ML20235Y872

Forwards Util 870710 Responses to NRC Questions Re Continued Use of Boraflex in Spent Fuel Pool Storage Racks at Facility.Boraflex Will Remain Acceptable for Use.Certificate of Svc Encl.Related Correspondence

ML20235Y872
Person / Time
Site:	Turkey Point
Issue date:	07/15/1987
From:	Frantz S NEWMAN & HOLTZINGER
To:	Cole R, Lazo R, Luebke E Atomic Safety and Licensing Board Panel
References
CON-#387-4077 OLA-2, NUDOCS 8707270085
Download: ML20235Y872 (20)

Text

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QU EMEU S99fR$,DM o NnwxAN & HoLTZINGER, E C.

3 JACK R. NEWMAN 8615 L STREET. N.W. -

' WILLIAM E. BAER. JR.

JOHN E. HOLTZsNCER,JR e DOUGLAS L BEREsrORD HAROLDF.REl$ WASHINGTON. D.C. 2O03 6 JADEA EATON MAURICE ARELRAD JANETE.B.ECKER J. A. BOUKNIGHT, JR. MERLE W. FALLON PAUL H. MCCM 202 955 66OO "j t """'"'

GEORGE L EDGAR 'g ut]L 11 4 U' P11O:13 'BRIAN " ".RG l$H MATHLEEN H. $HEA JILL E. GRANT

@UGLAE G GREEN ANDREW N. GREENEe MAROL LYN NEWMAN PAMELA A. LACEY JOHN T. $70 UGH JR ,f; FRANK R. LfNDH

. JAMES 8. VASILE I -- KEVIN J. LIPSON MICHAEL A. BAUSER ' b' KATHLEEN M. McDERMOTT ALVIN H, GUTTE RMAN JEFrREY B. MULHALL*

cDWARD J TWO E' July 15, 1987 'aao' a a^ mama JAMES B. MLCOK JR JANE 1.RYAN CIEVIN P. GALLEN PAUL J. SAVIDGE' THOMAS A. SCHMUTZ DONALD J. SILVERMAN MICHAEL F. HE ALY JACOLYN A. SIMMOP S ROBERT 4. WHITE ROBERT H. SOLOMON SCOTT A. HARMAN JOSEPH E. $TUBBS STEVEN P. FRANTI NANCY A. WHITE

• DAVID B RA$nsN ROBIN T. WIGGINS*

ROBENT LOWEN$TEIN *NOT ADMff7CD IN D C HERSERT B COHN ERNEST C. BAYNARD,lia DrCOUNELL Dr. Robert M. Lazo, Chairman Administrative Judge Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Dr. Emmeth A. Luebke Administrative Judge Atomic Safety and Licensing Board "U . S . Nuclear Regulatory Commission Washington, D.C. 20555 Dr. Richard F. Cole Administrative Judge Atomic Safety and Licensing Board U.S. Nuclear Regulatory Commission Washington, D.C. 20555 In the Matter of FLORIDA POWER AND LIGHT COMPANY (Turkey Point Plant, Unit Nos. 3 and 4)

Docket Nos. 50-250, 50-251-OLA-2

Dear Administrative Judge:

Please find enclosed a letter dated July 10, 1987, from l Florida Power and Light Company (FPL) to the NRC, which provides FPL's responses to three NRC staff questions concerning the continued use of Boraflex in the spent fuel storage racks at Turkey Point.

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) 8707270085 870715 PDR ADDCK 05000250 G PDR l 15d

NEwxAN & Hol.TZINGER. P. C.

e Dr. Robert M. Lazo, et al.

July 15, 1987 Page Two AF these responses state, testing and experience indicate that Boraflex may undergo some physical change and shrinkage during usage, but that the Boraflex will remain acceptable for use. Additionally, Turkey Point has a surveillance and testing program which will be sufficient to detect any changes in the neutron attenuation properties and physical distribution of the Boraflex and thereby assure its continued acceptability. Finally, sensitivity studies indicate that Boraflex at Turkey Point would be acceptable even if conservative and unrealistic assumptions are made regarding postulated degradation of the Boraflex.

Sincerely, g

,f';' d r , (y Steven P. Frantz Co-counsel for Florida Power

& Light Company cc: Service List l

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t P o Sf)4 IJOOO Jt NO BE AC- F L L'J:3

, 9 FLORIDA POWER & LIGHT CO'%1PANY JULY 10 1987 L-87-279 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen: ,

Re: Turkey Point Units 3 and 4 Docket No. 50-250 and 50-251 Request for Additional Information '

Boroflex Usage at Turkey Point Attached is Florido Power & Light Company's response to your June 9,1987 request for additional information concerning the continued use of Boroflex of Turkey Point.

Should there be further questions, please contact us.

