should be noted that fan cooler operability has a small effect on building pressure until the ECCS systems switch to the recirculation mode. Then, the fan coolers only have a gradual effect on containment response. They are only required to limit containment pressure until the RCS is being cooled by heat removal through OTSGs or by the decay heat removal system.

. i 5211-87-2199 December 10, 1987 Also, it should be noted that upgrade of the EFW system to be safety grade assures that OTSGs will be available to remove decay heat during high energy line breaks inside containment as well as for many small break LOCAs. For large break LOCAs, the RCS depressurizes to the LPI system pressure before fan coolers have any significant impact on containment pressure.

In effect, fan coolers only protect the containment from overpressurization due to small break LOCAs with loss of EFW which are beyond the design basis.

Even then, there is ample time to diagnose the problem with instruments available in the containment (i.e. containment temperature and pressure).

In summary, it is GPUN's position that there is : 1) appropriate control room  !

indication to determine fan cooler operability; 2) ample time available to i determine the fan cooler heat removal capacity if there is an indication of {

problems in fan cooler operation; 3) a relatively small effect of containment fan coolers on containment pressure. Therefore, the existing combination of TMI-l instruments should be considered an acceptable alternative equivalent to )

the Regulatory Guide 1.97 recommendations, as allowed by Generic Letter 82-33, Section 6.2.

We trust the additional information herein satisfactorily supports our position that the TMI-l instrumentation described provides an acceptable alternative equivalent to the Regulatory Guide 1.97 requirements for pressurizer level, pressurizer heater status and heat removal by the containment fan heat removal system. We request that NRC reconsider the SER conclusions for these variables based on this additional information.

If any further information is required, please contact us.

f /  :.

H. D. ill Vice President and Director, TMI-l DJD/It 5488g Attachments: Table 1 - Regulatory Guide 1.97 Requirements of Category 1 l Instruments i Figure 1 - Pressurizer Level Indication '

cc: J. Stol z, USNRC j G. Edison, USNRC j W. T. Russell, USNRC, Region I  ;

R. Conte, USNRC, TMI-l Site l

l l

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I 1

s TABLE 1 REG. GUIDE 1.97 REQUIREMENTS OF CATEGORY 1 INSTRUMENTS 2)

Human Factors Review LT-777 RC-LT-1,2,3 Service, Test, Calibration LT-777 )

Program RC-LT-1,2,3 I

Direct Measurement LT-777 RC-LT-1,2,3 l Control Room Display LT-777 l

RC-LT-1,2,3 j l Class IE Power source LT-777 I

RC-LT-1,2,3 (l ) l Environmental Qualification LT-777 RC-LT-1,2,3 Quality Assurance LT-777 )

RC -LT-1,2 ,3 Interface Isolation Devices LT-777 (Not required for RC-LT-1,2,3)

Channel Availability LT-777(3)

(limited out of service time) RC-LT-1,2,3 Seismic Qualification LT-777 Redundancy LT-777 redundant to RC-LT-1,2,3 Recorded RC-LT-1,2,3 selected channel only 1

Connected to vital power electrical distribution system through an isolation device.

2 Criteria is for entire instrument loop including temperature elements.

3 TMI-l Tech. Spec. Section 3.5.5 requires at least one pressurizer level channel be operable.

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