ML050490046

Proposed Technical Specification Changes Implementation of Alternate Source Term Request for Additional Information Emergency Ventilation System

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, VIRGINIA23261 February 17, 2005 U.S. Nuclear Regulatory Commission Serial No.05-078 Attention: Document Control Desk NL&OS/ETS RO Washington, D.C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 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 Innsbrook 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.

Acknowledged before me this 17

!f%

day of .J.k6- ,2005.

A My Commission Expires: &. 3 J, .

(SEAL)

Attachment 1 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 (Dominion)

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 3.7.10.1 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.

Attachment 2 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 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) p r o v i d e s a protected environment from which o p e r a t o r s can c o n t r o l th,e u n i t following an uncontrolled r e l e a s e of r a d i o a c t i v i t y , The MCR/ESGR EHS co (LCO 3.7.13) an LCO 3.7.14).

The MCR/ESGR EV f i l t e r and r e c i r supply f i 1 tered independent and a c t u a t e automatically i n r e c i r c u l a t i o n . Either of these trains can a l s o be aligned t o provide f i l t e r e d o u t s i d e a i r f o r pressurization when appropriate. One t r a i n from the o t h e r 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 o u t s i d e a i r

• l+W approximately 60 minutes a f t e r the event.

Each t r a i n c o n s i s t s of a h e a t e r , 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 of gaseous a c t i v i t y

( p r i n c i p a l l y i o d i n e s ) , and a fan. Ductwork, valves, and instrumentation a l s o form p a r t of t h e system.

train$ a r e capable of performing t h e s a f e t y functions em@

s u p p l y i n g 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 , e e e

• a r e required f o r independence a n d redundancy.

Upon r e c e i p t of the a c t u a t i n g s i g n a l ( s ) , normal a i r supply t o and e x h a u s t 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 a c t u a t e 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 the 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 c o n s i s t s o f the MCR, ESGRs, computer rooms, logic 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 the s t a i r w e l l behind the MCR. Approximately 60 minutes a f t e r a c t u a t i o n of 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 m a n u a l l y 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 envelope through HEPA f i l t e r s and charcoal (continued)

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 by t h e c o n t r o l room accident dose analyses f o r t h e most SAFETY ANALYSES 1 i m i t i ng design b a s i s a c c i d e n t f is s i on p r o d u c t r e 1 ease

( c o n t inued) presented i n t h e UFSAR, Chapter 15 (Ref. Z).&,LLlseer @

The w o r s t 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 n o t i m p a i r t h e a b i l i t y o f t h e system t o p e r f o r m i t s d e s i g n 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 5 0 . 3 6 ( c ) ( Z ) ( i i ) .

L co p r e s s u r i z e and t o p r o v i d e f i l t e r e d a i r t o t h e MCR/ESGR r e q u i r e d OPERABLE t r a i n s

envelope, assuming a s i n g l e f a i l u r e d i s a b l e s one o f t h e two ld r e s u l t i n exceeding t h e c o n t r o l 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 t h e event r e 1 ease.

The MCR/ESGR EVS-MODES 1, 2, 3, a when t h e i n d i v i d u a l components necessary t o l i m i t o p e r a t o r exposure a r e OPERABLE i n t h e t .

• r e q u i r e d t r a i n s o f t h e MCR/ESGR EVS-MODES 1, 2, 3, and rL5m 3 0 +Mi: +,YaFR,)

An MCR/ESGR EVS t r a i n i s OPERABLE when t h e a s s o c i a t e d :

a. Fan i s OPERABLE;

b. Demister filters, HEPA filters and c h a r c o a l a d s o r b e r s a r e n o t e x c e s s i v e l y r e s t r i c t i n g flow, and a r e capable o f p e r f o r m i n g t h e i r f i l t r a t i o n f u n c t i o n s ; and c . Heater, ductwork, valves, and dampers a r e OPERABLE, and a i r f l o w can be m a i n t a i n e d .

The MCR/ESGR EVS i s shared by U n i t 1 and U n i t 2.

