ML19345A526
| ML19345A526 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/03/1974 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8011240123 | |
| Download: ML19345A526 (14) | |
Text
Proposed Change No. 114 Supplem:nt No. 1 Telephone bl7 3bb-90\\\\
twx FIO-J 90 0739 YANKEE ATOMIC ELECTRIC COMPANY
/
m.
$N 20 Turnpoke Rood Westborough, Massochusetts 01581 Y
k'A M E$
~* /
May 3, 197' A C h ' Q f.)Ny
- q%
/
wwu
?
y% f:" r
/N t
us m h MAY u 1974
-G,
s
)
- k. -
N 'f $' N.
MAY 6 1974 * ?
-l United States Atomic Energy Cou: mission s;..a.,n Washington, D. C.
20545 Attention: Directorate of Licensing
/T -
- ')
$sNd[f 4~
84ss*7
/f
- aa sem
Reference:
1.
Yankee Aton.ic El'..:tric Ccmpany Proposed Change T
No. 114, Replacement of Core Instrumentation.
76 License No. DPR-3 (Docket No. 50-29) 2.
Telephone conversation with Mr. Fred Burger and Mr. Dunlop Scott on April 16, 1974.
Dear Sir:
The following additional information to Reference 1 is provided in accordance with Reference 2.
We are listing the seven questions of Reference 2 followed in each case by our response.
Question No. 1.
Provide a complete description of the new incore instrumentation similar to pages 107:1 through 107:8 of the Facility Hazards Summary Report (FHSR).
Response: We have attached to this supplement revised FHSR pages 107:1 through 107:10 that describe the proposed replacement incere instrument package.
If the Proposed Change, Reference No. 1 is approved these pages will replace existing pages 107:1 through 107:8 of the FHSR.
Question No. 2.
Include in the description figures similar to pages 107:4a and 107:4b of the FHSR that show the design of the flux
/
thimble seal at reactor head.
l l
Response: We are including four figures to show the design of the seals at the reactor head. These pages will be numbered 107:4 through 107:7. ~ 107:4 is a cutawsy view of the proposed instrumentation within the reactor vessel.
107:5 shows the details of the conoseals and is i
applicable to any one of the four head penetrations.
107:6 shows the pressure boundaries for the two thermocouple head penetrations while 107:7 shows the pressure boundaries for the riux detector thimble columns.
1 l
8011240/2 3 8
l EEGUL!CORY DOCKET FILE COPY h
m United' States Atomic Energy Commission May 3, 1974 Attn: Directorate of Licensint Page Two Question No. 3.
Describe in detail the leak detection system for thimbles and what capability exists for individual thimble isolation.
Response: The leak detection system consists of a drain header connecting the two ten path units and core paths C4 and DS, a pressure switch and drain solenoid valve in the drain header, and an alarm and reset button mounted on the control console. A leak in a thimble will cause water to flow up the thimble and collect in the drain header. The increasing height of water will actuate the pressure switch, which in turn energizes the console leak alarm and opens the drain valve.
Each thimble can be isolated by a shear valve, which is capable of isolating a thimble even if a flux detector is inserted in the core.
Question No. 4.
What is the basis for the conclusion that total ficw and flow distribution is not changed?
Response: Westinghouse Electric Corporation performed a flow /
pressure drop calculation which indicated that the change in pressure drop caused by the new internals structure is less than 5 psi. The margin of conservatism in the core performance calculations is such that this change is insignificant. This conclusion will be verified by actual thermocouple readings taken during plant startup testing.
Question No. 5.
Justify the acceptance of conoseal and svage seals used in the seal assembly as Class 1 features.
Response: The thermocouple seal assemblies which are the only places where svage fittings are used as Class 1 boundaries, are essentially identical to the seal assemblies used in present design Westinghouse plants.
The only differences are the use of a threaded protective cap versus a clip retainer design, and a slightly smaller diameter to fit the smaller reactor vessel head penetration inside diameter.
The conoseal design for both the flux columns and thermocouple columns is identical to that used on present design Westinghouse plants.
As stated in Proposed Change No. 114, the design of the seal assemblies, as well as materials of manufacture, are in compliance with ASME Section III requirements.
Question No. 6.
Provide assurance that flow induced vibration of the thimbles in upper plenum will not cause thimble failure.
Response: Flow induced vibration caused by cross flow in the upper plenum has been considered in the design of the instrument support structure.