Very truly yours, YkWM C. O. W d Group President Nuclear Energy COW /RG/gp Attochment cct Dr. J. Nelson Groce, Regional Administrator, Region 11, USNRC Senior Resident inspector, USNRC, Turkey Point Plant

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Boraflex Usage at Turkey Point Quastion 1 B2scd on the recsnt expericnca partaining to degradation of Boraflex in~ spent fuel pools at Quad Cities and Point Beach Nuclear Power Plants, provide justification to demonstrate the continued acceptability of Boraflex for application in the Turkey Point spent fuel pool.

Response Boraflex is the neutron absorbing poison used in the Turkey Point spent fuel racks. This material assures a shutdown margin of 5%.with no boron in the spent fuel pool water..

As discussed in Section 4.7.2 of the Turkey Point Units 3 and 4 Spent Fuel Storage Modification, Safety Analysis Report, dated March 14, 1984, Boraflex has undergone extensive qualification testing to study the effects of gamma and neutron irradiation in various environments and to verify its structural integrity and stability as a neutron absorbing material. These tests indicated that Boraflex maintains its neutron attenuation capabilities when subjected to an environment of borated water and 1.03 x 10 11 rads gamma radiation.

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Additionally, -

further tests have recently been conducted and preliminary results indicate that some shrinkage (a maximum of about 2%) can occur in Boraflex,

and that this shrinkage is complete at approximately 10 1 x 10 rads gamma.

Three plants have reported the results of their first Boraflex surveillance. Of these three, the Boraflex material used at Point Beach Nuclear l Power Plant has received the highest accumulated dose. This Boraflex material has been in use for a total of five years, and some of the Boraflex panels have received a 20 year-equivalent radiation i dose due to the spent fuel management techniques used at Point Beach. The examination of the 2" x 2" sample coupons at Point Beach (which had 10 a maximum exposure of 1.6 x 10 rads gamma) showed that the coupons had experienced changes in physical characteristics such as color, size, hardness, and brittleness. However, the nuclear characteristics of the. samples had not experienced any unexpected changes, and the boron absorbing properties of the samples met the acceptance criteria for maintaining the 5% A k/k shutdown margin. Point Beach also examined two full size (150" long x 8" wide) Boraflex panels, which had a maximum exposure of about 10 1 x 10 rads gamma. These panels had a far lesser amount of physical changes than the 2" x 2" sample coupons. Thus, the examination of the Point Beach

coupons and Boraflex panels indicates that, while some physical changes in Boraflex may occur with accelerated radiation exposure, the Boraflex will retain its neutron absorbing characteristics.

Prairie Island has also examined two large (8" x 12") Boraflex coupons. One of the coupons (which had a 6 month exposure) had an appearance similar to the as-manufactured Boraflex. The other coupon (which had a 32 month exposure) had some slight physical changes similar to that experienced by the Boraflex panels at Point Beach.

The Boraflex panels in the Quad Cities racks (which had an exposure of about 10 rads gamma) were

. examined by a neutron surveillance technique.

Gaps were noted in the Boraflex panels, and review of the size and number of gaps was performed.

This review indicated that the gaps were attributed to a rack design and fabrication process which did not allow the Boraflex to shrink without cracking.

The Quad Cities racks were designed to hold smaller BWR fuel and did not utilize a protective wrapper for installing the Boraflex. The fabrication process required the Boraflex material to be glued and firmly clamped in place to the stainless steel

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fuel rack. walls.- This process did not allow for the predicted shrinkage of Boraflex and as such  !

gaps developed. Additionally, the Boraflex panels .

at Quad Cities were not constructed from a single sheet of Boraflex, resulting in pre-existing breaks  !

in the Boraflex panels. Less than half of the )

l Boraflex panels at Quad Cities had gaps. Furthermore, the gaps in the Boraflex panels at Quad Cities varied in length up to a maximum of 4" and were located at various places along the heighth of the panels.. A k-effective analysis of the Quad 4

Cities spent fuel pool demonstrated that these '

gaps did not cause Quad Cities to exceed its 0.95 limit on k-effective.

Turkey Point racks are designed to hold the large PWR fuel assemblies. Boraflex panels were constructed from a single sheet of Boraf' lex and are held in the stainless steel cell wall by enclosing it with a wrapper plate. During fabrication, a cut-to-length sheet of Boraflex was attached to the wrapper plate with adhesive applied in short lengths (up to 2 1/2" long) at a maximum of 16 places (8 per -

side) along the length of the Boraflex. The purpose of the adhesive was to provide temporary support during the spot welding process and not for long-term

_ 5 binding. The wrapper provides an enclosure which protects the Boraflex from the flow of water, very much like that used in the original Boraflex qualification testing. Additionally, the wrapper enables the Boraflex panel to remain in place without the necessity of tightly clamping the panel in place.

