ML20236G364

From kanterella
Jump to navigation Jump to search
Proposed Tech Specs,Allowing Startup of Facility W/Flow Indication from 19 Jet Pumps & Revising Certain Jet Pump Surveillance Provisions
ML20236G364
Person / Time
Site: Millstone Dominion icon.png
Issue date: 07/31/1987
From:
NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20236G356 List:
References
NUDOCS 8708040227
Download: ML20236G364 (17)
v • d • e


Text

--_ __

1 Docket No. 50-245 B12609 l

Attachment 1 Millstone Unit No.1 Jet Pump Instrumentation Amendment Request Proposed Amendments to Technical Specifications 27 97072g e7080 DOCg OSOOOppg g PDR P July 1987

} <

l _ - ---

LIMITING CONDITION FOR OPERATION 3.6 PRIMARY SYSTEM BOUNDARY G. Jet Pumps

1. Whenever the reactor is in the STARTUP/ HOT STANDBY or RUN modes, all jet pumps shall be intact and all operating jet pumps shall be operable. If it is determined that a jet pump is inoperable, an orderly shutdown shall be initiated and the reactor shall be in a COLD SHUTDOWN or REFUEL CONDITION within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.  !
2. Flow indication from each of the twenty jet pumps (except that flow indication from only 19 jet pumps is acceptable prior to and during Cycle 12 operation) shall be verified prior to initiation of reactor startup from a cold shutdown condition.

3 The indicated core flow is the sum of the flow indication from each of the twenty jet pumps. If flow indication failure occurs for two or more jet pumps, immediate corrective action shall be taken.

If flow indication cannot be obtained for at least nineteen jet pumps, an orderly shutdown shall be initiated within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and the reactor shall be in a COLD SHUTDOWN or REFUEL CONDITION within 34 hours3.935185e-4 days <br />0.00944 hours <br />5.621693e-5 weeks <br />1.2937e-5 months <br />.

SURVEILLANCE REQUIREMENT 4.6 PRIMARY SYSTEM BOUNDARY G. Jet Pumps

1. Whenever there is a recirculation flow with the reactor in the STARTUP/ HOT STANDBY or RUN modes, jet pump integrity and operability shall be checked daily by verifying that the following two conditions do not occur:

l

a. Thq recirculation pump flow differs by more than 10% from the established speed-flow characteristics; or l
b. The indicated total core flow is more than 10% greater than the core flow value derived from established power-core flow relationships.
2. Additionally, when operating with one recirculation pump with the equalizer valves closed, the diffuser to lower plenum differential pressure shall be checked daily, and the differential pressure of any

! jet pump in the idle loop shall not vary by more than 10% from established patterns.

3 The baseline data required to evaluate the conditions in Specification 4.6.G.1 and 4.6,0.2 will be acquired each operating cycle.

I

\

Millstone Unit 1 3/4 6-13 J

3.6 and 4.6 PRIMARY SYSTEM BOUNDARY -

BASES A break in a jet pump decreases the flow resistance characteristic of the external piping loop causing the recirculation pump to operate at a higher flow condition when compared with previous operation.

The change in flow rate of the failed jet pump produces a change in the indicated flow rate of that pump relative to the other pumps in that loop.

Comparison of the data with a normal relationship or pattern provides the indication necessary to detect a failed jet pump.

For Cycle 12 operation, flow indication for jet pump "K" will be determined by flow indication from the adjacent, paired jet pump "J,"

based upon historical jet pump performance characteristics.

The jet pump flow deviation pattern derived from the diffuser to lower plenum differential presmtre readings will be used to further evaluate jet pump operability in the tent that the jet pumps fail the tests in Sections 4.6.G.1 and 2.

Agreement of indicated core flow with established power-core flow relationships provides the most assurance that recirculation flow is not --

bypassing the core through inactive or broken jet pumps. This bypass flow is reverse with respect to normal jet pump flow. The indicated total core flow is a summation of the. flow indications twenty individual jet pumps.

