ML19263D274

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Summarizes 790306 Meeting W/Ge Re Proposed Statistical Method for Analyzing Rod Withdrawal Transient at Power for BWR/6s.W/list of Attendees,Meeting Agenda & Viewgraphs
ML19263D274
Person / Time
Issue date: 03/15/1979
From: Brooks W
Office of Nuclear Reactor Regulation
To: Kniel K
Office of Nuclear Reactor Regulation
References
NUDOCS 7903270233
Download: ML19263D274 (24)
v • d • e


Text

-

h UNITED STATES

[,.

j, h NUCLEAR REGULATORY COMMISSION (g !

WASHINGTON, D. C. "

g s

f MAR 151979 MEMORANDUM FOR:

K. Kniel, Chief, Core Performance Branch, DSS THRU:

G D. Fieno, Section Leader, Reactor Physics Section, Core Performance Branch, DSS FROM:

W. Brooks, Reactor Physics Section, Core Performance Branch, DSS

SUBJECT:

SUMMARY

OF MARCH 6,1979 MEETING WITH GENERAL ELECTRIC TO DISCUSS PROPOSED STATISTICAL METHOD FOR ANALYZING xvu WITHDRAWAL TRANSIENT AT POWER FOR BWR/6s A meeting was held with representatives of the General Electric Company and members of the staff on March 6,1979 in Bethesda, Maryland. The meeting was held at the request of General Electric to permit them to present to members of the staff some details of a proposed new way to analyze rod with-drawal error generic analyses for boiling water reactors of the BWR/6 class.

General Electric hoped to obtain some feeling for staff reaction to the proposal and staff concerns with respect to it. The attendees are listed in Enclosure 1.

General Electric proposes to perform a generic, statistically based analysis of the rod withdrawal transient for BWR/6 reactors and may later perform a similar analysis for BWR/4 and BWR/5 reactors. The reason for the present action is connected with the rod withdrawal limiter portion of the Rod Pattern Control System, which is to be employed on the B"R/6 class of reactors. The rod withdrawal limiter acts to limit the distan-that a control rod or con-trol rod bank may be withdrawn to an amount which is dependent on the core power at which the transient is initiated.

Because of the large number of calculations required and the difficulty of determining the worst case a de-terministic analysis for each plant is exceedingly expensive. Thus a generic, statistical analysis is desired.

General Electric presented slides (Enclosure 2) which outlined the methods and gave an example of their use. Several specific comments, in particular regarding the data base and the statistical formulation, were made by the staff and noted by General Electric for discussion in its proposed report.

This report will probably be presented as an appendix to the safety analysis report presented for the final design approval on the GESSAR docket toward the end of this year. General Electric has indicated that they will provide 7903270A3.3

K. Kniel.

a draft of this submittal within a few months and we will review and comment on prior to its formal submittal.

This meeting was concerned with the technical aspects of the proposal.

It should be emphasized that this proposal would introduce statistical.nethods into the analysis of a design transient. Such introduction ej.uquire man-agement attention.

X _D f,.:

~-

W. Brooks Reactor Physics Section Core Perfonnance Branch

Enclosures:

As stated cc. Joel Fray M/C 682 General Electric Company 175 Curtner Avenue San Jose, California 95125 D. Fieno H. Richings W. Brooks B. Morris H. Vander Molen R. Mattson F. Schroeder R. Fraley OR, SS&EA, PM, SS ads SD & RES ads I&E (3)

S. Varga L. Tripp D. Brinkman NRC PDR

List of Attendees General Electric flRC Joel Fray D. Fieno, CPB, DSS Dick Stinn H. Richings, CPB, DSS J. F. Klapproth W. Brooks, CPB, DSS B. Morris, RS, DOR H. Vander Molen, RS, D0R

Copies of Slides Providad hv General Electric

~

BWR/6 R0D WITHDRAWAL LIMITER SYSTEM PROPOSED ROD WITHDRAWAL ERROR GENERIC ANALYSIS AGENDA 1.

PURPOSE 2.

