ML20133N246
| ML20133N246 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 08/02/1985 |
| From: | Ainger K COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 0457K, 457K, NUDOCS 8508130420 | |
| Download: ML20133N246 (13) | |
Text
{{#Wiki_filter:= 1 o / Commonwealth Edison One First Nation:1 Pirr*, Chic'go, lihno s Address Reply to: Post Office Box 767 Chicago, Illinois 60690 August 2, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Byron Station Units 1 and 2 Braidwood Station Units 1 and 2 Environmental Effects of High Energy Line Breaks NRC Docket Nos. 50-454, 50-455 50-456 and 50-457 References (a): May 17, 1985 letter from K. A. Ainger to H. R. Denton (b): May 20, 1985 letter from B. J. Youngblood to D. L. Farrar
Dear Mr. Denton:
Reference (a) informed you of revised predicted environmental parameters resulting from high energy line breaks in the Steam Generator Blowdown (50) and Auxiliary Steam (AS) systems. High energy line breaks in these systems were found to have a greater potential effect on environmental conditions than originally predicted. In order to justify continued operation of Byron Unit 1 until permanent modifications could be installed, we have posted personnel at designated locations in the Auxiliary Building so that the breaks could be promptly detected and terminated manually before environmental conditions exceeded predicted values. Included in reference (a) was a conceptual description of our plans for the permanent modifications to detect and isolate these breaks along with our schedule for installation of the modifications. Reference (b) provided your concurrence with our temporary measures to deal with the effects of these lines breaks and also requested that we submit the details of the permanent modifications for NRC review. Enclosed is a detailed technical description of the permanent modifications that will be installed by August 31, 1985 on Byron Unit 1. The modifications consist of temperature sensors mounted in potentially affected areas coupled with automatic isolation of the systems, control room alarms, and appropriate procedures. 8508130420 850B02 I PDR ADOCK 05000454 t p PDR j
m g H. R. Denton August 2, 1985 Similar modifications, depending on specific break locations, will be installed on Byron Unit 2 and Braidwood Units 1 and 2 prior to their ~ respective fuel load dates. Please address any questions regarding this matter to this office. One signed original and fifteen copies of this letter and enclosure . are provided for NRC review. Very truly yours, K. A. Ainger Nuclear-Licensing Administrator 1m Enclosure cc: Byron Resident Inspector 0457K l 1
7 ELB MONITORIDE/ ISOLATION DESIGN FOR SD AND AS SYSTEMS In order to assure that a high energy line break (HELB) in the Steam Generator Blowdown (SD) or the Auxiliary Steam (AS) Systems does not result in significant increases in Auxiliary Building temperatures, modifications are being made to isolate those systems in the event of a break. Due to the internal flow resistance of the systems and the potential for a variety of break sizes, system flow monitoring was found to not be an optimal method of break detection. The modifications, therefore, consist of temperature sensors mounted in potentially affected areas coupled with automatic isolation of the systems, control room alarms and appropriate procedures. SD SYSTEM MODIFICATIONS The SD System consists of blowdown lines from each steam generator which penetrate the containment boundary and travel through the Main Steam Tunnel to a point (station location Q-10) where the lines penetrate into the Auxiliary Building. In the Auxiliary Building the piping is then routed into the blowdown condenser room. Breaks are postulated at the point where the piping enters the Auxiliary Building and in the blowdown condenser room as shown on Figure 1C. Temperature Sensors are being installed at the locations indicated nn Figure IC. At each of these sensor locations, redundant 1E instruments will be installed, receiving power from electrical divisions 11 and 12, respectively. When the temperature in either area reaches 1500F, an alarm will be sounded in the control room