ML20244D943: Difference between revisions
StriderTol (talk | contribs) (StriderTol Bot insert) |
StriderTol (talk | contribs) (StriderTol Bot change) |
||
| Line 15: | Line 15: | ||
| document type = INTERNAL OR EXTERNAL MEMORANDUM, MEMORANDUMS-CORRESPONDENCE | | document type = INTERNAL OR EXTERNAL MEMORANDUM, MEMORANDUMS-CORRESPONDENCE | ||
| page count = 11 | | page count = 11 | ||
| project = | |||
| stage = Other | |||
}} | }} | ||
Latest revision as of 12:32, 5 October 2021
| ML20244D943 | |
| Person / Time | |
|---|---|
| Issue date: | 04/23/1986 |
| From: | Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Bernero R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20195F761 | List:
|
| References | |
| FOIA-87-714 IEIN-84-81, NUDOCS 8606120647 | |
| Download: ML20244D943 (11) | |
Text
_ - - _ _ - -
- v ATTACHMENT 2
/pe ency c UNITED STATES
- i y -
+y ,
g s
NUCLEAR REGULATORY COMMISSION
- RE GION I
. e, Q f s31 PARK AVENUE gs [f xiuc er rRussiA.eEuusvov4uir ie4os
[ APR 2 31986 MEMORANDUM FOR: Robert M. Bernero, Director Division of BWR Licensing, NRR FROM: Richard W. Starostecki, Director Division of Reactor Projects, Region
SUBJECT:
POTENTIAL GENERIC PROBLEM WITH BWR RHR VALVE MISALIGNMENT DURING SHUTDOWN COOLING OPERATION
REFERENCES:
(a) IE Information Notice No. 84 81: Inadvertent Reduction in Primary Coolant Inventory in Boiling Water Reactors During Shutdown ard Startup.
(b) AEOD Power Reactor Events, Volume 5, No. 4 (c) GE SIL No. 388, RHR Valve Misalig : ment During Shutdown Cooling Operation for Bds 3/4/5 and 6.
T*.is memorarduc describes a potentially generic problem with the BWR Residual Heat Removal (RHR) System Shutdown Cooling (SDC) mode design at some plants ar.d the inadequate controls by Standard Technical Specifications on these systems. References (a) and (b) describe recent events at BWR facilities involving inadvertent reductions in reactor vessel inventory while the reactor was shutdown or starting up. Reference (c) describes potential drainage paths from the reactor vessel that may occur due to operator error while in the RHR shutdown cooling mode and recommends that operating procedures and training p-ograms be upgraded as necessary.
During a routine resident inspector review of a Susquehanna Nuclear Safety Assessment Group (NSAG) report, several concerns were noted relating to the Technical Specifications governing the RHR system and the interlocks associated with the system. In addition, the report noted that current administrative controls were inadequate to define and control " operations with the potential for draining the reactor vessel". The report stated that a review of industry data, which included a draf t EPRI report (NSAC-88), identified 25 incidents involving inadvertent drainage of the reactor vessel. Of these events, 22 involved pathways in the RHR system.
The attachment to this memorandum describes the potential generic problem with the Residual Heat Removal System (RHR) Shutdown Cooling mode design and the applicable Technical Specifications. I recommend evaluating this item for a change to Technical Specifications or other appropriate action. Note that despite previous NRC and industry actions there continues to be a problem in this area. Seven additional events have occurred since issuance of Ir. formation Notice No. 84-81.
\8606120647 860521 1I /f 1 est suse-RD-89ENERIC W
2
- '_ Memorandum _for Robert M. Bernero If you have further questions, please call either Lore'n Plisco (FTS 8-717-542-2134) or Jack Strosnider (FTS 488-1123) of my staff.
1)
M R. W. Starostecki, Director Division of Reactor Projects
Enclosures:
~
- 1. Potential Generic Issue
- 2. Loss of Inventory Events Involving RHR System
- 3. RHR System Diagram 4 Technical Specification Table 3.3.2-1
E. Jordan, IE
- 5. Ebneter, RI C. Heltemes, AEOD CRP Directors, Regions II, III, IV, V J. Partlow F. Miraglia i
l 4
a i
l i
l 1
d e
! ENCLOSURE 1 l
l . POTENTIAL GENERIC ISSUE 1
i 1.0
Subject:
Residual Heat Removal System Valve Misalignment During Shutdown Cooling Operation.
