ML20248G791
| ML20248G791 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 03/31/1989 |
| From: | Schnell D UNION ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20248G793 | List: |
| References | |
| ULNRC-1958, NUDOCS 8904130574 | |
| Download: ML20248G791 (8) | |
Text
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1901 Gratiot Street
. Post C1fice Box 149 St. Louis. Missoun 631fi6 314-554 2650 i
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. UNION oonatsr. schne11 Etscruic sc?"c?> ~ ?c ~ "'
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March 31, 1989-U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, D.C. 20555 ULNRC-1958 Gentlemen:
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DOCKET NUMBER 50-483 CALLAWAY PLANT REVISION TO TECHNICAL SPECIFICATION 3/4.7.6 CONTROL ROOM EMERGENCY VENTILATION SYSTEM
References:
- 1) ULNRC-1747, dated March 25, 1988 l
- 2) NRC letter from T. W. Alexion to D. F.
Schnell, dated November 18, 1988
- 3) ULNRC-1833, dated December 28, 1988
- 4) NRC letter from T. W. Alexion to D. F.
Schnell, dated. February 2, 1989 The purpose of this letter is to provide the additional information requested by Reference 4 to support the NRC Staff review of the proposed revisions to the Callaway Technical Specifications concerning the Control Room Emergency Ventilation System. The proposed Technical Specification revision was-transmitted to the NRC by Reference 1.
The attachment to this letter provides Union Electric's response to the' Staff questions transmitted by Reference 4.
If you have any questions concerning this matter, please contact me or Mr. D. E. Shafer of my staff.
Very truly yours,
/
I Donald F. Schnell i
JMC/ dis Attachment
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8904130574 890331 PDR ADOCK 05000483 l
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7-cc: _ Gerald Charnoff,.Esq.
= Shaw, T ittman, Potts & Trowbridge 2300 N. ~ Street, N.W.
Washing ton, D.C.
20037 Dr. J. O. Cermak CFA, Inc.
4 Professional Drive (Suite 110)
Gaithersburg, MD 20879 R.
C. Knop Chief, Reactor Project Branch 1 U.S.
Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn,' Illinois 60137 Bruce Little Callaway Resident Office U.S. Nuclear Regulatory Commission RR#1 Steedman, Missouri 65077 Tom Alexion (2)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 1 White Flint, North, Mail Stop 13E21 11555 Rockville Pike
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Rockville, MD 20852 l
I Manager, Electric Department i
Missouri Public Service Commission
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P.O. Box 360 4
Jefferson City, MO 65102 l
U.S.
Nuclear Regulatory Commission i
ATTN:
Document Control Desk l
I Washington, D.C.
20555 1
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D. Shafer/A160.761
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Nuclear-Date E210.01-DFS/ Chrono D.
F. Schnell' J.
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Stiller G.
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Randolph R..J.
Irwin H. Wuertenbaecher W. R..Campbel1 A. C.
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STATE OF MISSOURI )
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i Donald F.
Schnell, of lawful age, being first duly sworn upon oath says that he is Vice President-Nuclear and an officer of Union Electric Company; that he has read the fotogoing document and knows the content thereof; that he has executc3 t.ne same for and on L
behalf of said company with full power and authority to do so; and that the f acts therein stated are true and cor rect to the best of his knowledge, information and belief.
By i
Donald F.
Schnell Senior Vice President Nuclear SUBSCRIBED and sworn to before me this [/
day of 446 1984/.
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fl0TARY f'USUC, STAIL OF MISSOURI I
MY COMMISSIGN EXPIRES APRIL 22, 1939 ST. LOUIS COUNTX I
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Attachment to ULNRC-1958 Page 1 of 4 Request for Additional Information Regarding the Proposed Revisions to the Control Room Emergency Ventilation " -tem Technical Specifications.
Question 1 In the December 28, 1988 response to Question 1, it is stated that the assigned fodine removal efficiencies are 90% for accident analysis but the charcoal is tested for 2 95% efficiency. However, Technical Specification 3/4.7.6, as submitted under Attachment 3 to the March 25, 1988 application, requires you to meet the laboratory testing criteria of Regulatory Guide 1.52, Revision 2, March 1978, Position C.6.a and C.6.b for a methyl lodine penetration of less than 1% (2 99% removal).
Clarify this apparent discrepancy concerning the accepted criterion that has been used in laboratory testing of charcoal.
Provide the basis for utilizing 90% organic iodine removal efficiency as the assigned iodine removal efficiency for accident analysis evaluation.
