ML20203K850

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Rev 0 to Training Lesson Plan LO-LP-36102-00-C, Recognizing Core Damage:In-Core Instruments
ML20203K850
Person / Time
Site: Vogtle  Southern Nuclear icon.png
Issue date: 04/23/1985
From: Brigdon R, Scukanec D
GEORGIA POWER CO.
To:
Shared Package
ML20203K798 List:
References
LO-LP-36102-, LO-LP-36102-00, NUDOCS 8608210381
Download: ML20203K850 (15)
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Text

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TRAINING MATERIAL ROUTING

- i L.c 4 /-J6/d2-dc - u INING MATERIAL NUMBER 4

/ REVISED MATERIAL -

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REASON FOR REVISION:

9'4 d MAJOR REVISION DUE TO ERRORS OR OMISSIONS.

REVISION DUE TO CHANGES IN EQUIPMENT. l y REVISION DUE TO CHANGES IN PROCEDURES /0PERATING INSTRUCTIONS OR l POLICY.

DESIRE ADDITIONAL GRAPHICS / HANDOUTS FOR THIS TRAINING MATERIAL OTHER '

COMMITTMENTS: YES k NO DRAFIING REQUEST FILLD OUT. YES NO N DATE SUBMITTE FOR SUPERVISOR'S REVIEW 7/2//f4 REVIEW SAT UNSAT

' APPROVAL SIGNATURE M DATE f ***** DATE NEEDED FOR FROM TYPING 97 *****

LIBRARY CLERK: -

l DATE TO TYPING EN DATE TO DRAFTING M/

/

DATE FROM TYPING DATE FROM DRAFTING A// / h COMPILED MATERIALS TO INSTRUCTOR FOR REVIEW. DATE t

INSTRUCTOR REVIEW: TYPING SAT UNSAT DEAFIING SAT Un5a1 REWORK: WHY?

DATE NEEDED BY SUPERVISOR REVIEW: TYPING SAT UNSAT

. DRAFTING SAT UNSAT

' REWORK: WHY? ',

t DATE NEEDED BY

' SUPERVISOR SIGNATURE DATE LIBRARIAN RECEIPT FOR INCLUSION /0UTDATING OF FILES. DATE

) FILE WORK DONE DATE i

. 8608210381 860814 .

PDR ADOCK 05000424 V PDR

"te .-

,e' Geor8 ia Power POWE1 GENERAT10N DEPARTMENT Qh

,, y VOGTLE ELECTRIC GENERA {lN,G.yNP TRAINING LESSON F, b .h Mrf 3 U TITLE: RECOGNIZING CORE DAMAGE:

wr sF ' P-08L-INCORE INSTRUMENTS NUMBER: a. w -cc n.e r<c c -w-1.s y i

PROGRAM: MITIGATING CORE DAMAGE REVISION: 16 AUTHOR: RICHARD D. BRIGDON DATE: -+/Was-APPROVED:

((M. DATE: 9./13/f

REFERENCES:

NUREG 0737. ITEM II.B.4,%pRr b MITIGATINGCOREDAMAGE,f"INCOREINSTRUMENTATION,"GENERALPHYSICS CORPORATION MITIGATING CORE DAMAGE, " RECOGNIZING CORE DAMAGE: INCORE INSTRUMENTS,"

WESTINGHOUSE ELECTRIC CORPORATION VEGP FSAR APPENDIX 4A, " RESPONSE TO NUREG-0737. II.F.2 INSTRUMENTATION FOR DETECTION OF INADEQUATE CORE COOLING," AMMEND. 3/85.

MCD TRAINING. VEGP FSAR. CHAPTER 13: ITEM 13.2.1.1.6 INSTRUCTOR GUIDELINES:

Lo -Ho -36f c.2-do - c - ac i

, HANDOUT: "MCD: INCORE INSTRUMENTATION," GR-He-061 t .

