TXX-4159, Forwards value-impact Analysis for Elimination of Large Primary Loop Pipe Ruptures.Proposed Exemption from Adding Protective Structures Recommended

Forwards value-impact Analysis for Elimination of Large Primary Loop Pipe Ruptures.Proposed Exemption from Adding Protective Structures Recommended

ML20084A418
Person / Time
Site:	Comanche Peak
Issue date:	04/23/1984
From:	Schmidt H TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Harold Denton Office of Nuclear Reactor Regulation
References
TXX-4159, NUDOCS 8404250007
Download: ML20084A418 (13)

Text

. Log # TXX-4159 File # 903.6 TEXAS UTILITIES GENERATING COMPANY M KYWAY Tt DWElf

• 100 Nt DHTII 4)t,lVE MTitEET, I..H. M1

• IBAI.I.AM TEXAN 73201 April 23, 1984 Dr. Harold R. Denton Director of Nuclear Reator Regulation U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Washington, D.C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION VALUE-IMPACT ANALYSIS FOR ELIMINATION OF LARGE PRIMARY LOOP PIPE RUPTURES

Dear Dr. Denton:

Enclosed please find forty (40) copies of the CPSES Value-Impact Analysis associated with the use of the alternate pipe break analysis to eliminate the need to postulate large primary loop pipe ruptures.

Should you have any questions concerning this matter please contact this office.

Sincerely, Homer C. Schmidt BSD:bjm Attachments

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60 t\

8404250007 840423 PM ADOCK 05000445 A . _ .

PM _,

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Page 1 of 12 VALUE-IMPACT AtALYSIS OF NOT ADDING PROfECfIVE STRLCfURES FOR IC IOOP BREAKS 1.0 Introduction his analysis presents a value-impact assessment of the mnsequences of exempting CPSES fran having to install protective structures to mitigate the effects of r<: actor coolant (RC) loop breaks. Wese protective structures include both jet shields to protect targets fran jet impingement loads and RC loop equipnent restraints. %is report relies upon trevious structural target interaction evaluations.

We proposed exemption will efficiently allocate public resources in the generation of electric power and decrease occupational radiation exposure.

Additional protective structures in already congested areas would incur large msts and significant occupational doses.

We safety concerns involve the effects of a postulated major double-ended pipe break in a reactor coolant loop. Unanalyzed loads on an essential structural or piping target could cause a loss of the safety function of the target.

2.0 Proposed Action aid Potential Alternatives It is troposed that CPSES be exempted from adding protective structures that either mitigate jet impingement loads on essential targets or restrain RC loop piping from damaging RC loop equipent after a IC loop line break.

mis proposal is based on consideration of occupational dose and cost 4 inpacts. We alternative muld be to require aiding trotective structures to withstand the jet impingement ~ loa 3s and restraint structures to protect BC loop equipnent. -

3.0 - Value-Impact Assessment Results Sunnary 'Ibtal Ebr 2 thits Value* (man-rem)

Occupational . exposure (operational) ' 156 man-rem nuch less than Public Health -0.8 man-rem Total Quantified Value 155.2 man-rem Impacts * ($)

-2,464,000

~

~ Jet Shield Inplementation Oost -

Restraint Shim 00st -

'276,840 Total Quantified Value --2,740,840.

and Fuel Ioad Delay .

and 25. weeks (unquantified)

~ ~

1*Value and inpact analyses based.on UnitL I. Pbr Unit 2 both the value and the negative irpact will increase (except Fuel Icad Delay which would be ~

minimal at this point).. ,

Page 2 of 12 4.0 Develognent of Qualification - Based on Unit 1 Data A.0 General Exposure md Cost Criteria A.1 Ebr Jet Impingement Protection his report applies to the following reactor coolant line breaks: (Ref. 1) 101 GA/B 201 GA/B 301 NA/B 401 GA/B 102 GA/B 202 GA/B 302 GA/B 402 G A/B 103 GA/B 203 GA/B 303 GA/B 403 GA/B 104 GA/B 204 GA/B 304 GA/B 404 GA/B 105 GA/B 205 GA/B 305 CWA /B 405 GA/B 106 GA/B 206 GA/B 306 GA/B 406 GA/B 107 IWR 207 IWR 307 IWR 407 IWR 1081 GA/B 2081 GA/B 3081 GA/B 4081 GA/B We essential targets of these breaks can be divided into three categories; structural; of Westinghouse pipiry3 smpe; and of Gibbs & Hill (G&H) piping scope. 'Ihe target / break interactions are identified below:

