ML20137M242
| ML20137M242 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/26/1985 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| 5211-85-2190, NUDOCS 8512030645 | |
| Download: ML20137M242 (10) | |
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1 GPU Nuclear Corporation NggIgf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number November 26, 1985 5211-85-2190 Office of Nuclear Reactor Regulation ATTN: John F. Stolz, Chief Operating Reactors Branch No. 4 U.S. Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Stolz:
Three Mile Island Nuclear Station, Unit 1, (TMI-l)
Operating License No. DPR-50 Docket No. 50-289 Condenser Offgas Iodine Monitoring and Sampling Program The purpose of this letter is to provide an update of the design information of condenser offgas iodine monitoring and sanpling program which wts submitted to you as Attachment 1 to Reference 1, Attachnent 1 to this letter provides the updated information.
Please note that the statement 2(f) of the GPUN letter dated July 3,1984 (Ref.1) has been deleted from the system design description because the pipe whip and jet impingement criteria are not applicable to this system since the iodine monitor is installed in the Turbine Building which is a seismic class III structure (Ref. 4).
To obtain flow rate as well as total flow measurements, an in-line rotometer will be installed instead of a totalizer as originally proposed (Ref.1 Item 2(d) 11).
Since a representative sample will be assured by the revised system design, installation of an isokinetic system (Ref 1 Item 2(a)) is not necessary.
This modification (see flow diagram attachment 2) will provide the capability to continuously sample the offgas particulate and radiofodine effluents which will be analyzed at least once a week.
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i GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
r 5211-85-2190 To reiterate an earlier commitment, GPUN is committed to installing this modification during the Cycle 6 refueling outage. The technical specification change request for this modification will be submitted to the NRC upon installation of the modification.
Sincerely, H. D. Hutill Director, TMI-l HDH/MI/hbt:0419A
References:
- 1. GPUN Letter dated 7/3/84 (5311-84-2165)
- 2. NRC Letter dated 5/11/84
- 3. GPUN Letter dated 4/18/84 (5211-84-2094)
- 4. THI-l FSAR update-1 section 5.1.1.3 cc:
J. Thoma R. Conte Attachments
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ATTACHMENT 1 SYSTEM DESIGN CRITERIA 1.0 PURPOSE AND SCOPE 1.1 Brief Sumnary of Background As stated in Technical Specification Table 4.22-2, the TMI Unit 1 condenser vacuum punp exhaust (condenser offgas) is sanpled periodically.
Installation of a system to continuously sample the '
condenser offgas has been under review and discussion between the NRC and GPUN. At the conclusion of these discussions GPUN committed to providing the capability to continuously sanple the condenser offgas for radioactive effluents (Reference H.D. Hukill to NRC letter #5211-84-2094 dated April 18, 1984).
The condenser offgas sampling system described herewith will provide this capability.
2.0 REFERENCES
2.1 Drawings - Latest Revisions NPS' Dwd. No.1153-1, Continuous Iodine Sampling System, Flow Diagram.
NPS Dwg. No.1153-2, TMI Continuous Iodine Sampling System, Piping Arrangement and Details.
NPS Dwg. No.1153-3, TMI Continuous Iodine Sampling System, Conduit Routing and Wiring Diagram..
GAI Dwg. No. C-302-131, Rev. 22, Condenser Air Renoval, Piping Flow Diagram.
GAI Dwg. No. E-304-131, Rev. 6, Condenser Air Renoval, Piping System.
2.2 Documents System Design Description Div.1 SDD-T1-661-G, Continuous Iodine Sampling of Condenser Offgas, Three Mile Island Nuclear Generating Station, Unit #1.
3.0 FUNCTIONS & DESIGN REQUIREMENTS 3.1 Functions This modification will provide a means for obtaining a representative sanple of the condenser offgas effluents passing through the common discharge header of condenser vacuum pumps.,
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r 3.2 Design Requirements This modification will provide:
(i)
An additional take-off point from the vertical portion of the offgas common discharge header of the condenser vacuum pugs, down stream of the Auxiliary Condenser tie-in.
Representa-tiveness of the sanple will be assured per ANSI N.13.1 (1969).
(ii) A sample chamber that can collect both particulates and fodines for analysis.
(iii) A sample chamber that can be quickly disconnected from the sampling systen to facilitate the periodic analysis of the collected sample.
3.2.1 Operational Requirements (i) During plant conditions where steam flows to the min condenser via the min turbine or bypass valves, the main condenser vacuum pumps are used to nintain the main condenser pressure at a subatmospheric pressure.
Similarly, when the min feed pump turbines are in operation the auxiliary vacuum punps mintain the auxiliary condenser at a subatmospheric pressure.
Both the main and auxiliary vacuum pumps discharge to a common header that discharges to the atmosphere.
This modification obtains its sanple from the vacuum pump common discharge header (inlet) and returns the air to the 16" main condenser vacuum pump suction line (outlet). The fluid conditions at the inlet and outlet of the sanple line, respectively, are:
a) Common Discharge Header:
Temperature (normal) - 125*F Pressure - Near Atmospheric Humidity - 1001; Capacity
- Free Air - 45 SCFM - 202 #/hr.