I TRANSPARENCIES:

Lc - TT-3 G i o i,- co - a. - oo n L G%c tv c67GCTWGS to . TF-3 610 g -cEs -oc Z GR-TP-081 INCORE INSTRUMENTATION to - TP 3(. lot - co.t - c03 GR-TP-081-<2- MIDS BLOCK DIAGRAM to . TF-ur04-oc-c-C0 V SR-TP-081 TYPICAL MIDS NEUTRON TRACE to - rF- 3(,to 4 - C - COS SR-TP-081 MIDS - AT POWER MEASUREMENTS w -TP- 36io1- to (- t:0 6 SR-TP-081-5. MIDS - LOW LEVEL MEASUREMENTS g.o _ fp - 36,o z -cc 4- 00 '/ .SR-TP-081-6 MIDS - MEASUREMENTS USING SPECIAL BATTERY g , rp -36 sol -co-C-0C p -SR-TP-081 MIDS - LOW LEVEL MEASUREMENTS USING SPECIAL BATTERY LO- [F-3blo 2 -o c a- co q &W8 M M - MNm SWRG NBWM SN 4 0 - ff- 3b to 4 - ec s-c : o SR @ -08 M MCE W WE TRACE

(_o - Tr, 3G ic t - CO ^-C ' ' SR-TP-081-10 COMPARISON OF NEUTRON AND GAMMA RESPONSE

_ 7p, 3 q ;e: - co-c- c ! 2. SR-TP-08 !-il- ANTICIPATED LOW LEVEL TRACE - PARTIAL CORE VOIDING

_ .7p 3cl o t -Cc -' - Ot 3 SR-TP-081-12 ANTICIPATED LOW LEVEL TRACE - SIGNIFICANT CORE DAMAGE

-SR-TP-081-13 DISTRIBUTION OF INCORE INSTRUMENTATION bo -.ff-36 o: -CC * '-C Wo 77-36lc2 -00'C Cl5 SR-TP-081- T/CLAYOUT

<_o - TF- 36 e c a - Co -D Cib 9R-TP-081 UPPER CORE SUPPORT STRUCTURE co go -ff--rP-3=Iod-3 L I 41 - C CO* -- %-017t *.SR-TP-081 P -SR-TP-081-17 THERMOCOUPLE - VOLTAGE TABLE (TYPICAL)

TMI THERMOCOUPLE RESPONSE 1 C C - TF-AIC E ~ CD 'C'O **1 -SR-TP-081-18 TMI THERMOCOUPLE MEASUREMENTS g 36,c z co -c -cLc SR-TP-081-19 TMI THERMOCOUPLE TIME HISTORY l 1 G ,

9 MASIB COPY I

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.9 1. PURPOSE STATEMENT: .

" THIS LESSON DESCRIBES THE USE AND RESPONSE OF THE VEGP INCORE INSTRUMENT PROBABLE CORE DAMAGE DURING POST-ACCIDENT CONDITIONS.

i

11. LIST OF OBJECTIVES:

--Terminal Obj ective

-At--the end of this lesson,-the student.will understand..the use of-the-VEGP-incore._

-4netrumentation in monitoring-coraJonditions_during post-accident scenarios- to-assess the..

.. presence-of-core-damage.

Erdli ; ^tjn:1;u

1. List the incore instrumentation systems and describe the general layout of each.
2. Describe the setup and operation of the MIDS for measuring low le, vel gamma fluxes, for various conditions. " -

i

3. Describe, in general terms, the function of the:

1

-- Keithley Picoammeter

-- Picoammeter Source

-- Special Battery Power Supply

4. Discriminate between a normal low level trace and a trace involving partial core uncovery and/or significant core damage.
5. Describe how thermocouples are used to determine when inadequate core cooling exists.

-Successful-completion of- this -lesson will be evidenced by a minimum score-of percent on an oral or written _examinat_ ion.

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-SR=tt-1)81 Y lil. LESSON OUTLINE: NOTES I. OVERVIEW i

A. Incores utilized in post accident situations to: l-f-00l

1. Determine effectiveness of core cooling by measuring core exit thermocouples.
2. Serve as alternate method of determining reactor vessel water level.
3. Determine various levels of core degradation.