In conclusion, the experience at Point Beach indicates that some physical changes may occur in Boraflex, but that the Boraflex will retain its neutron attenuation properties. Additionally, both testing of Boraflex and the experience at Quad Cities -

indicates that some shrinkage in Boraflex may occur, but that this shrinkage is limited to a maximum of 2 to 3% of the length of the Boraflex.

The Quad Cities Boraflex panels had some gaps because the racks did not permit the Boraflex to shrink without cracking. Since there are differences in the manufacturing process of the Boraflex used at Quad Cities and Turkey Point, the experience at Quad Cities may not be applicable to Turkey Point. In any case, due to the small size and the random orientation of the gaps at Quad Citites, the gaps did not cause the k-effective of Quad Cities spent fuel pool to exceed the 0.95 limit.

Therefore, FPL considers that the Boraflex is acceptable ,

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for continued use at Turkey Point.

Question 2 Based on the recent information, provide any changes to the in-service surveillance program for Boraflex neutron absorbing material and describe the frequency of examination and acceptance criteria for continued use. Provide the procedures for testing the Boraflex i

material and interpretation of test data, s

Response To confirm that the Boraflex at Turkey Point is acceptable for continued use, FPL will conduct two types of examinations of the Boraflex. First, as described in the Turkey Point Units 3 and 4 Spent Fuel Storage Facility Modification, Safety Analysis Report, dated March 14, 1984. Section 4.8, Testing and In-service Surveillance, FPL will conduct an in-service surveillance program.

This program will evaluate both Region I and Region II Boraflex samples for the following:

I. Physical Characteristics A. Examine the stainless steel jacket and note whether the material is smooth or exhibits any visible damage.

B. Examine the Boraflex poison sample and note whether the material is smooth

or exhibits any visible changes (color, pitting or cracking, etc.).

I C. Measure specimen (s) weight and volume, and calculate its density. l D. Measure the hardness of the specimen (s).

II. Nuclear Characteristics A. Take a neutron radiograph of the specimen (s) to determine the uniformity of boron distribution.

1 B. Perform attenuation measurement of the<

specimen (s), and determine the B 1 ading..

10 The minimum area density of boron should be equal to or greater than 0.02 gm/cm 2 for Region I and 0.012 gm/cm 2 for Region II.

Second, FPL will conduct a surveillance program to detect any spatial distribution anomalies in the Boraflex panels. This program, called " Blackness Testing", will involve the use of a fast neutron source and thermal neutron detectors. The thermal neutron detectors will be connected to four chart recorders which will record the presence of thermal neutrons. The number of thermal neutrons will -

be low if the boron carbide is present in the Boraflex material. If gaps or voids are present,  ;

the number of thermal neutrons will increase and a

be recorded by the chart recorders. This arrangement of instruments would detect gaps or anomalies in the Boraflex panels. The Blackness Testing technique was utilized successfully by Quad Cities to determine the existence of gaps in their spent.

fuel racks. FPL will perform the baseline testing

• in late July or early August for several storage cells in both Region I and Region II that have received the highest cumulated exposure to date.

FPL will then retest these cells on a regular interval to be determined at a.later date. This interval will be based on FPL's results and EPRI and industry data. -

l FPL's surveillance programs will be sufficient to detect any changes in the neutron attenuation properties of the Boraflex and any changes in the physical distribution of the Boraflex. As a result, these programs will assure that the Boraflex in the Turkey Point spent fuel racks will be acceptable for continued use.

Question 3 Describe the corrective actions to be taken if degraded Boraflex specimens or absorber is found in the spent fuel pool.

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. Response FPL will follow the industry efforts concerning the performance of Boraflex. EPRI, Bisco (the manufacturers of Boraflex) and several utilities are analyzing data as it becomes available.and will notify the industry of the results. FPL will evaluate these results and determine whether any additional actions are warranted for the Turkey Point spent fuel racks.

A sensitivity study has been performed to determine l .

l whether the Boraflex material at Turkey Point l

would be acceptable if it develops gaps. As discussed above, tests and the Quad Cities surveillance

indicate that 2% shrinkage could occur. If it l

l is conservatively assumed that this shrinkage 1

would cause gaps in the Turkey Point Boraflex, the shrinkage could result in a two or three inch gap. If it is postulated that such gaps would occur in every Boraflex panel at exactly the same location (which is an extremely conservative and unrealistic assumption based on the Quad Cities data), the attached curves show that the Turkey Point spent fuel pool would still maintain the '

required shutdown margin. This shutdown margin does not account for the 1950 ppm boron in solution which adds an additional 30%d k/k shutdown margin.

Therefore, should the Boraflex degrade, the spent

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fuel could still be stored at Turkey Point with the required shutdown margin.