2.0 Description of Problem:
During a licensee review of industry events, twenty-two incidents were identi.fied which involved inadvertent reduction in primary coolant inventory through the RHR system (See Enclosure 2). On six occasions the reactor vessel was drained directly to the suppression pool via the 20-inch shutdown cooling suction lines due to misalignment of the RHR pump suction valves. The flow rate through this path has been calculated to exceed 20,000 GPM.
2.1 RHR System Shutdown Cooling Isolation Automatic isolations are designed to shut the sh.tdown cooling suction valves in the event of excessive flow in the shutdown cooling suction line or low water level in the reactor vessel. Twenty-one of the vessel draining incidents occurred with the SDC suction valves (F008 and F009) open (See Enclosure 3). Nine of the events-were terminated by automatic closures of the SDC suction valve's. In three incidents, the automatic isolation function did not actuate when required.
Although these automatic isolations are extremely important during Operational Condition 4 and 5. Technical Specifications only require the reactor vessel low level and high flow isolation to be operable in Conditions 1, 2, and 3, when the valves will normally be closed (See Enclosure 4). This appears to be a significant ommission in the Technical Specifications, since it is clear that these solation signals should be operable when the valves are normally open.
2.2 RHR pump Suction Valve Interlocks There are a number of potential inventory loss paths on a shutdown BWR, many of which can be initiated by a single mispositioned valve.
A flow path exists when the suppression pool suction valve (F004) and shutdown cooling suction valve (F006) are open simultaneously (See Enclosure 3). Six events have been documented where the reactor vessel was drained to the suppression pool via this 20-inch shutdown cooling suction line path. At Susquehanna, interlocks exist to prevent opening the F004 valve when the F006 is open, and vice versa. There is no requirement to test these interlocks. A survey of other plants by the licensee and the inspector found that most have interlocks only one way, and some have no interlocks. It is vital to have the interlocks 4perable, but it is interesting to note that Technical Specifications are silent concerning the opera-bility of these interlocks during Operational Conditions 4 and 5.
Enclosure 1 2 2.3 Operations With Potentsgl, or Draining the Reactor Vessel Technical Specifications se ain numerous references to " Operations with potential for drainin3 the reactor vessel" (OPDRV) yet it is not defined. The bases section does not provide any guidance.
Susquehanna attempted to come up with their own definition in order to provide some guidance to their operators during outages in order to determine what activities should be classified as OPDRDVs. During certain equipment failure, Technical Specifications require suspension of these activities. Their review found that there were no formal controls implemented at the station. A survey of other plants found that no other plant had administrative controls or definitions, and PWR's did not even have the requirement in Technical Specifications.
The concern was if an LCO was to be entered, how do the operators determine which activities already in progress are OPDRVs. Additional concerns related to what minimum size opening constitutes an OPDRV, whether the elevation is important, and how many barriers were required to ensure work was not considered an OPDRV.
3.0 Corrective Action Susquehanna has implemented surveillance procedures and administrative controls to verify that the RHR System Shutdown Cooling isolation features are operable prior to Operational Condition 4 and 5. In
- addition the F004/F006 valve interlocks are tested prior to going into the shutdown cooling mode. The licensee is planning to submit a Technical Specification change to add some of these testing requirements.
The licensee has implemented administrative procedures which define and control operations with potential for draining the reactor vessel. For example, operation of the RHR system is an OPDRV unless the suction valves interlocks and SDC automatic isolations are operable. Systems with pene-trations greater than 1-inch below the top of the active fuel are con-sidered potential paths. Cavity drainage is also considered.
4.0 Generic Implications Industry experience shows that inadvertent reactor vessel draining can occur during RHR evolutions. Anytime that a manipulation of the RHR system is conducted when the SDC valves are open or are opened, the potential exists for draining the reactor vessel. There have been at least 22 docu-mented incidents of inadvertent reactor vessel inventory loss through the RHR system. (It should be noted that many of the events which may not be terminated by an ESF actuation, er which occurred prior to fuel load, were not reportable to the NRC). The SDC isolation on high flow / low level and the suction valve interlocks are vital in mitigating the event or preventing it. Current Technical Specifications do not require the automatic isolation instrumentation to be operable in Operational Conditions 4 and 5, when it is most likely to be needed. The suction valve interlocks are not addressed in Technical Specifications at all, and are also not included in some plant designs.
Enclosure 1 3 It appears that although there have been numerous inadvertent draining incidents, the industry is currently relying on procedural controls and operator training to prevent recurrence (See Enclosure 5). A review of the recent events reemphasizes that additional Technical Specification requirements may be warranted.
