ML19345A575
| ML19345A575 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 03/18/1974 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8011240223 | |
| Download: ML19345A575 (11) | |
Text
Proposed Change No. 114
@Mnio7 Fib Q7 Telephone bl7 366-90ll rwx 7tO-3 90-0 73 9 YANKEE ATOMIC ELECTRIC COMPANY n.
b-( YANKEE
_.mn 20 Turnpoke Road Westborough, Massachusetts 01581 N. -
c' m March 18, 1974 c3
\\k' P f I' N
[
bb United States Atomic Energy Commission c
g251974
- w Washington, D. C.
20545 A
"'?c:cmr I
Attention: Directorate of Licensing
Reference:
1.
License No. DPR-3 (Docket No. 50-29)
O /
g 2.
Yankee Atomic Electric Company letter dated September 18, 1972 3.
WCAP-7607 "In-Core Instrumentation,"
J. J. Loving, dated July, 1971
Dear Sir:
Pursuant to Section 50-59 of the Ccmmission's Regulations, Yankee Atomic Electric Company hereby requests to make the following changes:
PROPOSED CHANGE: Reference. is made to Section 107, Core Instrumentation, of the Facility Hazard Summary Report (FHSR). We propose the followin 4/g, A s 4
r
" Replace the present incore instrumentation system with y
a new system consisting of a support structure, twenty-six y Upf (26) thermocouple positions and twenty-two (22) flux path C
l positions. The control and monitoring system located in the t-i main control room will also be replaced.
r 4
(.
REASON FOR CHANGE: During the plant's two.ve year operating history, t.
h,gi i\\
l incore =onitoring systems (flux wires ano thermocouples) have required l
many repairs and/or modifications to keep the system operable.
Diffi-l culties have been experienced with the flux mapping drives, the drive control system and particularly the reactor vessel instrument port seal assemblies. At the present time a number of the flux wire paths are unusable.
I DESCRIPTION OF CHANGE: The,aresent incore temperature and flux wire path support structure will be replaced with a structure containing twenty-six (26) ther=occuple paths which will monitor fuel assembly outlet tempera-l tures at various positions in the core. The structure will also contain l
twenty-two (22) paths for the insertion of movable fission chambers to monitor the neutron flux within fuel assemblies located at various positions in the core. Page 107:3 of the attached Draft FHSR pages showa the core coordinates of the thermocouple and flux path positions.
8011240 M 3 l
O A
Unitsd Statas Atomic Energy Connission March 18, 1974 Atta: Directorate of Licensing Page Two The support structure rests on the upper core support plate, and is des gned to telescope to allow the flux thimbles to be withdrawn f rom the core at refueling. Figure 1 of this Proposed Change shows the structure in isometric view.
The control and monitoring equipment for the present system located in the main control room will be replaced.
Insertion of the movable fission chambers in the various paths and the indication and recording of the neutron flux signals and thermocouple readings will be accomplished from the main control room.
j SAFETY CONSIDERATIONS: The incore instrumentation system is not required for any protective or plant control systems; however, it is used to provide operating data that may be used for power shaping and core burnup deter-mination.
The incore instrument suyoort structure does not provide any core support function. The new structure will have a negligible effect on the reactor vessel pressure drop, and thus will not affect reactor vessel flow.
The flux thimble tubing and the flux thimble and thermocouple reactor vessel head port seals form part of the reactor coolant system pressure boundary. Since the interconnecting tubing between the reactor vessel head penetrations and the flux mapping system isolation valves, see page 107:4 of the attached Draf t FHSR, would be subjected to primary system pressure in the event of a thimble leak, the tubing and isolation valves are designed for primary system pressure and temperature.
COMPLIANCE WITH CODES AND STANDARDS: The new incore instrumentation system and support structure is classified in accordance with ANSI N18.2 " Nuclear Safety Criteria for the Design of Stationary Pressurized Water Reactor Plants". Under these criteria, the reactor vessel head port seal assemblies are Safety Class 1 and the flux thimble tubing in the vessel and exterior to the vessel up to the isolation valves are Safety Class 2.
l As required by 10CFR50, Paragraph 50.55a, these items are designed, fabricated and constructed in accordance with Section III of the ASME i
l Boiler and Pressure Vessel Code, Subsection NB (Safety Class 1) or Subsection NC (Safety Class 2) as applicable.