109 Structural Targets (Ref. 1)

Break Ibs. Targets Fbr Each Break 101, 102, 201, 202- 1 Pen. Sleeve 301, 302,.401, 402 103, 104, 105, 204, 6 Walls / Floors 303, 304, 305, 404, 405 106, 203, 206, 306 3 Walls / Floors 107, 207,'307, 407 -1 Wall / Floor 1081, 2081,.3081, 406 4 Walls / Floors.

205, 403, 4081 5 Walls / Floors s

4

- . , e

Page 3 of 12 27 Westinghouse Soape Piping Targets (includes valves) (Ref. 2)

Break Nos. Break Nas.

Target Line No. (Info. ) Target Line No. (Info.)

10" SI-1-103-2501R-1 103, 104, 105, 3" CS-1-235-2501R-1 106, 304 405, 106, 1081 10" RC-1-21-2501R-1 103, 104, 106, 6" SI-1-101-2501R-1 203, 205, 206 1081 ,

1-1/2" SI-1-199-2501R-1 103 10" RC-1-37-2501R-1 203, 206 4" RC-1-18-2501R-1 103 10" SI-1-180-2501R-1 204, 2081 12" RH-1-1-2501R-1 103, 104, 105, 3" CS-1-1-2501R-1 204, 2081 106, 405,  ;

12" RC-1-7-2501R-1 104, 105, 405 2" RC-1-53-2501R 205, 303, 304 12" RH-1-2-2501R-1 104, 105, 403, 6" RC-1-29-2501R-1 207 404, 405, 406 10" SI-1-106-2501R-1 105, 405, 406 6" SI-1-102-2501R-1 303, 305, 306 12" RC-1-69-2501R-1 105, 404, 405 6" RC-1-46-2501R-1 303, 307 l

10" SI-1-181-2501R-1 303, 304 10" RC-1-78-2501R-1 403, 404, 406, 4081 10" RC-1-55-2501R-1 306' 10" SI-1-182-2501R-1 403, 404,

'405, 406, l- 4081 l

10" SI-1-105-2501R-2 3081 3" CS-1-79-2501R-2 403 6

14" RC-1-135-2501R-1 403 4" RC-1-75-2501R 403

- 6" BC-1-70-2501R-1 403 27 'Ibtal Westinghouse Scope Targets.

l r

Page 4 of 12 16 G&H Scope Piping Targets (includes valves) (Ref. 2)

Target Line Ib. Break Ibs. Target Line No. Break Ibs.

3/4" PS-1-6-2501R-2 103, 403, 404 2" MS-1-206-1303-2 1081 3/4" PS-1-28-2501R-2 103 2" MS-1-341-1303-2 1081

, 18" N-1-19-1303-2 104 18" N-1-18-1303-2 204 3/4" MS-1-6-2505-2 104, 105, 106 1 MS-045 & Tubing 2081 204, 205, 304 2" MS-1-199-1303-2 2081 305, 3081, 404 405 3/4" MS-16-2505-2 104, 105, 106 2" MS-1-339-1303-2 2081 3/4" MS-1-11-2505-2 104, 106, 203 18" N-1-17-1303-2 304 204, 205, 304 2" MS-1-218-1303-2 403 305, 3081, 404 405 '

3/4" MS-1-21-2505-2 104, 105, 106 18" N-1-20-1303-2 404 403, 405, 406 43 total G&H scope break-target interactions Amng the many assumptions in this analysis, it is first assmed that the breaks would rot be sielded at their murce. his is mfeasible per m earlier investigation. Therefore, any target requiring protecticm would be sielded at the target itself. Secondly, it is assumed that after the stress analyses on structural targets are cmpleted the result would be that there are no macceptable structural interactions. Eis is based on CPSES structural target interaction evaluations to date. Therefore, l no sields will be designed to protect structures from the reactor coolant line breaks.

