ML20196G491
| ML20196G491 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/29/1988 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| A06837, A6837, B12810, NUDOCS 8803090210 | |
| Download: ML20196G491 (11) | |
Text
. _.
o:
e o[N O
General Offices
- Se' den Street, Berlin, Connecticut
'b T
)'iU$s5e 5Ec~o*=~
P.O. 80X ^io E.E"25.cc,~
HART {65 50dl ORJ, CONN ECTICUT 06141-o270 k
k J
(203'/
1 February 29, 1988 3
)
Docket No. 50-336 812810 Mi&d Re:
10CFR50, Appe:1 dix R t
U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 i
f Gentlemen:
)i Millstone Nuclear Power Sta' ion, Unit No. 2 +
10CFR50, Appendix lR Reauest for Exemotion By letter dated September ?5', 1987,(I) the NRC Staff transmitted to Northeast Nuclear Energy Company (liNECO) an inspection report provic'ir,g the results of an NRC special team safety inspection of Millstone Unit No. 2's conformance with sections of 10CFR50, Appendix R, Fire Protectici..
The inspection report identified one violation of 10CFR50, Appendix R, Section III.G.2.b, in that were separated by less than the required horizont3 'fliary feedwater headers redundant Isolation Valves 2FW43A and B of the aux 1 distance of 20 feet, and there were intervening combustibles present with rr suppresnion and detection capabilities.
In a let'.er otted October 23, 1987,(2) NNEC0 provided the NRC Staff with the response t'> the inspection report and committed to semit an exemption request to the NRC Staff addressing the subject auxiliary feedwater valves.
NNEC0 provided the NRC Staff with February 1, 1988, as the estimated exemption request submittal date. The exemption request is provided as Attachment 1.
The concept of equivalent fire protection $s established in Appendix A to Branch Technical Position APCSB 9.5.1 which recognized that there were unique plant configurations that required fire protection features that are r.ot identical to those listed as acceptable by the NRC Staff.
Some of these arrangements have been accepted by the NRC Staff as providing equivalent protection to the requirements of Section Ill.G of Appendix R based on the (1)
W. V. Johnston letter to E. J. Mroczka, dated September 25,
- 1997, "Inspection No. 50-336/87-16."
(2)
Letter dated October 23, 1987, "Millstone Nucle Ar Power Station Unit No. 2, Response to inspection Report No. 50-336/87-16.'
CMo f/@ N
\\ \\
{
8803090210 880229 DR ADOCK 05000336 W
PDR gl
I o
U.S. Nuclear Regulatory Commission B12810/Page 2 February 29, 1988 licensee's Fire Hazard Analysis. The exemption provisions of 10CFR50.48(c)(6) and 10CFR50.12(a) allow exemption requests if a licensee can show that the required plant modifications to meet one of the three stipulated requirements of Section III of Appendix R would not enhance fire protection safety in the facility, and the present configuration provides or ensures an equivalent level of fire protection.
NNECO requests that the NRC Staff apply this concept to the exemption requested in Attachment I since the application of *egulations in this partic-ular circumstance is not necessary to achieve, or would not serve, the under-lying purpose of 10CFR50, Appendix R.
The purpose of Section III.G of Appendix R is to provide adequate fire protection to structures, systams, and components important to safe shutdown. NNEC0 believes that the existing plant configuration discussed in Attachment I fully satisfies this requirement.
There is no need to provide additional protection or separation between redundant compc:1ents that will continue to fulfill their required functions in the event of a fire.
Also, NNEC0 believes that the exemption requested in Attachment I satisfies the standards of 10CFR50.12(a)(1) and 10CFR50.12(a)(2)(ii),
in that:
(1) this exemption, as described in, will not present an undue risk to the public health and safety, and is consistent with the common defense and security; and (2) special circumstances are present for this exemption in that the application of the regulation in this particular circumstance is not necessary to achieve the underlying purposes of Appendix R to 10CFR Part 50.
In addition, NNEC0 has held discussions with the NRC Resident Inspector and tha NRC Region I Staff concerning the acceptability of suspending the hourly fire watch patrol after submission of this exemption to the NRC Staff.
NNEC0 maintains that there are no safety concerns associated with the removal of the fire watch patrol and intends to suspend the fire watch patrol upon receiving concurrence from the NRC Resident and Region I Staff, expected on March 4, 1988.