and the four 50 containment isolation valves will be automatically closed as shown on Figure 18. These valves are shown on Figure 1A (S0002, B, D, F and H). As shown on Figure 1A, the 50 System has only one containment isolation valve on each line due to the fact that it is a closed system inside the containment and requires only one automatic isolation valve to meet GDC requirements for containment isolation. As a redundant feature to assure that the system is isolated in the event of a malfunction of one of the 5D002 valves, procedures will be developea to require local manual isolation of the system by closing the 50001 valves when the alarm in the control room is activated. This can be accomplished because the 50001 valves are located in the safety valve rooms which are remotely located from Auxiliary Building break locations. AS SYSTEM MODIFICATIONS The AS System provides low pressure (50 psig) steam to various Auxiliary Building loads including the boric acid and radwaste systems. Auxiliary steam is furnished either by the AS boiler or by extraction steam. In either case the AS routed to the Auxiliary Building flows through pressure )
. regulating valves AS013 and AS167 in the Turbine Building and is then routed in the Auxiliary Building in the AS Tunnel where it is distributed to various loads (see Figure 2A). At postulated break locations in the Auxiliary Building where the break is large enough to affect a large general area and the break effects cannot be shown to be restricted to non-safety areas, temperature sensors are being installed to alarm if the temperature reaches 1500F and to initiate automatic isolation of the AS System from the Auxiliary Building areas. Figures 2C through 2F show the break locations and sensor locations. The temperature sensor design provides lE redundant instrumentation at the necessary locations. When the temperature reaches 1500F, a signal will be initiated to close the A5013 and AS167 valves (Figure 28) and an alarm will annunciate in the control room. These valves fall closed and are located in the Turbine Building in the Category II portion of the AS System. The electrical system (cables, conduit, and solenoids) for the AS013/AS167 isolation is made up of lE components which have been reclassi-fled as non-safety because they cross into the Turbine Building, while in the Auxiliary Building the system is seismically supported. To assure that steam flow is isolated in the event of failure of the AS013 or AS167 valves, procedures will be developed rquiring local manual closure of valve AS012 after receipt of the control room alarm. This will provide redundancy in the isolation of the AS System and can be accomplished because the AT12 valve is located in the Turbine Building remotely located from the Auxiliary Building break locations. 0435K j
(- {lGURE 1A j STEAM GENERATOR BLOWDOWN CONFIGURATION 7 (UNIT 1) j .x 4 SDOO1 B,D, F orH SDOO2B,D, F orH _ __.4-- _+- - - + 1 .1 BLOWDOWN CONDENSER -i. 4+~ s.. g:;,. i% (.s'.' .$.S STEAM ^ _ ISOLATION VALVE ROOM _ STEAM TUNNEL AUXILIARY BUILDING -1 _ _4-p_ CONTAINMENT WALL s O e k e
F. ~ ] FIGURE 1B S.G. BLDN ISOL VALVES TEMPERATURE CONTROL ( BLOCK DI AGRAM ) AREA 1 AREA 2 } S D PIPE PENETRATION CORNER CONDENSER ROOM i (E21)E11 (E21)E11 (E22)E12(E22)E12 (E21)E11 (E21)E11 (E22)E12 (E22)E12 TEMP. TEMR TEMR TEMR TEMR TEMR TEMP. TEMP. SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH U .U U U ) .) U U U(E21)E11 I(E22)E12 RESET RESET HAND SWITCH HAND SWITCH I DESCRIPTION OF OPERATION SOL = c WHEN TEMPERATURE REACHES 150* F (2)lSDOO2B IN ANY OF TWO AREAS, THE CORRESPONDING 50L TEMPERATURE SWITC+iES WILL ACTUATE TO = C LOSE ALL FOUR ISOLATION VALVES. REDUNDANT SWITCHES ARE PROVIDED TO (2)lSDOO2D AVOID ANY MALFUNCTION. SOL VALVES REMAIN CLOSED UNTIL THEY ARE C ~ M ANUALY RES-ET. (2)lSDOO2 F SOL C (2)lSDOO2H
FIGURE 1C l STEAM GENERATOR BLOWDOWN SYSTEM HELB MONITORING h h (UNIT 1) g i 73-6 e i I (1 SDO1EB 3) (1SDO1EA 3) l l (1SDO1ED 3 1SDO1EC 3) OSDO1F 6) t 33 / / i 1 / -[ -1r- (( f I I I . g. g p 4p !!ll w fun'- n lllll y + A3OO a 5 L-A301 A304 5M: H q A302 x A305 I A303 (1SDO1LA 14 h N E TS E TS TS E TS E 7 <~ ~'t. P
- i. cs.
