ML080530395

Response to Request for Additional Information Regarding Proposed Amendment to Reduce Maximum Ventilation System Filter Pressure Drop

ML080530395
Person / Time
Site:	Cook
Issue date:	02/13/2008
From:	Peifer M Indiana Michigan Power Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
AEP:NRC:8751, TAC MD5931, TAC MD5932
Download: ML080530395 (7)

Text

Indiana Michigan Power INDIANA Cook Nuclear Plant MICHIGAN One Cook Place Bridgman, MI 49106 POVER AERcom A unit of American Electric Power February 13, 2008 AEP:NRC:8751 10 CFR 50.90 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-Pl-17 Washington, DC 20555-0001

SUBJECT:

Donald C. Cook Nuclear Plant Units 1 and 2 Docket Nos. 50-315 and 50-316 Response to Request for Additional Infonnation Regarding Proposed Amendment to Reduce Maximum Ventilation System Filter Pressure Drop (TAC Nos. MD5931 and MD5932)

REFERENCES:

1. Letter from J. N: Jensen, Indiana Michigan Power Company (I&M), to U. S.

Nuclear Regulatory Commission (NRC) Document Control Desk, "License Amendment Request to Reduce Maximum Ventilation System HEPA/Charcoal Pressure Drop Allowed by Technical Specifications,"

AEP:NRC:7751, dated June 13, 2007 (ML071730047).

2. Letter from P. S. Tam, NRC, to M. W. Rencheck, I&M, "D. C. Cook Nuclear Plant, Units 1 and 2 - Request for Additional Information Regarding Proposed Amendment to Reduce Maximum Ventilation System Filter Pressure Drop (TAC NOS. MD5931 AND MD5932)," dated January 14, 2008 (ML080100695).

Dear Sir or Madam:

By Reference 1, Indiana Michigan Power Company proposed to amend Facility Operating Licenses DPR-58 and DPR-74, for the Donald C. Cook Nuclear Plant. The proposed amendment would revise the Technical Specifications to impose lower, i.e., more restrictive, limits on the maximum pressure drop across the combined high efficiency particulate air filters and charcoal adsorbers in three safety-related ventilation systems. These ventilation systems are the Control Room Emergency Ventilation System, the Engineered Safety Features Ventilation System, and the Fuel Handling Area Exhaust Ventilation System. Reference 2 transmitted a U. S. Nuclear Regulatory Commission Request for Additional Information regarding the proposed amendment. This letter provides the requested information.

U. S. Nuclear Regulatory Commission AEP:NRC:8751 Page 2 to this letter provides an affirmation statement regarding infonnation in this letter. provides information requested by Reference 2. Copies of this letter and its enclosures are being transmitted to the Michigan Public Service Commission and Michigan Department of Environmental Quality, in accordance with the requirements of 10 CFR 50.91. This letter contains no new regulatory commitments. Should you have any questions, please contact Mr. James M. Petro, Jr., Regulatory Affairs Manager, at (269) 466-2491.

Site Vice President

Enclosures:

1. Affirmation

2. Response to Request for Additional Information c: J. L. Caldwell, NRC Region III K. D. Curry, AEP Ft. Wayne, w/o enclosures J. T. King, MPSC MDEQ - WHMD/RPMWS NRC Resident Inspector P. S. Tam, NRC Washington, DC

Enclosure I to AEP:NRC:8751 AFFIRMATION I, Mark A. Peifer, being duly sworn, state that I am Site Vice President of Indiana Michigan Power Company (I&M), that I am authorized to sign and file this request with the Nuclear Regulatory Commission on behalf of I&M, and that the statements made and the matters set forth herein pertaining to I&M are true and correct to the best of my knowledge, information, and belief.

Indiana Michigan Power Company Mark A. Peifer Site Vice President SWORN TO AND SUBSCRIBED BEFORE ME THIS I"' DAY OFV+/- "runtL,2008 Notary Public My Commission Expires M WO.WN M n 1, 0 0 My CormMIsslor Fxoin ja--%-2

Enclosure 2 to AEP:NRC:8751 Response to Request for Additional Information Documents referenced in this enclosure are identified on page 3 and 4.

By Reference 1, Indiana Michigan Power Company (I&M) proposed to amend Facility Operating Licenses DPR-58 and DPR-74, for the Donald C. Cook Nuclear Plant. The proposed amendment would revise the Technical Specifications (TS) to impose lower, i.e., more restrictive, limits on the maximum pressure drop across the combined high efficiency particulate air filters and charcoal adsorbers in three safety-related ventilation systems. These ventilation systems are the Control Room Emergency Ventilation System, the Engineered Safety Features Ventilation System, and the Fuel Handling Area Exhaust Ventilation System. Reference 2 transmitted a U. S. Nuclear Regulatory Commission (NRC) Request for Additional Information (RAI) regarding the proposed amendment. Each question in the RAI is restated below followed by I&M's response.

RAI Question I Are the calculated maximum allowable filter assembly pressure drops for the various systems greaterthan the combinedfilter vendors' recommended maximum pressure drop values?

I&M Response to Question I Based on vendor certified fan curves, each fan has more than sufficient capacity to provide the minimum flow at the calculated maximum total pressure drop for the associated system. The maximum filter drop for the filter assembly is the sum of the maximum filter drop for individual filters sections. This is combined with the losses for other ducting components to determine the total system loss. In this manner, the calculations assure adequate overall system performance.

