ML20101J831
| ML20101J831 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 06/01/1992 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Dangelo T NRC |
| Shared Package | |
| ML19311A923 | List: |
| References | |
| NUDOCS 9207010268 | |
| Download: ML20101J831 (9) | |
Text
JUN 01 '92 04:46Pt1 G E tiUCLEAR BLDG J P.1 g 00 '
GEAbdouErwgy ABWR
- / /
Date 6/t /92 To Tony o %c,eto Fax No.
x-
-. o.e.y This page plus _5 L page(s)
From J Acw Fox Mail Code ML 175 Curtner Avenue -
San Jose, CA 95125 Phone (408)925 4 814 FAX (408)925-1193 or (408) 925-1687 Subject couvat e nut uvonoovnaw c t caer i
Message Arv4cuso etcasc e sum S RV L O AO E [ E!6 !S 2-M G6T \\M G)
- ATTAcausNT A -
'.ecrac%em s_ poa swatt toe tr/c /sweae) e
- ExMIB tT 6 - S ECY 3 57 T3SvG ll O')
- ATTA c u M s NT C - c MVG GT 4G AMD Co NTAw etsu T Lo AOS ( S/6 / 97. M GW M G }
n b.Y ha&f.
/
/M
/gldp './l//d /dd 9207010268 920601 t
^
g jk'[8/}lJEl I
/$/
A PDR J
z m _ m 1ee-r,1 x - > m1 em
, JUti 0. '9s' 04846Pri G E I W LEAR BLDG J P
ATTACHMENT A GE response to DSER open items, related to SRV actuation---loads, which woro' identified and discussed in GE/NRC neetings on May 6, 1992 at the NRC office in Rockville.
This response is consistent with the GE/NRC discussion in these-meetings.
OPEN ITEM 8
- 1. Address SRV loads resulting from valves reopening before the tailpipe is cooled and completely vented.
- 2. Were the suppression pool-temperature limits considered in analyzing steady stato SRV steam flow conditions?
- 3. The SRV discharge line X-quenchers are identical.to those used in the Mark II and Mark'III designs.
What are the benefits of this design to the ABWR?
The discharge loads for the ABWR were calculated as they were for the Mark II and Mark III designs.
Is this appropriate.
l l'
l-
RESPONSE
1.
In defining SRV actuation loads for' design' evaluation of-ABWRL c:ntainment, both first actuation and-subsequent actuation (i.e.,_
valve reopening before the-tailpipe ~is cooled'and completely _
vented) _ cases were considered"and analyzed.
These: loads were determinou Athi defined in accordance with the guidelines-specified' and documented in NUREG-0802.
- 2. Suppression pool temperatures associated with steady l state steam l
m _
JUN 01 '92,04847Pl1 G E IOCLEAR BLDG J P.3--
7 i-J condensation are no longer-needed and, hence, were not considered.
Recent studies (performed by GE for BWR Owners Group) have F
concluded that suppression _ pool temperature limits (specified in NUREG-0783) associated with steady state SRV steam flow conditions are not needed.
Steam condensation loads with quencher discharge
{
devices over the. full range of pool: temperature up to saturation 4
are low compared to loads due to SRV discharge-line air clearing and LOCAs which will be considered'and defined for-the ABWR 4
containment design evaluations.
Results and conclusions from these i
recent studies are described and discussed in NEDO-30832, Class I, l
-December 1984 (" Elimination or Limit on BWR Suppression Pool-l Temperature'for SRV Discharge With-Quenchers), which'is being reviewed by-the staff.
In view-of1the: conclusions.from these-I recent studies, it is now believed that suppression pool j
temperature limits (NUREG-0783) in analyzing steady state SRV steam p
-flow conditions no longer apply.
]
However, ABWR design does retain the-restrictions-~en the allowable operating temperature envelcpe intended to avoid unstable steam condensation, consistent with:the restrictions 41n place for curre'nt operating plants.
Also, ABWR suppression pool temperature monitoring. system conforms to the requirements and guidelines j
specified in'NUREG-0783.'
j 3.--ABWR-design utilizes the same:X-quencher discharge:-device as thati used in Mark II and Marki1II plants.