(continued)

North Anna U n i t s 1 and 2 B 3.7.10-3 R e v i s i o n 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 C o n t r o l Room/Emergency S w i t c h g e a r 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 it y System (EHS) p r o v i d e s a p r o t e c t e d environment f r o m which o p e r a t o r s 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 r e l e a s e 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% c a p a c i t y 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 s u p p l y 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 u n i t MCR/ESGR EVS t r a i n s on t h e a c c i d e n t u n i t can a c t u a t e 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 t h e s e t r a i n s can a l s o be a l i g n e d 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 a p p r o p r i a t e . One t r a i n f r o m t h e o t h e r u n i t can be m a n u a l l y a c t u a t e d 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 a p p r o x i m a t e l y 60 m i n u t e s a f t e r t h e e v e n t . 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 c h a r c o a l 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 i o d i n e s ) , and a fan. Ductwork, valves, dampers, and i n s t r u m e n t a t i o n a l s o f o r m p a r t o f t h e system. One EVS t r a i n i s capable o f p e r f o r m i n g t h e s a f e t y f u n c t i o n o f s u p p l y i n g o u t s i d e 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 r e q u i r e m e n t s o f LCO 3.7.10. Two o f t h e t h r e e r e m a i n i n g t r a i n s (1-HV-F-42, 2-HV-F-41 , and 2-HV-F-42) a r e r e q u i 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 s u p p l y t o and exhaust f r o m 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 a c t u a t e t o r e c i r c u l a t e a i r , and a i r f l o w f r o m t h e b o t t l e d a i r banks m a i n t a i n s a p o s i t i v e p r e s s u r e i n t h e MCR/ESGR envelope. The MCR/ESGR envelope c o n s i s t s o f t h e MCR, ESGRs, computer rooms, l o g i c rooms, i n s t r u m e n t r a c k 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 b e h i n d t h e MCR.

A p p r o x i m a t e l y 60 m i n u t e s 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 a c t u a t e d 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 t o t h e MCR/ESGR (con t inued)

N o r t h 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 by t h e c o n t r o l room a c c i d e n t dose analyses f o r t h e most SAFETY ANALYSES l i m i t i n g design basis accident f i s s i o n product release (continued) p r e s e n t e d i n t h e UFSAR, Chapter 15 (Ref. 2 ) . T h i s a c c i d e n t a n a l y s i s assumes t h a t a t l e a s t one t r a i n i s a l i g n e d f o r c o n t r o l room p r e s s u r i z a t i o n a p p r o x i m a t e l y 60 m i n u t e s a f t e r a c t u a t i o n o f b o t t l e d a i r , b u t does n o t t a k e any c r e d i t f o r a u t o m a t i c s t a r t o f t h e t r a i n s i n t h e 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, t h e MCR/ESGR EVS t r a i n a s s o c i a t e d w i t h 1-HV-F-41 can n o t be used t o p r o v i d e o u t s i d e a i r f o r f i l t e r e d 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 i t s a i r i n t a k e w i t h r e s p e c t 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 r e q u i r e m e n t s o f LCO 3.7.10.

The w o r s t 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 n o t i m p a i r t h e a b i l i t y o f t h e system t o p e r f o r m i t s d e s i g n 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).

I LCO Two independent and redundant MCR/ESGR EVS t r a i n s a r e r e q u i r e d 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 m a n u a l l y a l i g n e d t o p r e s s u r i z e and t o p r o v i d e 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 d i s a b l e s one o f t h e two r e q u i r e d OPERABLE t r a i n s . T o t a l system f a i l u r e c o u l d r e s u l t i n exceeding t h e c o n t r o l room o p e r a t o r dose l i m i t s o f 10 CFR 50, Appendix A, I

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 e v e n t o f a 1a r g e r a d i o a c t i v e r e 1 ease.

I The MCR/ESGR EVS-MODES 1, 2, 3, and 4 i s c o n s i d e r e d OPERABLE when t h e i n d i v i d u a l components necessary t o l i m i t o p e r a t o r exposure a r e OPERABLE i n t h e two r e q u i r e d 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 n o t be used t o s a t i s f y t h e r e q u i r e m e n t s o f LCO 3.7.10.

An MCR/ESGR EVS t r a i n i s OPERABLE when t h e a s s o c i a t e d :

a. Fan i s OPERABLE;

b. Demister f i l t e r s , HEPA f i l t e r s and c h a r c o a l adsorbers a r e n o t e x c e s s i v e l y r e s t r i c t i n g f l o w , and a r e capable o f p e r f o r m i n g t h e i r f i l t r a t i o n f u n c t i o n s ; and

( c o n t inued)

N o r t h Anna U n i t s 1 and 2 B 3.7.10-3