RBM VERSUS RWL SYSTEM 3.

PROPOSED PROCEDURE OVERVIEW 4.

DESIGN CRITERIA 5.

DETAILED PROCEDURE DISCUSSION 6.

PROCEDURE CONSERVATISMS 7.

SAMPLE CALCULATION AND PRELIMINARY RESULTS 8.

RWL PHYSICS DESIGN REQUIREMENTS 9.

MLHGR C0f.SIDERATI0r.i 10.

SUMMARY

JFK 2/21/79

THE PURPOSE OF THIS PRESENTATION IS TO PRESENT,AN OVERVIEW 0F THE BWR/6 R0D WITHDRAWAL LIMITER SYSTEM PHYSICS DESIGN REQUIREMENTS.

THE FOCUS IS ON THE CONCEPT.

THE NUMBERS HAVE BEEN CHECKED BUT DO NOT REPRESENT A LEVEL OF VERIFICATION CONSIST-ENT WITH A #1NAL DESIGN. JFK 2/21/79

R00 BLOCK MONITOR (RBM)

AND R00 WITHDRAWAL LIMITER (RWL) COMPARIS0N RWL RBM (PROPOSED)

APPLICABLE PLANTS BWR/2-5 BWR/6 POD WITHDRAWAL MODE SINGLE SINGLE OR GANG R00 BLOCK LOCAL FLUX DISTANCE INCREASE R0D WITHDRAWAL ERROR DETERMINISTIC STATISTICAL ANALYSIS PLANT SPECIFIC GENERIC ANALYTICAL METHOD OF 3-D BWR 3-0 BWR PREDICTING AMCPR*

SIMULATOR SIMULATOR OPERATING PLANT SAFETY LIMIT SAFETY LIMIT PERFORMANCE MONITORING MCPR MCPR UNCERTAINTIES AMCPR PREDICTION WORST CASE DESIGN BASIS AMCPR UNCERTAINTIES aMCPR FROM IS 95/ 50 FROM STATIS-CYCLE SPECIFIC TICAL ANALYSIS INCLUD-DETERMINISTIC ING aMCPR PREDICTION CALCULATION UNCERTAINTIES

  • CHANGE IN MINIMUM CRITICAL POWER RATIO

_ y.

JDC 2/21/79

PROPOSED GENERIC PROCEDURE OVERVIEW FLOW DIAGRAM BASE R00

();

PATTERNS f

q IMCPR* FIT AS GANGED R00 FUNCTION OF (2)

WITH0RAWAL (4)

POWER, FLOW SIMULATION

<r y

aMCPR FIT AS IMCPR 95/50 (3)

FUNCTION OF (5)

CURVE POWER, FLOW, FEET WITH-DRAWN, IMCPR 1r y

y ALLOWABLE WITHDRAWAL DISTA;CES AS (6)

A FUNCTION OF POWER

GENERAL COMMENT

S:

e STATISTICAL BASIS e

STANDARD DESIGN TOOLS INITIAL MIMINUM CRITICA~ POWER RATIO

_a_

JFK 2/21/79

BWR/6 RWE PROTECTION CRITERIA THE DESIGN BASIS AMCPR FOR RWE'S INIT I ATED FROM THE TECHNICAL SPECIFICATION OPERATING LIMIT AND MITIGATED BY THE RWL SYSTEM WITHDRAWAL RESTRICT-TIONS SHALL BE DETERMINED SUCH THAT THERE IS 95%

PROBABILITY AT THE 50% CONFIDENCE LEVEL THAT ANY RANDOMLY OCCURRING RWE WILL NOT RESULT IN A LARGER AMCPR.

. JFK 2/21/79

DETAILED PROCEDURE DISCUSSION STEP 1 BASE ROD PATTERNS AND NOMINAL IMCPR 1.

TYPICAL R0D PATTERNS COVERING ENTIRE OPERATING MAP.

2.

CONSTRAINTS MCPR > 1.20 MLHGR 1 13.4 kw/ft PREDICTED CRITICAL Keff +.005 3.