Pursuant to the requirements of 10CFR170.12(c), enclosed with this exemption request is the application fee of $150.
We hope you will find this information satisfactory, and we remain available to answer any questions you may have.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY t
'E. A Mroczkay Senior Vice President cc:
W. T. Russell, Region I Administrator
- 0. H. Jaffe, NRC Project Manager, Millstone Unit No. 2 W. J. Raymond, Senior Resident Inspector, Millstone Unit Nos.1, 2, and 3
A Docket No. 50 115 B128.n Exemotion Reauest February 1988
B12810/Page 1 February 29, 19o0 Millstone Unit No. 2 Exemotion Recuest Exemotien Recuest Section III.G(1)(a) of 10CFR50, Appendix R, requires that one safe shutdown train remains free of fire damage.
To assure that one train remains free of fire damages,Section III.G(2)(b) of 10CFR50 requires that a 20-foot separa-tion zone free of intervening combustibles with suppression and detection exists between redundant components.
NNEC0 requests an exemption from the above requirement of Section III.G(2)(b) of 10CFR50, Appendix R, requiring a 20-foot separation free of intervening combustibles for the redundant Isolations Valves 2FW43A and B of the auxiliary feedwater heaters.
Description The auxiliary Feedwater Control Valves 2FW43A and B are normally closed.
At least one of the two valves is required to open to permit flow of auxiliary feedwater to a steam generator upon loss of normal feedwater.
The valves are located on the 14'-06" elevation of the turbine building (Fire Area R-3).
The valves and their control cables are separated by less than 20 feet with no fire barriers.Section III.G.2 of 10CFR50, Appendix R, specifies requirements for the separation of cables and equipment... "that could prevent operation or cause maloperation due to hot shorts, open circuits or shorts to ground, of redundant trains of systems necessary to achieve and maintain hot shutdown conditions...."
A circuit analysis was performed as part of the Appendix R compliance review which concluded that the only credible failure due to damage from a fire in Fire Area R-3 would cause the valves to go to the required open position.
Therefore, fire damage could not prevent operation of the auxiliary feedwater system.
On this basis, it was NNEC0's position that the separation requirements of III.G.2 were not applicable and that the valves, although not free from "fire damage," would open and an operable flow path would be maintained.
However, due to the critical nature of these valves, NNECO agreed during the Appendix R audit conducted by the NRC during the week of July 13, 1987, to formally submit the failure analysis and request an exemption to Section III.G.2 of Appendix R.
Area Fire Hazard Analysis The area Fire Hazard Analysis, as submitted previously to the NRC Staff in the Millstone Unit No. 2 Fire Hazard Analysis, is provided as Enclosure 1 to this attachment.
Justification for Exemotion The purpose of this analysis is to show that a fire in the vicinity of 2FW43A and B would result in the valve failing open.
The analysis specifically addresses 2FW43A. The analysis of 2FW438 would be similar and would result in the same conclusion.
q B12810/Page 2 February 29, 1988 The valves are air-operated.
Upon loss of air to the operator, the valves will fail open. They are equipped with pneumatic positioners for remote valve position control.
The positioner is controlled by a Foxboro I/P convei cer (PY5276).
The air supply to the valve operator is controlled by a normally energized, three-way solenoid (HY5276) located at the valve.
To initiate l
auxiliary feedwater, this solenoid would be de-energized to vent air from the operator allowing the operator spring to fully open the valve.
One possible failure is a 125-VDC
(+) hot short to Wire No. 21 of Cable Z1HV5276/B (reference attached sketch).
This hot short would prevent de-energization of HY5276.
However, even with this solenoid energized, the valve can still be opened pneumatically by the positioner mechanism.
Ther 0-fore, an additional failure is required to prevent this valve from opening.
The second failure required would be a hot short to PY5276, which operates on a 4-20 ma signal from a 10-VDC power supply.
On loss of the signal due to opens or shorts to ground, the valve would go to the fully open position.
The only available potential within the same conduit in Fire Area R-3 with the cable to PY5276 is 125 VDC.
Per conversations with the manufacturer, a two-wire (one positive and one negative) 125-VDC hot short applied to PY5276 would cause the low-voltage device to fail in the loss of signal condition causing the valve to open.
If the impedance of the hot short did result in a i
reduced voltage below the failure threshold of the device, it would have to be of the correct polarity to cause the device to supply air to close the ' valve.