Capacity
- Vapor - 443 #/hr.
2 nain vacuum pumps and 2 auxiliary vacuum pumps I
b) Main Condenser Yacuum Pump Suction:
Temperature (norml) - 71.5*F Pressure - approx. 2" Hg Abs.
Humidity - 100%
Capacity ** Free Air - 30 SCFM - 135 #/hr.
Capacity ** Vapor - 295 #/hr.
The condenser offgas sampling system uses the differential pressure between the vacuum purip discharge and suction headers to motivate the sampled fluid through the sampling system.
(ii) The hydraulic resistance of the sampling system shall be designed to provide the required sartpling flow for the differential pressure in (1) above.
(iii) Provide means for measuring the flow rate associated with the sampling line.
Isolation valves will be provided for removal and replacement of the sampling charrber. The collected sample will be removed for analysis, a minimum of once every seven days. A nanual flow control valve will be installed in the sample line to obtain the design flow through the system.
(iv) Provide administrative controls to minimize the radiation exposure to personnel.
3.2.2 Structural Requirements The structural design basis of this modification will be consistent with the design basis of the Condenser Air Removal System. The modification will be classified Seismic Class III as defined in FSAR Section 5.1.2.3.
All tubing and valving will be connected and supported in such a nenner that any stresses due to weight, thernal transients, internal tubing conditions and external environment will be within the maximum allowable stresses for 1
the existing supports and structures.
3.2.3 System Configuration and Essential Features The addition of this modification will not defeat nor degrade any existing features and functions of condenser air removal system and offgas condenser Radiation Monitoring System.
- 2 main pumps _
r-3.2.4 Maintenance Requirements The equipment nanufacturer's recommended procedures will be followed in conjunction with TMI #1 mechanical and electrical corrective paintenance procedures for valves, instruments and other equipment installed per this modification.
Sufficient space will be allowed around pipe routing and installed equipment for personnel access, in-place maintenance and equipment removal.
3.2.5 Surveillance & In-Service Inspection TMI Surveillance procedures applicable to the Condenser Offgas Radiation Monitoring System apply to the piping valves, instruments and other equipment installed on this design.
4.0
, UALITY ASSURANCE Q
This modification is classified as "Important to Safety". Quality Assurance requirements will be in accordance with " Operational Quality Assurance Plan for Three Mile Island Nuclear Station Unit #1."
The naterials for this modification will be commercial grade for an "ITS" application.
5.0 DETAILED SYSTEM DESCRIPTION 5.1 Sampling System 5.1.1 The condenser offgas sampling system as shown on the flow diagram (NPS No.1153-1) obtains. continuous representative samples from the 10" vent stack of the Condenser Air Removal System downstream of the Auxiliary Condenser tie-in. Quick disconnect couplings are installed on the inlet and discharge sides of the sanple chamber to facilitate removal of the sample chanber for analysis.
5.1.2 A representative air sanple is drawn through a sanpler chanber.
The sample chanber can collect both particulates and iodines from the sanpling flow stream via a HEPA and cartridge filter.
5.1.3 Once the sample is drawn through the probe located in the flow stream, the dryness of the gaseous stream is naintained with heat tracing installed on the surface of the sample line.
The heat tracing naintains the temperature of the stream at 185*F + 5'F.
During nornal operations the temperature of tWe water vapor and noncondensable gases mixture ranges from 125'F to 170*F. Heating the mixture to 185*F reduces the possibility of the sanple reaching, its dew point temperature, thus avoiding water vapor condensation in tne line and possibly reducing the efficiency of the sampling fil ter. -.
5.1.4 The sampling system flow rate is measured via a rotometer located downstream of the sample chamber.
5.1.5 The nanually operated flow control valve downstream of the rotometer will be adjusted in order to maintain constant flow in the sampling loop to compensate for increase pressure differential across the high efficiency filter and/or the radiofodine cartridge filter in the sample chanter. Also, the flow is adjusted for any change in the steady state conditions in the 10" vent stack or in the condenser vacuum pumps suction header. A nominal 1 SCFM + 20% flow rate will be mintained in the sample system loop!
5.1.6 The sanple probe is installed on the vertical 10" vent stack of the condenser air removal system (i.e., downstream of the vacuum pumps) at elevation 333 f t., which is greater than 10 stack diameters from the last stack opening at elevation 322'.
Installation of the sanple probe in a vertical run of pipe prevents stratification of the particulates due to gravity.
In addition, the velocity of the flow stream to be sampled is sufficiently high for turbulent flow. This assures good mixing in the sanpled flow stream.
5.2 Component Descriptions 5.2.1 The RADeC0 Model 2500-44 Sample Chanber contains an in-line combination HEPA filter (Hollingsworth and Vose Model LB-5211, or equivalent) and cartridge (Model No.. CP-100 or equivalent) as unufactured by Science Application, Inc.