The total core flow measuring instrumentation sums reverse jet pump flow as though it were forward flow. Thus, the indicated flow is higher than actual core flow by at least twice the normal flow through any backflowing pump. Reactivity inventory is known to a high degree of confidence so that evrn if a jet pump failure occurred during a shutdown period, subsequent power ascension would promptly demonstrate abnormal control rod withdrawal for any power-flow operating map point.

A nozzle-riser system failure could also generate the coincident failure of a jet pump body; however, the converse is not true. The lack of any substantial stress in the jet pump body makes failure impossible.

H. Recirculation Pump Flow Mismatch The LPCI loop selection logic is described in the FSAR, Section 6.2.4.2.

For some limited, low probability accidents, with the recirculation loop operating with large speed differences, it is possible for the logic to select the wrong loop for injection.

For these limited conditions the core spray itself is adequate to prevent fuel temperatures from exceeding allowable limits. However, to limit the probability even further, a procedural limitation has been placed on the allowable variation in speed between the recirculation pumps.

The analyses for Quad Cities indicate that above 80% power the loop select logic could not be expected to function at a speed differential of 15%.

Below 80% power the loop select logic would not be expected to function at a speed differential of 20%. This specification provides a margin of 5%

in pump speed differential before a problem could arise. If the reactor is operating on one pump, the loop select logic trips that pump before making the loop selection.

Millstone Unit 1 B 3/4 6-6

k --

i Docket No. 50-245 B12609

it j, ,

o Attachment 2 i

Millstone Unit No.1 Jet Pump Instrumentation Amendment Request

, Summary of General Electric Evaluation l

'1 1

l l

I July 1987 3 i

1 1

l l

l

. _ _ . _ __ _______ _________ _ A

Millstone Unit No.1 3et Pump Instrumentation Amendment Request t

Summary of General Electric Evaluation General Electric has evaluated the technicalimplications of Millstone Unit No. I operation with 19 jet pump instrumentation lines. The scope and results of that evaluation are summarized below.

A. Technical Specification Core Performance Analyses Review General Electric reviewed Millstone Unit No.1 Technical Specifications  !

for potential impact due to operating with one jet pump instrument line inoperable. The only provisions potentially impacted which would require modification are those subject to this amendment request.

The review also verified consistency with Reference 1 and 2 provisions and recommendations with respect to reactor recirculation and total core flow performance and measurement.

B. 3et Pump 3 and K Flow Bias General Electric also evaluated means to determine total core flow with flow indications from 19 jet pumps. An alternative means for making that determination was necessary because indicated total core flow presently is determined by summing individual jet pump flows from 20 jet pumps. With the instrument line for 3et Pump K inoperable, indicated core flow would only be 19/20 of actual.

To address this condition, Set Pump 3 flow (jet pump paired with 3et Pump K), adjusted for known flow bias, will be input into the flow summer for Jet Pump K. General Electric examined the historical flow bias between jet pump pair 3 and K. From this data, an adjustment factor was determined to adjust Jet Pump 3 flow indication so as to simulate Jet Pump K flow.

The resultant increase in flow uncertainty is discussed in the next section.

C. Uncertainty Analysis General Electric also assessed whether the above process significantly l reduced safety margins by increasing the uncertainty in total core flow J

predictions. As discussed in Reference 1, General Electric has performed bounding statistical analyses which provide conservative safety limit

, Minimum Critical Power Ratios (MCPRs) applicable to all GE 8 x 8 fuel l designs in BWR/2-6 reload cycles.

The uncertainty inputs used in the bounding analyses include an assumed i

2.5 percent uncertainty for total core flow. The plant-specific value for Millstone Unit No.1 is 2.27 percent with instrumentation for all 20 jet pumps operable. General Electric reevaluated this plant-specific uncertainty to account for operation with 19 operable jet pump instrumentation lines.

i

B12609/ Attachment 2 Page 2 Based upon historical data for Jet Pump K (inoperable instrumentation) and Jet Pump 3 (paired jet pump partner) flows, GE recalculated Millstone Unit No. I uncertainty if Jet Pump 3 flow is used to simulate Jet Pump K in the flow summer with the historic bias added, as described in Part B above.