4 ENCLOSURE 2 LOSS'0F INVENTORY EVENTS INVOLVING RHR SYSTEM DATE PLANT EVENT DESCRIPTION 3978 Hatch 1 RHR Pump Suction Valves, F004 and F006, opened at the same time. Prior to fuel load. Vessel was drained to torus, torus drained to Rx Bldg. About 4 feet of water on lower level of Rx Bldg. No automatic isolation occurred.
1/8/79 Peach Bottom 3 Minimum flow valve (F007) failed open while (LER 79-002) in SDC. Loss of reac::r coolant to suppression pool tereinated by SDC isolation on low water level.
8/13/79 Hatch 1 While 'B' loop RHR was in SDC, reactor vessel decreased due to leakage in the F0048 valve.
5/26/80 Hatch 1 Minimum flow valve st.:k open while in SDC (LER 80-063) caused level decrease.
S/27/81 Oyster Creek While in SDC, reactor level began to
/,LER 81-038) decrease due to tube leaks in the RHR heat exchanger. i 6/11/82 LaSalle 1 Loop 'A' line drained during LLRT of ;
(IN 84-81) drywell spray isola ticn. valve. RPV drained l (LER 82-042) to RHR line when loop returned to service.
System automatically isolated on low level.
4/3/83 Grand Gulf Shif ting from SDC mode to LPCI line up but F004 and F006 valves were opened at the same time. F008 and F009 valves were also open. Indication light on SDC suction valve was burned out. SDC automatical)y
~
isolated to terminate drainage. Level >
decreased about 50-in:hes.
4/7/83 Susquehanna 1 Min flow valve open while aligning system (LER 83-056) for SDC. Level decreased 20-inches.
Enclosure 2 2 DATE PLANT EVENT DESCRIPTION S/15/83 . LaSalle 2 Draining RPV to suppression pool via SDC loop 'B'. While shifting to loop 'A' F004A and F006A were opened at the same time.
(Event was prior to fuel load). Control for SDC isolation valves had been transferred to the Remote Shutdown Panel which bypassed the interlocks.
9/14/83 LaSalle 1 LPCl injection testable check valve stuck (IN 84-81) open due to maintenance error. Drain path (LER 83-10i,) to suppression pool was set up by valve alignment for a relay logic test.
Level decreased 50-inches.
4/18/84 Susquehanna 2 F024A and F008 valves were not fully closed during flushing of RHR piping. Vessel level dropped 54-inches before automatic vsolation on low level.
5/22/84 Limerick 1 During process of filling and venting a RHR heat exchanger, the F004 valve in the other RHR division was opened. A manual crosstie valve between the pump suctions of both divisions was opened. When F008 and F009 valves were opened the vessel drained to suppression pool prior to fuel load.
S/23/84 WNP-2 Isolated line drained to LRW while warming (IN 84-81) up 'B' loop for SDC. SDC isolation valve inadvertently closed, when reopened RPV level was lost. Level decreased 25-inches before automatic isolation on low level.
9/9/84 Pilgrim Maintenance personnel stroked valve in containment spray line to check limit switch operation. One RHR pump was running in SDC and reactor vessel water sprayed into the primary containment.
9/24/84 Brunswick 2 RHR in SDC. Operator attempted to drain (IN 84-81) torus to LRW via RHR system, but forgot that system was aligned to SDC instead of torus cooling. Automatic isolation terminated event.
Enclosure 2 3 1
DATE PLANT EVENT DESCRIPTION 4/27/85 .
Susquehanna 2 Operator attempted to lineup 'B' loop RHR (LER 85-016) into SDC mode. Reactor vessel level decreased 35-inches and waterhammer occurred when operator opened heat exchanger bypass valve (F0488). Water from reactor refilled RHR piping which had been inadvertently drained to the main condenser during the warmup process.
Operator' attempted placing 'B' loop RHR into SDC mode. SDC isolated on high flow when reactor water filled injection line which had steam pockets.
5/7/85 WNP-2 Shifting from SDC to LPCI lineup. Pressure pool sucticn valve (F004) opened before SDC
- suction valve (F006) was shut. Operator did not allow for the stroke times of the valves.
5/16/85 Susquehanna 1 Min flow valve failed open while starting
'C' pump for SDC.
5/20/85 Susquehanna 1 Min flow valve failed c:en while starting
'A' pump for SDC.
7/26/85 Shoreham Shifting from SDC to LPCI. F004 valve opened before F006 valve shut.