B. Incore Detector System consists of:

1. Moveable Incore Detectors
2. Core Exit Thermocouples II. MOVEABLE INCORE DETECTOR SYSTEM A. General System Description Note: Limit discussion of MIDS
1. Six fission chamber detectors which may be remotely to general overview
positioned in the core for flux mapping. " -

l 0

---a , s.

Uk8 3 - 90 percent enriched U-235

b. Neutrons interact with U-235 coating producing ion pairs which are collected by biased electrodes

- Current output proportional to the neutron

  • density in vicinity of the detector.
2. TP-oc 2.

Detectors driven into core via conduits from -GR-TP-081-b Reactor Vessel bottom head through concrete shield up to thimble seal table.

a. Thimbles closed on reactor end and are dry.
b. Conduits serve as extensions of reactor pressure boundary.

3.

TP-OO3 Six drive units push helical-wrapped cable through -SR-TP-081 thimbles.

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a. One detector per drive unit (A-F)
b. Each detector can service 20 to 30 thimbles (normally 10).
1) Positioning provided by 5 and 10 path
  • rotary transfer devices and wye units.

3

a .u n -. -

em =

-l'ill. LESSON OUTLINE: NOTES

2) Loss of one drive will not impair full

, functional capability of system.

1

c. Ruptured thimbles may be isolated at seal table with or without the detector retracted.

B. Ability of MIDS to Sense Gamma Levels

1. Designed to respond to neutrons, but will still TP-OC 4 S" r 001-3 detect gamma radiation.
a. Ionization of gas in fission chamber
b. Sensitivities
1) Thermal neutrons 10 -l7 amps /nv 1 nv = 1 n/cm -sec
2) Fast neutrons 10- amps /nv n = neutron density n

Camma rays 10

-14 ""

3) amps /R/hr Y = neutron velocity em see -
2. MIDS integrated output at 100 percent power i

i a. Reactor output

1) Thermal neutron flux 10 13 yy
2) Fast neutron flux 5 x 10 13 nv 8
3) Camma flux 5 x 10 R/hr
b. Full power MIDS output
1) Thermal neutrons 1 x 10-4 ,p,
2) Fast neutrons 5 x 10-5 ,,p,
3) Camma flux 5 x 10 ~0 amps
4) Totaloutpugissumof1through3:

approx. 10 amps Therefore: Gamma contribution at power is only approximately 3 percent of total I flux

c. TP-C CS MIDS recorder setup S". r -Goi-4
3. MIDS' shutdown output
a. Shutdown power level 4

, t U - f I- A l', l - L C, L.

-sa ua i' lil. LESSON OUTLINE: NOTES

1) Neutron level 10' nv 6
2) Gamma level 10 R/hr
b. MIDS shutdown output

~

1) Neutrons 10 amps

-0

2) Gammas 10 amps
3) Total output 10-8 ,,p,
c. Essentially all of detector output is due to gamma interaction.
d. MIDScapableofdgsplayingdetectorcurrents as low as 5 x 10 amps.

For reading shutdown conditions picoammeter must be utilized.

C. Low Level Detector Setup

1. Picoammeter used to: " -

I

a. Measure source and intermediate range flux during startup physics testing.

! b. Measure shutdown gamma plots

c. Measure coaxial cable leakage HL C06
2. Use accomplished by: -GR-TP-081 a. Connecting picoammecer input cable to detector power supply external connection.

. b. Placing front panel switch to external.

3. Picoammeter output available from:
a. Visible meter output
b. Recorder via battery supply chassis
4. Special battery j TP- C07
a. Used to power detectors if normal power 4R-TR-081-6 supply too noisy for low signal measurements.
b. Rated 0-100 VDC; 0-50 u amps
c. To place in service:

5

L.Q - < i - A l C <. s u %.