The recalculated uncertainty of 2.273 percent for Millstone Unit No.1 is well within the bounding analyses assumption of 2.5 percent.  ;

In summary, existing safety margins are not significantly affected by the minimal increase in core flow prediction uncertainty. Prior analyses i performed which relied on the core flow predictions, including the reload  !

analyses done in support of Cycle 12, remain valid. I j D. LOCA Analysis  ;

i Recognizing that flow instrumentation for 3et Pump K is simply blocked, and there is no indication that this line has been or could become severed, General Electric nevertheless evaluated whether a broken instrument line could impact plant operation or existing LOCA analyses. General Electric calculated the flow even with a completely severed line to be less than 10 gpm which would bypass the core and not be available for core cooling.  ;

GE determined this flow diversion would have a negligible affect on plant 1 operation and LOCA analyses for Millstone Unit No.1.

REFERENCES i

1. NEDE-240ll-PA-8-US, General Electric Standard Application for Reactor Fuel, GESTAR II, May 1986.
2. Service Information Letter (SIL) 330, Jet Pump Beam Cracks, June 9,1980.

i 1

_______________a

i

. l Docket No. 50-245 i B12609 "

l i

)

Attachment 3 Millstone Unit No.1 Jet Pump Instrumentation Amendment Request Summary of Remote Visual Examination

-)

i l

July 1987 l 1

r. . . _. . _ _ _ _ _ _ _ _ _ _ _ _ _ - _

Millstone Unit No.1

' Jet Pump Instrumentation--

" Amendment Request '

'l L LSummary of Rem'ote Visual Inspection A VT-3 (Remote Visual Examination) inspection was conducted'on July 18, 1987, to verify the . functional. Integrity- of Jet Pump No.10 (Jet Pump K) and its res'pective sensing line. The examination was performed in accordance with Site

. Procedure 10603, " Remote Visual inspection of the Jet Pumps, Top Core Guide .i Radial Restraints, and Shroud Annulus Region. i.

' The components inspected are as follows:

1. Jet Pump. Instrumentation Sensing Line Penetration Weld -
2. L3et Pump Instrumentation Sensing Line (from the jet pump penetration to the base of the jet pump)
3. Jet Pump Instrum.entation Sensing Line'(at the Jet Pump Instrumentation  !

Nozzle Penetration)-

4. 3et Pump Hold Down Beams

'5. 3et Pump Inlet Elbow

6. . . . 3et Pump Suction Inlet ,

7.. ~3et Pump Inlet Mixer Yoke i

8. 3et Pump Inlet Riser Brace Arm
9. Jet Pump Mixing Section
10. Jet Pump Wedge and Restrainer Section i
11. - Jet Pump Diffuser Section
12. Jet Pump to Shroud Baffle Plate Seat l Permanent examination documentation,. including videotape, is retained on site.

.No indications were noted as a result of this examination.

r/

1 Docket No. 50-245 B12609 l.

l l

l 1

Attachment 4 i

i Millstone Unit No.1 l 1

l Jet Pump Instrumentation J

Amendment Request Proposed Surveillance Program Summary

)

1 i

i I

i i

I July 1987

_ - _ _ _ _ _ _ _ l

Millstone Unit No.1 3et Pump Instrumentation Amendment Recuest Proposed Surveillance Program Summary

1. Baseline Data Data will be obtained during start-up to obtain reactor recirculation performance . monitoring checks and expected operational bands. This information will be used to assess potential changes in reactor rec.irculation that could result from, among other reasons, degraded jet pump performance.
11. Performance Measures (As Suggested in SIL-330)

The following will be monitored at least once each week for six weeks following resumption of operation. Thereaf ter, these measures will be performed monthly. As indicated below, these measures serve primarily as indications of possible core flow degradation which will trigger further evaluations. These performance measures are in accordance with General Electric's SIL-330, and were cons dered appropriate to reliably indicate jet pump failure in NUREG/CR-3052.1)

A. Core Flow vs. Square Root of Core Plate P A change in core resistance (determined by comparison of core flow and the pressure delta across the core plate) is the principal indicator of- recirculation system performance changes. This data will be employed in determining whether unexpected recirculation system performance changes are due to core changes (which relationship would change over time) or jet pump degradation (which relationship would remain constant over time), if this surveillance reveals a 15percent deviation from the normal range, a more detailed evalua-tion will be required.