9/24/85 Peach Bottom 2 Realigning 2A RHR pump from SDC to full flow test. Rx suction to 2C pump open F006L at same time discharge to suppression pool opea in 2A line.
1 J
ENCLOS0RE 3 c
. s
=
~1 e
2 5
- . .bE &
- $ JE4 -'
E '1.*/ O '
I69 p.4 -
- ; I.
- j
- . 4 .
i 13c= 4. e . .. . , .
a r- -
- =-
} - -
.s- I .-
ic : ra. -
l*
es
.4" gw' l==
g!g'i
-* & }
' 9 "- .
=.,
n q *
- i El ip ' =
=
2 Y m . IC I
. V. : L '_ 4,:
3: 1.%
,.- , )
~
- ?=
55 -
E:
- *c~ l' *
. ~ g
.J : 2% g .g . =
I -n-
- .J m ....
s,
- = == - Y
- : l
-*ws
=a: = ,J., __L.
= ,
- =6 ,
.y g ..
.i >
e
. .. . 2 v
E
' t - % , ,5 v3 5.* ."I .9 .~--
. I t s. u-.o,g .L n- --
.s
. =
? = :
2
. "et. .1 t r
- O 2.' ?'
f 1:1 9;,'; J .
.L .q 1
l __
j s = .
E,
<;"y i ::- .
=. :
l . _ ..."= ': :
= .
=
4 .'
i n ..
=
,N; J
tl. ,,: - , 4, .; .
v o.
o . g~ n ,. , -
y - , , , '..
e g i.' ;
- T e a ) . ,. {
C =
,m- M, --. v. . .rJ.: ' ,, - ; p . ,. : e I. ,i g *.
E
=
f,r '. 4 "' la p;, g
-< ,2 F, -e
- *;,7 ,....pA. , %4 ,-
g,
= . < .c n o
,..p- v a 5' .-
3 * - i= .
.<' 't sh " .
$'3 z -
. .C.- . e o '\ : : .
- : : : Pt.
2(h3r!
4 pf
" % , : .":"S
= ;-
= g
- 4. ( E* :.i~ -
M = (= - - I
- " : .o ,
'c 1 s./
~
~~
.. o 3 -*
- 4
-~
- l#.
-. L___ w-5 ... .J ' . =,1 ~
s g
3:O i .
- )
- O sd6 ff 4:
, 3 MM . - E. s
g -' r 2: ~ ' ' --- :
({i F - ~ - - -
"i 6
l l l N
O I
T C 6 6 6 6 6 4 6 A 2 2 2 2 2 2 2 L
EAN LNO BOI .
AI T 3 3 3 3 3 3 3 CTI I AD , , , , , , ,
LRN 2 2 2 2 2 2 2 PEO .
PPC , , , , , , ,
AO 1 1 1 1 1 1 1 N
O S)
I Lb T E(
A N
) T NM d N MAE e E UHT u M MCS n U I Y i R NES t T I L 2 1 1 1 1 1 2 n S MBP o N AI C I RR N
- I E A 2 T P L
. A O 3 U S
. T ) I 3 C a A ( E
.E N) D B A L N O s O A U M M M N Z B O I ( M A I Tl T T AA Y A LN A L OG R O SI P S I S S I
D h A ng E ii H - H
/ t h G u- 0 N C 1 I r3 e h H L e R r g O tl H u ai ah -
O ae R s eH eg n C Wve ( s e
r A -
ri i h
o e r
Al i N ll l r g t u W e eP t e t - i a s O s , s nr n i i s D sw eo s) ee eu ee l
t e T mt mr - i r U VL Vv pa pu n P H i i r i t w I S r- rs ue ua o l o os qp qr l l l M tl ti E m E e F a e E ce cm e p u w N T av ar RT R m R n y O S ee ee il H e H a r I Y Rl RP R a RT R M D T S C
N R U H . . . . . .
F R a b c d. e f g P
I R .
T 7 E 1l3REE2 ' EZ~
u); ,
u' '
" E 3&8e O.
.. ENCLO5URE 5
- )CLE A A SE AviCES DEPARTMENT e SAN JOSE. CALIFORNIA 95125 February 1983 SIL No. 388 File Tab E Category 4 AID-67 RHR VALVE MISALIGNMENT DURING SHUTDOWN C00LINC OPERATION FOR BWRs 3/4/5 AND 6 The purpose of this Service Information Letter is to transmit the subject Application ~ Inf ormation Document, AID-67, to owners of operating BWRs.