In areas where the thimble tubes could be subjected to cross flow they are protected inside a conduit. This conduit is attached to the middle and l
upper frames of the support structure. Thus, integrity of the thimble tubes is assured by the integrity of the protective conduit.
Unitzd Stctes Atom.4-Ensrgy Cer,miazion May 3, 1974 Atta: Directorats
. Licensing Page Three The natural frequency, and forcing frequency for the conduits, as well as flow induced stresses were determined for the outer conduit and the clamps holding the conduits to the frames.
When dynamic amplification is taken into account, using a very conservative amplification factor, a stress level of 14,000 psi is calculated. This is well below the Code allowable limit of 26,000 psi consequently, fatigue is not a concern.
Question No. 7.
Considering the possibility of thimble failure and necessary isolation, will the thimbles be adequately protected against missile damage to preclude uncontrolled leakage of primary coolant?
e
Response
Experience with the original instrumentation system has shown that the leaks that have occurred in the thimbles were all located in the region of the reactor vessel head penetration. The new support structure has been designed such that the thimbles in the head oenetration area are not pressure boundaries; thus, we are quite confident that the probability of any more thimble leaks is quite low.
The leaks that have occurred in the past have not been catastrophic failures, but rather through-wall leaks of a small size. However, even assuming the extreme case of a complete circumferential severance of two chimble tubes, a failure of the external thimble tubes would not result in an uncontrolled loss of reactor coolant; the fluid loss from the two thimbles would be less than the capacity of two charging pumps (allowance has been made for one of the three charging pumps to be out of service).
Plant operations will be controlled such that no more than two failed thimbles will be valved out at any one time; if more than two are leaking a plant shutdown will be initiated to plug the leaking paths.
We trust that you v111 find this information satisfactory; however, should you desire additional information feel free to contact us.
Respectfully submitted, i
YANKEE ATOMIC ELECTRIC COMPANY Louis H. Heider Assistant Vice President COMMONWEALTH OF MASSACHUSETTS)
)ss.
COUNTY OF WORCESTER
)
l Then personally appeared before me, Louis H. Heider, who, being duly l
sworn, did state that he is an Assistant Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the fore-going request in the name and on the behalf of Yankee Atomic Electric Company and that the statements therein are true to the best of his knowledge and belief.
A Armand R. Soucy Notarf Public My Commission Expires September 9,.1977 y
6 107:1 Draft 107 CORE INSTRDENTATION Design Bases The primary function of the in-core instrumentation system is to provide measured data which may be used in evaluating the neutron flux distribution in the reactor core as well as outlet temperatures of the fuel assemblies.
This data may be used to evaluate thermal margins and to estimate local fuel burnup.
The bases for the design of the in-core monitoring system are as follows:
a.
Detector positions and thermocouple positions are selected to obtain a complete picture of the core temperature and flux pattern, using quarter core sy==ctry as an operating mode.
b.
Flux detectors of the movable fission chamber type are used.
c.
Chromel-alumel thermocouples are used.
d.
The information obtained from the flux detectors may be used for fuel management' purposes and to assess core performance.
It will not be relied upon for automatic protective or control functions.
The In-core Instrumentation System consists of Chromel-Alumel thermo-couples at fixed core outlet positions and movable miniature neutron detectors which can be positioned anywhere along the center line of the fuel assembly vertical axis. The basic system for insertion of these detectors is shown on page 107:8.
Thermocouples Chromel-Alumel thermocouples are inserted in guide tubes that penetrate the reactor vessel head through seal assemblies, and terminate at the upper end of the fuel assemblies. Thus they monitor the exit flow of coolant. The thermocouples are provided with two primary seals, a conoseal which seals the thermocouple columns to the reactor head and swage type fittings to seal the individual thermocouple tubes to the columns. The thermocouples are supported in guide tubes in the upper core support assembly. Thermocouple readings are monitored by a precision recorder located in the control room. The thermocouple locations are shown on page 107:9.
l Movable Neutron Flux Detector Drive System l
Miniature fission chamber detectors can be remotely positioned in guide thimbles to provide flux mapping of the reactor core. The stain-less steel detector shell is welded to the leading end of the helical wrap drive cable and to a stainless steel sheathed coaxial cable. The f
thimble paths, into which the miniature detectors are driven, enter the reactor core from the top of the reactor vessel. The thimble locations within the core are shown on page 107:9.
l'
107:2 Draft The thimbles serve as a pressure barrier between the reactor coolant and the atmospnere; thus, they are closed at the lover end and dry on the inside.