B. Reactor Recirculation Pump Flow vs. Recirculation Pump Speed The pump operating characteristic is determined by the flow resis-tance from the loop suctica through the jet pump nozzles. A decrease in the flow / speed ratio' indicates a plug, flow restriction, or loss in pump hydraulic performance. An increase in the ratio indicates a leak or new flow path between the pump discharge and jet pump nozzle.

This data is used to check for both plugging in the jet pump and large leak.a. which would decrease flow resistance. The action level for a detailed evaluation for this surveillance is 15 percent deviation from the normal range.

(1) NUREG/CR-3052," Closeout of IE Bulletin 80-07: BWR Jet Pump Assembly Failure," dated November,1984.

l l

t. 2

.i I

B12609/ Attachment 4 Page 2 C. 3et Pump Loop Flow vs. Recirculation Pump Speed This relationship provides a direct indication of jet pump performance ,

by relating jet pump flow to drive speed (flow). The jet pumps respond )

to the flow resistance seen from the jet pump discharge through the bottom head, core, separators, and downcomer annulus. The action level for a detailed evaluation for this surveillance is +5 percent deviation from the normal range.

D. Individual Jet Pump Flow vs. Total Core Flow Data reflecting this relationship will be used to generate two sets of plots. The first set will contain the expected range of individual jet pump flows as a function of total core flow for all jet pumps with operable instrumentation. The second set of plots will contain the expected scatter in the data obtained by the data acquisition equip-ment.

This data will be used to look for the follouing:

1. An unexpected change in jet pump flow that could be caused by a broken jet pump. A detailed evaluation will be performed if the data for individual jet pump flows fall outside the 95%

confidence interval for the base data.

2. An unexpected increase in noise in the jet pump that could be caused by a loose, vibrating jet pump. A detailed evaluation will be performed if the data for individual jet pump falls outs'.de the 95% confidence interval for the standard deviation for the base data.

III. Daily Surveillance Checks At least once per day the following surveillance checks will be performed.

A. Recirculation pump flow must be within 10 percent of established recirculation pump speed-flow characteristics. Whenever this acceptance criterion is not met a detailed evaluation will be performed. (Technical Specification 4.6.G.la).

B. Indicated total core flow must be within 10 percent of the core flow value derived from the established power-core flow relationship.

When this acceptance criterion is not met a detailed evaluation is to be performed. (Technical Specification 4.6.G.I b).

C. Individual jet pump flow deviation from the average loop jet pump flow must be less than 10 percent. NNECO will perform a detailed evaluation whenever this acceptance criterion is not met. This check will be performed for all jet pumps with operable instrumentation as part of the 1-OPS-10.10, Operating Log--Shif t Surveillance Schedule.

c. _ __

w

  • E B12609/ Attachment 4 l-Page 3 D. Normalized jet pump flow deviation must be less than 10 percent. If j .this acceptance criterion is not met, a detailed evaluation is to be performed. This check will also be performed for all jet pumps with operable instrumentation as part of the 1-OPS-10.10, Operations Log- 1

-Shif t Surveillance Schedule.