VARIABLE CORE PARAMETERS CORE SIZE CONTROL R00 PATTERN CYCLE CORE EXPOSURE XENON CONDITION POWER FLOW OUTPUT OF STEP 1:

IMCPR DATABASE AS A FUNCTION OF POWER AND FLOW. JFK 2/21/79

s e

FIGURE I NOMINAL IMCPR AS A FUNCTION OF POWER AND FLOW l

I f

I t

1 i

e i

BWR/6 OPERATING MAP 100 -

_ _ ]. _3 0. _

90 -

1.50 W

80 -

1.80 70 -

2.10 c

60 -

g

_ _ S d.Q. -..

f s'

50 -

2.80

~

g

~

y 40 _

y-m C=

30 -

,i 20 -

10 -

0 i

i i

i i

i i

0 10 20 30 40 50 60 70 80 90 100 PERCLNT CORE FLOW 6

6 JFK 2/21/79

STEP 2 STATISTICAL EVALUATION OF IMCPR 1.

STATISTICALLY FITTED 2.

CURRENT MODEL QUADRATIC IN CORE TOTAL POWER AND FLOW OUTPUT OF STEP 2r 9 5 , P R O B A B I L I T Y / 5 0 *c' CONFIDENCE IMCPR AS A FUNCT'ON OF CORE AVERAGE POWER AND FLOW. JFK 2/21/79

STEP 3 IMCPR CURVE 95/50 1.

IMCPR 00'4 N RATED. LOW CONTROL LINE AND 95/50 fil N I MUtd FLOW CONTROL VALVE LINE 2.

IMCPR VALUES EASILY ATTAINABLE WITHOUT R0D PATTERN OPTIMIZATION.

3.

RWL SYSTEM NOT RE0VIRED BELOW 20% POWFR.

OUTPUT OF STEP 3:

IMCPR AS A FUNCTION OF CORE POWER 95/50

_9_

JFK

FIGURE 2 BWR/6 IMCPR CURVE 95/50 3.20.

3.00-2.80' 2.60-2.40' 2. 2 rf i:

E

!E 2. c r.

1.87 1.60-1.40-

1. 2 &

1.00 i

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20.0 40.0 60.0 80.0 100.0

-10_

JFK CORE F0WER (%)

f FIGURE 3 BWR/6 IMCPR CURVE S5/50 COMPARIS0N TO OPERATING PLANT DATA

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1.0u 0 20.0 40.0 60.0 80.0 100.0 JFK CORE POWER (%}

2/21/79

I STEP 4 GANG ROD WITHDRAWAL SIMULATION 1.

INITIATE RWE FROM R00 PATTERNS DEVELOPED FOR IMCPR CALCULATIONS (STEP 1).

2.

INCREMENTAL WITHDRAWAL OF "RANDnM", HIGH WORTH GANGED CONTROL RODS.

OUTPUT OF STEP 4:

AMCPR DATABASE AS A FUNCTION OF POWER, FLOW.

FEET WITHDRAWN AND IMCPP JW 2/21/79

/

STEP 5 STATISTICAL EVALUATION OF aMCPR 1.

STATISTICALLY FITTED.

2.

STATISTICAL MODEL e

AMCPR/IMCPR e

QUADRATIC IN FEET WITHDPAWN, LINEAR IN POWER AND FLOW 3.

AMCPR = (SMCPR/IMCPR)95/50 IMCPR 95/50 OUTPUT OF STEP 5:

955 PROBABILITY /505 CONFIDENCE AMCPR AS A FUNCTION OF POWER, FLOW AND FEET WITHDRAWN. JFK 2/21/79

STEP 6 ALLOWABLE CONTROL R00 WITHDRAWAL DISTANCES aMCPR(X),X2)

+ MCPR

= RMCPR 1

Safety Limit where:

RMCPR = REQUIRED MCPR TO ALLOW A X)

FOOT WITHDRAWAL AT X % POWER 2

2.