Also, note that the ANSI 510, 1976 refurence you mentioned in Question 1 should be ANSI 510, 1975.
Response
Charcoal from the pressurization and filtration system filter units is tested per the criteria of Regulatory Guide 1.52, Revision 2, March 1978, Position C.6.a and C.6.b for a methyl iodine penetration of less than 1%.
The corresponding assigned efficiencies per the aforementioned Regulatory Guide and Generic Letter No. 83-13, March 2, 1983, are 95%.
Accident analysis assumes 90% charcoal efficiency for added conservatism.
Question 2 The December 28, 1988 response stated that:
1)
Question 1 - The upper flow rate for the filtration system will be changed to a maximum of 2700 CFM versus the original change request of 2800 CFM,
- 11) Question 3(a) - Control building and auxiliary building (elevation 2047 feet) areas are serviced by the control building pressurization fans and the upper flow limit to these areas would be changed from 2000 CFM 10%
to 2200 CFM + 800 CFM, and 111) Question 3(d) - The pressurization flow to the control room will be increased from 400 CPM to 560 CFM.
Meanwhile, the March 25, 1988 application identific1 the following information:
1)
Figure 1, Simplified Schematic of Control Building Ventilation - The flow range of 360-560 CFM from pressurization unitt will be filtered through flitration units, prior to control room distribu; ion, along with flitration unit recirculation flow range of 1440-224G CFM, and
- 11) Attachment 3, 'iechnien1 Specification 3/4.7.6 - The filtration system flow rate is 2000 CFM (4800, -200) and the pressurization system flow rate is 2000 CFM (+800, -400) with 500 CFM (+500, -50) of fresh air.
Attachment to ULNRC-1958 1
Page 2 of 4 i
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The licensee must provide the applicable proposed Technical Specification 3/4.7.6 (Attachment 3) for which the approval is sought, and provide a l
balanced flow diagram for the emergency mode (control building isolation during a radiological emergency) including all significant rated flow data.
Also, provide all high and low conditions as allowed by Technical Specifications. Assure that this information is consistent with all information provided under Docket No. 50-483.
Also, provide clarification concerning your statement that the control building pressurization fans serve the control building and auxiliary building (elevation 2047 feet) areas during the emergency mode.
In a typical design, a separate ventilation system is provided for the control building (to maintain positive pressure in order to prevent outside unfiltered inleakage entering into it) and the auxiliary building (to maintain negative pressure in order to contain a contaminated environment from leaking out of it).
Response
Figure 1 provides revised flow data for the proposed system flow changes.
The revised upper limit flow for the flitration system of 2700 CFM (original request was 2800 CFM) is shown along with corresponding changes in the upper flow limits for the recirculation flow of 2160 CFM (original request was 2240 CFM) and 540 CFM for the control room pressurization flow (original request was 560 CFM).
Note that the flows are provided in the format of rated, high and low conditions. The pressurization flow of 2200 CFM (+800, -400) is correct.
The corrected proposed Technical Specification 3/4.7.6 is attached.
Also attached is a revicad Table 1 of Air Flow Rates that was submitted in j
ULNRC-1747, dated March 25, 1988 as Attachment 1.
The December 28, 1988 response to question 3(a) stated in part " Pressurization I
unit fans (CGK04A and CGK04B) and associated ductwork are located in the Control Building.
The filtration units (FGK01A and FGK01B) are located adjacent to the control room on 2047' level of the Auxiliary Building.
Both areas are serviced by the Control Building pressurization fans."
Clarification of this statement follows.
" Areas" as used above refers to the Control Building and the rooms containing FGU01A and FGK01B adjacent to the control room on 2047' level of the Auxiliary Building.
This does not include the entire 2047' level of the Auxiliary Building.
These rooms also contain the control room air conditioning equipment.
Per FSAR section 6.4.2.1 these rooms are defined as part of the control room envelope. The rooms are pressurized by the pressurizi.t on system via the control room filtration units and control room air conditim ors which take a portion of the pressurization system return flow from the ctale l
spreading rooms and discharge it to the control room air conditioning i
equipmer_t rooms through dampers GKD324 and GKD325.
This information is consistent with FSAR Section 6.4.2.2 which states that the pressurization system serves the control room air conditioning equipment rooms.
A separate ventilation system is provided to maintain the Auxiliary Building at a negative pressure.
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Attachment to ULNRC-1958 -
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Page 3 of 4
. Question 3 Based on the information presented, the staff cannot concur in.your December 28, 1988 response to Question 3(d) which states, "therefore a significa.t. reduction in control room pressurization flow would be required to create any control room infiltration concerns." If desired, clarify the -logic leading to:your conclusion.