The drive system for the insertion of the minature dctectors consists basically of two drive assemblies, five-path rotary transfer assemblies, ten-pate rotary transfer assemblies, and stop valves, as shown on page 107:10.
Each drive assembly consists of a gear motor which pushes the helical wrap drive cable and detector through the selected thimble path and includes a storage device to accommodate the total drive cable length when fully retracted.
Manual isolation valves (one for each thimble) are provided for closing the thimbles. When closed, the valve forms a reactor coolant pressure barrier.
The manual isolation valves can isolate a thi=ble while a detector drive cable is inserted into the thi=ble by shearing off the drive cable.
A small leak would not prevent access to the isolation valves and thus a leaking thimble could be isolated during plant operation.
Control and Readout Description The control and readout system provides means for inserting the miniature neutron detectors into the reactor core and withdrawing the detectors while plotting neutron flux versus detector position. The thimbles are distributed nearly uniformly over the core with about the same number of thimbles located in each quadrant.
The control system consists of two sections, one within the vapor container, and the other within the main control room. Limit switches in each transfer device provide feedback of path selection operation. Each gear box drives an encoder for position feedback. One five path operation selector is provided for each drive unit to insert the detector in one of five functional modes of operation. A ten path rotary transfer device is used to route each detector into any one of up to ten selectable paths.
A common path is provided to permit cross calibration of the detectors.
The control room contains the necessary equipment for control, position indication, and flux recording for each detector. Additional panels are provided for such features as drive motor controls, core path selector switches, plotting and gain controls.
'A " flux-mapping" consists, briefly, of ' selecting (by panel switches) flux thimbles in given fuel assemblies at various core quadrant locations.
The detectors are driven to the bottom of the core and stopped auto-matically. An x-y plot (position versus flux level) is initiated with the slow withdrawal of the detectors through the core from bottom to a point above the top.
In a sbnilar manner other core locations are selected and plotted.
Each detector provides axial flux distribution data along the center line of a: fuel assembly. Various radial positions detectors are then compared to obtain a flux map for a region of. the Core.
107:3 Draft Support Structure The in-ccre instrumentation (thermocouples and flux detector paths) are positioned and supported in the reactor by the in-core instrumentation support structure, which is shown on page 107:4.
The support structure consists of three frames, a support plate, four guide columns, two thermocouple columns, two flux columns,. twenty-two flux detector thimbles and twenty-six ther=occuple thimbles.
Each of the three frames is constructed of flat stainless steel plate welded together to form a lattice.
The control rod guide tubes cccupy the open regions of each lattice. The support plate has similar holes for the guide tubes.
The two flux thimble columns and two thermocouple columns exit the r'eactor through the instrument port. penetrations in the reactor vessel head.
These penetrations are located above four of the eight fixed shim rods. A cross sectional view of the incore instrumentation is shown on page 107:4.
In order that the upper core support barrel can be removed and stored for refueling it is necessary that the flux thimbles be removed from the core.
This is accomplished by the telescoping guide columns.
The guide columns consist of an outer column, which supports the middle frame, upper frame and support plate, and an inner column, which is connected to the lower frame.
At refueling, the movable frames and plate are pulled upwards, which removes the thimbles from the core.
The structure is then locked in this position.
A cutaway view of the reactor vessel showing the new incore instrumentation equipment is shown on page 107:4. A general view of the conoseal arrangement for the four seal assemblies is shown on page 107:5.
Four seal assemblies are provided for the four instrument ports in the head.
The thermocouple column port seal is shown on page 107:6 and the flux column port seal is shown on page 107:7.
_.m
6 107:4 Draft N
It
" Q '^ O Q INSTRUMENTATIO!! PENETRATION
&pf i
SEAL ASS'Y (4) e gL6_uS l
(8[ff kll
' 2Ef 5
~
'N IN
[
b THERM 0 COUPLE SUPPORT I
'JI COLUMN (2) h dl]bd e
L j,jh Eq_
GUIDE COLUMN ASS'Y (4)
- s P.],c
- ' [= h :p FT.ggjAE$r
=e FLUX CCLUMN (2) j
/\\
M SUPPORT PLATE (1)
.l \\ m p,
/,
,6
\\
ma
., j N UPPER FRAME (1)
[%lt f $
C' j{![:' M j j
J MIDDLE FRAME (1) d-w4 B^TTOM FR#iE (1)
,/
V
[
THERMOCOUPLE (26)
[ ,
,f FLUX THIMBLE (22)
/f i
1 1
jM l
- % d N,7 2![h
?
