ML20212B732

Evaluation of Proposed CRD & Orifice Assembly 300 F Temp Limits,Fort St Vrain Nuclear Generating Station

ML20212B732
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/30/1986
From:	Barnes B, Nalezny C, Udy A EG&G IDAHO, INC.
To:	NRC
Shared Package
ML20212B738	List: ML20212B732 ML20212D848
References
CON-FIN-D-6023 EGG-NTA-7355, TAC-61601, NUDOCS 8612290307
Download: ML20212B732 (19)

Text

' '

E NcL0 rV RE 4 EGG-NTA-7355

.. i EVALUATION OF THE PROPOSED CONTROL ROD DRIVE AND ORIFICE ASSEMBLY 300*F TEMPERATURE LIMITS ,

FORT ST. VRAIN NUCLEAR GENERATING STATION TAC No. 61601 INEL Reviewer - 8. L. 8arnes INEL Reviewer - A. Udy .

INEL Program Mgr - C. L. Nalezny -

NRC Lead Reviewer - P. Shemanskt i NRC FSV Project Mgr - K. Heitner  !

NRC Program Mgr - M. Carrington 1

Published November 1986 l EG&G Idaho, Inc.

Idaho Falls, Idaho 83415 Prepared for the U.S. Nuclear Regulatory Commission '

Washington, D.C. 20555 under DOE Contract No. DE-AC07-76ID01570  !

i FIN No. D6023 .

l f6(pl O 4 5W7R/ L ~ pp.

i

r' ABSTRACT This EG&G Idaho, Inc., report presents the results of a review of the acceptability of operating the control rod drive and orifice assemblies (CR00A) of the Fort St. Vrain Nuclear Generating Station at temperatures up to 300"F. The review concludes that the submittal by the licensee, Public Service Company of Colorado does not adequately qualify the CR00As for operation at elevated temperatures (up to 300 F) and that the CR00As should be restricted to operations up to their present operating limit.

i, l

l Docket No. 50-267 TAC No. 61601 i 11 l

t

..l i

l

! FOREWORD This report is supplied as part of the " Review of Plant Specific Licensing Actions for Operating Reactors," Task 1-9 being conducted for the U.S. Nuclear Regulatory Comission. Office of Nuclear Reactor Regulation, Division of PWR Licensing-8, by EG&G Idaho, Inc., NRR and I&E Support Branch. -

I The U.S. Nuclear Regulatory Comission funded the work under authorization 8&R 20-10-10-11-2,! FIN No. 06023. ,

1 i

i. .

i i

5 i  :

e i

4 ,i i

I,

. Docket No. 50-267 I TAC No. 61601 0

g i ni I

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

. i -

o I

2 '

CONTENTS ABSTRACT .............................................................. 11 FOREWORD ..............................................................

i ii 1.C BACKGROUND .................'......................................

-y 1 .

?

2.0 EVALUATION ....................................................... 2

3.0 CONCLUSION

S ...................................................... 4 Ii

4.0 REFERENCES

.................'...................................... 5 s APPENDIX A--QUESTIONS AND CONCERNS RELATED TO THE PROPOSED FORT ST. VRAIN CONTROL ROD DRIVE AND ORIFICE ASSEMBLY 300*F TEMPERATURE LIMITS .................................... 8 i

i e

I I

l l.

6 i

s 9

g I

i i

e e

t i

I ,

i l

-g, i;

i iv l

1 s';.

i CONTROL R00 DRIVE AND ORIFICE ASSEMBLY

, J00*F TEMPERATURE LIMITS FORT ST. VRAIN NUCLEAR GENERATING STATION s

1.0 BACKGROUND

J There are 37 pairs of control rods at the Fort St. Vrain huc' ear Generating Station. Each pair is operated by 1 of 37 control rod drive and orifice assemblies. The pair of rods can be~ inserted or withdrawn by operating the control rod drive shim motor, or the pair of rods can be I

released for a controlled fall into the reactor core.

~

i

Reactor scram is accomplished by releasing an electromagnetic brake on the end of the control rod drive shim motor shaft. The weight of the I -

control rod then turns the cable drum, th'e gear train assembly and the motor rotor. 1he speed of insertion is controlled by dynamic braking of ,

the control rod drive shim motor. Currently, control rod scram tests are.  !

performed biweekly.