MAXIMUM ALLOWABLE WITHDRAWAL DISTANCE:

IMCPR RMCPR

=

95/50 OUTPUT OF STEP 6:

FINAL WITHDRAWAL DISTANCES AS A FUNCTION OF CORE AVERAGE POWER.

-l'.-

JFK 2/21/79

RWL STATISTICAL ANALYSIS CONSERVATISPS 1.

IMCPR BASED ON NON-0PTIMIZED ROD PATTERNS.

95/50 2.

ONLY HIGH WORTH CONTROL R0D GANGS WITHDRAWN TO DETERMINE AMCPR.

3.

SINGLE R0D WITHDRAWALS NOT INCLUDED IN AMCPR DATABASE.

4.

LONVOLUTE IMCPR AND AMCPR 95/50 95/50.

5.

CONSTANT XENON.

6.

AMCPR's FOR 100% FLOW

/.

R00 BLOCK SETPOINT MARGIN TO ALLOWABLE WITHDRAWAL JFK 9, f

SAMPLE CALCULATION AND PRELIMINARY RESULTS 80% POWEP./70% FLOW a.

IMCPR

= 1.380 95/50 b.

AMCPR l' GANGED WITHDRAWAL

( AMCPR/IMCPR)95/50 = -0.0817 AMCPR),

(-0. 0817 )(1. 38) = -0.113

=

c.

RMCPR 1.183 RMCPR). = 1.07 +

-0.113

=

~

FEET AMCPR AMCPR WITHDRAWN

_IMCPR 95/50 1

.0817

-0.113 1.183 2

.1 tG

-0.206 1.276 4

.252

-0.348 1.418 6

.320

-0.442 1.51 2 d.

MAXIMUM ALLOWA8LE WITHDRAWAL RMCPR = IMCPR AT 3.4' WITHDRAWN 95/50 JFK 2/21/79

)

FIGURE 4 RMCPR VERSUS FEET WITHDPAWN 80% POWER /70% FLOW 1.60.

~~'

=-

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- 3 :=;.;..

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we,,ea IMCPR95/50

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1.20-

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1.10-l~~~~~~~~---

l.

l i

1.00 e

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0.0 2.0 4.0 6.0 FEET WITHDRAWN JFK 2/21/79

FIGURE 5 ALLOWABLE WITHDRAWAL DISTANCES 4

f I

I t

1 I

f f

BWR/6 OPERATING MAP 1.5 100 -

90 -

80 -

3.0 3.0 o j

70 -

O[

60 -

5.0 5.9 3 5.0 o 8u 50 -

E 46 -

e 9.5 9.5 g E

a0 -

20 -

12.0 10 -

0 0

10 20

'30 40 50 60 70 80 90 100 PERCENT CORE FLOW

. JFK 2/21/79

RWL PHYSICS DESIGN REQUIREMENTS 1.

POWER DEPENDENT SET POINTS 2.

R00 BLOCK POINTS SET AT MINIMUM ALLOWABLE WITH-DRAWAL DISTANCE.0VER PO!4ER RANGE.

3.

SET POINTS CHOSEN TO PROVIDE OPTIMUN FLEXIBILITY WITH ADEQUATE SAFETY MARGINS.

R00 BLOCK SETPOINTS 12 10 -

U -~

8-S t; e_

"E 4_

g--

2.-

1 C

i i

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20 40 60 80 100 CORE POWER

(%) JFK 2/21/79

FIGURE 6 BWR/6 R00 WITHDRAWAL ERROP MAXIMUM LINEAR HEAT GENERATION RATE

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0.0 10.0 20.0 30.0 40.0 50.0 PEAK PELLET EXPOSilRE (GWD/STU) JFK 1#1}/7Q

SUMMARY

1.

GENERIC ANALYSIS FOR BWR/6 R0D WITHDRAWAL ERROR.

2.

STATISTICAL BASIS 3.

NRC COMMENTS / FEEDBACKS e

ACCEPTABILITY OF PROPOSED STATISTICAL APPROACH e

REQUIRED DOCUMENTATION, CALCULATIONS, ETC. JFK

'/1

/-Q

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