.lk')
f,
. i-h
{
)
f h
I i
's, f
- I YANKEE R0WE IN-CORE INSTRUMEllTATION GENERAL ASSEMBLY POORDEciu...s l
107:5 Draft
!j4 C 75 l i
'I f
THERMOCOUPLE Ii ii THERMOCOUPLE REDUCING
~
UNION 1
P I
FLUX THIMBLE EXTENSION l{:,
CONDUIT
_ FLUX THIMBLE UNION
.i
~
l l
FLUX THIMBLE OR I
'~~ THERM 0 COUPLE CONDUIT
(
JACKING SCREWS METAL "0" RING SEAL J
(UPPER)
JACK SCREW PLATE METAL "0" RING SEAL y
(LOWER) f "Q' FN'd FN CLAMP
-s
'p INSTRUMENTATION
-fy
~ '-
}
lw MALE FLANGE i
Ak'N
~
i INSTRUMENTATION PENETRATION d
I TO VESSEL HEAD SEALING ARRANGEMENT
/,'
s
/~
'N HEAD ADAPTOR f
- ~700gj)2mem
107:6 Draft 0
THEP140 COUPLE O
REDUCING UNION d _._ __
SEALING SURFACE
./p THERM 0 COUPLE CONDUIT p
SV y
\\
k
'N SEAL WELD I
1e@
N~.
INSTRUMENTATION
- ~.
y 1,,
't
(
3 1 r
3 I f
1 i
I
['
f 1
'F 1
(
l
+
v.
s
. THEPJiOCOUPLE COLUMN s
1.#
s
-!s s
N s
ii THERMOCOUPLE CONDUIT s
N THE?f40 COUPLE COLUMN TO INSTRUMENTATION PENETRATION I
t s
SEALING ARRANGEMENT N
E r
>i i
i s
107:7 Draft L$ w
! 2 il SEALING SURFACE bII h1
-ih c>,
_ _ INSTRUMENTATION PEllETRATION
,B
'/ 1l.
I f
L L
i
/
/
FLUX COLUMN p
i-bl!
/ s r
t
- , 's
~.
i h,
j O/
2
]d b'
fM)bQ,
'N s -
t u,
L I
N, x\\ SEAL WELD s
N FLUX THIMBLE
(
a FLUX THIMBLE TO INSTRUMENTA-l
.I TION PENETRATION SEALING ARRANGEMENT f4ff/..;,
"il SUPPORT PLATE m-
.r
~
d 107:8 LRAFT SAFETY SWITCHES LlHIT SWITCHE' g
$-PATH TRANSFERS IN TERCCNNE C T I::0 ogsyg TU31NG UNITS
~
X-~~10-PATH TRAN
~
s j,.
ISOLATION VALYCS q
Q~
T/c
.. )
,1, i t
J 7
i i
f N
h V
l l
h lj7 b 5 ] $ :
? 95
!1 tjoea Us[?@)I]fnnM l
j il
<~' d u YANIG.E iiijCLEAR l
BASIC IN-CORE INSTRUMENTATION SYSTEM l
PC'.ER STATION t
l
i s
~
107:9 DRAFT no a..
g 9
gga i
m U
E a
o s
e a
w n
8 m
w a
d
=
8 R
u o
o e
o 9
M m
w s:
m
=
U R
a A
P e
$g o
8 S-g8
=
om o
B O
mo y
in g
m M
2 H
8
~~('
m.
E e
H 2
9 4
O D
I u
g g
3 M a bR f
E e
O*
O z
e o
E 9
Ed O
h"h g
L e
g e
d~
z s
6 to e,
0 0
G.
O e
j
~2 g
cc O
O O
O, 0
0, 0,
y 2
~
y 0
0 0,
O e
4 ta cc O
d O
g Q
O u
g N
O v
m b
a o
3
a
\\
4 i
l I
i 1
Drive A Drive B I
i i
i l
t l
5 Path 5 Path j
Transfer A Transfer B i
'i C4 E
DS S
N C4 E
DS S
i l
5
- Storage I
L s
Rf i
T I
c c
1 Notes 10 Path 10 Path i
Transfer A Transfer B 1.
Al, A2, etc. refers to drive paths, not core coordinates 2.
