ML20209E899

Discusses Status of CRD & Orificing Assembly (Crdoa) Refurbishment Efforts.First 37 Crdoas Refurbished & Installed.Summary of Design Changes & Test Results Encl

ML20209E899
Person / Time
Site:	Fort Saint Vrain
Issue date:	06/25/1985
From:	Lee O PUBLIC SERVICE CO. OF COLORADO
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-85224, TAC-55294, NUDOCS 8507120341
Download: ML20209E899 (19)

Text

j k PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 840

• DENVER, COLORADO 80200 June 25, 1985 OSCAR R. LEE o d M . Wain y,c c ,,, c . , o ~ , Unit No. 1 P-85224 Regional Administrator Region IV U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 Attention: Mr. Robert Martin Docket No. 50-267

SUBJECT:

Status of CRD0A Refurbishment Ef forts

REFERENCES:

1) NRC Letter, Wagner to PSC - FSV Dated December 17, 1984 (G-84470)

2) PSC Letter, Gahm to Region IV

-r- Administrator,

$ (C)[!! 0 $7 d. D Dated February 3, 1985 (P-85046)

3) NRC Letter, Martin to Lee, JUL - I 1985 Dated January 17,.1985(G-85024)

~

4) NRC Letter, Denise to Lee,

, Dated April 8, 1985 (G-85127)

5) PSC Letter, Warembourg to Johnson, Dated January 31, 1985 (P-85037)

6) PSC Letter, Warembourg to Johnson,.

Dated June 13, 1985 (P-85201)

7) PSC Letter, Lee to Region IV Administrator, Dated January 30,1985(P-85032)

8) PSC Letter, Lee to Johnson, Dated March 21, 1985 (P-85099)

Dear Mr. Martin:

1 1

The purpose of this letter is to inform the Nuclear Regulatory .

Commission (NRC) that Public Service Company of Colorado (PSC) has  !

completed refurbishment of the first thirty-seven control rod drive 7 l

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'and orificing assemblies (CRD0A's). Those refurbished CRD0A's are now installed in the reactor', and the seven remaining spares are in the process of- refurbishment for the 'next refueling outage. A summary of actions that have been taken to ensure the operability of the Fort St. Vrain CRDOA's follows.

Subsequent to the June 23, 1984 event where six of thirty-seven control rod pairs failed to insert into the core upon scram under the automatic velocity limited free-fall system, PSC initiated actions to identify the root cause of the event and restore the deficient CRD0A's to an operable status. The six CRD0A's that failed to scram were the first to be examined and rebuilt with an additional four being examined and rebuilt to various degrees afterwards. No definite cause for the failure to scram could be identified, but indications were that shim motor bearing wear and debris buildup was the primary contributor.

During this initial phase of_PSC's efforts, several other problems were also identified which were specifically unrelated to the failure to scram problem. First, CRD0A instrumentation anomolies began manifesting themselves, apparently induced by the high moisture content in the primary coolant. Second, a control rod absorber string suspension cable failed; the cable was evaluated, and stress corrosion cracking was identified as the failure mechanism (see-Reference 7). Third, during functional testing of one CRDOA's reserve shutdown (RSD) system, it was discovered that only thirty to forty of the eighty pounds (nominal) of RSD material was expelled.

Inspection and chemical analysis of the RSD material remaining in the RSD hopper revealed boric oxide crystallization which facilitated bridging of the boron balls inside the hopper (see Reference 8). A number of studies were initiated to fully evaluate each of the problems identified, and a summary of the activities performed in the initial phase was presented to the NRC~ in meetings held on November 28 and 29,1984 (see Reference 1).