SR-LP-081 i;' 111. LESSON OUTLINE:

NOTES

1) Disconnect detector cable from normal SR-TP-08 F7-

, supply and reconnect to the battery. TP-CCf

2) Connect battery external connector to picommmeter.
3) Select the Keithley position.
5. Picoammeter Source
a. Used to bias out lov level leakage or noise signals for better resolution TP-C C9
b. Primarily used for calibration -GR-ir-08128-
c. Controls
1) Range switch (10 -5 to 10-12 ,,p,)
2) Multiplier Switches (3)
3) Polarity (1)
6. It should be noted that only one pair can be run " -

l at a time when using the battery and picoammeter.

! a. 7 minutes / pair m

b. 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> for complete nap

'\

D. MIDS Surveillance in an Accident

1. MIDS can be used to allow the operator to get a better understanding of core conditions under an accident situation.
2. Will cover four possible core conditions to illus-trate MIDS use and response
a. Only most obvious situations covered.
b. Operator taist be aware other conditions could exist. (Good system knowledge is required)
c. MIDS may not be completely functional during accident due to adverse containment conditions.

NkE: For first three situations the MIDS must be set j up in the low level configuration.

CONDITION I: SHUTDOWN CORE WITH NO VOIDING OR CORE DAMAGE A. Assumptions 6

c w -a- 4R-LP-081- wu x u

? lil. LESSON OUTLINE: NOTES Plant has tripped (ARI) 1.

2. Source Range detectors responding TP-cit, B. MIDS Response .SR-TP-081 ^ /
1. Signal almost total.ly gamma flux causing ionization of fission chamber gas.
2. Grid depressions primarily result of low burnout condition in area of grids (i.e., low gamma producing fission fragments).
a. Similar to neutron trace
b. Gamma producing fission fragment concentration in this area lower due to less fission.

Tf- O H C. Comparison of Neutron and Gamma Traces SR-IP-081-10

1. Gamma grid depressions not as deep or distinct as neutron traces N a. Gammameanfreepath(k g ) larger u -

- detector sees more area under gamma flux, 6

lessening the grid detail

b. Neutron depressions typically 15 percent lower than surrounding fuel area

- gamma depressions typically only 5 percent '

lower

2. Neutron traces have reflector peak at bottom of core whereas gamma traces do not.

- Reflector peaks would occur in upper core region but detector does not cover this area.

CONDITIONA: SHUTDOWN CORE WITH PARTIAL OR TOTAL CORE VOIDING A. Assumptions

1. Reactor shutdown (ARI)

Core half-voided (upper six feet steam) 2)

B. H:}SResponse

1. Lower six feet similar to CONDITION I indications
2. Upper six feet significantly different 7

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1R=hP-081 c' lli. LESSON OUTLINE: NOTES

a. Higher overall gamma level and grids are less SR-TF-661 l well defined. T1 O l '
b. Top core decay-off is more gradual than in the unvoided area.
3. Background for described conditions

(.- x steam "**

,- a. greater than

> O *' b. Therefore: detector " sees" a larger core area.

4. Characteristic Partial Voiding Response
a. The grids are less well defined
b. Top of core becomes less distinguishable.
c. Overall flux level is higher
5. Full Voiding Response
a. Grid smearing and gradual decay-off will " -

l exist at the bottom of core as well.

i i

b. Increase in signal level will not be apparent Note: Core plots shown are antici-i pated results based on engineering judgement.
  • CONDITION 3: CONSIDERABLE CORE DAMAGE WITH AND WITHOUT CORE VOIDING A. Assumptions
1. Core shutdown (ARI)
2. Fuel cladding considerably breached and loose pellets exists in some areas of the core.
3. Damage not so severe as to prohibit detector insertion.

B. MIDS Response for Fully Flooded Core

1. Loose pellets in top of core collected near grids co I{-(3I3 mem -0&1=12_

causing increase in indication 2.' Cladding failure predominant in upper, center core regions.

