ML20248J696
| ML20248J696 | |
| 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 | |
| ML20248J700 | List: |
| References | |
| ULNRC-1958, NUDOCS 8904170004 | |
| Download: ML20248J696 (8) | |
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UNION I,6LECTRIC Dead MnX g March 31, 1989 i.
U. S. Nuclear Regulatory Commission
' Attn: Document Control Desk Mail Station P1-137 Washington, D.C. 20555 ULNRC-1958 Gentlemen:
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
- 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
' in.!ormation requested by 'i.eference 4 to support the NRC Staff 4
review of the proposed r9 visions to the Callaway Technical Specifications concerning the Control Room Emergency' Ventilation System.
The proposed '.echnical Specification revision was I
transmitted to the NF'i-by Reference 1.
The attachment to this letter provides Union Electric's I
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 your i
Donald F. Schnell JMC/ dis Attachment L
f 8904170004 890331 PDR ADOCK 05000483!
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'Shaw, Pittman, Potts & Trowbridge 2300 N.
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20037 Dr. J. O. Cermak CFA,.Inc.
.4 Professional. Drive (Suite 110)
Gaithersburg, MD 20879 R. C.-Knop Chief,. Reactor 1 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 RRil Steedman, Missouri 65077 Tom Alexion (2)
Office of Nuclear Reactor' Regulation U.S. Nuclear Regulatory Commission l' White; Flint, North, Mail Stop 13E21 11555 Rockville Pike-Rockville, MD 20852 Manager, Electric Department Missouri Public Service Commission P.O., Box 360 Jefferson City, MO 65102
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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 foregoing document and knows the content thereof; that he has executed the same for and on
-behalf.of said company with full power and authority to do so; and-that the f acts therein stated are true and correct to the best of his knowledge, information and belief.
b By Donald F. - Schne11 Senior Vice President Nuclear SUBSCRIBED and sworn to before me this 3// day of
,198f, 0l BARS Th J. PFAkF ficiARY PU3DC STATE OF MISSOURI MY COMMIS$10N EXPIRES APRIL 22, 1939 ST. LOUIS COUNTX
Attachmsnt to ULNRC-1958 Pags 1 of 4 Request for Additional Information Regarding the Proposed Revisions to the Control Room Emergency Ventilation System Technical Specifications.
Question 1 In the December 28, 1988 response to Question 1, it is stated that the assigned iodine removal efficiencies are 90% for accident analysis but the charcoal is tested for > 95% efficiency.
However, Technical Specification 3/4.7.6, as submitted under Attachment 3 to the March 23, 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 iodine penetration of less than 1% (> 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 reference 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, Positien 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 1
changed to a maximum of 2700 CFM versus the original change request of f
2800 CFM, l
li) Question 3(a) - Control buildir.g 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 iii) Question 3(d)
'The pressurization flow to the control room will be increased from 400 CFM to 560 CFM.
Meanwhile, the March 25, 1988 application identified the following information:
i)
Figure 1, Simplified Schematic of Control Building Ventilation - The flow range of 360-560 CFM from pressurization units will be filtered through filtration units, prior to control room distribution, along with filtration unit recirculation flow range of 1440-2240 CFM, and
- 11) Attachment 3, Technical Specification 3/4.7.6 - The filtration system flow rate is 2000 CFM (+800, -200) and the pressurization system flow rate is 2000 CFM (+800, -400) with 500 CFM (+500, -50) of fresh air.
Attichm:nt to ULNRC-1958 Pcgn 2 of 4 The licensee must provide the applicable proposed Technical Specification i
3/4.7.6 (Attachment 3) for which the approval is sought, and provide a i
balanced flow diagram for the emergency mode (control building isolation t
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 i
I 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 bui' ding (to maintain positive pressure in order to prevent outside unfiltered inteakage 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 filtration system of 2700 CFM (original request was 2800 CFM) is shown along with corresponding changes in the upper l
flow limits for the recirculation flow of 2160 CFM (original request was 2240 1
CFM) and 540 CFM for the control room pressurization flow (original request i
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.
j Also attached is a revised Table 1 of Air Flow Rates that was submitted in ULNRC-1747, dated March 25, 1988 as Attachment 1.
The December 28, 1988 response to question 3(a) stated in part " Pressurization 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 stater ant follows.
" Areas" as used above refers to the Control Building and the rooms containing FGK01A and FGK01B adjacent to the control room on 2047' level of the Auxiliary i
Building.
This does not include the entire 2047' level of the Auxiliary I
Building.
These rooms also contain the control room air conditioning i
equipment.
Per FSAR section 6.4.2.1 these rooms are defined as part of the l
The rooms are pressurized by the pressurization system via the control room filtration units and control room air conditioners which take a portion of the pressurization system return flow from the cable spreading rooms and discharge it to the control room air conditioning equipment rooms through dampers GKD324 and GKD325.
This information is consistent with FSAR Section 6.4.2.2 which states that the pressurization d
system serves the control room air conditioning equipment rooms.
A separate j
ventilation system is provided to maintain the Auxiliary Building at a
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negative pressure, j
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AttechmInt to ULNRC-1958 Pags 3 of 4 I
Question 3 Based on the information presented, the staff cannot concur in your December 28, 1988 response to Question 3(d) which stater,."therefore a significant reduction in control room pressurization flow would be required to create any control room infiltration concerns."
If desired, clarify the logic i
leading to your conclusion.
I t
Response
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 environment conditions.
The December 28, 1988 response 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, i
i the March 25, 1988 application proposed a Technical Specification 4.7.6.e.3 with a reduced control room pressurization requirement from 1/4 inch of w.g.
to 1/8 inch of w.g. relative to the outside atmosphere during system j
operation.
i 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 less of coolant accident should be modified accordingly for the appropriate unfiltered.inleakage due to the reduced pressurization inside the control room.
Response
j Environmental conditions which could create an atmospheric differential 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 basis for the Callaway Plant.
The information contained in FSAP Section 9.4.1.2.3 concerning a potential 80 CFM inleakage into the control room when the ccatrol 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 pathvay 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 Section 9.4.1.2.3 as well as additional information requested by the AEC question.
The conclusion reached was that temperature differences, barometric pressure changes and ventilation systems servicing adjacent spaces do not have 1
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Attachmsnt to ULNRC-1958 Pago 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 yelocity 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 assumed to be 1.0 meter /second for analysis of control room doses.
The AEC question did not require any consideration cJ 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 pressure of 1/4 inch w.g. was selected, consistent with the control room pressurization system capability, as a reasonable value to calculate inleakage.
The 1/4 inch w.g. was not selected based on environmental conditions postulated to occur at the site.
The design of the control room pressurization system and the ability to maintain control room habitability are described in Callaway FSAR Secticas 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.
I In conclusion, the information contained in FSAR Section 9.4.1.2.3 concerning the occurrence of a positive 1/4 inch w.g.
external pressure (with respect to I
the control room) was based on hypothetical conditions which were not required to be postulated for analysis of control room habitability.
The value of 1/4 inch w.g. was not selected based on environmental conditions expected to occur I
at the Callaway Plant.
Therefore, the dose analysis performed for the control room need not be modified to include inleakage due to external environmental conditions.
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