ML050490046
| ML050490046 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 02/17/2005 |
| From: | Hartz L Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 05-078 | |
| Download: ML050490046 (12) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY
- RICHMOND, VIRGINIA 23261 February 17, 2005 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Serial No.05-078 NL&OS/ETS RO Docket Nos. 50-338 License Nos. NPF-4 50-339 NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 PROPOSED TECHNICAL SPECIFICATION CHANGES IMPLEMENTATION OF ALTERNATE SOURCE TERM REQUEST FOR ADDITIONAL INFORMATION EMERGENCY VENTILATION SYSTEM In letters dated September 12, 2003 (Serial No.03-464) and November 3, 2004 (Serial No. 04-494A), Virginia Electric and Power Company (Dominion) requested amendments in the form of changes to the Technical Specifications to Facility Operating Licenses Numbers NPF-4 and NPF-7 for North Anna Power Station Units 1 and 2, respectively.
The proposed changes were requested based on the radiological dose analysis margins obtained by using an alternate source term consistent with 10 CFR 50.67.
In a February 9, 2005 telephone conference call, the NRC staff requested additional information regarding the Main Control Room and Emergency Switchgear Room emergency ventilation system. The information requested is provided in the attachment to this letter.
If you have any further questions or require additional information, please contact Mr. Thomas Shaub at (804) 273-2763.
Very truly yours, Leslie N. Hartz Vice President - Nuclear Engineering Attachments Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 Atlanta, Georgia 30303 Mr. M. S. King NRC Senior Resident Inspector North Anna Power Station Mr. S. R. Monarque NRC Project Manager U. S. Nuclear Regulatory Commission One White Flint North 1 1555 Rockville Pike Mail Stop 8-HI2 Rockville, Maryland 20852-2738 Mr. J. E. Reasor Old Dominion Electric Cooperative I nnsbrook Corporate Center 4201 Dominion Blvd.
Suite 300 Glen Alien, Virginia 23060
Serial No.: 05-078 Docket Nos.: 50-338/339
Subject:
RAI - Alternate Source Term COMMONWEALTH OF VIRGINIA
)
COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Leslie N. Hartz who is Vice President - Nuclear Engineering of Virginia Electric and Power Company. She has affirmed before me that she is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of her knowledge and belief.
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Acknowledged before me this 17 day of.J.k6-
,2005.
A My Commission Expires:
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Serial No.05-078 Proposed Technical Specification Changes Implementation of Alternate Source Term Request for Additional Information Emergency Ventilation Systems North Anna Power Station Units 1 and 2 Virginia Electric and Power Company
( Dom i n io n)
Serial No.: 05-078 Docket Nos. : 50-338/339 Page 1 of 2 RAI - NORTH ANNA ALTERNATIVE SOURCE TERM In letters dated September 12, 2003 (Serial No.03-464) and November 3, 2004 (Serial No. 04-494A) Virginia Electric and Power Company (Dominion) requested amendments in the form of changes to the Technical Specifications to Facility Operating Licenses Numbers NPF-4 and NPF-7 for North Anna Power Station Units 1 and 2, respectively.
The proposed changes were requested based on the radiological dose analysis margins obtained by using an alternate source term consistent with 10 CFR 50.67. In a February 9, 2005 telephone conference call, the NRC staff requested additional information regarding the Main Control Room and Emergency Switchgear Room emergency ventilation system. The information requested is provided below.
Background
The current dose consequence accident analyses assume that the control room is isolated and pressurized by bottled air and one train of the Emergency Ventilation System (EVS) provides filtered recirculation air flow in the Main Control Room/Emergency Switchgear Room (MCR/ESGR) in the event of a radiological accident during Modes 1 through 4. After depletion of the bottled air (which does not occur for at least 60 minutes), a second train of EVS is used for pressurization. As a result, three trains of EVS are required to meet the single failure criterion. It should be noted that cooling of the MCR/ESGR for equipment operability and human habitability is performed by a separate, safety grade, redundant air conditioning system that recirculates the MCR/ESGR air and is governed by TS 3.7.1 1.
Based on the Alternative Source Term dose consequence analyses, which do not crediVassume filtered recirculation air flow during Modes 1 through 4, changes are proposed to LCO 3.7.10 since only one 100% capacity MCR/ESGR EVS train is required to provide pressurization. Specifically, the Loss of Coolant Accident analysis credits EVS pressurization after the first hour and isolation of the control room but does not credit recirculation of the air within the control room at anytime. The Main Steam Line Break, Steam Generator Tube Rupture, and Locked Rotor Accident do not credit EVS recirculation, pressurization, or isolation to meet the dose limits. Therefore, in order to accommodate single failure and maintain the MCR/ESGR habitable from a dose perspective for the AST case, only two EVS trains are required to be operable to meet the single failure criterion. The EVS requirements for the Fuel Handling Accident (FHA) are governed by TS 3.7.14.