3. Peripheral assembly indications would be different 8

a . u . .s ~ e 4R-EP-081-lli. LESSON OUTLINE: NOTES C. MIDS Response for Partially Flooded Core

1. Indications in Part B would be superimposed on Figure shown for Condition II (TP- O t?- )
2. Signal level higher in voided regions
3. Decay-off at top and bottom of core will be more gradual in the voided versus non-voided condition.

D. Less severe conditions are more likely than conditions just discussed.

1. Significant cladding deterioration (pitted or breached) due to ZR-H2 O reaction.
2. Fuel stacks are still intact.
3. No significant characteristics other than previously discussed.

CONDITION 4: SIGNIFICANT CORE DAMAGE SUCH THAT DETECTOR INSERTION IS HINDERED 5: -

A. Assumptions

1. Core shutdown - all rods may or may not be fully inserted.
2. Core damage so severe as to allow only partial or no insertion of incore detectors.
a. Most likely to occur in upper, central regions
b. Amount of insertion available will give operator a general idea of amount of core damage.

B. Using MIDS to Locate Damage

1. Insert detector until stopped by damage and reading detector position to build 3-D map.
2. Picoammeter not needed for this core condition.

III. CORE EXIT THERMOCOUPLES A. GekoralSystemDescription

1.
  • 50 chromel-alumel thermocouples used to measure

(('-l4 S R=1r-us t at3-exit temperature

-$R-trpps43 14

2. Located on upper core plate at various locations. JarTP-0&E if'~lis 9

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SR-LP-081-S 1

lil. LESSON OUTLINE: NOTES 3.

Clad in stainless steel sheathed with aluminum

oxide insulation.
4. Thermocouple characteristics
a. T/C output linear with respect to temperature
b. Accuracy L) t2*F from 0 to 530*F
2) 13/8'F from 530 to 700*F
3) Upper limit - +2300*F B. Calculation of Assembly Enthalpy Rise
1. Initial Assembly Conditions
a. K designates assembly

, b. Tc- Assembly inlet temperature

c. Tk - Assembly outlet temperature d -

)

2. Calculation Assumpticus

}

a. Assembly enthalpy rise I

(delta h)k h(Tk ) - h(Tc)

b. Average core enthalpy rise '

h(TH ) - h(Tc) delta h ,,= L-B TH = hot leg temp.

where B = fraction of core bypass ficw B = .04 for VEGP Unit 1

3. Using above, F calculated delta H Peaking factor can be yT/C , delta h K deltaHK delta h core pT/C , h(Tg ) - h(Tc) j' delta H K ,

h(TH ) - h(T,)

(1-B) .

4. An incore flux map is performed and F 4 is
  • calculatedbyfluxintegrationtechnigggaH rg,1,,3 = integral rod powec for asseu m average rod power-10

. .- n ---- -w w -

ec-t.V-Juu1 c: u GR-L"-081-

III. LESSON OUTLINE: NOTES
5. F related to F by mixing factor M g.

ta delta H

\, s. u 4=Fdelta "K F

T/C J delta H K

b. Hg updated monthly and is based on full flow conditions.

NOTE: Keep in mind that under accident conditions.

F calculations generated by computer using mIIkngYactorsareinvalid.

Under post-accident conditions, the real parameter of concern is basically the thermocouple reading itself.

C. Thermocouple Indications on Plant Computer

1. Computer programmed for inadequate cooling
  • Presently Plant evaluations * ,,

" Vogtle-SPDS system

a. 5 T/C with range to 2200'F uses all T/C for monitoring ICC.
b. Remaining TC range to 1200*F.
2. Computer corrects all thermocouple readings for reference temp. variations.
a. 110*F variations
b. Accuracy 25% between 750*F and 2200*F D. Post Accident Monitoring
1. Computer inoperable
a. Expanded readings can be taken at the in-core display panel in control room
b. Reference temperature readings may be taken locally at Remote Processing Units (RPU) A3 and B3.
1) In case of off normal containment

, conditions.