IV. Jet Pump 3/K Surveillance Because 3et Pump K flow instrumentation is inoperable, the surveillance program for its paired jet pump (3et Pump 3) will be augmented as follows:

A. At least three times per week 3et Pump 3 flow will be plotted versus total core flow and compared to the baseline ~ data described in l Section II, Part D. The action levels will also be the same as those described in Section II, Part D. SIL-330 describes the expected behavior. of the sister jet pump for various failure modes and the routine Technical Specification surveillance is acknowledged to be adequate . to assess the failures. The additional surveillance being performed on 3et Pump 3 will provide added assurance of Jet Pump K integrity.

i L .- - . - - - - - - - - - - _ - - - _ -

l...

Docket No. 50-245 B12609 l

1 l

Millstone Unit No.1 J' et Tamp Instrumentation Amendment Request FIGURES -

July 1987 l

c DRYERS i STEAM allTLET h /

h U / STEAM SEPARATORS f 30

<= nt= =

(

- _. -STEAM SEPARATION PLEEM g

1 r y DRIVING FLOR

\ f ,' = = D 1 f h j jfDRIVEN FLOW

) '

CORE y

j )

s NJE1 P W O )

I i , , _ -DOWNCOWER EGION

  • r RECIR;. PUWP J L.

REACTOR PLEMJW FIGURE 1 Millstone Unit No. 1 Simplified Recirculation System

< .. i

l

) - *a y ,

./

I i Il

'* **? "M .

\

A4 '

m AnsER N I exan -

'N e - - Assam  !

l j

-- pJ  ;-

n so d:

/, -- DIF F USER r_ >

I l #s l

u

_=%,*3 .

FIGURE 2 Millstone Unit No. 1 Jet Pump Assembly

.....1

I * ,

I b 4 f s

_Q

)e ,l$ E o -

a :>

lt.Lb, E

~

5 g i L $

je Ig ----~~ ath b 7 P f$ 5 Bf

[3 f

l 2

~* -

3'

+

I ( ,g ,

4

f Iyti 4 k)il {2 L._ '

as . ,

w+ki~ m)o

'__g f i d!

ht tt h '

[

8e -

y *g.

8  : -

o 4' w i (9 :7, E ?yf

??N$1" 5 V' i  ? !g ls gh: . ' ':e E a ., u y5 5

og;' ' ljg, 23 n

't G ,j

@l*

N ' . . .l I35 e

y <

.c g

>:r E

it I 5  :

lly ll W l , 5

~

,1

e. d e- ,

g'

, t Sk f$

c y l '

93 ER

?? I L PF 4 '!

d 9 3(

- k

_ ,6 '

si o! !!!1.

(E$ e gU h lVY Idg J~ DD G 6 0 i

FIGURE 3 Millstone Unit No. I Rep] aced JPI Nozz]e Assembly

}

)

T T N _

TSA 0

^ N ST E( S )R 6 I ML SC h _

0 EA E 5 HR CE R- -

MC AS L

NM 9I D 1. N PN. OY E SA I

= 6L L

EL mP OLRR 1

E / RE WA 3E NS O

T yg W

fA RE I

R T k i OV CO 4 BS 4 AERS NR UTg E hM F

N/ / -

8 CL EY T

N 5U \ m e I

2. B A WA Oi . 0

\' x8

1 w

~

=

1 N E 0

? *W' I

'0 "

M V 0

A. p9/

2 YE 3

1, 2 t\ }II 4 OLZ -

'= e R S

3 L LZ AO 1

p7p N GD NA 1

9 R

0 q W O

L T L SC T

XT 1 5 N ES O

7

(

(

m I T

AX LE UD E

R A

S N

=

=

m

/

I M)D 5A CN L

AE CL U H N

W ODO E

2L FR SCI 1 C OS SES

(_ NS T N

MS SA IOE E NA CL 1

0 T R T 5 1 AS OE 6 0 D. C OF PHmY R LO O MTN 1

(

- A C N;DO 8 D =

MTN

_ 7. LA ES: R I LT LI EO CU AWSB

=

L 3 CT S

(

O N 1 2

,aW"

= Ego ?? 9-E  %# eE" a Cg h n T':

gar  ?"83E  % $o p5

' lu

Retrieved from "https://kanterella.com/w/index.php?title=ML20236G364&oldid=3178941"