The probability of a two-wire DC hot short of the correct polarity occurring from an external cabic is sufficiently low to consider the occurrence of the event incredible.
This is consistent with guidance provided in Generic Letter 86-10.
In summary, a two-wire DC high-impedance hot short of the correct polarity, which alone is not credible, would have to occur in conjunction with a Hngle-wire hot short on HV5276 to prevent 2FW43A or B from opening.
It is a..portant to note that sinea these dual failures would have to occur to both valves concurrently to render the auxiliary feedwater system inoperable, it is concluded that a fire in Fire Area R-3 could not prevent the opening of at least one of the two valves, u d auxiliary feedwater would remain operabl=.
t Note that this analysis does not take credit for the loss of the air supply to the valve operators, which could occur as a result of the fire and which would result in both valves opening regardless of the state of the electrical control units.
Based on the above, NNEC0 maintains that a fire in Fire Area R-3 would not prevent auxiliary feedwater from being supplied to the steam generators, and that this analysis provides the justification for the requested exemption.
i l
r
r e
1 fuMIME BUILDING AUXILIARY MILDING (EL. 14' 96')
fWIRE No. 21
% (+)
(
)
125YDC SM lM CABLE N0. 21HY5276/B i
(-)
HV5276 b
AUXILIARY FIINATER VT.O.
IMlf!ATION LOGIC CABLE N0.
r%
- 21HU5276/H 3
i A0Y T U
l l
--o 4-20 ne SICML ilNST.
'm 'T O.
(+) (-)
' AIR AuxlLIARY rupWifER PV5276 TLOW CON!R0L LOGIC 2-TW-434 1/F (YALUE $N0684 IN CLOSD POSIfl0N)
I 2
$XETCH OF 2-DI-436 O
b n
r--
S Docket No.50-33G B12810 Fire Hazard Analysis February 1988
FE i
Millstone 2 Fire Hazard Analysis Turbine Building Fire Area No. T-1 General Elevation Zone A El. 14' 6" Appendix R, Fire Area R-3 MAJOR EQUIPMENT Safe Shutdown Instrument air compressors (for shutdown) o Auxiliary feedwater cables (Trains A, B, & C) o Service Water Cables (Trains A, B. & C) o Auxiliary Feed Valves (2-FW-43 A & B) o Safety Related o
None Nonsafety Related o
None FIRE PROTECTION l
Suppression Wet-pipe automatic sprinkler systems provided for the north and south o
sides. The system control valves (2-FIRE-28 and 2-FIRE-33) are located at columns 18-E and 24-E, elevation 14'6", respectively. The systems alarm at the main fire alarm control panel C-26, Zone 4(N) and Zone 33(S).
Hose stations are located throughout the zone, o
Dry chemical and carbon dioxide portable fire extinguishers are located o
throughout the Fire Zone.
The auxiliary feed pump cable trays are prot-cted with a wet pipe o
automatic sprinkler system. The system does not have a control valve.
i o
The tool and equipment storage areas are protected with wet pipe autematic l
sprinkler protection. The systes control valve (2-FIRE-87) is located j
at column 25-E.5, elevation 31'-6".
The system alarms at the main fire alc.ru panel C-26, Zone 16.
Detection o
None 5-129 FRA-2 December 1986 L
4.
DESIGN FEATURES i
o-Ceiling - Open grating separates elevations 14'6" and 31'6".
o Floor --Concrete on grade.-
o North Boundary - 12 inch thick reinforced concrete exterior wall.
o South Boundary - Nominal 12 inch thick concrete block wall to Unit 1 with a rolling steel, 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated.. Class A fire door; 12 inch thick concrete block wall to Fire Area T-2 with a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, Class A door.
These walls provide an' approved 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated fire barrier.
o~
_ East Boundary - 12 inch thick reinforced concrete exterior wall, West Boundary - 2 feet thick reinforced concrete wall to the Auxiliary o
- Building, Large openings are located in the ceiling to upper levels of the Turbine o
Building.
5 COMBUSTIBLE LOADING Floor Area = 31,802 square feet COMBUSTIBTJ MATERIAL QUANTITY HEAT POTENTIAL (BTUs)
'}
Cables 596.35 cf 274,343,532
- Luba Oil'(Transient) 6,400 gal.