RAI Question 2 How do the handbook resistance values compare with the "as installed" and "as operated" pressure loss values? Are the "as installed" pressure loss values from a testing and balancing (TAB) report?

I&M Response to Question 2 The measured air flow rates and associated filter pressure drops are consistent with the predictions of the calculations. Adequate flow is consistently obtained over the .range of operating filter pressure losses, as evidenced by data from surveillance procedures that record flow and filter pressure drops. Original TAB reports are not readily available.

to AEP:NRC: 8751 Page 2 RAI Question 3 The licensee indicates that the "less than four inch water gauge" acceptance criterion is based on vendor recommended values for the HEPA [high efficiency particulate airi/charcoal adsorber assembly. Are pre-filters installed? If pre-filters are installed, why are they not included in the filter assembly total allowablepressuredrop?

I&M Response to Question 3 The systems involved in the proposed TS change (the Control Room Emergency Ventilation System, the Engineered Safety Features Ventilation System, and the Fuel Handling Area Exhaust Ventilation System) have either panel type or Rolomatic type pre-filters. The calculations are specific to each system and account for the pre-filter differential pressure. However, inclusion of the pre-filter differential pressure in the surveillance test depends on the type of pre-filter installed in the system. For panel type pre-filters, the differential pressure may vary depending on the dirt loading. Accordingly, the pre-filter differential pressure is included in the surveillance for the system that contains panel type pre-filters. Where Rolomatic type pre-filters are used, the differential pressure is expected to remain constant because the filter material is continually advancing. Therefore, the pre-filter differential pressure is not included in the surveillance. The system-specific information is as follows:

Control Room Emergency Ventilation System

• The pre-filters are panel type pre-filters.

• A 1.0 inch water gauge pressure drop for the pre-filters is assumed in the I&M calculation.

• A single gauge measures differential pressure across both the pre-filter and HEPA filter.

• The four inch water gauge total allowable pressure drop specified in the proposed TS surveillance requirement will include the pre-filter differential pressure since it may' vary.

• Consistent with TS, the Control Room Emergency Ventilation System calculation confirms that the system can maintain a flow rate of 6,000 cfm +/- 10 percent (%) with a four inch water gauge differential pressure drop across the pre-filters, HEPA filter, and charcoal adsorber.

Engineered Safety Features Ventilation System

" The pre-filters are Rolomatic type pre-filters.

• A 0.5 inch water gauge pressure drop for the pre-filters is assumed in the I&M calculation.

• There is no differential pressure gauge across the pre-filter.

" The four inch water gauge total allowable pressure drop specified in the proposed TS surveillance requirement will not include the pre-filter differential pressure since it is essentially constant.

" Consistent with TS, the Engineered Safety Features Ventilation System calculation confirms that the system can maintain a flow rate of 25,000 cfm +/- 10% with a 0.5 inch water gauge differential pressure drop across the pre-filters, and a four inch water gauge differential pressure drop across the HEPA filter and charcoal adsorber.

to AEP:NRC: 8751 Page 3 Fuel Handling Area Exhaust Ventilation System

" The pre-filters are Rolomatic type pre-filters.

" A 0.5 inch water gauge pressure drop for the pre-filters is assumed in the I&M calculation.

• There is no differential pressure gauge across the pre-filter.

• The four inch water gauge total allowable pressure drop specified in the proposed TS surveillance requirement will not include the pre-filter differential pressure since it is essentially constant.

" Consistent with TS, the Fuel Handling Area Exhaust Ventilation System calculation confirnis that the system can maintain a flow rate of 30,000 cfm +/- 10% with a 0.5 inch water gauge differential pressure drop across the pre-filters, and a four inch water gauge differential pressure drop across the HEPA filter and charcoal adsorber.

RAI Question 4 If testing (TAB or ANSI N509 §8.5. 1) has not been performed, how does the licensee assure that the ventilation systems will provide the required minimum airflow at the requested maximum

(<four inches water gaugere)filterassembly pressure drop?

I&M Response to Question 4 I&M considers that the system-specific calculations provide adequate assurance that the required minimum air flow will be provided at the requested maximum filter assembly pressure drop of less than four inches water gauge. The system-specific calculations are straightforward and relatively simple in nature. The calculations sum the losses for each duct system component, based on standard industry empirical data, e.g., data from the American Society of Heating, Refrigeration, and Air-Conditioning Engineers Fundamentals handbook. The total system resistance is evaluated against vendor certified fan curves. Although flow rate testing has not been performed at maximum filter drop, flowrate and differential pressure measurements during surveillance testing show a correlation between "as operated" and "as analyzed" system performance. Therefore, the TS required surveillance of filter differential pressure and air flow is consistent with the purpose of ANSI N510 airflow and capacity tests, i.e., verification that the design airflow can be achieved with the fan as furnished, under actual field conditions at maximum and minimum filter pressure drop.

References

1. Letter from J. N. Jensen, I&M, to NRC Document Control desk, "License Amendment Request to Reduce Maximum Ventilation System HEPA/Charcoal Pressure Drop Allowed by Technical Specifications," AEP:NRC:7751, dated June 13, 2007 (ML071730047).

to AEP:NRC: 8751 Page 4

2. Letter from P. S. Tam, NRC, to M. W. Rencheck, I&M, "D. C. Cook Nuclear Plant, Units 1 and 2 - Request for Additional Information Regarding Proposed Amendment to Reduce Maximum Ventilation System Filter Pressure Drop (TAC NOS. MD5931 AND MD5932),"

dated January 14, 2008 (ML080100695).