The FHA only credits one train of EVS for pressurization and only requires two trains to meet the single failure criterion.
NRC Question 1 Currently two MCR & ESGR emergency ventilation system trains from the affected unit and one from the opposite unit are required to be operable in Modes 1 through 4. Is each of the three trains capable of supplying 100% of the required capacity during Modes 1-4?
Serial No.: 05-078 Docket Nos.: 50-3381339 Page 2 of 2 Dominion Response:
Each of the four MCR & ESGR EVS trains is a 100% capacity train capable of being aligned for recirculation or pressurization.
The Bases section is being revised to indicate that each train is capable of handling 100% capacity. The revised Bases pages are attached for your information.
NRC Question 2 What is the basis for eliminating SR 3.7.10.3? Is this SR a repeat of 3.7.10.1 and if so is 3.7.1 0.1 actuated automatically or manually?
Dominion Response:
SR 3.7.10.3 tests the automatic initiation of the EVS trains. Since the accident analysis to support the AST changes does not credit recirculation flow at any time during the accident and only credits pressurization flow after the first hour for operator dose mitigation, the automatic initiation function of the EVS is not required to establish operability of the EVS. One hour provides ample time to manually start the EVS in the pressurization mode. The automatic start feature of the EVS is not being physically removed. Rather the automatic start is being removed from the system operability requirements.
SR 3.7.10.1 is a manually initiated test of the EVS trains. SR 3.7.10.3 is a test of the automatic initiation feature of the EVS.
The Bases section is being revised to further clarify these assumptions. The revised Bases pages are attached for your information.
Serial No.05-078 Proposed Technical Specification Changes Implementation of Alternate Source Term Revised Bases Pages (for information)
North Anna Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion)
MCRIESGR EVS-MODES 1, 2, 3, and 4 B 3.7.10 B 3.J PLANT SYSTEMS B 3.7.10 Main Control Room/Emergency Swi tchgear Room (MCR/ESGR) Emergency Ventilation System (EVS)-MODES 1, 2, 3, and 4 BASES BACKGROUND The MCR/ESGR Emergency Habi t a b i 1 i t y System (EHS) provides a protected environment from which operators can control th,e u n i t following an uncontrolled release of radioactivity, The MCR/ESGR EHS co (LCO 3.7.13) an The MCR/ESGR EV LCO 3.7.14).
f i l t e r and recir supply f i 1 tered independent and actuate automatically i n recirculation. Either of these trains can also be aligned t o provide filtered outside a i r f o r pressurization when appropriate. One t r a i n from the other u n i t k+eq&-rLJ f c r reckmhfy, can be manually actuated t o provide f i l t e r e d outside a i r
- l+W approximately 60 minutes a f t e r the event.
Each train consists of a heater, demister f i l t e r, a high efficiency particulate a i r (HEPA) f i l t e r, an activated charcoal adsorber section f o r removal of gaseous a c t i v i t y and instrumentation also form p a r t of the system.
train$ are capable of performing the safety functions em@
supplying outside filtered a i r f o r pressurization, eee redundancy.
Upon receipt of the actuating s i g n a l ( s ), normal a i r supply t o and exhaust from the MCR/ESGR envelope i s i s o l a t e d, +
two-t r a i n s of MCR/ESGR EVS actuate t o recirculate a i r, and airflow from the bottled a i r banks maintains a positive pressure i n the MCR/ESGR envelope. The MCR/ESGR envelope consists o f the MCR, ESGRs, computer rooms, logic rooms, instrument rack rooms, a i r conditioning rooms, battery rooms, the MCR t o i l e t, and the stairwell behind the MCR. Approximately 60 minutes a f t e r actuation of the MCR/ESGR bottled a i r system, a single MCR/ESGR EVS t r a i n is manually actuated t o provide f i l t e r e d outside a i r t o the MCR/ESGR envelope through HEPA filters and charcoal (continued)
(principally iodines), and a fan. Ductwork, valves, are required f o r independence and North Anna Units 1 a n d 2 6 3.7.10-1 Revision 8-
MCR/ESGR EVS-MODES 1, 2, 3, and 4 B 3.7.10 BASE:
APPLICABLE SAFETY ANALYSES (cont i nued) by the control room accident dose analyses f o r t h e most 1 i m i ti ng design basi s accident f i s s i on product re1 ease presented i n the UFSAR, Chapter 15 (Ref. Z).&,LLlseer @
The worst case s i n g l e a c t i v e f a i l u r e o f a component of t h e MCR/ESGR EVS, assuming a loss o f o f f s i t e power, does not impair the a b i l i t y o f the system t o perform i t s design function.