As for the sove_ Westinghouse scope piping targets, Westinghouse has

( completed the stress analysis and has determined new support load data l for 195 supports. tese new loads must be malyzed to determine if jet loa 3 protection is required. Based on Westinghouse experience at other plants, the results of further malyses will be at nost the addition of a very few jet bmpers. It is therefore . assumed . for this analysis that no jet bepers will be required. Rese' assumptions have a conservative effect on both the value and impact results..

+- = g w w

" Page 5 of 12 2 ,

l i

A field walkdown of the above G&H piping targets was conducted to make general assumptions on the locations, sizes, configurations of the jet shields and their supporting members. It is assuned that there is one jet  !

shield for each piping target even though the shield may be very large or j long to protect from several breaks and fran several directions.

%erefore, there would be only 16 shields to be aided. All shields would require periodic painting inspection and painting. '

l A.2 For IC RIuipment Restraints Wis malysis applies to the following restraints which are designed to prevent daage to RC loop equipment after a postulated line break: for each of 4 loops there are two restraints on the crossover leg elbows,1 restraint on the crossover leg vertical run, and 1 restraint on the stem generator inlet line elbow.

As these restraints are designed only to operate after m IC line break,- the gap' between the shim on the restraint and the piping must be maintained under

< all other conditions including sutdown, normal operating, seismic, ed

! water / stem hamner loadings (Ref. 3). Exempting CPSES fran these protective structures for m BC line break eliminates these murces. of possible unaccounted for interactions in cases where the gaps are not maintained.

B.0 Occupational-Exposure-Operational

' B.1 From Jet Shields Operational occupational exposure dose due to additionalt rotective

~s tructures is avoided by the proposed exemption to protecting essential targets from RC loop breaks. This dose would be incurred due to the

!' slowing down of normally anticipated work activities plus newly added routine maintenance of thesezjet shields in the steam generator-compartments.

I-To calculate the dose rate portion due to work slowdowns the normal manpower L traffic into the' stem generator compartments in the jet shield areas during reactor sutdowns in a plant year _(py) .is estimated as follows:

In' Service Inspection -- 18 men'9 1'* ea.

L Maintenance _(tube cleaning and plugging; .manway cover-handling; pump, valve, flange, '

~4 men 0 0.5 wk ea.

and tank-work) - ,

. Eddy Current Testing -

1 3' men 9 1.* ea..

Operations (supervise various' ' 3 men' e .1

• ea.

- -activities)

Radiation Protection -- -3 men 911-* ea.

Mise?(painters, scaffold 11 men e 1

• ea.:

builders, laborers, inspectors-

andl engineers);

TomL 40 man'* s/py A f

Page 6 of 12 7 .

We installation of these massive jet shields in congested areas would cause an assumed 3% increase in each workers time spent nearby. (bntributing factors to the slowdown include increased inaccessibility for personnel and equipnent to and from gimary system components, increased congestion between adjacent compartments, occasional jet shield removal and replacenent (often requiring polar crane time) to gain access to valves md equignent, and nore difficult Inusekeeping in areas of high contamination possibility. Thus the extra time in this radiation area due to slowdown is as follows:

.03 x 40 mm wks/py x 40 py = 48 mm wks me portion of increased dose rate for new routine maintenance inclu3es periodic paint inspection and repaintirv3 of the shields and would require support from scaffold builders, laborers, inspectors and radiation pcotection personnel. It is assumed that in the 40 year plant life the 16 shields will require painting 5 times each and require 8 workers at a conservative 15 manhrs per shield. %us the painting time over 40 years is as follows:

16 shields x 15 manbrs/ shield x 5 times x man * = 30 man As 40 manhrs hen, the total increased time in the shield area is the following:

TOTAL = 48 man * + 30 man * = 78 man *s Ibw it can be assaned that all workers will receive m average 25 mR/hr.