The discovery of stress corrosion cracking in the CRD0A cables and boric acid crystallization on the RSD material, as well as the lack of a definite failure mechanism being identified.for the six CRD0A's failing to scram on June 23, 1984, led to a decision to refurbish all

! of the CRD0A's, restoring them to a "like new" condition. The major objectives of this program were established to include:

1) Refurbishment of all shim motors, replacing all motor bearings with new bearings,

2) Refurbishment of all 200 Assembly gear trains,

3)- Replacement of all CRD0A instrumentation with new components,

4) Replacement of all- stainless steel suspension cables with Inconel 625 cables,

5) Replacement of all RSD material with material manufactured under new specifications which significantly reduce the amount of B 20, impurities available for conversion to boric acid crystals,

6) Installation of CRDOA temperature monitoring devices,

7) Installation of CRD0A purge seals designed to inhibit primary coolant from entering the 200 Assembly gear train and motor area,

8) Refurbishment of all orifice drives, and

9) Replacement of miscellaneous CRDOA components with like components made from materials not as susceptible to chloride stress corrosion.

~

To ensure that a thorough knowledge of the.CRD0A's was attained prior to starting the refurbishment program, vendor (GA Technologies - GAT) support was solicited, but nearly all of the GAT personnel originally assigned to the design and manufacturing of the Fort St. Vrain CRDOA's had since left the company. PSC was able to locate one of the people responsible for developing the CRDOA 0&M manual and another individual who worked with him on the CRD0A's originally.

Both were brought to Fort St. Vrain in December, 1984, as expert consultants.

The CRDOA Refurbishment Program was developed and initially implemented during the period beginning in mid-November, 1984, and ending in early February, 1985. It was developed using the experience gained in the initial phase activities and the knowledge provided by the two CRD0A experts in addition to the in-house expertise already available. Implementation of the program involved the design and manufacture of special CRD0A handling equipment so that up to five CRD0A's could be worked simultaneously in an assembly line fashion.

Existing procedures for the maintenance of CRD0A's were extensively rewritten based on ieviews of vendor supplied 0 & M manuals, design and. fabrication drawings, and additional clarifications on specific design and operation details obtained from original manufacturers.

Personnel from all associated areas of expertise within PSC were

involved in'the procedure preparation. Those areas of expertise incl _uded, but were not limited to: Maintenance, Health Physics, Quality Assurance, Nuclear Engineering, Technical Services Engineering, and Nuclear Betterment Engineering. Again, the expert consultants provided significant insight as well. Quality Control inspection criteria were included to ensure original design component standards as a minimum. Additional inputs were incorporated based on a review of the procedure by the Senior Resident Inspector.

Contract personnel arrived on site approximately three weeks before the scheduled start of work for. training purposes. A letter of agreement with the union representing PSC. Maintenance allowed the hiring of special non-union " precision" mechanics for work on the delicate 200 Assembly motor and gear train aspects. A spare CRD0A

~200 Assembly motor and gear train was repeatedly disassembled and reassembled under the guidelines of the rewritten procedures.

Further refinements to the procedure were accomplished at this point.

Union contract personnel were trained on.the operation of new CRDOA handling equipment, and all personnel received extensive Health Physics training.

-Work on the first CRD0A began on February 6, 1985. This CRDOA was refurbished in its entirety prior to beginning the assembly line type process so that all aspects could be evaluated and verified acceptable. Numerous procedure revisions were made to improve workability. Several improvements to the original design were implemented. A summary of all design changes made to the CRD0A's is provided in Attachment 1. The overall refurbishment process was presented to the NRC in Reference 2, and all aspects of the CRDOA refurbishment program were discussed at length in meetings held on January 15, 1985, and February 20-22, 1985 (see References 3 and 4).

As the CRD0A Refurbishment Program progressed, several changes in scope were made to accommodate improvements to the original design and additional maintenance activities which'were deemed prudent for improving overall CRD0A' performance. Specific improvements to the original design beyond those previously identified included the increasing of the cable drum inside diameter to third stage pinion gear clearance to eliminate potential interference, and the installation of a slack cable switch bushing cap to ensure positive bushing retention. Additional maintenance ~ activities performed on all CRDOA's beyond those previously identified included relubrication of the 200 Assembly and orifice drive gear trains and examination and recoating of shim motor stators as necessary to restore them to original design specifications.