I Regulatory Guide 1.20 " Vibration Measurement on Reactor Internals" requires that reactor internals be subjected to pre-operational. testing to demonstrate that flow-induced vibrations similar in nature to those
_ expected during operation will not cause damage.
Yankee intends to meet the intent of Regulatory Guide 1.20 by employing the following test program:
l
United States Atomic Energy Cc= mission March 18, 1974 Attn: Directorate of Licensing Page Three "Following installation of the new flux =apping system incore structure, the new internals will be continuously monitored for vibration induced damage as follows:
1.
During nor=al operating conditions the flux =apping system will be lined up with all thi=ble isolation valves open.
This will ensure that any vibration induced tube failures, and the resulting leakage, will be =enitored by the leak alarm system, which is part of the flux mapping system.
The leak alarm will sound in the control room. If a leak develops the thi=ble isolation valves can be shut to li=it loss of coolant.
2.
At the first refueling outage following installation of the new internal structure, the structure will be visually examined to the extent practicable in the upper core support barrel, to determine if any damage has occurred. One core life, which generally represents in excess of one year of operation, yepresents approximately 10,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> of service, or 3.6 x 10 seconds.
Even at the unrealistically low frequency of 1 Hz the internal structure would have experienced 3.6 x 10 seconds cycles required by Regulatory Guide 1.20.
The calculated forcing frequency for the thimble tubes is approximately 30 Hz, thus 10' cycles will be reached after approximately 93 hours0.00108 days <br />0.0258 hours <br />1.537698e-4 weeks <br />3.53865e-5 months <br /> of operation.
3.
Prior to forming of the tubes for the structere they will be subjected to an external hydro test.
In addition, the formed flux thimbles will be internally pressurired to test the tubing integrity.
Yankee considers this program adequate to ensure the integrity of the syste= based on the following reascus:
i 1.
The structural portion of the incore system structure is very l
similar to the original structure, which has proven itself in 12 years of operation.
l 2.
The only significant difference between the old and new structure is the routing of the flux thimble and thermocouple tubing in the reactor vessel head plenum region. The proposed monitoring program will allow inspection of this area.
SCHEDULE OF CFE GE: This change will be implemented during the Core X - XI refueling scheduled to commence on May 10, 1974. Pages 107:1 through 107:8 of the FESR will be replaced _with the attached pages 107:1 through 107:5.
l l
United States Atcmic Energy Ccmmisssion March 18, 1974 Attn: Directorate of Licensing Page Four We trust you will find this information satisfactory; however, should you desire additional information feel free to contact us.
Respectfully submitted, YANKEE ATOMIC ELECTRIC COMPANY "Yh Louis H. Heider Assistant Vice President COMMONWEAL.TH OF MASSACHUSETTS)
)ss.
COUNTY OF WORCESTER
)
Then personally appeared before me, Louis H. Heider, who being duly sworn, did state that he is an Assistant Vice President of Yankee Atomic Electric Ccmpany, that he is duly authorized to execute and file the foregoing request in the name and on the behalf of Yankee Atomic Electric Ccmpany, and that the statements therein are true to the best of his knowledge and belief.
AR /
Armand R. Soucy Notary Public My Commission Expires September 9, 1977 I
.W-"'
e
li Thermocouple Column i
Guide L
Column ~
Flux (4)
Flux Column ll N$'
l.
M Thermocouple Column f
1 k
/
k
/
)
O e
eN cu t e
p r
y Support Flate f
l%
A
- s. $
l v
v h
/
l.
a t
Middle Frrae-1; s
Lower Frame
+
~
/
A 0
p
=-.