'During operation of the Fort St. Vrain reactor, temperatures within ,

Fl l

the upper housing compartments (are measured. The temperature of the housing closure plates, the control drive shim motor cases, and the upper housing compartment floors are measured. In addition, the temperature of each of the individual control rod drive motors is monitored, with specific

),! '

action required if the motor temperature exceeds 250*F or 1'f the area

!? helium temperature exceeds 300'F. t l*

[ A test (Reference 1) was performed on a spare control rod drive and orifice assembly. The test was to evaluate the effects of operation at temperatures up to 300*F on the components that could negate a control rod 1 scram due to component failure at the elevated temperature.

] .

i N.

6 i

4 l

2.0 EVALUATION The test report on the effects of operation of the Fort St. Vrain ControlRodDriveandOrificingAssembliesattemperaturesupto30p*F (Reference 1) and the FSV Updated Final Safety Analysis Report (UFSR) *

(Refere.;ce 2), were reviewed against the relevant requirements of Chapter 3.11 and Chapter 4.6 of the NRC Standard Review Plan (References 3 and 4). While the Standard Review Plan was written for pressurized water  ;

reactors (PWRs), the general requirements of Chapters 3.11 and 4.6 are relevant because they deal with environmental qualification of mechanical and electrical equipment and the functional design of control rod drive systems. A number of related documents (References 5 to 30) were also reviewed in the course of the evaluatien.

When the submittal was evaluated against the requirements of Chapters 3.11 and 4.6 of the Standard Review Plan (References 3 and 4), it was' evident that the licensee had rot used the relevant guidance of the Standard Review Plan when preparing the submittal. As a result.there were a number of deficiencies. The following are examples of the type of deficiencies identified in the review.

5 The licensee did not develop functional, operational, and design specifications based on the environment that the CRDOAs would be expected to operate in. The operating experience of t'he FSV reactor should have been used to develop revised specifications.

The licensee's submittal did not provide acceptance criteria developed from the functional, operational and design specifications against which to evaluate the test results.

The tests were not performed under conditions that are representative

~

! of conditions in Fort St. Vrain (i. e., tests were performed with dry helium, while moisture is potentially present in the Fort St. Vrain .

reactor especially if there is a moisture ingress event).

I 2

[ The licensee did not provide information on the mechanical, and electrical properties of the materials in the CRD0As as a function of temperature, humidity, pressure, and radiation.

. The test was performed for a very limited time (1. e., 14 days,at 300*F ) . The licensee's submittal did not explain how the dats would be extrapolated to the length of time the CRD0As would be required to operate at elevated temperatures.

Appendix A tc this report presents a more complete list of concerns '

and questions developed in the course of this evaluation. Appendix A should not be considered a Request for Additional Information. The overall quality of the submittal was such that merely addressing the questions and comments in Appendix A still might not produce an acceptable submittal.

Instead, it is suggested that the licensee refer to the appropriate sections of the NRC Standard Review Plan to understand the degree of rigor

. required in a submittal of this type, and revise the entire submittal. The revised submittal should include or consider such items as functional, operational and design specifications, acceptance criteria, material

. specifications, material properities, test specifications, test operating procedures, test data, and the necessary supporting analyses.

O e

3 l 1

l I

- . . - - - . _ _ _ . _ _ _ _ _ . _ _. ._. _ _ _ - ,-_ _ - _ _ _ _ ~

I.

3.0 CONCLUSION

S Based on the information provided in the submittal of May 16, 1986 (Reference 1), the Fort St. Vrain control rod drive and orifice ass;emblies l can not be considered qualified to operate at 300*F. The submittaf aiad the .

I Updated FSAR were reviewed against the relevant requirements of the NRC Standard Review Plan for environmental qualification of mechanical and -

electrical equipment, and functional design of control rod drive systems.

The findings of the review were that acceptance criteria based on functional, operational and design specifications for the CRDOAs were'not developed and used in conjunction with the subject tests; and that the tests were not representative of the expected Fort St.' Vrain operating environment.