Near the end of the CRD0A Refurbishment Program, it was discovered that certain replacement 200 Assembly motor and gear train bearings

did not meet design specifications (e.g. shim motor bearings were provided by the manufacturer with eight balls instead of the specified nine). The problems associated with the bearings have been resolved through engineering evaluations and qualification testing of the "eight ball" bearings. A report on this. testing and evaluation was submitted via Reference 6.

To confirm that the 18 CRDOA's which had been refurbished prior to the Enforcement Conference on April 24, 1985, and that selected CRD0A's refurbished subsequent to that Conference were completed in accordance with high quality standards, audits of completed work packages were conducted by Quality Assurance.

As part of the control rod drive refurbishment, NFSC G-85-02 Audit, the Fuel Handling Procedure Work Packages (FHPWP's) governing the refurbishment of the CRD0A's were reviewed for proper documentation with emphasis on the QC hold and witness points and for records of task sign-out/ sign-in and completion. A limited review of two FHPWP's was completed, and 26 FHPWP's were examined in depth. The QC hold and witness points were examined to ensure that the points were signed by QC personnel. If these points were not signed, further investigation was done to determine the reason (s) and resolve the situation.

In addition to reviewing completed FHPWP's, the NFSC G-85-02 Audit reviewed Procedure Deviation k norts (PDR's) related to the CRD0A work, concerns and corrective actions identified in the NFSC G-85-01 Audit, and conducted a review of the D1201-200 series drawings on the CRD0A's. This D1201-200 review addressed the notes on the drawings relative to conflicts with the CRDOA refurbishment program, correctness of revision, and resolution of deficient areas noted during the review process.

If a situation could not be resolved, a Corrective Action Request (CAR) was issued. The recommended corrective action in each case addressed a determination of material impact on the CRDOA work as a result of the discrepant condition noted in the CAR. Resolution of all CAR's with respect to material impact on the CRD0A work will be completed prior to startup.

The Nuclear Engineering Division obtained the services of a consultant to conduct a review of the CRD0A drawings and 0&M manuals to verify that all design requirements specified on the GA drawings or in the CRD0A 0 & M manual, which relate to the CRD0A refurbishment program, have been appropriately considered in the procedures being used to control the CR00A refurbishment work or have been appropriately considered in the purchase orders for spare parts.

Upon completion of the review, any requirements related to the CRDOA m

refurbishment work, which are specified on the CRD drawings or identified in the 0&M Manual which were not specifically incorporated in the procedures or specified in purchase orders for spare parts, will be resolved prior to startup.

The Nuclear Production Division selected a representative sample of nine CRDOA's to be reworked for installation of slack cable switch bushing retainers and/or back-EMF considerations, and inspected them for quality indicators such as loose bolts, improper lockwiring, frayed cables, Resistance Temperature Device (RTD) positioning, general surface condition, etc. Additional back-EMF and RP-5 testing was also completed on all nine CRD0A's. No indication of overall quality workmanship problems were detected.

CRD0A post refurbishment testing was conducted on all CRDOA's including both functional and performance testing. The functional tests , included verification of proper position indication, limit.

switch protective functions, performance of RSD system integrity and primary and secondary reactor vessel seal integrity per already

. established functional criteria. Additional testing was conducted to verify proper installation of RTD's.

The performance testing criteria was established and submitted via Reference 5 prior to the initiation of the refurbishment program. At that . time, only four of the thirty-seven CRD0A's in core met the criteria. This performance criteria were based upon original performance testing conducted by the designer. They included minimum pre-electromotive force acceleration and steady state velocity stability requirements. The results of back-EMF testing are provided in Attachment 2. "Before" and "after" refurbishment torque testing was also ' performed- to establish shim motor and gear train rolling resistance, which provides a basis for determining operational acceptability of the shim motor and gear train assembly (see Attachments 3 and 4). As verified by post refurbishment performance

. testing, all CRDOA's refurbished surpassed the performance acceptance criteria.

The actions taken during the refurbishment program restored the CRDOA's to a "like new" condition thereby ensuring reliable operation. The modifications to the CRD0A's did not alter their design intent or function, involve a change to the Technical Specifications or an unreviewed safety question. A description of u

the modifications, including a summary of the safety evaluation of each, will be submitted to the NRC in the annual report in accordance with the provisions of 10 CFR 50.59.