, '[
Thermocouples (26).
d.Q ks jr dj Flux ubles s
~
YANKEE NUCLEAR POWER STATION
-INCORE INSTRUMENT SUPPORT TRU
-FIGURE l.
f h
107:1 DRAFT 107 INCORE INSTRUMENTATION The In-Core Instrumentation System consists of Chromel-Alumel thermocouples at fixed core outlet positions and movable miniature neutron detectors which can be positioned at the center of selected fuel assemblies, anywhere along the length of the fuel assembly vertical axis. The basic system for insertion of these detectors is shown on page 107:4.
Ther=occuples Chromel-Alumel thermoccuples 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 svage type fittings to seal the individual ther=occuple tubes to the columns.
The thermocouples are supported in guide tubes in the upper core support assembly.
Ther=o-couple readings are monitored by a precision recorder located in the control rocm.
The thermocouple locations are shown on page 107:3.
1 Movable Neutron Flux Detector Drive System Miniature fission chamber detectors can be remotely positioned in guide thimbles to provide flux mapping of the reactor core. The stainless steel detector shell is welded to the leading end of a helical wrap drive cable and to a stainless steel sheathed coaxial cable. The thimble paths, into which the miniature detectors ?re driven, enter the reactor core from the top of the reactor vessel. TLe thimble locations within the core are shown on page 107:3.
The thi=bles serve as a pressur barrier between the reactor coolant and the atmosphere; thus, th:y are closed at the lower end and dry on the inside.
The drive system for the insertion of the miniature detectors consists basically of two drive assemblies, five-path rotary transfer assemblies, ten-path rotary transfer assemblies, and stop valves, as shown on page 107:5.
Each drive assembly consists cf a gear motor which pushes the helical wrap drive cable and detector through the selected thimble path by means of a special drive unit and includes a storage device to accomodate the total drive cable length when fully retracted.
Zanual 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 thimble while a detector / drive cable is inserted into the thimble 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.
Centrol and Readout Description The control and readout system provides =eans for inserting the miniature neutron detectors into the reactor core and withdraving the detectors while
107:2 s
DRAFT 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 rocm. 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 drived to the bottom of the core and stopped automatically.
An x-y plot (position versus flux level) is initiated with the slow with-drawal of the detectors through the core from bottom to a point above the top.
In a similar 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 of detectors are then compared to obtain a flux map for a region of the core.
I l
l l
Au / :.3 DRAFT
(
8
?
ge E
r 5
I U
o r
^
r.a
=
a o
a*
S m
8
=
to
.-a E*
4
+
m
=
s E
R x
o o
e U
R M
m w
m
=
d 5
R a
A 9
a u
=g o
S 31 M 8
)
=
o=
o B
O mo y
<b
)
G5 5
m 9
m,
-p 1
8
(~
n X
g a
l 29 4
O O
I g
g u
3 m
I 3=0 e
e o
2 E
O 2~$
k ge g
L O
0, s
e
=
d' 2
Ms d
Lu O
O 9
D O
4 32 g
3 0
0 0
0 0
0 e
e s
m2 y
0 0
O,
-Q g
g
]
cc O
d O
q Q
O U
g O
0, s
107:4 DRAn SAFETY SWITCliES LlHIT $wlTCMC' g
5-PATN TR ANSFERS-~,
IN T E RCOM h!C T I::'
drive TUSING gggy3
.-10-PATN TRANSFERS s
T ISOLATION VALVES T/C D
/
1
(~)
I,f i
f i
J c
i l
/
N h
V 1
l rney!nca gnrnsav m.
b
- k 53j Y!JillE tiUCI.ZAR ASIC M-COE MSTR N TAU 0iN SYS M P0h3R STATICII
i I
?
I i
Drive B Drive -A i
i i
l 5 Path 5 Path l
Transfer A Transfer B 1
C4 E
D5 S
N C4 E
D5 S
a I
- Storage n
s 3r s
r s
m T
c c
1 i
r v
e
)
Notes l
10 Path 10 Path i
Transfer A
. Transfer B 1.
A1, A2, etc. refers to drive i,
paths, not core coordinates
=
I 2.