O e

1 i

b i .

h 4

i

4.0 REFERENCES

1. GA Techriologies Inc., Final Reoort - FSV CR00A Hiah Temoerature Functional Test, Document 908813. May 14, 1986.

2. Public Service Company of Colorado, UPDATED FSAR. Revision 3 for Fort Saint Vrain Nuclear Power Plant. -

3. Chapter 3.11 " Environmental Qualification of Mechanical and Electrical Equipment,"

. U. S. Nuclear Regulatory Comission, Standard Review Plan. NUREG-0800, Rev. 2 July 1981.

4. Chapter 4.6, " Functional Design of Control Rod Drive System," U. S.

Nuclear Regulatory Commission Standard, Review Plan. NUREG-0800, Rev 2, July 1981.

5. D. W. Warembourg, Public Service Company of Colorado, letter report to E. H. Johnson, NRC Region IV, Evaluation of CRDOA Bearings, Jur.e 13, 1985.

6. E. E. 81sson and W. J. Anderson, Advanced Bearina Technolog, Cleveland, Ohio, NSA SP-38, Lewis Research Center, 1964.

7. P. Freeman, Lubrication and Friction London, Whitefriares Press Ltd.,

1962.

8. F. P. Bowden and D. Tabor, The Friction and Lubrication of Solids, Clarencon, Oxford University Press, 1958.

9. :A. Palmgren, Ball and Roller Bearino Enaineerino, Philadelphia, Third Edition, S. H. Surbank and Co. Inc., 1959..

10. ' Anti-Friction Bearing Manufacturing Association (AFBMA) Inc., "AFBMA Standards for Instrument Ball Bearings," Section 12. Revision 2, AF8MA, New York, October 1966.

11. Plant Engineering Training Systems, Unit 4, Bearinas lubrication, Edited by Clifford R. Sayre, Technical Publishing Company, Barrington, IL., 1970.

12. . Plant Engineering Training Systems, Unit 2, Lubrication, Edited by Clifford R. Sayre, Technical Publishing Company, Barrington, IL., 1970.

l

13. FMC Corporation, Link-8elt Division, Bearina Technical Journal,

, Indianapolis, Indiana, First Edition, 1970.

s 1

14. M. E. Campbell, Solid Lubricants. A Survey, National Aeronautics and 9 - Space Administration Report NASA SP-5059(01) by Midwest Research Institute, Kansas City, Missouri, 1972.

i 4

15. G. R. Palin, Plastics for Enoineers. An Introductory Course," Pergamon Press, New York, Library of Congress Cat. Card No. 66-28420, 1967.

16. E. H. Johnson, NRC, 1tr. to 0. R. Lee, Public Service Company of Colorado, " Transmittal Letter for Attachment, Los Alamos National Laboratory Report", March 12, 1985.

I 0

o . .

17. Metals Handbook, 8th Edition, Volume 2, Heat Treatina. Cleaning and l Finishina, Edited by Taylor Lyman, American Society for Metals Metals Park, Ohio, 1964.

18. E. R. Braithwaite, Lubrication and Lubricants, Elsevier Publishing Company, London and New York, 1967.

19. D. Dawson and G. R. Higg'7 son, The Fundamentals of Roller Gea Lubrication /Elasto-Hydrodynamic Lubrication, Pergamon Press, London and New York, 1966. *

20. F. J. Clauss, Solid L~ubricants and Self Lubricatina Solids, Academic l Press, New York and London, Library of Congress Catalog Card l No. 70-137615, 1972.

21. N. Tipei, Theory of Lubrication With ADDlications to liauid and Gas-Film Lubrication, Edited by W. A. Gross . Stanford University Press, Stanford, California, 1962.

22. J. Gansheimer and R. Holinsky, " Molybdenum Disulfide - Solid Lubricant and Chemical Additive," Paper C285173, Proceedings Published for the First European Tribology Congress, Institute of Mechanical Engineers, by' Mechanical Engineering Publications Limited, London and New York, 1975.

23. O. C. Bridgeman, Editor, "The Role of Viscosity in Lubrication" Proceedings of ASME Symposium March 10-11, 1958, Lubrication Division of American Society of Mechanical Engineers, New York, NY.

24. The Institution of Mechanical Engineers, " Proceedings of the

. Conference on Lubrication and Wear (in London), October 1-3, 1956 The Institution of Mechanical Engineers, Westminster, London SWI.