If you have any questions, please contact Mr. M. H. Holmes at (303) 571-8409.

Sincerely, b]~ ts

0. R. Lee, Vice President Electric Production ORL: FJN/skd Attachments L

ATTACHMENT 1 Design-and material changes listed in the table below were made to increase the reliability and improve the performance of the CRD0As.

Among these;were design modifications such as the' installation of a slack cable bushing retainer cap, the enlargement of the inner cable drum inner diameter and the installation of eyebolt and tube hole cover assemblies. Material changes were also implemented to reduce susceptibility to chloride stress corrosion. Other material changes were made to accommodate expedient material delivery or increase material. temperature ranges; which had no significant affect on component quality, performance or reliability. Bearing discrepancies not listed are noted in Reference 6 of this letter.

Control Rod Drive And Orificing' Assembly Changes Dwg. No.

D1201-100 Control & Orificing Assy.

The helium line connector o-rings were replaced using o-rings made of ethylene propylene to increase the o-ring temperature rating.to 300 F.

The following note changes were made:

Alternate material specs, are called out for the new ethylene' propylene o-rings for delivery time purposes.

Use of "Cerac" SP111 lubricant was specified in place of Jetlube SS-30 on all bolt threads to increase the temperature rating.

. D1201-102 Bearing Lubrication Procedure A step was added in the procedure to wash the bearing in ethyl alcohol to insure removal of all residual acid from a previous step.

D1201-105 Tab Washer-T Alternate material spec. ASTM A366 was specified for j fabrication purposes.

D1201-111 Housing Aluminum Alloy 6061-T6'per ASTM B221 was specified as an alternate material for the aluminum casting for fabrication purposes.

All small radii for casting purposes were deleted on machined parts.

Casting classes for inspection were revised to show inspection requirements in certain areas.

j. .

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D1201-115. Reserve Shutdown and Helium Purge Lines i: -

'The tube material was changed from stainless steel to Inconel 600 per SB163 or SB167 to avoid possible i stress corrosion problems, t

The connector & elbow material was changed from SST to

, carbon steel to avoid stress corrosion problems.

i 01201-150 Process Procedure for Electromagnetic Assys.

General Electric RTV #162 sealant was specified as an y alternate sealant because of availability.

The glass fiber filler content was revised to show the

, amount actually used.

- D1201-200 Control Rod Drive Assy.

Replace the rewind gear cap screws with screws made of alloy steel to avoid possible stress corrosion

_. problems.

A note was added to specify a bolting torque of 20 l in.-lb. to the rewind gear cap screws to avoid

overstressing of the screw.

D1201-206 Flange, Inner, Cable Drum Aluminum plate 6061-T6 per ASTM B221 is specified as

, an alternate material to the aluminum casting for j fabrication purposes.

The inside diameter is increased by 0.040 in. to avoid rubbing. '

j D1201-207 Hub, Cable Drum h

Aluminum Alloy 6061-T-6 per ASTM B221 is specified as an alternate material to the aluminum casting for fabrication purposes.

D1201-217_ Motor & Brake Assy.

The insert material in the socket head cap screw was

. changed to KEL-F to increase the temperature rating to

, 300 F.

i A note change was made to delete the reference to the old environmental test for the motor. The motors will be tested per the new environmental test spec. 12-U-5.

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_3 D1201-217 Motor & Brake Assy. (cont.)

An alternate protective treatment for electroless nickel plating was called out per MIL-C-26074B(1) since the original Kanigan process is no longer available.

01201-218 Shim Motor The note specifying the test speed for the motor changed from 2200 to 2400 rpm to be consistent with test requirements.

A Long Lok set screw LL62XA62J2E was listed as an alternate to increase the temperature rating of the set screw. The insert material is KEL-F.

Locking specification RM-3-1, Class B, type II was specified to increase the temperature rating to 300 F.

The rotor imbalance was revised to be consistent with drawing D1201-217.

The encapsulation mixture used on the shim motors was revised to represent the mixture used on all motors manufactured.