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A etudy has beer esopletod to detorains the effeet ef 3aps in'80ROFu K poisen plates es spent fuel reek K,gg. m basis for this study was the Turkey poitts Unit 3 Region 1 spent fuel storage raaks. .

Aniel gaps in the 30ROFu x ranging free O to 10" were aedeled expliettly ustag XIIIO. h ee gaps were medeted in one half of and in all of the poisen plates la the raak.

The results from the XD0 ealemistions were applied as adders to the originally saleulated rask X,gg and unsertalaties. N details of the calculation af the original E,gg with u serrainties are attashed.

The Kell 0 salaulattene and the original criticality analysis assume a maaiman U.235 entishment of 4.5 w/s. N resulta are presented in Figures 1 and 2.

It was aise requested that the ease type of data be provided with a mazisun U.235 enriehment of 4.1 w/o assumed. The original criticality analysis imeluded a study whiek shesed the sensitivity of rask K,gg to fuel enrishment for the Easten 1 spent fuel reaks. This study was used to dete mine that the deeresse in U.238 enrishment from 4.8 w/o to 4.1 1 w/o results ta a 0.018 AK doerease ta rask I,gg. This ana11 hge in

- fuel enrishment dess met significantly effset the reactivssy worth of the 38pe in the poissa plates. N data for the study using the 4.1 w/o fuel was predueed by subtraestag she 0.018 AK free the results af sh,s 4J ai/s Anal daug. Zhs zasulas af shis aassed sau$ ars presented la Figures 1 and 3.

h data presented La this report are the results of a data 11*d

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sensitivity study and are repressatative of the reeuita that would come from a complete reanalyeLa of the Turkey Feist Unit 3 Region 1 spent fuel eterage raaks.

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7 The fellowing text was taken directly from the Turkey Feint criticality analysis report. .

Sased on the analysis describe above, the following equation 1Ls used to I develop the final K,gg for the Turkey Point Region 1 spent fuel storage reekst. I

• eff * " nominal + Emethod

• Ipart + 3aseh

• II *neminal I

+ (ksmethed)

• II'sesh) I ,

ktore:

K g ,g = nasinal case XRp0 K,gg = 0.9150 8,,gg = aethod bias determined free bAnshaark eritical comparisons = 0.0 2 3 = bias to secount for pelsen particle self. shielding '

Pt.rt = .0025 M i

l S

meh - bias to secount for material thiekness and construction toleranse = 0.00760 M i ks 95/95 uncertainty in the nesinal ease KEpo g ,g= X,gg =0.00601 AK 1 ks g g = 95/95 uncertainty in the mothed bias = 0.013 AK km,,4 = 95/95 uncertainty assestated with material thickness and construetten tolerances = 0.00721 AK

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Substituting calculated values in the order listed above, the result is:

K,gg = 0.9150 + 0.0 + 0.0025 + 0.00740 + t(0.00601)2 + (0.015)2 {

+ (0.00721)2 31/2 = 0.9403 J

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./t o UNITED STATES OF AMERICA __

NUCLEAR REGULATORY COMMISSION' '^$f[ l BEFORE THE ATOMIC SAFETY AND LICENSING BOARD e7 1120 Aio:14 tra DGCC },.

) b r '. 9.

In the Matter of )

)

FLORIDA POWER & LIGHT COMPANY ) Docket Nos. 50-250 OLA-2 1

) 50-251 OLA-2 (Turkey Point Nuclear Generating )

Units 3 & 4) )

)

CERTIFICATE OF SERVICE 4

I hereby certify that copies of the attached letter in the above captioned proceeding were served on the following by deposit in the United States mail, first class, properly stamped and addressed, on the date shown above.

Dr. Robert M. Lazo, Chairman Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Dr. Emmeth A. Luebke Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Dr. Richard F. Cole Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Atomic Safety and Licensing Board Panel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Atomic Safety and Licensing Appeal Board Panel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Office of Secretary U.S. Nuclear Regulatory Commission l Washington, D.C. 20555 Attention: Chief, Docketing and Service Section (Original plus two copies)

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l 8 l l Joette Lorion

! 7210 Red Road #208 l Miami, FL 33143 l

Colleen P. Woodhead Office of Executive Legal Director U.S. Nuclear Regulatory Commission Washington, D.C. 20555 l

l l Norman A. Coll, Esq.

l Coll, Davidson, Carter, Smith, Salter & Barkett '

3200 Miami Center 100 Chopin Plaza Miami, FL 33131

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• S$even P. Frantz V Nceman & Holtzinger, P.C.

1615 L Street, N.W.

Washington, D.C. 20036 (202) 955-6600 .

Co-counsel for i l Florida Power & Light Company i

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Dated: July 15, 1987 l

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