25. *8 earing Steels: The Rating of Non-Metallic Inclusion," May 22-24, 1974, Proceedings of American Society for Testing and Materials, ASTM Special Technical Publication 575, ASTM, Philadelphia,'PA, Library of Congress Catalog No. 74-28982.

26. Public Service Company of Colorado, Fort Saint Vrain Project, Document SD-12-3, " Control Rod Drive System," Issue E, 7/24/73.

27. Public Service Company of Colorado, Fort Saint Vrain Project, Document SD-12-2, Issue C, 12/26/68.

. 28. GA Technologies, "FSV Control and Orificing Assemblies," Paper Copies

• l of Viewgraph Slides Listing FSV CRDM Specifications and Related Data.

lI 29. E. H. Johnson, NRC, letter to 0. R. Lee, Public Service Company of 7

Colorado, Safety Evaluation by the Nuclear Reaulatory Commission. Fort St. Vrain Nuclear Generatino Station. Public Service Company of C61orado, Docket No. 50-267, July 12, 1985.

L 4

\

. 30. C. F. Obenchain. EG&G Idaho, Inc., ltr report to F. L. Sims, Department of Energy, Idaho Operations Office, Transmittal of Letter Report on Review of Public Service Comoany of Colorado Control Rod Drive Bearino Report, (FIN A6701) - Oben-180-85, July 10, 1985.

e b

e i

I I .

9 i

5 l:

f k ___ __ . _ . ._. - - . _

. _ _ . . . _ _ . ~ . - _ _ _ . - - . _ - - - - . . ~- - - -

d APPENDIX A QUESTIONS AND CONCERNS RELATED TO THE PROPOSED FORT ST. VRAIN CONTROL ROD DRIVE AND ORIFICE ASSEMBLY 300*F TEMPERATURE LIMITS ,

t 3 t

• I l

b j .

l-I ,

O e

s L

r i

I 8

3

~ . . - - , - - . . _ _ _ . -. . _______ _. - ,_ , -,._- _ _ . _ . _

APPENDIX A OUESTIONS AND CONCERNS RELATED TO THE PROPOSED FORT ST. VRAIN C.ONTROL R00 DRIVE AND ORIFICE ASSEMBLY 300*F TEMPERATURE LIMITS s

=

_l

1. Section 5.1 of Reference 1 lists the nujor components contained in a control rod drive and orifice assembly (CRDOA). For each component, provide information on the temperature limiting materials and the manufacturer's recommended temperature limit for that component and material. Please provide the technical specification's for the basic insulation (electric) used for the control rod drive' motor (CRDM),

motor coil windings (rotor and stator), EPON 828 and all other electrical insulating material used in the CRDM including the DC 4 clutch brake mechanism. In particular, provide the dielectric strength and other mechanical and electrical properties as functions of temperature and humidity.

2. Address the acceptability of the heat effects described in Section 8.2.11 of Reference 1 on nylon cable ties, wire markers and other components in the housing upper compartment.

What is the possibility that further degradation'of CRDM electrical i l

i insulation and cable tie material could result in contamination of the  !

l CRDM ball bearings. Could degradation products keepit,he CRDM brake from releasing given a signal to scram?

i

3. Apparently all or most of the degradation of electrical insulating naterials and cable ties was related to the 300*F test of a single -

i sample CRDM which lasted only 14 days and included some 20~ scram tests. How much more degradation would likely occur under the same conditions in 3 to 5 years of continuous operation?

e t

9 9

4. The tests were performed using clean dry helium. Address the difference in dielectric strengths and other effects of moist helium coolant and CRDOA purge helium with respect to the clean dry helium used in the test. Are any changes of the dielectric materials:or thicknesses being considered as a result of possible reductio s in .

dielectric strength?

5. Address the continued degradation of CRD shim motor insulation resistance with time in the presence of a moist helium atmosphere.

Would additional or continued insulation cracking occurring over a 3 to 5 year period be likely to result in failure to operate, or more importantly, failure to scram (Ref. 1, pg. 30, para. 2 and pg. 36, item 6)?

f. Address the aging (accumulative effects of moisture, temperature, time

,and radiation) of the tested CRDOA in comparison to those CRD0As.that have seen normal reactor service.