%is is inferred using m exposure rate of 50 mR/hr just at the outside channel head mmway cover (Ref. 4) where several workers will be located (near jet shields). However, many personnel will be located on the floor level where the exposure rate has fallen off very sharply with distance.

mus 25mR/hr is a realistic assumption causing the total increased dose due to the addition of the jet shields to be 78 man *s x 40 man hrs x 25 maem = 78 mm Itm mm

• man hr B.2 From FC Equipnent Restraints here is no significant occupational exposure dose to be saved at this.

point in thit 1 by exempting CPSES from fully installing tlw IC Equipnent

' Restraints.. m is is because with the exception of the properly sized shims the restraint structures are fully installed. While there would be same removal of pipe straps, pipe clamps and a few restraint kickers (most of which have had other items attached to them by now) so that the pipe can be fully insulated these individual items me int located such that they impede workers progress measurably. An exemption for thit 2 ~

however, would save the entire restraint structure from being . installed which would save several man-rems (unquantified for this study).

%ere is no requirement to inspect these restraints after plant operation nor will. they be painted m there is no ' exposure for those activities.

m

Page 7 of 12 i C.O Public Health It is assumed that the risk to public health of not adding jet shields and equipment restraints is similar to the risk of not adding modifications to mitigate asymmetric blowdown loads on Erimary system omnponents which is assessed in Ref. 5. mis analysis shows that the ridc to public health of the

' proposed exemption for Comanche Peak will be more conservative than the risk to public health determined in Ref. 5. his is acccm.plished by performing a simple weighted average population density calculation. This shows that the population, per individual, closest to the plant has a heavier worth the the population, per individual, furthest from the plant. i s

Ref. 5 used a unifonn population densi of 340 people per square mile (which i

.is an average of all.US nuclear power ant sites). From Ref. 6 using the 4 ctnulative populations projected for 1 90 (further contributirg to a  !

conservative risk value) we get the following:

CUMULATIVE IOPUIATION  !

(Mues trom site)  ;

0-10 0-20 0-30 0-40 0-50  ;

17,930 37,843 120,827 594,707 1,198,040 he simple unweighted population density figure for the 50 mile radius is '

1,198,040 people W (50)2 miles = 152.5 people /sq. mile Men fran this data we em show the population is heavily distributed at the '

outer fringes of the 50-inile radius nodel as follows:

20-30 30-40 40-50 0-10 10-20 17,930 19,913 82,984 473,880 603,333 he areas that the above populations occupf as functions of' outer radius r x and a inner radiust x-1 Ax = 6 (rx -rx-1 )

+

The population densities' as a function of their distances from the-site shows there are more people in the outer sections of the 50 mile radius. This is figured: i POPUIATION IEEEITY(PBOPLE/SQ.MI) 0-10 10-20 20-30 ~30-40 40-50 ,

17,930 19,913 82,984 .473,880 603,333

• (1'02) *(20 2-10 2) . *(302-202 ) 5(40 2-302) Jtt50 2-402)

= 57.1 = 21.1 '~= 52.8 =-215.5 = 213.4 L Se simple weighted average population density is:

~

57.1 + 21.1 + 52.8 + 215.5 + 213.4

^

. 5

= 112 people /sq. mi.

Page 8 of 12

'Ib insure conservatism throughout the 40 year plant life, using the Ref. 5 values for the year 2020, the simple weighted merage population density is:

98.9 + 36.0 + 85.0 + 375.7 + 376.9 5

= 194.5 people /sq. mi.

Rese results show that in all cases for tin years 1990 and 2020 both the unweighted p>pulation densities md the simple weighted merage population densities the Cmanche Peu specific case will result in a much lower public health risk than the 340 people /q. mo. figure used in Ref. 5.