Respon_se See response to Question 4.
. Question 4 The December 28, 1988 response. to Question 3(d) states that FSAR section 9.4.1.2.3 states that less than 80 CFM inleakage to the control room would result'from isolation with no pressurization and an atmospheric differential pressure of positive (+) 1/4 inch of water gauge (w.g.) due to environm6nt conditions. The December 28, 1988 respouse to. Question 2 states that the control room dose calculations performed for Callaway Plant assume no unfiltered inleakage as a result of control room ingress and egress.
- Also, the March 25, 1988 application proposed a Technical Specification 4.7.6.e.3 j
with a reduced control room pressurization requirement from 1/4 inch of w.g.
i to 1/8 inch of w.g. relative to the outside atmosphere during system operation.
Provide clarification concerning the basis for your response to Question 3(d).
It appears that at the reduced control room pressurization from 1/4 inch of w.g. to 1/8 inch of w.g. relative to the outside atmosphere, the unfiltered inleakage to the control room should be somewhere between 0 CFM and 80 CFM during environmental conditions. Therefore, the dose calculations for the limiting case of the loss of coolant accident should be modified accordingly j
for the appropriate unfiltered inleakage due to the reduced pressurization inside the control room.
Response
Environmental conditions which could create an atmospheric differential j
pressure of positive 1/4 inch water gauge (w.g. ) with respect to the control room, during accident conditions, were not a design or licensing bcsis for the Callaway Plant. The information contained in FSAR Section 9.4.1.2.3 1
concerning a potential 80 CFM inleakage into the control room when the control room is isolated but not pressurized was provided in a response to Atomic Energy Commission (AEC) question, Item 6.7, submitted in Revision 2 of the SNUPPS Preliminary Safety Analysis Report (PSAR), September 1974.
The AEC question requested identification of potential leakage paths, contributions from each pathway and pressure differential estimates due to
-wind, temperature differences, barometric variations and ventilation units servicing spaces adjacent to the control room.
The response, contained in PSAR Section 9.4.1.2.3, provided the discussion contained in current FSAR l
Section 9.4.1.2.3 as well as additional information requested by the AEC l
question. The conclusion reached was that temperature differences, barometric pressure changes and ventilation systems servicing adjacent spaces do not have l
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Attachment to ULNRC-1958 Page'4 of 4 a significant effect on control room leakage and the ability to pressurize the control room. Wind velocity does have the potential to overcome a pressure differential across the control room boundary However, as discussed in PSAR Section 9.4.1.2.3, increased wind velocity creates higher atmospheric dispersion and reduced control room doses.
Doses would be reduced due to the increase in wind velocity assumed. The wind velocity was conservatively-asnumed to be-1.0 meter /second for analysis of control room doses.
The AEC question did not require any consideration of inleakage for an unpressurized condition in calculating control room doses.
In order to respond to the AEC question, an analysis was performed to quantify potential leakage from all identified sources for an unpressurized control room.
In order for inleakage to occur, a positive external pressure with respect to the control room must be postulated.
However, the pressure to be assumed for the requested analysis and the criteria to be used to calculate the pressure was not specified in the AEC question.
As the control room pressurization system is a redundant, safety related system, there are no credible single failures which could compromise the system's safety function of control room pressurization. Therefore, in order to perform the inleakage analysis, a positive pressurc of 1/4 inch w.".
was selected, consistent with
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the control room pressurization system cap 6;111ty, as a reasonable value.to calculate inleakage..The 1/4 inch w.g. w.s not selected based on environmental conditions postulated to occur at the site.
i The design of the control room pressurization system and the ability to l
maintain control room habitability are described in Callaway FSAR Sections 6.4 and 9.4.
Based on the ability to pressurize the control room using redundant safety grade systems, the dose calculations performed for control room habitability assumed no inleakage. The control room ventilation system design and radiation dose analyses performed were reviewed and accepted by the NRC during issuance of the construction permit and operating license for the Callaway Plant.
In conclusion, the information contained in FSAR Section 9.4.1.2.3 concerning G o occurrence of a positive 1/4 inch w.g. external pressure (with respect to the control room) was based on hypothetical conditions which were not required to be postulated for analysis of control room habitability. The valun of 1/4 inch w.g. was not selected based on environmental conditions expected to occur at the Callaway Plant.
Therefore, the dose analysis performed for the control room need'not be modified to include inlenkage due to external environmental conditions.
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