7. 'The single CRDOA tested at a nominal 300*F did not fail to function in 14 days. However, to say that the CRDOA passed the test is controversial; it marginally passed the test is about the best one can

> ' 'say. How can a single sample which marginally (degradation of shim motor and related electrical insulating material and wire ties) passed the 300*F test for only 14 days be used as a basis to extrapolate that 37 such units would operate up to 300*F for 5 years without failure?

! 8. Sections 1.0.1 and 8.3.3 of Reference 1 note that repairs had been made in the shim motor leads. The report concludes that these repairs were not adequate to allow the use of this motor in the reactor (at elevated, i.e., up to 300*F temperatures). The licensee should ,

' identify other CRDOAs that have had similar repairs to either the shim motor, brake or the orifice drive motor and correct the potential .

insulation breakdown.

f 10

s

9. Section 3.8.1.1.2 of the updated FSAR (Reference 2) identifies a maximum ^ temperature rating of the control rod drive motor (CRDM) of 272*F. The specifications for the lead wires call for a temperature rating of 257'F. This seems to be borne out by the post-test observationofbreakdownoftheinsulationresistanceinthejotor stator windings (Sections 1.0.1 and 8.3.3 of Reference 1). The post-test insulation value was 5 kilohm versus 10 megohm. Relate these observations to the proposed operation at elevated ,

temperatures. Comment on why this coil (s) had to be replaced after the test when the test results imply that the test CRDOA and the 37 operational units are suitable for 300*F operation.

10. Please provide the materia 1' specifications for the CRDM ball bearings. Specifications for the inner and outer races (440C) and the balls (WC), cages, and retainers are requested. Material hardness and related heat treating details and surface finish of critical ball and raceway surfacts are of particular interest. This data will be compared with related data in the Section 4.0 list of references to determine if 300*F operation would result in shorter or less reliable bearing service life.

l

11. Sections 1.0.4 and 8.3 of R,'eference 1 show an increase in the setpoint of the reserve shutdown pre'ssure (from 10 psi to 12.5 psi) switch setpoint (10.5 psia is the maximum limit specified). We consider the sample size and results insufficient to conclude:that operation at 300*F is acceptable. It is unknown whether complete failure would occur with continued high temperature operation. Additionally, it has a -

not been shown that licensee surveillance is frequent enough to detect an imminent failure. Demonstrate that this component is acceptable for operation at 300*F. ,

, 12. To what extent would a 300*F temperature limit for the CRDM impact the ,

reliability of the reserve shutdown system (RSS)? In particular, aggolmeration of the RSS absorber material has already occurred and has required the modification of the absorber formulation. Address

. t i

I

- i the possibility that a combination of increased temperatures and moisture could cause a reoccurrence of the agglomeration of the boron carbide balls thereby rendering the RSS inoperable (Ref. 2, Section 3.8.4.2).

t  !.

13. The contact resistance of one of the rod retract switches had deteriorated to 0.14 ohm before the post-test examination (Section 1.0.7 and 8.3.11 of Reference 1). Address the acceptability of this switch at continued,long term (i.e., approximately 5 years) operation at 300*F; is the contact resistance likely to further degrade?

14. Section 7.1.3 of Reference 1 reports a 2% shift in the output of the N potentiometer. The report does not conclude that the potentiometer is usable in temperatures up to 300*F. Address the acceptability of this '

component for elevated temperature. operation. Additionally, verify, -

bytest,thatnofailureofjthepotentiometerassemblyat300*Fcould prevent a scram from occurring (such as mechanical binding of the -

1 wiper or shaft). Afterthejaforementionedtest,wefurtherrequest i disassembly of the potentiometer to verify that no heat rela'ted failure of internal parts has occurred. The potentiometer should be exercised while at 300'F to' simulate

shinsning and other normal control

~

rod motion for this test to!be valid.

15. Describe the preselected pass / fail condition for the back electromotive force (EMF) scram test sequence (Section S.2.2 of Reference 1). Explain the significance of this test and its detected failures. .lustify the acceptance of the CRD0A operating at 300*F with regard to these test failures.

b 16. :Please provide the technica'l specifications for the MOLYCOTE X106 CRDM

! lubricant. This information will be compared with similar data in the -

.- attachedlistofreferencesltodetermineif300*Fcontinuouslow j friction operation is probable.