The other factor that makes the Conanche Peak ris less that the value of Ref.

5 is the considered number of plant years. Ref. 5 considered the number of remaining plant years for 16 plants at 23.6 yr. to give a total of 377 py.

As the number of plant years is a multiplying factor to give total risk then again the Cmanche Peak specific rid is less ard by a factor here of 9.4.

Assuming all the other assumptions of Ref. 5 apply to the O)manche Peak case, we know the value to public health of not adding protec':ive structures for RC loop breaks at Q)manche Peak will be much nore conservative than the Ibf. 5 nominal estimate of industry total (16 plants) public risk value of -3.4 man-rem.

Using the 9.4 factor, CPSES Public Health value much less than

-0.4 man-rem.

D.0 Implementation Cost D.1 Jet 911 elds We impact to CPSES of rot installing the jet shields is avoidance of analysis, design, fabrication, installation and maintenance costs as well as replacement power costs due to fuel load delay.

If jet shields were to be required the first step would be to perform the analyses for all break-target interactions to determine if a shield is necessary in each case. The costs of them are as follows:

1. Stress hialysis For 109 Structural - 48 man hrs. ea. @ $65/ man hr = $340,080.

Interactions For 43 G&H Piping - 16 man irs. ea. 0 $65/ man hr = $ 44,720.

Interactions For 195 Supports - 10 man hrs. ea. @ $55/ man hr = $107,250.

of Westinghouse Scope lines

'IorAL STRESS ANALYSES = $492,050.

Page 9 of 12 As discussed above, this analysis assumes the results of analysis on both structural targets and Westinghouse line supports to be that no shields or jet bumpers will be required. So, only the 16 G&H target shields would be f' designed. Wen, two conservative assumptions are made that minimize the time and cast factors. For one, the three stress analyses will be performed simultaneously by separate groups. We other is that as mon as a group of these targets which are located closely together (estimate 35% per field check) are malyzed then design may begin rather than waiting for all 43 analyses to be completed. It follows then the fuel loM delay (before start of design) due to analysis is (43 G&H Interactions x 0.35 x 16 man hrs / Interaction x 1 mm wk/40 man hrs] ; 3 workers = 2.0 man wks.

2. Design, Fabrication, and Installation In order to further facilitate minimum fuel load delay it is assmed that 3 designers and 1 checker can produce a total 3 designs in each 3 week period and alm that staffing is increased enough to complete installation of the 3 designs within the next 3 week period md m on. W is is a very conservative assumption as many problems could be encountered that would Md significant cost and delay. If the sove schedule is followed, then the delay attributable to design, fabrication md installation is Design of 3 shields - 3 weeks Design of 3 shields & install previous 3 shields - 3 weeks Design of 3 shielda & install revious I 3 shields - 3 weeks Design of 3 shields & install previous 3 shields - 3 weeks Design of 3 shields & install gevious 3 shields - 3 weeks Design of 1 shield & install previous 3 shields - 3 weeks Install Irevious 1 shield - 3 weeks

'Ibtal shields -16 Total time required -21 weeks costs for the design, fabrication and installation of those 16 shields is extrapolated from costs of previous shields. Designire costs will be the same as gesently encountered because the manpower mw available can support this schedule. However, fabrication ard installation durity heavy load periods muld require more staff. We number of Civil Engineers and drafters who check fabrication drawings and hilti bolt locations would double md an increase in CBI, welding md NDE personnel who initiate drawings, check, fabricate, install, inspect and paint would be required. Wese costs are Designers - design & dieck 16 shields @ $19,500 ea. = $312,000.

Civil Engr. - 4 men @ $44.44/mm hr. @ 40 man hrs /*

@ 18 wks = $127,987.

- 2 men 0 $44.44/ man hr. @ 40 mm hrs /*

@ 3 wks = $10,666.

Installation + materials = 16 shields x ($9400 CBI cost / shield + $1410 others cost / shield + $1410 materials) = $195,520.

