ML020700275
| ML020700275 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 03/05/2002 |
| From: | Trepanier T Entergy Nuclear Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2.02.015 | |
| Download: ML020700275 (5) | |
Text
Entergy Nuclear Generation Co.
Pilgrim Nuclear Power Station 600 Rocky Hill Road Plymouth, MA 02360 Mike Bellamy March 5, 2002 Site Vice President US Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555
SUBJECT:
Entergy Nuclear Generation Company Pilgrim Nuclear Power Station Docket No. 50-293 License No. DPR-35 Pilgrim Response to NRC Request for Additional Information Related to the Proposed License Amendment 3/4.7.B.1.a.2, Standby Gas Treatment (SBGT)
Heater Requirement LETTER NUMBER:
2.02.015
REFERENCE:
ENGC Letter to NRC, Proposed License Amendment Change to the Technical Specifications (TS) 3/4.7.B.1.a.2, Standby Gas Treatment (SBGT) Heater Requirement, dated August 22, 2001
Dear Sir or Madam:
By the referenced letter, Entergy Nuclear Generation Company (ENGC) proposed to amend Pilgrim Operating License No. DPR-35 in accordance with 10 CFR 50.90. The proposed amendment relates to changes to Technical Specification, 3/4.7.B.1.a.2, Standby Gas Treatment (SBGT) Heater Requirement. The attachment to this letter provides the Pilgrim response to the NRC request for additional information.
Should you have any questions regarding this letter, please contact Walter Lobo at (508) 830-7940.
Thomas Trepanie Commonwealth of Massachusetts)
Country of Plymouth
)
Then personally appeared before me, Thomas Trepanier, who being duly sworn, did state that he is acting Site Vice President of Pilgrim Nuclear Power Station and that he is duly authorized to execute and file the submittal contained herein in the name and on behalf of Entergy Nuclear Generation Company and that the statements are true to the best of h_"
owledge and belief.
My commission expires:9& -9.
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DATE 202015
Pilgrim Response to NRC Request for Additional Information cc: Mr. Douglas Starkey, Project Manager Project Directorate 1-3 Office of Nuclear Reactor Regulation Mail Stop: O-8B-1 1 White Flint North 11555 Rockville Pike Rockville, MD 20555-0001 U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Senior Resident Inspector Pilgrim Nuclear Power Station Mr. Robert Hallisey Radiation Control Program Center for Communicable Diseases Mass. Dept. of Public Health 305 South Street Jamaica Plain, MA 02130 Mr. Steve McGrail, Director Mass. Energy Management Agency 400 Worcester Road P.O. Box 1496 Framingham, MA 01701-0313 202015
Attachment:
I1.
Ltr. 202015 Page 1 ATTACHMENT 1 REQUEST FOR ADDITIONAL INFORMATION PILGRIM NUCLEAR POWER STATION PROPOSED LICENSE AMENDMENT CHANGE TO THE TECHNICAL SPECIFICATIONS 3/4.7.B.1.a.2 STANDBY GAS TREATMENT (SBGT) HEATER REQUIREMENT
- 1. NRC REQUEST The first paragraph on page 4 of ATTACHMENT A, of the August 22, 2001, submittal states that "the effects (e.g., increased electrical load and heat load on components and charcoal) of the larger heaters have been evaluated and found not to adversely impact other equipment."
With regard to that statement, please provide a detailed discussion as to why the increased electrical load of the larger heaters will not adversely impact other equipment during a design basis accident. In your response, please consider the increased loading on supply breakers, cable sizing, motor control center loading and diesel generator loading. Please provide sufficient data to support the conclusion.
- 2. PILGRIM RESPONSE Pilgrim has installed increased heater capacity using 10 CFR 50.59 provisions to meet the 70% relative humidity (RH) design requirements for the charcoal beds in the Standby Gas Treatment System (SGTS) and is requesting NRC approval for a more restrictive Technical Specification surveillance. The 10 CFR 50.59 review considered the impact of increased heater capacity on supply breakers, cable sizing, 480V motor control center loading and diesel generator loading and has concluded that increased heater capacity along with component replacements does not adversely impact other equipment. The result of this evaluation is described below. The modification has increased the rated heater capacity to approximately 30.2 kW at 480V AC with a capacity of approximately 23.4 kW at degraded voltage conditions.
To ensure that the increased heater capacity did not adversely impact the equipment, the scope of the modification included component replacements to accommodate the higher capacity of the heater and/or to provide new components that have appropriate Environmental Qualification (EQ) documentation for the updated temperature conditions. The heater capacity modification included replacement of the existing 30A, 3-pole circuit breakers with 50A breakers for each SGTS unit. The four contactors for the four banks of heaters in each unit and the 480/120V AC-control transformer for each SGTS unit were also replaced. In addition, some of the wiring in contactor panels was replaced and new cables were installed from these panels to the bank of heaters. This entire scope of the modification was evaluated and found to not adversely impact other equipment.