The development and design of
[
this. quencher device'was based:en_many_ years-of testing-and l
-development work, and' performance:of this device has been is well tested and confirmed through scaled and_large-scale (including.
-in-plant tests) testing.. This quencher; device has been f
demonstrated to be very_ effective in minimizing air-clearing-pool
' boundary loads, and in providing a stable' steam condensation L
process during steady state SRV steam flow conditions.
Therefore, m..
B, war 6MMeU'-- _ ~,..- _._,AtQbR JetifA.- JAL &.. _..
JLJi 01 '92 04:47PM G E ti) CLEAR DLDG J P.4 by utilizing this well tented quoncher device, ABWR design benefits from the many years of testing and development work, For detail on this sub-)ect, 000 attached EXHIBIT A 1
1 l
4 4
f
,, Ari 01 '92 0414?M1 G C f VLCAD DLEG J P,5 2XHIBIT A SAV Actuation Pqql_A nnd gy.jivArodynam_ic Lqqdt A nummary donoription of aRV actuation hydrodynamic loads and the methodology used in calculating and defining such loads for the ADWR design are described here.
- 1. INTRODUCTION During the actuation of a safety relief valvo (SRV), the air initially contained inside the SRV diachargo line is compresund and subseq"ontly expelled into the suppression pool by the SRV blowdown steam entering the SRV line.
The air exita_through holss drilled into an X-quenchor devico which is attached to the SRV discharge lino.
The X-luenchor discharge device promotes effective heat transter and stable condensation of discharged steam in the suppression pool, thereby minimizing suppression cool boundary loads.
ADWR design ut.4.lizes the same X-quencher discharge device as that used in Mark II and Mark III donignn, shown in Figure A-1.
The design conf 4 uration of this quencher device is based on many years of testing and developed work, and performanco of this quenchor device has been well tested and confirmed through scaled and large-scale (including in-plant tests) testing.
This discharge device has demonstrated its effectiveness in minimizing air-clearing pool boundary loads, and also provides a smooth and stable condensation C
process during steady state SRV steam flow conditions.
Thorofore, by employing this well donigned and tosted X-quanchmt discharge devico, ABWR design benefits from the many years of-testing and development work.
A reduction in the parl boundary loads will help in reducing the structure design cost, anC a stable steam conjunsation process mm,n.
,,Jun 01 '92 omem G t to:Ltra ILIG J P,6 1
should be of help ir, plant operation.
Figuro A-2 sho'^n tho quenchor azimuthal locationo in the suppronnion pool.
This arrannement distributan low, intermedioto and high pressure set-pcint valves uniformly around the pool region to preclude concerront adjacent valvon actuation.
- 2. QUENCHER DISCRARGE LOADS After the air exits into the nupprossion pool, during the actuation of SRV, the air bubblon (diccharging from holon in the quenchor arns) i coalesce and oscillate as Rayleigh bubble while rining to the pool froo nurfaco.
The oncillating air bubblon produce hydrodynamic loads i
on the pool boundary and drag loads on structures submerged in the pool.
After the air has been expelled, atoam oxits steadily and condenses in the pool.
This condensing steady state SRV steam flow j
has been found to produce negligible pronsure loading on the pool boundary, as evident from tanting of this X-quencher dischargo device The calculation methodology unod for defining the quencher air-clearing pool boundary loads for the ABWR design is based on and concistent with the staff approved methodology (documented in NUREG-0002) for Mark II and Mark III containments equipped with this X-quencher discharge device.
This methodology is baned directly on empirical correlations which woro developed from and based on data obtained from mini-scale, small-scalo, and large-scalo (including in-plant tests) tests conducted to develop a load definition methodology for X-quancher discharge loads during SRV actuation.
This 7
methodology defines correlations which can be used to calculato the magnitudo of quonchor air clearing loads on pool boundary an a 4
function of cavoral key parameters.