The document is transmitted for information only. For additional information contact your local General Electric service representative.
Prepared by: R. E. Bates Approved by: tH W Issurd by: -
D.L.Laytjn, Manager D. L. Allred, Manager Customer Service Support Customer Service Information Froduct
Reference:
Ell - Residual Heat Removal System l
GENER AL h ELECTRIC NO womanN*. on RErnESENTatsON (IPRESSED OR IMPLtED is uaDE wfTH RESPECT TO YME ACCumACY Cou%ETENE15 DR USEFmNESS Or TH5 iNr onuaisoN GENEna, ELE Cf AC CMANT ASSUMES NO RESPONSIBILITY FOR LiABtif v OR DAW AGE w<M MA Y RE SULT F ROM TME USE OF THIS INronwareoN I
e' .
e GENERAL ElECTRfC NUCI EAR POWER SYSTEMS ENGINFFRING DEPARTMENT
. APPLICATlON INFORMATION DoctMENT AfD. 67 OCTOBER 1987 RHR YALVE MISALIGNMENT DURING SHUTDOWN COOLlNG OPERATION FOR BWR 3/4/5/6 l
Prepared by: I hu
. A. Alem Mechanical Process Systems Design Approved by: (*
- A. J. Jernes, Meneger Mechanical Process Systems Design f5 d QA L. F. Fidrych, Manager Plant Systems Design C P 1 W A i d ,Je t. I '
J.p.Stapleton,' Manager Projects Engineering C. / M 'I B 06.1 g 6_s60521 %1) ,,
RD-BGENERIC 8
4
- DISCLAIMEP OF PESPONSIBIIITI Neither This document was prepared by or for the General Electric Company.
the General Electric Company r.or any of the contributors to this document:
A. Makes any warranty or representation, express or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this document, or that the use of any information disclosed in this document may not infringe privately owned rights, or ;
B. Assumes any responsibility for liability or damage of any kind which ;
may result from the use of any inforr.ation disclosed in this document.
I
.l j
l e '
45.82
a .
APSTRACT The Boiling Water Reactor (BWR) Residual Heat Removal (RHR) system is provided with several modes of operation. These modes of operation involve 1 both safety and non-safety related functions, and where practical, make ,
common use of the RHR components (pumps, heat exchangers, piping, etc. ) One of the most frequently used modes of the RHR system is the shutdown cocling ,
mode, which cools the reactor system and maintains the system in a cold shutdown condition. RHR shutdown cooling is entirely controlled by manual cperator actions and is, therefore, subject to operator error which could result in hydraulic and thermal conditions not specifically considered during the design process. The purpose of this Application Information Document ( AID) is to review issues associated with operator error during reactor system shutdown cooling of all classes of BWRs (3-6) and to highlight the importance of operator training and operator compliance with plant operating procedures.
I 4
l 1
l
- - - - - - - _ _ _ _ . _ _ _ ._ 1
. e
' TABLE OF CONTENTS I. INTRODUCTION b
II. RECOMMENDATIONS III. DISCUSSION
.es 65 i
l l
1
- 111 -
L___ ___
RER VALVE MISALIGNMENT DURING SHUTDOWN COOLING OPERATION FOR BWR t/4/6/6 I. INTRODUCTION !
j
' A. Backaround The function of the shutdown cooling aiode of the RHR system is to cool the reactor system and maintain the system in a cold shutdown condition. When in the shutdown cooling sode, hot water from the Reactor Pressure Vessel (RPV) is drawn from the RPV, cooled by the RHR heat exchangers (service water cooling), and pumped back into the RPV. Selected valve interlocks are provided in the RHR system to minimize valve misalignments and other operator errors during this mode of operation. However, a comprehensive valve interlock arrangement has not been provided for all the RHR valves that cocid be actuated during shutdown cooling. This approach is consistent with accepted design practices, and the RHR system design is considered fully acceptable and in compliance with all safety and non-safety related requirements. However, BWR field experience har shown such misalignment could result in RHR and related system components experiencing hydraulic and thermal conditions which cay not have been explicitly considered durir.g the design process, anc For EWE /f ,
in some cases, may result in limited equipment damage.
there is also a possibility that such valve misalignment could result in reverse flow of hot reactor water to the containment spent fuel storage pool via the RHR piping connection to this pool.
Such water intrusion into the pool could result in pool water contamination and undesirable increases in pool temperature.