2) Tables will be provided for conversions NMfr-
3) Readings taken with millivoit potentio-meter 11

g

=

cc -(,,,.. K j G -'; -

Sa-LP-081 --

i

'Ill. LESSON OUTLINE: NOTES

2. Exsaple Calculation i
a. Plant conditions
1) Containment temperature 360*F
2) Normal reference junction box temperature 160*F.
b. If remote reading at incore panel was 23.198 millivolts, what would actual exit temperature bei
1) 23.198 millivolts is more chan 1040'F (from table)

This reading is abnormally low due to ---

change in reference junction temperature (RJT).

2) RJT temperature correction EHF at 360*F = 7.427 av EMF at 160*F = 2.896 my " -

I' delta error = 4.531 mv

3) Actual Temperature = Measured EMF

+ delta error.

Actual Temp = 23.198 + 4.531 = 27.729 mv 27.729 mv 1230*F (from table) *

4) Calculation shows an error of as much as 200*F due to RJT variations Keep in mind that this error is short term since containment spray should reduce containment temperature.

E. Inadequate Core Cooling

1. For LOTW-LOCA accident the maximum expected exit temperature range is 620-650*F.

For small break LOCA's with minimum safeguards, j expected temps. may reach 700*F (will recover as

, level is reestablished).

2.' Basis for determining ICC is tied to T/C readings.

a. Indications of ICC* *From VECP E0P 1922H
1) T/C greater than 1200*F (any one) 12

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cc ~ c('- Al 2..- : '

4 -LF-081~~

fill. LESSON OUTLINE: NOTES i

2) T/C greater than 700'F (any one) and Reactor Vessel Level less than 39 percent (approximately 3.5 feet from core bottom)
b. Computer trend block includes:
1) Highest T/C Temperature
2) Ave RCS Pressure
3) Saturation Temperature
4) Saturation Pressure
5) Saturation Margin
6) Selected Thermocouple Temperatures (Average of 10 highest)
7) Source Range Detector Response
8) Intermediate Range Detector Response F. Lessons Learned from TMI " -
1. T/C Setup at TMI
a. 52 T/C located in core exit
b. Chromel-Alumel (same as VEGP)
2. Figure indicates number of fuel assemblies whose 774tf SR-TP-081-E7-readings were off-scale high four hours into accident (greater than 700*F).
3. 7-Ol et Figure shows more representative set of readings -SR-TP-081 (Taken by Met. Ed I&C Foreman)
a. Chaotic situation present
b. 2000*F difference between M9 and M10 possibly result of:
1) Substantial fuel movement from M10 to M9 (contributing to high heat load) j 2) T/C degradation

,g 4.[ Long term cooling process plot -SR-TP-081-19_.

a. Note some T/C still read off scale high and continue to do so.
  • 13

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n . - - - , - , .- . . , - . . - - - . - - . . , . - , - , . - . . - - . . - - . , ,-,n-~

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..- Ill. LESSON OUTLINE: NOTES

b. May be attributed to:

i

1) Fuel packing around T/C junction in T/C cups
2) Establishes inability to establish ~

adequate cooling.

5. Comment
a. TMI operators for the most part did not use incore instrumentation
b. Most data, though available, was taken as inconsistent with expectations and therefore inaccurate.

IV.

SUMMARY

A. MIDS can be used tot 1.. Readily determine damaged core conditions

2. Measure reactor vessel level (time consuming, so * -

i primarily a backup to RVLIS)

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B. Thermocouples can be used to:

1. Provide accurate indication of core cooling
2. Provide indication of core blockage C. Manual or remote overranged readings can be obtained and corrected for post accident environmental conditions inside containment. .

D. T/C and MIDS must be used together to provide an accurate indication of core conditions during normal and accident conditions.

i Can be used separately during accident to indicate i

general trend of core cooling.

! E. Inadequate core cooling exists if:

1. Any thermocouple reads greater than 1200'F or 2., Any thermocouple reads greater than 700*F and reactor vessel level is less than 39 percent (assumes RCP's operating). .

I

  • 14

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