The key parameters are of two categories: i) which are rolated to the X-quenchor devico configuration, and 11) which are related to the plant specific SRV dischargo lino configuration mm v o,m m m _ m, _ % %._w
3 m i 01 '92 04 4PH G E lOCLEM DLDG J P,7 a
This Mark II and Mark TII methodology definon procedures for defining the pool boundary loads due to the first and subsequent DRV actuation (valve reopening before the ta11 pipe 10 cooled and completely ventod) conditions, and the loads due to multiple valvo actuation conditions (when more than one quencher bubble exists in the pool).
3.
ABWR DESIGN QUENCHER DISCKARGE LOADS P
3.1 Air Clearina Pool Bomidary LQAda Quencher discharge pool boundary loads for design evaluation of the ABWR design are dofined in accordance with the methodology defined in NUREG-0802.
In defining the design loada, both single and multiple valve discharges for first and subsequent actuations were considorod and analyzed.
The multiple-valven discharge caso covers the events in which all SRVu actuato-which would-result in mont' severe loading condition on the pool boundary.
For plant transients-which result in rapid RPV pressure increase rates, the valves are actuated almost simultaneously.
However,-variation in time of actuation, valve openi.1g time, and individua1' discharge lino longths will introduce differences in phasing of the oucillating air bubbles in the suppre ssion pool.
Prosence of difference in phasing'among tho-oscillating air bubbles is found to have a mitigating effect or the pool boundary loads.
As a conservative approach, ABWR design does not consider and take.
credit-for the mitigating effect due difference in phasing among the oscillating air bubbles.
Multiplo valvos dischargo case for.the-ABWR design considers and includes two loading conditions which reprenant
--n
-~
, A#i 01 '92 04:49F11 G C NUCLEAR DLDG J P8 most severe symmetric and anymnotric loading conditions.
a.
All oscillating air bubbles from all valves in phaso - the most novoro nymmetric loading condition.
b.
Occillating air bubbles in one half of the pool 1800 out of phase to those in the other half of the pool - the most severe asymnotric loading condition.
3.2 Sitadr. Sign LqondensAtion_C.QDditionn After air discharge through the SRV line is completed, steady steam flow from the quencher is established.
Discharged steam condenses in the immediatn vicinity of the discharge device.
Availablo test data indicate that SRV steady steam discharge through X-quencher device is a stablo atuam condennation procons resulting in an innignificant loading on the pool 'soundary, as shown -in Figure A-3. Thono loads are found to be substantially low compared to loads due to quenchor air clearing and LOCA pool boundary loads, Thereforo, dynamic loading condition during quencher steady stato steam condensation process is not considered and defined for the ABl!R containment design ovaluation.
operating practice of earlier DWRs, in anticipation that extended steam blowdown into the pool will heat the pool to a lovel where the condensation procona during steady state SRV stoam flow conditionn may_
become unstable, restricts the allowable operating temperature envelope of the pool-in the technical Specifications'so to avoid occurrence of unstable steam condensation.
NUREG-0783, currently, specifiou acceptance criteria related to the supproosion pool temperature limits for steady state steam condonsation :endition, as well as requiromonts and guidelines for the:supprossion pool temperature monitoring system.
Recent studies (performed by GE for BWR Owners Group), subsequent to
-um,-
__ - m_mm_um b
JLe4 01 '92 04 50Pl1 G C t0:Ltes DLDG J P.9 l
~
the iscuance of NUREG-0783, have concluded that steady steam flow through X-quencher devices is expected to be a stable and smooth l
condensation procoon over the full range of pool temperature up to i
naturation.
Results and conclusions from thono rocent studies aro l
l describod and discunned in NEDO-30832, Class I, December 1984
(" Elimination of Limit on BWR Suppression Pool Temporature for SRV l
Discharge With Quenchers"), which la being reviewed by the staff.
In view of conclusions from theno recent studies, it is now concluded that suppression pool temperature limits (specified in NUREG-0703) in l
analyzing eteady state SRV atoam flow conditions no longer apply, and,
(
hence, they were not considered for the ABWR design.
However, ABWR l
design does retain tne restrictions on the allowable operating temperature enve?ot,n, similar to those in place for current operating plants.
This will assure a more safor plant operation.
Also, the ABWR supprosnion pool temperature monitoring syntom conforms to tho l
requirements and guidelines specified in NUREG-0783.
l l