I The MCR/ESGR EVS-MODES 1, 2, 3, and 4 s a t i s f i e s C r i t e, r i o n 3 o f 10 CFR 50.36(c)(Z)(ii).
L co pressurize and t o provide f i l t e r e d a i r t o t h e MCR/ESGR envelope, assuming a s i n g l e f a i l u r e disables one o f t h e two required OPERABLE t r a i n.
r e s u l t i n exceeding the control room o p e r a t o r dose l i m i t s o f 10 CFR 50, Appendix A, GDC-19 (Ref.
i n the event re1 ease.
The MCR/ESGR EVS-MODES 1, 2, 3, a when the i n d i v i d u a l components necessary t o l i m i t operator exposure are OPERABLE i n the t.
- r e q u i r e d t r a i n s o f t h e s
ld
+Mi:
+, Y a F R, )
MCR/ESGR EVS-MODES 1, 2, 3, and rL5m 0 3
An MCR/ESGR EVS t r a i n i s OPERABLE when t h e associated:
- a. Fan i s OPERABLE;
- b. Demister filters, HEPA filters and charcoal adsorbers are not excessively r e s t r i c t i n g flow, and a r e capable o f performing t h e i r f i l t r a t i o n functions; and
The MCR/ESGR EVS i s shared by Unit 1 and Unit 2.
(continued)
North Anna Units 1 and 2 B 3.7.10-3 Revision
Insert for Bases 3.7.10
- 1.
Due to the location of the air intake for 1-HV-F-41, it can not be used to satisfy the requirements of LCO 3.7.10. Two of the three remaining trains (1-HV-F-42, 2-HV-F-41, and 2-HV-F-42)
- 2.
This accident analysis assumes that at least one train is aligned for control room pressurization approximately 60 minutes after actuation of bottled air, but does not take credit for automatic start of the trains in the recirculation mode or any filtration of the recirculated air.
- 3.
1-HV-F-41 can not be used to satisfy the requirements of LCO 3.7.10
- 4.
(e.g., excessive control room inleakage or excessive Emergency Core Cooling System leakage)
MCR/ESGR EVS-MODES 1, 2, 3, and 4 B 3.7.10 B 3.7 PLANT SYSTEMS B 3.7.10 Main Control Room/Emergency S w i tchgear Room (MCR/ESGR) Emergency V e n t i l a t i o n System (EVS)-MODES 1, 2, 3, and 4 BASES BACKGROUND The MCR/ESGR Emergency Habi t a b i 1 i t y System (EHS) provides a protected environment from which operators can c o n t r o l t h e u n i t f o l l o w i n g an u n c o n t r o l l e d release o f r a d i o a c t i v i t y. The MCR/ESGR EHS c o n s i s t s o f t h e MCR/ESGR b o t t l e d a i r system (LCO 3.7.13) and t h e MCR/ESGR EVS (LCO 3.7.10 and LCO 3.7.14).
The MCR/ESGR EVS was designed as f o u r 100% capacity redundant t r a i n s t h a t can f i l t e r and r e c i r c u l a t e a i r i n s i d e t h e MCR/ESGR envelope, o r supply f i l t e r e d a i r t o t h e MCR/ESGR envel ope. The two independent and redundant uni t MCR/ESGR EVS t r a i n s on t h e accident u n i t can actuate a u t o m a t i c a l l y i n r e c i r c u l a t i o n. E i t h e r o f these t r a i n s can a l s o be aligned t o p r o v i d e f i l t e r e d o u t s i d e a i r f o r p r e s s u r i z a t i o n when appropriate. One t r a i n from t h e o t h e r u n i t can be manually actuated t o provide f i l t e r e d o u t s i d e a i r approximately 60 minutes a f t e r t h e event. Each t r a i n consists o f a heater, demister f i l t e r, a h i g h e f f i c i e n c y p a r t i c u l a t e a i r (HEPA) f i l t e r, an a c t i v a t e d charcoal adsorber s e c t i o n f o r removal o f gaseous a c t i v i t y
( p r i n c i p a l l y iodines), and a fan. Ductwork, valves, dampers, and instrumentation a l s o form p a r t o f t h e system. One EVS t r a i n i s capable o f performing t h e s a f e t y f u n c t i o n o f supplying outside f i l t e r e d a i r f o r p r e s s u r i z a t i o n. Due t o t h e l o c a t i o n o f t h e a i r i n t a k e f o r 1-HV-F-41, i t can n o t be used t o s a t i s f y t h e requirements o f LCO 3.7.10.