A note was added to specify the protective coating used on the shim motor stator & rotor previously manufactured by the supplier.

The rotor and stator dimensional tolerances were changed to insure a minimal diametral air gap of 0.014 inches after painting.

The permanent magnet is bonded to the shaft. This alternate assembly method is permitted to avoid the requirement for the light interference fit between the permanent magnet and the shaft.

D1201-219 Brake Assy.

A socket head cap screw was replaced by an alloy steel screw to avoid stress corrosion. A cadmium plating was used.

The set screw was torqued to 16 in.-lb. to avoid overstressing of the screw.

A Long Lok screw was specified as an alternate screw due to availability.

L______._______

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s D1201-221 Retainer, Bearing, Shim Motor Stainless steel type 17-4 PH was specified as an alternate material. This material is to be used when increased brake holding torque is required to satisfy the design requirements.

D1201-223 End Bells Aluminum alloy 6061-T6 per ASTM B221 was specified as an alternate material to the aluminum casting for fabrication purposes.

The corner radii are not required on the machined parts.

01201-227 Tie Bolt AISI C-1215 is an alternate material spec. for availability reasons.

MIL-C-26074B(1) was specified as an alternate protective treatment since the original Kanigan process is no longer available.

01201-231 Gear Box Housing Carbon steel plate per ASTM A516, GR70 was specified as an alternate material to the steel casting for fabrication purposes.

The corner radii are not required in the machined parts.

D1201-232 Pinion Housing Steel plate or bar per AISI 1015 thru 1020 was specified as an alternate material to the steel casting for fabrication purposes.

D1201-244 SH. 2 of 2 Cam An alternate cam with a different geometry was permitted to provide better limit switch operation.

Stainless steel 410 was used on the new cams for fabrication purposes.

01201-246 Bracket, Limit Switch Aluminum alloy 6061-T6 per ASTM B221 was specified as an alternate material to the aluminum casting for fabrication purposes.

L.

01201-250 Cable Assy.

A note was added describing the new cable pull test to 3500 lb.

A torque of 8 in.-lb. was specified for the set screw to avoid overstressing of the screw.

A torque of 150 in.-lb. was specified for the nut bushing to avoid overstressing during assembly.

A stainless steel retaining ring was used to replace a carbon steel retaining ring for availability reasons.

A 304 stainless steel screen & spring was changed to 416 stainless & I-X750 Inconel respectively.

D1201-251 Cable The cable material was changed from AISI 347 stainless steel to Inconel 625 per ASTM B-446 to avoid stress corrosion problems.

01201-252 Anchor, Cable The anchor material was changed from AISI 304 stainless steel to AISI 416 stainless steel to avoid stress corrosion problems.

The anchor was gas nitrided to avoid welding or galling. Dry lubricant "Cerac" SP111 is used to avoid added friction.

01201-255 SH. 2 of 2 Nut Bushing The nut bushing for the cable assembly involved a geometry change to allow for better limit switch operation.

D1201 259 Bearing Bearing model SS3207 or equal was specified for availability reasons.

01201-260 Bearing Bearing model MRC-210S-ST or equal was specified for availability reasons.

01201-262 Segment Restrictor Stainless steel 416 per ASTM A582 was specified as an alternate material to the stainless steel casting for fabrication purposes.

u

1 D1201-262 Segment Restrictor (cont.)

The 416 SST is heat treated per MIL-H-6875 to Rockwell hardness of C25-32 for fabrication purposes.

01201-263 Rod End The rod end material was changed from 304 stainless steel to Inconel I-625.

01201-275 Closure Assy.

The o-rings are replaced with o-rings made of ethylene propylene to increase the temperature rating of the o-rings to 300 F.

Alternate material specs. are given for the o-rings for availability reasons.

01201-279 Plug The o-ring was replaced with an o-ring made of ethylene propylene to increase the temperature rating of the o-ring for availability reasons.

01201-281 Support Aluminum alloy 6061-T6 per ASTM B221 was specified as an alternate material to the aluminum casting for fabrication purposes.

Corner radii are not required on machined parts.