Extra personnel for peak periods = $4500/Wc @ 15 wks = $ 67,500.

'Ibtal design, fabrication, installation $713,673.

Page 10 of 12 D.2 restraint Shim Installation he impact to CPSES of not installing the shims to complete the design of the RC loop equipnent restraints is avoidan of machining and installation costs as well as replacement power costs due to fuel load delay. 'Ihese o sts are as follows.

1. Offsite machining = $ 30,000

2. Manhours

a. Craft - 140 manteurs @ $35/hr =$ 4,900

b. Engineering - Westinghouse and site -

8 men @ 8 days @ 24 hrs / day 0 $75 avg. cost /hr = $115,200

'10tal Cost bhlm installation = 4IDU,IUU All shims are not required the pipe straps, pipe clamps, and my restraint kickers that were not dsed for other purirses could be removed so that the insulation could be patched. Estimated costs for these are:

1. Manhours-craft to remove straps, el , kickers -12 manhrs @

S35 =$ 420

2. Insulation

a. Material =$ 60

b. Craft time - 20 manhrs/ joint

@ 16 joints @ $35/manhr = $ 11,200.

'Ibtal (bst to Fully Insulate (amunt saved if shims required) 11,680.

Net Bestraint Shim Installation Oost

= $150,100 - $11,680 = 138,420.

to shim replacement alone will impact compartment closure and therefore building closure and therefore fuel load bt an estimated mnservative 2-weeks.

E.0 Maintenance Cbsts E.1 For Jet Shields As mentionedt reviously thez,e 16 shields will require periodic inspection and occassional repaintinq. 21s requires support personnel for a total of 8 workers for 5 paint jobi. ia the 40 year plant life. Assuming a time requirement of 15 man hours per shield and a continued manpower cast of

$22/mm hr. and not including material msts all of 411ch are conservative will yield the following:

16 shields x 15 manhrs/ shield x (5 times /40 yrs) x $22/ man hr

= $26,400 total painting costs

. - - . .. . - ~.

Page 11 of 12 0 E.2 Ebr Restraints No painting or other inspection of the restraints is required after the shims are first verified.

5.0 Conclusions he summary results fbr the value-impact assessment as shown below. We estimates for cost and dose indicate that the proposed action sinuld be recomended. Wese estimates do rot show negative benefits for either dose or cost. %e following observations can be made:

• This analysis assumed that if implementation of jet shields were required, a fuel load delay is preferable to installation during plant outages. We after Inwer work in containment would increase the occupational dose rate, require nore worker and support personnel time and still require some additional cbwntime leading to replacement power costs.

^

• Wis analysis does rot aidress values or impacts of accidental occupational exposure, public property nor onsite property effects. Ref. 4 values for these can be used as approximate figures for comparison.

Summary of Value-Impact Assessment Value Impact 152.2 man-Rem - $2,740,840 as well as 25 weeks fuel load delay to Unit 1.

4 .

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. . Page 12 of 12 REFERENCES

1. CPSES - Field Danage Study Group Field Walkdown Package of thit 1 Containment, Problem 149A, B, C, & D, Ibv. AB-0, 10-8-83.

2. WPr--6834,' Jet Impingement Ioals from ICL Breaks, T. R. Puryear to J. B. George, December 6,1983. ,

3. NUREG 2136 Effects of Ibstulated Event Devices on Ibrmal Operation  ;

of Piping Systems in Nuclear Power Plants, May 1981.

4. Designers Raliation Exposure AIARA Manual, Westinghoum Electric Corp. Table 4-2, kv. 2 (Draft), 1982.

5. Leak Before- Break Analysis by Pacific Wrthwest Iaboratory as Attachment to Enclosure 4, Ibgulatory . Analysis of Mechanistic Fracture Evaluation of Reactor Coolant Piping A-2 Westinghouse Owners Group Plants, WCAP 9558, Rev. 2, May.1982.

6. CPSES Final Safety Analysis Report, Table 2.1-5, Rev. O.

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