J i ii . I 6

, i i i

! 12 i

p .

17. How hot did the CRDOAs get during the three instances of recorded CRD0A failure without purge gas flow (Ref. 2, Section 3.8.4.1, para. 1,2,&3)?

18. Provideadetaileddescription,suchasanengineeringdrawing,ofthej CRDM cable anchor devices.- From the material provided it is difficult to tell if these devices contain poured lead or other materials that might be sensitive to increased operational temperature limits for the CRDM. If the materials or devices are different on each end of the cables, provide this.information for all variations.

19. Does the li'censee intend to substitute new more temperature resistive materials in the CRDM for those materials that were observed'to deteriorate or perform questionably?

20. If degradation of the CRDM materials (electrical insulation, molybdenum disulfide lubricant which may degenerate to molybdenuhi trisulfide, which may result in corrosion of metallic surfaces, chemical interactions with water vapor, and oxidation of seal materials) is in any significant way attributable to chemical reactions which are normally relatively slow, address the possibility i' that increased operating temperatures could hasten these undesirable chemical reactions. A common rule of thumb for chemical reactions says that within fixed phases of the reacting materials (liquid stays ~

liquid, solid stays solid, etc.), the rate of a chemical reaction is If some proportional to the fourth power of the absolute temperature.

CRDM components are presently replaced or serviced every 5 years for

' eperational temperatures of say 215'F, then an increase to 300*F might require repair, service, or replacement more often as calculated below.

• Syrs. - (300*F + 459"F)

• Y yrs (215"F + 459"F)

Solving this equation for Y, the new time maintenance interval, yielfis Y-3.1 years. This represents a 38% reduction in time. Address this concern.

13 l

l

21. Please explain why the 50 called reduced starting moments for the CRDM did not produce greater speeds rather than lesser speeds (Ref. 1, pg. 29, Section 8.3.2).

22. If additional high temperature CRDM testing is done, consider he ,

addition of two microphones to monitor CRDM motor and gear box noise levels at ambient, 215'F, and 300*F temperatures during scram and shim -

operations. This could shed light on the abnormal control rod position plot (Ref. 1, pg. 30, Section 8.3.4).

23. Why was the CRDOA shim motor at a relatively constant 289'F when the helium environment surrounding it for 391 hours0.00453 days <br />0.109 hours <br />6.464947e-4 weeks <br />1.487755e-4 months <br /> was 300* to 303*F?

Could this temperature difference be instrumentation error? Also with

~

20 operational tests of the shim motor at the 300*F temperature (289'F?), why was no temperature rise indicated each time the shim motor was operated. A nominal motor temperature rise of l'F per, minute was anticipated based upon Figure 8.10 (pg. 148) (Ref. 1, pgs. 34, 148, and 154).

24. Address the possibility of generic errors in the Belleville was'her stackup in the test CRDM relative to the 37 inservice CRDMs. What are ,

the consequences of such an error (Ref. 1, pg. 35)?  !

25. Address the possibility of the same bolt torque error found on the test CRDM occurring on the 37 operv ional CRDMs. Normally, bolts are torqued to within about 90% of ultimate load by design. If 32 bolts were found to be torqued to 150 ft-lbs instead of the required 105 ft-1bs, more than simply retorquing the bolts to the proper lower limit would be required. A detailed inspection of these parts seems in order, as a minimum, if there is any pos 'hility that 150 ft-lbs ,

could overstress these bolts. The review material provided gave no indication of the bolt size or grade or similar details for the mating ,

threaded holes (Ref. 1, pg. 35, item 7).

I 14

26. Address the question of whether or not the calculated starting moment figures cited in the range of 17 to 20 inch-ounces could prevent a scram from occurring. A figure of 15 inch-ounces has been used in the past as a limiting condition for a successful scram (Ref 1, pgs. 45

& 144, and Ref. 14, Attachment 2, Los Alamos National Laborato,ry FIN A7290 report of March 12, 1985, pg. 5, Section 2.1.3). _f

27. Please provide a description of the seals at the bottom of the CRD0A housing, at the control rod cable seals, and the seal (s) at the reserve shutdown guide tube. A materials list and technical specifications relating to temperature limits and radiation resistance, is requested.

4 e

15

.-. _ _ - . _ . - _ .-._ _. . - - ..