C4 is core path C4 1
3.
DS is core path DS
(
A B
A 10 B 10 A 9 B 9 A 8 B 8 es i
A 7 B7
$0' N6 B 6 N C, a 5 B5 A 4 B 4 B 3 A 3 A 2 B2 1
1
l
'A AEC DIt IBUTION FOR PART 50 DOCKET MA,T_
,A, L 2490 (TEMPORARY FORM)
CONTROL NO:
PI*E: Fbd A
20 RPT OTER No$e'e Atomic Electric Coinpany W:ceborough, Mass. 01581 Mr. L.H. Heider 3-18-74 3-25-74 X
TO:
ORIG CC OTER SENT AEC PDR XXX AEC 3 signed SENT LOCAL PDR XXX CLASS UNCLASS PROP INFO INPUT NO CYL -
DOCKET NO:
XXX XXX 40 50-29 DESCRIPTION:
ENCLOSURES:
Ltr requesting a change to tech specs.....
Proposed Changes to Tech Specs....
notarized 3-18-74...trans the following...
ACKNOWLEDGED (40 cys encl rec'd)
DO NOT REMOVE PLANT NAME:
Yankee FOR ACTION /INFORMATION 3-25-74 JB BUTLER (L)
SCPWENCER(L)
ZIDiANN(L)
REGAN(E)
W/ Copies W/ Copies W/ Cord ts W/ Copies CLARK (L)
STOLZ(L)
DTC tR(E)
W/ Copies W/ Copies W/ Copies W/ Copies GOLLER(L) 7ASSALLO(L) t.tGHTON(E)
W/ Copies W/ Copies W/ Copies W/ Copies KNIEL(L)
'SCHDfEL(L)
YOUNGBLOOD(E)
W/ Copies W/fCopies W/ Copies W/ Copier
~
~
INTERNAL DISTRIBUTION
/
P(* FTIJJ TECH REVIEW DENTON A/T IND R
LIC ASST
' AEC PDR HENDRIE GRIMES BRAI'IMAN
/ OGC, ROOM P-506A SCHROEDER GAMMILL DIGGS (L)
SALTZMAN
/ MUNTZING/ STAFF MACCARY KASTNER GEARIN (L)
- 5. HURT CASE KNIGHT BALLARD GOULBOURNE (L)
PMNS GIAMBUSSO PAWLICKI SPANGLER LEE (L)
MCDONALD BOYD SHA0 MAIGRET (L)
/ DUBE w/ Input MOORE (L)(BWR)
STELLO ENVIRO SERVICE (L)
DEYOUNG(L)(PWR)
HOUSTON MULLER SHEPPARD (E)
INFO
/SKOVROLT (L)
NOVAK DICKER SMITH (L)
C. MILES P. COLLINS ROSS KNIGHTON
/TEETS (L)
B. KING DENISE IPPOLITO YOUNGELOOD WADE (E)
/ E. Coupe
/ REG OPR TEDESCO REGAN WILLIAMS (E)
WILSON (L))
PILE & REGION (3)
LONG PROJECT LDR S. REED (L MORRIS LAINAS STEELE BENAROYA HARLESS VOLIMER A_
EXTERNAL DISTRIBUTION E4 1 - LOCAL PDR d
/ 1 - DTIE(ABERNATHY)
(1)(2X10)-NATIONAL LAB'S 1-PDR-SAN /LA/NY
/ l'- NSIC(BUCHANAN) 1-ASLBP(E/W Bldg,Rm 529) 1-GERALD LELLOUC E 1 - ASLB(YORE /SAYRE/
l-W. PENNINGTON, Rm E-201 GT BROOKHAVEN NAT. LA3 WOODARD/"H" ST.
1-CONSULTANT' S 1-AGMED(Ruth Gusse: ant
/16 - CYS ACRS XZrDf23GC Sent to Teets NEWMARK/BLUME/AGBABIAN RM-B-127, GT.
3-25-74 1-GERALD ULRIKSON...ORNL 1-RD.. MULLER..F-309q
_