C4 is core path C4 3.
DS is core path DS g
A 10 B 10 A 9 B 9 A 8 B 8 ts e i
4 A 7 B7 i
l A 6 B 6 n 5 B5 o
i-a 4 B 4
)
A 3 15 3 A 2 B2 j
1 1
AEC D' l', *T'"I O : FOR F*RT 50 EFCURT PA TAL 7 7. p
, q ym y(T 3 p. '.'
i)
CONTROL N0:,,jg91
}
. mg(i i{
j
{)
'b m!'
l 7 77.g g
l F d0.4 :
!!EMO RPT O!. R Yankee Atomic Electric Compat Westborough, Massachusetts L. H. Heider 5-3-74 5-6-74 X
TO:
ORIG CC
Directorate of Licensing 3 signed 37 CI iSS UNCLASS PROP INFO INPUT NO CY3 REC'D DCCKZT 1:0:
XXX 40 50-29 E:iCLCSU?2S :
DESCRIPTION:
Ltr furn responses to 4-16-74 phone conversation Add'l info in support of proposed change re proposed change #114 and trans the following.,to Tech Specs #114 Ltr notarized 5-3-74 DO Nur ia.niu vm ACKNOWLEDGED PLANT Nid'Z : YANKEE ROVE (40 cvs anc1 ree'd)
FOR ACTICN/II:7C'E' TION SCTLE"(L)
SCID;2NCER(L)
ZID'.AN'i(L)
PIGAN(E)
W/ Copies W/ Copics W/ Copies W/ Copics CLARK (L)
STOLZ(I)
DICIER (E)
W/ Copies W/ Copies W/ Copies W/ Copies PNtR(L)
VASSALLO(L)
KNIGHTCC(E)
W/ Copies
,W / Copie:
W/
Copies w/ copies ENIEL(L)
/ PURPLE (L)
YCUNG;I. COD (E)
W/ Copies W/3 Copias W/ Copies W/ Copies INIC UAL DISTR'9U2 g.' :,G F I L.7.,
TECF REVI'~~'
Ddl ION A / T I ?"',
IENDRIE GRn'ES "IC ASa_i psaAIn;js
,m.
..a SALI2 MAN
/0GC, KCCM P-506A SCHRO DER CA}0'ILL DICGS (L) 3*
/1:UNIZING/ STAFF MACCARY KASTNER GEARIN (L)
CASE KNIGHT BALLARD GOUL30UFC;E (L)
PLA'S GI!O!SUSSO PAWLICKI SPANGLER LE r- (r )
Mw-,s m..,,LD u
l BOYD SIL\\0
!GIGRET (L)
DUBE w/ Input MOORE (L)(EWR)
STELLO ENVIRO REED (E)
IU 0 DZYCIPJG(L)(WR)
HOUSTON MULLER SERVICE (L)
C. EU SKOVROLT (L)
NOVAK DICKER SHEPPARD (L) l
- 3. EG (E/%-333)
/ COLLER(LJ tr ROSS KNIGHTON SLATER (E)
ECER P. COLLINS IPPOLITO YOUNGELOOD SMITH (L)
DENISE TEDESCO REGAN
/TEETS(L)
EISENHUT
/ M. JINKS (2)
LONG PROJECT LDR WADE (E) jREGOPR FILE & REGION (3)
LAINAS WILLIAMS (E)
MORRIS BENAROYA HARLESS g7;303 (L) l STFP,E VOLU!E'l EXTEFJiAL DISTRIBUTI O i
1 - LCCA' PDR l
/ - TIC (ABEi'i Ii'l)
(1)(2)(1G'-NATIC:3L LAE'S 1-PDR-SAN /LA/ST 1 - USIC(3rCHA:1AN) 1-is3LEP("/U Elds,:6 529) 1-GERALD L*.L'CU-~~~
1 - A2L3 1-W. Pc. u.u GN, Rm E-201 GT ER00KEAVE: UT.
'.2.~.
1 - P. R. DAVIS (AEROJET NUCLEAR) 1-CONSULTANT'S 1-AGMCD(1uth Gur:-a-
/16 - CYS ACRS h e..:G ND. MARK /ELisC/AG3AEIAN F31-3-12 7. CT.
Sent to Lic Asst Teets 5-7-74 1-GERALD ULi.!KSC:i.. 0CUL l-ED..!!ULLOs. 7-F 1-B & M SWINZ3 ROAD, Rm E-201 GT