925,420,800 i
- supply for Turbine Lube oil system passes through the zone.
4 Heat Potential (BTU /fta) = 37,726 l
ASSUMED FIRE DURATION O h:urs 29 minutes CONSEQUENCES OF A FIRE Due to the fire protection features currently insta: ed, a fire is axpected to be rapidly detected and suppressed by either automatic suppression systems or manual fira fighting activities. Fire fighting strategies are available to assist the firo brigade in combating the expected fire hazards.
The fire protection features r
preytded for the zone will minimize any potential adverse impact. on safe shutdown
)
I capability.
_s i
5-130 FMA-2 I
December 1986 J
I 7 (immmusi " M y h i
c.
.M ' M i
l ni h
lljOM 1.y, >t j,t i i l
,i i
If Asm li a 1,-
- lgE I.
i lo h
,; 1 i,.A i e; l
4 j
OL.
I I
I et og
. ~ ai
- 'H I
il 's e i, e air, o
-~<4 ! O 6 "
I F
-l B ! !.
i rg i
a e
- u::
v 4
lif l
%!@[@
g, Il M* ll Y
n
's1 v
i hi _@d j l
l l@!Wti y i
t Iy
- T i
lua!!ut14 a4 c
i 3
O O
- unmiA, naaml rinir;r n:rls >
e.
o CU1 r
O 0,
!p3 r
y u n n n!:
i 1 I ~
R O
CH I
ll Cj'a
- a 8
p lj!,n!
! o 03 di;1'lI 1
C D%
i hl 18@
O g'
el.H i
i-CL Q=0 E dg' l l
O O
' !.,f l
i
_q'
,m l
ti i
l
=
l Le i
II
- _ -- I cm c'
r;;
s%
ll 7 ----!
=
i
!! !!f "i d l10
~
~
l~ l!_ qh.,i )1),
I 4i
@@@E@ i 118j3
__j l'.O li l
.flll5 " i 3 19 ll ,I I I I r:jt t-h r, v i li..- i j :i i l,i, l y ,c we .! b I 1: a e M II. in ' 1n jl 'oig/;ill;;l), l' ii 10 ; 7g ljj!! b-l il,g u! ~~ _3 i
== s c 3 ,0 t 3, [ r c
- a LI o
_ j g 5 O O l C;li II$ % o! _tm li8i! r jHll'U lg,l q 4 ,l pill j' l ' Q I A j i ,p d W I jf di ,a ~ a q ._l_._,_ .- h l}g e s II l ,}
- 3 e
i <s! E f._ u-~ da 3 ,r. m...., b r f - 3 1
- s m-i
'.l!d<h."'5, I! lll l s 'l, M i !!1815 I'j f, l 39 ;g;; g i e gli ol .,5, m I vi;u_, ; .i t a a s, 11 3 l I I d b
- llji, I. }
1gl_ L.,' a 1 l .iti )! i-i
9*821-g Su i TA ( ; )1 "'8' 1 3 Pi!! 2 I 'llGMii j!' .L ,1 i j . I-1- n 'I'" l.i e 'a.w. a l mi r 1 i ,., 3 .o s T}. fl4lL: A 0 l I I m ji 'l
- d O, '
o@f i .i-_;lj! a l g 'J so i 7 y) [y , 'g. v I ' J I, i$g) I I 5 II II, Is l v ,1 3: 2.!-4 'l ;li l li ,- e l 1 [g .n i I ll l l O oi 4.+...., O O iq ! @ O ci, 1 O 0; r! ! P ai,- -- - - - - - - s O oi i I O O! /Oihr!ii O fi-yg O o '"hi i L = 1 1 g l-g{ di l l _l Cl ,I g; @h 5) l j ll' J----..a 6 ~ n ~ ~ 1i-I' 3 i
- :' l i
il'O l' l l p.r., i ), it p .\\ \\ 2 5: f,h 'lllll l I l1 io '~ Ib I -i. 5 , j 't is ;Ij:jaji [ g , -,jl ~ h C.,1 8 lo y ,,L,!; Q oi l ~ %j o g r, u; N.cO! h o go
== l} d*l]I g. LJ [ l u n joo 'O I L i, u LJ
- y 3
jl1 p; I;oin i C-Cl w jj_ <3 i r g,"- s f E. I g-i Ja 55! .== l
- '}}