The HEPA filter is installed upstream of the CP-100 cartridge to collect particulates that would degrade the cartridge's collection efficiency.
The Model CP-100 cartridge is a heavy duty aluminum case containing 40 to 50 mesh charcoal designed to remove total todines. The efficiency of the CP-100 cartridge in retaining iodine is better than 98 percent for a range of flow rates up to 5.0 SCFM.
The snufacturer will provide a Certificate of Perforence based on the j
manufacturer's perfornance testing to confirm the retention capability of the filter.
l 5.2.2 Flow Meter Indicator l
Flowmeter indicator (FI-1107), Model 1350 manufactured by Brooks is provided.
5.2.3 Sample Probe The sample probe will be fabricated from 1" diameter 316 stainless steel pipe.
Two withdrawal points located within the vent stack flow stream divert the required sample flow to a comnon nanifold to assure a representative sanple.
The probe is flanged to the pipe to facilitate removal and clea ni ng.
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5.2.4 Heat Tracing Chemelex self limiting type heat tracing is used with standard heating cable and circuit design of 0.104 ohm /ft.
This gives approxinately 10 watts /ft at 120 volts.
5.2.5 Thermostat A thermostat Model #AMC-1B as nanufactured by United Electric is grovided for control of the heat tracing (i.e.,185*
1 5 F).
A second thermostat Model #AMC-1B as nanufactured by United Electric provides a high temperature alarm (i.e.,195*
1 5*F).
5.2.6 Equipment Panel The sample chamber, flow meter and electrical controls are located on a local panel located on the columns adjacent to the vent stack at column F-4 in the Turbine Building. All equipnent is labeled with the appropriate GPUN identification number, and word identifiers.
5.2.7 Pressure Indicators Pressure Indicators PI-1226 & PI-1227 (Ashcrof t Model 1000) will be located up and downstream of the sanple chamber to indicate the differential pressure across the sample chanber 6.0 SYSTEM ARRANGEMENT The Condenser Offgas Sampling System arrangement is as shown on NPS Dra' ting No.1153-2, which is available at the site for NRC review.
7.0 SYSTEM INTERFALE 7.1 The modification's sample probe is located in the vent stack of the Condenser Air Removal System.
The sample return line discharges into the suction line of the nain condenser vacuum pumps.
7.2 Electrical power for the system will be provided from an existing 120V power supply line (Heat Trace Panel 18, breaker No.10),
located in the Turbine Building.
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7.3 The system tubing and equipment will be supported by the existing butiding framing.
8.0 SYSTEM LIMITATIONS, SET POINTS, AND PRECAUTIONS 8.1 Sampler The charcoal absorber in the sample chamber is naintained at a temperature well below the charcoal ignition temperature, as described in Section 8.2, thus reducing the hazards of overheating or fire and consequent escape of radioactive material.
8.2 Heat Tracing The heat tracing is a resistive heating system, the temperature rise above anbient caused by the system will vary roughly as the square of the voltage applied and as such the system voltage should be maintained at rated or set values.
Set points in the heat tracing include a temperature element for the operating temperature, a high temperature alarm (with manual reset) and a solid state power supply voltage.
Heat Tracing Set Point 185* 1 5'F High Temperature Alarm Set Point 195* 1 5'F 9.0 OPERATION The entire system is used on a routine continuous basis and does not require specific testing to ensure operability.
9.1 Sampler Replacement The sample chamber containing the HEPA filter and cartridge is to be replaced approxinately once a week for laboratory analysis.
Before removing the sample chamber, the sample chanber will be isolated by closing valves VA-V43 and VA-V44.
The replacement sample chanber with a new HEPA filter and cartridge is, connected to the system and isolation valves VA-V43 and VA-V44 are opened. The system flow is to be adjusted as required using valve VA-V45, 9.2 Flow Control The required flow of 1 SCFM + 20% is naintained by regular inspection of the rotometer as necessary to determine how frequently flow adjustments are required.
m 10.0 MAINTENANCE 10.1 Maintenance Approach
. All components are easily accessible in the event maintenance is necessa ry.
10.2 Preventive Maintenance Preventive maintenance includes:
10.2.1 Cleaning of the sample probe.
10.2.2 Visual inspection of all system components at time of cartridge replacement.
11.0 TESTING Testing shall be perforned on the heat tracing to verify the performance characteristics in accordance with Section 8.2.
Hydrostatic testing of the tubing shall be in accordance with ANSI Standard 831.1-1969.
The Tubing System Design Pressure is 50 psig.
12.0 HUMAN FACTORS The equipment panel for housing the sample chanber and instrumentation is located at column F-4.
The panel will be approximately 16" X 12",
the bottom of which will be 5'-0" above the floor.
The rack will be mounted on the panel support legs.
Quick connec't couplings will be provided for ready removal and replacenent of the sanple chamber.
GPUN's Human Factors staff will review the instrumentation located on the column F-4 panel to ensure that the flow indicator, conponent location, etc. are in accordance with the TMI human engineering guideli nes. t