1
s.
e B. PurDose It is the purpose of this Application Information Document ( AID) to review the technical issues associated with the operator errors during the shutdown cooling mode of RHR systes operation, and to alert the BWR Owners and their Architect Engineers ( AE) to the possible consequences of those errors.
II. ?ECOFFENDATION if necessary, It is recommended that Utilities review this issue and, upgrade their plant operating procedures / operator training programs to minimize operator errors duritIg cperation of the shutdown cooling mode of the RHR system. Furthermore, utilities may wish to assess the consequences of particular events resulting from any potential operator errors and identify any design actions they say consider prudent.
III. DISCUSSION The shutdown cooling mode of the RHR system is a manually operated mode.
It is placed into operation by the operator when the RPV pressure has 2
reached a predetermined icvel (cbout 135 psig for cost BWR pesduct lines),
nWK field esperience has shown snd the RPV water level is above level 3 1
I that, during shutdown cooling operation, operatora, on occasion have The correct inadvertently opened non-shutdown cooling RHR valves.
procedures for valving the shutdown cooling mode is specified in the RHR operating procedures presented in the GE Operation and Maintenance A
Instruction (0&MI) manual, and if followed, such errors will be avoided.
brief description of some of the possible operator errors which could are given in the occu,r, and the possible events following the error, following paragraphs and summarized ir. Table 1.
LPCI Suction Valve One of the possible plarit operator errors is inadvertent opening of the Low Pressure Coolant Injecticn (LPCI) suction line va;ve (E12-F004 ), which, when opened, vould allow the RPV water to flow ir.to the suppression poc1 (Path I/ Figure 1). At the present, there is a va;ve inter 1cck to 'mir.icize operator errors by preventing the shutdown cooling suction line valve (E12-is not fully T006) frc= cpening if the LPCI suction line valve (E12-F004) c1 c oe d. H ow ev er, an operator can inadvertently o;en E12-TC0h after shutdown cooling has been established, Thir flow condition could cabse significar.t loads on the interf acing cocponents such as the contair.cer.1 penetration, suction strair>ers, or pipe supports. Also, flashir.g coolc occur as the hot reactor e
Valve identities are for a typical EWR/6 RHR syetec. Equivalent valves en other product lines are identified on Figure 1.
?
~
, e water dapesssurizss in tha piping carrying it fro?3 th0 rSoctor to the suppression pool. This flashing condition could add to the loads on the RHR pump /sotor and piping. Incorrect opening of the LPCI suction valve is a consideration for BWR sodels 3 through 6.
With this type of valve misalignment, there is a potential for draining the reactor vessel down to Level 3 However, the shutdown cooling suction line isolation valves should close automatically when the vessel water level j reaches this point (Level 3) . Since Level 3 is well above the top or the l
l core, no core uncovery would result from misalignment or the LPCI suction valve, as the Reactor Core Isolation Cooling (FCIC) system and the other Emergency Core c ooling Systems (ECCS) would p*Yllte water to the vessel inventory below Level 3 In addition to this type or inadvertent misalignment, plant operators have deliberately used this flow path to lower the RFV water level during preof -
and startup tests. This incorrect use of the RHR system, which cay occur in Bk'R3 thru 6, has led to damage of the screens of the suppression pool suction strainer, and should not be used to lower RPV water level.
Test Return Line Valve RPV water can be diverted to the suppression pool when the RHB test returr.
line valve (E12-r02h) is f redvertently opened durir.g shutdown coo 11i:6 operation (Path II/ Figure 1). This (Iow condition, applicable to BWR 3 thru 6, coild cause significant loads on the containment per.etration, piping, and pipe supports.
k
a 4
~ . . e n e A P rey A A
. C unl / / / e Uti a N N N eLV R
se sv mal up a myV i B b, b, b, b, n e a a a a S
i t
wn oi M t l L E.
l F
B O
R P
T I N
f E M n N so l G t i o I
n rt o
. L t r ee b, b, b, b, oa pr P
1 A sunv a a pt t S et il a a uer n E.
I TeL R a V S ne e l M : en m B s nPl n A R t n a i n iprt ti r a T l i
e t R n i eS n o P m o F p / nn C m gi o O o nai r C i t t pe Y pncmp R i ouup A de PCSPU M t M n d. d. d, d. c ) ) ) )
t i
I Ct nv oee c, c. c. c, f e )a b cd c S_ P. t il a f I cL b, b, b, b, A u V a S a a n _
s e
t o
N t
ce 3 4 5 6 up d y R R R R oT W W W W r B B B B P
i