TS j=-d {1 . y, SDO1LB 14) TS I ~ // l E TS LEGEN D~. C FOR IGURES i E TS qg n{ . TEMPERATURE SENSOR 1SDO1A TUNNEL _ _ AUX. HIGH ENERGY LINE BREAK NO. EL.364'- O~ i BLM (= )LINE IDENTIFICATION fREA
c 3 flGURE 2 A AUXILIARY STEAM CONFIGURATION (UNIT 1) i a z _p-AS OAS013 OAS 012 [h ~ AUXILIARY -E' STEAM O AS167 BOILER '= = TURBINE AUXILIARY BUILDING BUILDING EXTRACTION ES STEAM 9 e rt
e FIGURE 2B AUX.STEhM ISOLATION VALVE TEMPERATURE CONTROL (BLOCK DIAGRAM ) f RECYCLE EVAP. RECYCLE EVAP. RADW.EVAP.OA RADW.EVAP.OB RADW EVAP OC AUX STM TUNNEL - OA OB E 11 E 12 E 11 E 12 E 11 E 12 E 11 E 12 E 11 E 12 E 11 E 12 TEMP. TEMR TEMR TEMP. TEMP. TEMP. TEMP. TEMP. TEMP. TEMP. TEMP. TEMP. SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH SWITCH l ) / l I I f / / l / l f / a6 ) ) ) ) U m s l' U DESCRIPTION OFOPERATION RESET RESET WHEN TEMPERATURE REACHES 150* F HAND SWITCH HAND SWITCH IN ANY OF SIX AREAS, THE CORRESPON DI NG TEMPERATURE SWITCHES WILL ACTU ATE TO CLOSE AUX.ST M.lSOL. VALVES (OASO13, OAS167). REDUNDANCY IS PROVIDED TO SOL AVOID ANY MALFUNCTION. l A VALVE REMAINS CLOSED UNTIL IT IS l MANUALY RESET. I OASO13-AFSV AND O AS 167-AFSV SOL B
- 8ASOl3-AFSV AND AS167-AFSV
<t
] FIGURE 2C AUX. STEAM SYSTEM HELB MONITORING (UNITS 1 &2) r ~ (AS TUNNEL AT COL M-23) 22 23 6*- O ' 21 _ l= = = 9'4 !5a ,s;.yao . 7 i.i Q: i.s.S 9::.- '~ 4 N .g a (O AS 33C - 6) ) = 1 (O AS 3OC - 4)
- 9 i
i i a, (O AS O3F -16) = ' h ~ TS i 3 =i.:. TS yys.:- . ; 6.
- s-q.:.
-:.' ni
- s e.;.
O BOTTOM TUNNEL -f EL. 3 9 4*- O A020 m S 9
- iX a
i . : v '. "IJ s * (s,Q ~, ~ "(l y ej e sis *: :L . q'e n 9 l l A O O 7}i } 'V{ 3 v. b-y 0%.k *- r.,.'.'..',. q,- i ~. 41,o r i / j p b / i I AO13 i I LEGEND: ^ SAME AS FIGURE '1C m m
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4 0 ~ 0 W c 3L f = B E ED.D l ,h, U l P I 2 TAO l iI EV B u [)) LEA S p O 2 2 )4 )4 ) I B B / / h4 3 3 1 B E D B-B A B )2 D - B 4 4 l P. D s A A B B A 6 6 0 O A L A 5 7 ) 3 3 S S S 2 6 3 A 3 AN F S A A A << F O 5 S VO S S 3 A c EC C A A O ( (O(O ~ S ~ I (O S A A S (O O I h(O T N )S (O A )) l 22 6 U S -'7 g 2T A. m M n S. = ^A ( M y .M G O l 4 N O O O I RR S S )6 % O t. A A u N OO TR A NO K B 'W% r I C( OT 3 A A O S c, 3 M R S F O A S O BO ~ A D2 L P (O D I A EA = se 3 H V 2 E E i: + 1 R ) M \\\\ U E 3 G E T I TS x \\ C l FSA g 'I p 4 YW Y E D l A h o O O}g -A S i j kS A M {L i' T A A B.2 O A 6 UP O 6 O A C F BV B A k Y E C S UEA I T A S J E l (O 2-4 S l R 4 R D. t' ( I l Y( j B 3 l 0 AN E I R A O VO l A 5 l EC M S l I ~ 3 3 3 4 T ~ '6 L S S X )6 A A A \\ I ]; ) 5 7 O U L O 6' E b l A B l 3X ] X a gY \\ 0 K S MT 6 a A 3 S O A ^ 9 v S (O 5 A U A ( O 3 (O C W O p A ^ C 't 5I E A ~s D A 6 S }:, N E 3 F
- f:
ER ,Q-G MU A A E S S l G E Al O (O ( ( (lL
FIGURE 2E 1 h AUXILIARY STEAM SYSTEM HELB MONITORING (UNITS 1&2) i AUXILIARY STgAM (RADWASTE EVAP. ROOMS) 7 3'- 6" I. -[5 (OWXY9AB 20) IN- ' 'Q g- -n i O E TS E TS E TS E TS. E TS O (OAS32AA 10 (OAS3 2 AB 1 OAS29A 10) f N 2AO10 2AOO8 4-N VAPOR BODY-i U TANK OWXO7DC U G~_D h .D ,_C- _ _9 i l g y x" N k T 2A614 - -l 3 VAPOR VAPOR v 3 3 O BODY TANK v BODY TA)4K @s - 2AO12 @s ss
- OWXO7DB, X
OWXO7D , 2A623 s i / 3 / d r N t n s [ 2A624D 7 2A606~ T - 2A604 2A600 M -_ fy 2A618 Z s_ 2A615 r._ j 2A619 2 A 605 2A609 s SA601 --d L " ~ 2A 610 - d' '-- J '-4 2A62O " ~Q ~ ^O' ~~ i 2A 611 'NN 2 A613 t L2 2A 602 [ PUMP 2AO11 A603 2A612 PUMP PUMP OWX31PA Q HEATING OWX31PB Q HEATING OWX31PC { HEATING ELEMENT ELEMENT ELEMENT OWXO6DA OWXO6DB ,(OWX113 AC 18 \\ l i (OWX113 AA 18 (OWX113 AB 18) EMPERATU RE SENSOR PROTECTING THESE AREAS ~ . LEGEND EL 414'-O' ALSO PROTECT AREAS SHOWN ON FIG. 2F (401'-O )' . ~ SAN 1E AS FIG.1C
FIGURE 2F h AUXILIARY STEAM SYSTEM HELB MONITORING (UNITS 1 &2) h AUXILIARY STEA/ (RADWASTE EVAP. ROOMS) 73'- 6* OAS 33AA-4 ) OAS32AA-10)(OWX105BB-2gOAS32 AB-10]' (OAS30 B - 4" ) ,';.{ .:i OASO3F-16) OAS 0 3G - 14) -{0 A S2 9 A - 10') ~ 24 M6 AOwx105BC-23 ouxime^-2r ap nc s <XI O5aA-2)- h gg pg C L_f J d I l l f M 1AO251 ),$ j (OWXIO5AC-2) IO5AE-2) d 6 31A6071 DWXI05AB-2) [, OWXl05AF-2) OWXI05AD-2) --(DAS95AA-2 ) h1 AO 5 ~ 1AO f][= (OWXY9AC-20) 1 6081 MAOl41 q I DWXY9AB20) N1AO211 H E GI w J t w / d RAD. EVAR RAD. EVAR "b RAD. EVAR 11A617 dONDEN$ER CONDENSER CONDENSER ONXO8DA CNVXO8C B OWX08DC OWXY9AA-20) l (O 3388-4 ) O AS 3OC 4F I ~ CAS33BA-4 ) -(H = " \\ h,h LEGEND-M33AB-4) M E: TEMPERATURE SENSORS A SAME AS FIG.1C PROTECTING THESE AREAS E L. 401*-0,, ARE THE SAME AS THOSE 1 NDICATED ON FIGURE 2E (EL414'-O~) .}}