- 3. Analysis of Effect on Functions:
A. Temperature The maximum SGTS unit and room temperatures were determined using assumptions that maximize these temperatures by including the maximum electric heater output and a conservatively derived effect from potential radioactive decay heat loading on the charcoal. The SGTS unit and room temperatures are highest when only one SGTS train is operating after the other train has accumulated the maximum quantity of Post Loss of Coolant Accident (LOCA) halogens and has the total charcoal decay heat loading on its charcoal beds but then becomes inactive (fan is shutdown).
Ltr. 202015 Page 2 The above conditions can occur if the SGTS "A" train were operated for the first 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> (8.3 days) after LOCA to adsorb the maximum halogen loading and then the system is swapped over to the "B" train. In this configuration, the "A" train charcoal is cooled only by the 500 CFM bypass air supplied by the active "B" train. The total heat loss to the SGTS room is maximized because the unit surface temperatures in the inactive "A" train are maximized due to the charcoal decay heat load and the low bypass air flow rate.
The highest temperatures in the SGTS units and room occur for cases where the total SGTS air flow rate is minimized at 3600 CFM, the electric heater output is maximized at 30.2 kW total, and there is 13.4 kW of energy generated by the radioactive decay of halogens on the charcoal in the inactive train. At these conditions, the SGTS unit air stream temperatures are highest for each of the calculated locations downstream of the electric heaters, downstream of the inactive charcoal bed (bypass air only), and for the mixed total exhaust air stream. At peak charcoal decay heat loading 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> after the LOCA, the SGTS unit air stream temperature downstream of the electric heaters entering the charcoal beds is 148°F; downstream of the inactive charcoal bed is 199 0F (bypass air only); the mixed exhaust is 155 0F (active plus bypass); and the SGTS room temperature is 1400F.
The SGTS room was previously defined as a mild temperature environment not to exceed 1300F. Accordingly, new electrical support components were installed and the EQ profile was updated to 140°F to meet the design basis requirement to demonstrate that all affected components have been evaluated for the new conditions. The existing control transformers and contactors for the inlet heaters were replaced with appropriate EQ profile. EQ data was also updated for new wiring installed. All other existing components requiring an EQ evaluation in their EQ Design Record Files were updated for the new temperature conditions.
Special consideration was given to the qualification status of the motor-operated Standby Gas Fan Outlet Dampers. For the emergency mode of operation, the outlet dampers are in the Full Open position and remain in that position, i.e., the damper is effectively a static component and the motor-operator has no required active function in the emergency mode. Therefore, the EQ Design Record File for this component does not require addressing the active operation of the motor-operator during the worst case Design Basis Accident temperatures.
The maximum SGTS unit air stream temperature entering the charcoal beds downstream of the electric heaters operating at 30.2 kW capacity is 1480F with a total flow of 3600 CFM (4000 CFM -10%). The over-temperature cutoff switch has a setpoint of 2000F. The highest temperature within or exiting the inactive charcoal bed was determined to be bounded by a maximum potential value of 2440F so that the air stream through the HEPA filters will be below the design basis value of 2600F.
Using a conservative heat transfer calculation for the decay heat load on the charcoal, it was determined that the charcoal temperature is bounded by a maximum potential value of 2530F. It is therefore concluded that the charcoal will be below the design basis value of 330°F under all conditions and iodine desorption is prevented.
Ltr. 202015 Page 3 B. Electrical Lead The increased heater capacity impacted the emergency diesel generator (EDG) loads. The increased EDG loads were evaluated, determined to be within the EDG ratings, and included in the EDG loading profile. The affected electrical calculations for ampacity and degraded voltage were updated to include the higher kW heaters. The undercurrent relay trip setpoint detecting SGTS inlet heater failures was updated. Design basis analysis for the SGTS airflow, temperature, humidity, charcoal temperature, and SGTS room temperatures were updated.
The updated design basis calculation uses a maximum SGTS flow rate of 4400 CFM (4000 CFM +10%), which is the highest potential flow rate for the SGTS system in actual operation.
The impact of increased heater capacity on 480-volt motor control centers was evaluated and the 480/120V AC-control transformer for each SGTS unit was replaced to accommodate the additional electrical loading.
C.
Summary Based upon the above described scope of the modification, analysis of impact, and updating of applicable calculations and EQ profile, Pilgrim has concluded that the effects (e.g., increased electrical load and heat load on components and charcoal) of the larger heaters have been evaluated and found not to adversely impact other equipment.