Two o f t h e t h r e e remaining t r a i n s (1-HV-F-42, 2-HV-F-41, and 2-HV-F-42) are requi r e d f o r independence and redundancy.
Upon r e c e i p t o f t h e a c t u a t i n g s i g n a l ( s ), normal a i r supply t o and exhaust from t h e MCR/ESGR envelope i s i s o l a t e d, two t r a i n s o f MCR/ESGR EVS actuate t o r e c i r c u l a t e a i r, and a i r f l o w from t h e b o t t l e d a i r banks maintains a p o s i t i v e pressure i n the MCR/ESGR envelope. The MCR/ESGR envelope consists o f t h e MCR, ESGRs, computer rooms, l o g i c rooms, instrument rack rooms, a i r c o n d i t i o n i n g rooms, b a t t e r y rooms, t h e MCR t o i l e t, and t h e s t a i r w e l l behind t h e MCR.
Approximately 60 minutes a f t e r a c t u a t i o n o f t h e MCR/ESGR b o t t l e d a i r system, a s i n g l e MCR/ESGR EVS t r a i n i s manually actuated t o provide f i l t e r e d o u t s i d e a i r t o t h e MCR/ESGR (con t i nued)
North Anna U n i t s 1 and 2 B 3.7.10-1
MCR/ESGR EVS-MODES 1, 2, 3, and 4 B 3.7.10 BASES APPLICABLE SAFETY ANALYSES (continued) by t h e control room accident dose analyses f o r t h e most l i m i t i n g design basis accident f i s s i o n product release presented i n t h e UFSAR, Chapter 15 (Ref. 2). This accident analysis assumes t h a t a t l e a s t one t r a i n i s aligned f o r c o n t r o l room pressurization approximately 60 minutes a f t e r actuation o f b o t t l e d a i r, but does n o t take any c r e d i t f o r automatic s t a r t o f t h e t r a i n s i n the r e c i r c u l a t i o n mode o r any f i l t r a t i o n o f r e c i r c u l a t e d a i r. Since, the MCR/ESGR EVS t r a i n associated w i t h 1-HV-F-41 can n o t be used t o provide outside a i r f o r f i l t e r e d pressurization (due t o the l o c a t i o n o f i t s a i r i n t a k e w i t h respect t o Vent Stack B) i t can n o t be used t o s a t i s f y t h e requirements o f LCO 3.7.10.
The worst case s i n g l e a c t i v e f a i l u r e o f a component o f t h e MCR/ESGR EVS, assuming a l o s s o f o f f s i t e power, does not impair t h e a b i l i t y o f the system t o perform i t s design function.
The MCR/ESGR EVS-MODES 1, 2, 3, and 4 s a t i s f i e s C r i t e r i o n 3 o f 10 CFR 50.36(c) (2) (ii).
LCO I
Two independent and redundant MCR/ESGR EVS t r a i n s are required t o be OPERABLE t o ensure t h a t a t l e a s t one t r a i n i s a v a i l a b l e t o be manually aligned t o pressurize and t o provide f i l t e r e d a i r t o t h e MCR/ESGR envelope, assuming a s i n g l e f a i l u r e disables one o f t h e two required OPERABLE t r a i n s. Total system f a i l u r e could r e s u l t i n exceeding t h e control room operator dose l i m i t s o f 10 CFR 50, Appendix A, GDC-19 (Ref. 3) f o r a l t e r n a t i v e source terms, i n t h e event o f a 1 arge r a d i o a c t i v e re1 ease.
I I
The MCR/ESGR EVS-MODES 1, 2, 3, and 4 i s considered OPERABLE when t h e i n d i v i d u a l components necessary t o l i m i t operator exposure are OPERABLE i n the two required t r a i n s o f t h e MCR/ESGR EVS-MODES 1, 2, 3, and 4. 1-HV-F-41 can not be used t o s a t i s f y the requirements o f LCO 3.7.10.
An MCR/ESGR EVS t r a i n i s OPERABLE when the associated:
- a. Fan i s OPERABLE;
- b. Demister f i l t e r s, HEPA f i l t e r s and charcoal adsorbers are n o t excessively r e s t r i c t i n g flow, and are capable o f performing t h e i r f i l t r a t i o n functions; and (cont i nued)
North Anna Units 1 and 2 B 3.7.10-3