Casting grade was specified for fabrication purposes.

The anodizing spec. on the drawing'was corrected to reference the proper specification.

D1201-282 Eyebolt An alternate material A36 carbon steel was specified for fabrication purposes.

D1201-284 Receptacle-Aluminum alloy 6061-T6 per ASTM B221 was specified as an alternate material to the aluminum casting for fabrication purposes.

Casting grade was specified for fabrication and inspection purposes.

D1201-286 Bushing Cap A slack cable bushing cap was added to insure positive retention of the bushing.

t

i D1201-287 Shim Shims with a 0.003" thickness were added to improve.

assembly operations.

01201-700 Shield Assy.

A button head socket cap screw was specified with an alternate alloy steel material to avoid possible stress corrosion problems.

D1201-811 Seal Ring The gask-o-seal was replaced with a seal made of ethylene propylene to increase the temperature rating of seal of 300 F.

01201-1079 Clevis Bolt The clevis bolts are replaced as the new bolts become available. The new bolts are made of Inconel X-750 to avoid possible stress corrosion problems. The corrosion resistant steel was used as the "old" material successfully passed qualification testing in a high chloride concentration solution. Actual examination of clevis bolts previously installed on CRDOAs which were resident in the reactor during power operation, were also made in the hot service facility using video monitors. No evidence of damage or cracking was observed.

An alternate material of 17-7 PH per AMS 5678 was specified for the retaining element for availability reasons.

.01201-1080 Tube Hole Cover Assy.

Two bellows seal assemblies have been' installed in the CRD cavity. The seals prevent natural circulation of primary coolant into the cavity through the holes around the reserve shutdown helium tube lines. This was done to prevent possible moisture carryover into the CRD cavity.

01201-1085 Eye Bolt Hole Cover Assy.

Two bellows seal assemblies have been installed in the CRD cavity. The seals prevent natural circulation of primary coolant into the cavity through the penetrations for the two shielding containter eye bolts. This was done to prevent possible moisture carryover into the CRD cavity, u

A D1201-1090 Access Cover Assy.

Four newly designed access cover plates are installed to prevent moisture ingress into the CRD cavity. The cover plates are fitted with integral gaskets to insure a tight fit. The cover plates also include the bolts and tabwashers to install them.

01201-1095 Spherical Bearing Assy.

No changes were involved and the new drawing was created for fabrication purposes only.

D1201-1096 Rod End The part, previously part 2 on D1201-263, was changed to Inconel 625 to avoid possible stress corrosion problems.

D1201-1097 Spring The aging treatment was changed to AMS 5699 since it is a more applicable spec. for tempering of springs.

The material was changed to Inconel X-750 to avoid possible stress corrosion problems.

D1201-1098 Insulator, Magnet No changes to the part are involved. The drawing was added to the documentation system.

D1201-1099 Washer The original part number was not available so this drawing was created for fabrication purposes only. No changes to the washer are involved.

. 'ATTACllMENT 2 CRDOAs PRE AND POST-REFURBISHMENT ACCELERATION PROFILES CRDOA PRE-REF F.E. POST-REF F.E. DELTA COMMENTS S. N. TEST DATE ACCEL. TEST DATE ACCEL. ACCEL.

1 850323 99.4 850411 125.1 25.7 1 2 850308 128.0 860316 127.9- .1 2 3 850428 95.5 860602 121.0 25.5 1

-4 850316 124.5 850415 123.2 -1.3 2 5 850312 82.5 850326 124.3 41.8 1 6 850220 103.0 850323 124.2 21.2 1 7 850329 82.7 850415 131.2 48.5 1 8 850505 85.9- 850603 126.7 40.8 1 10 850517 120.0 850621 121.4 1.4 1 11 850419 123.6 850423 124.5 .9 3 12 850415 105.0 850504 122.9 17.9 1 13 850410 104.2 850524 111 1 6.9 5 14 850531 103.2 850611 101.1 -2.1 1 15 850202 88.8 850322 129.0 40.2 1 16 850417 114.9 850427 123.9 9.0 1 17 850408 63.5 850524 117.5 54.0 1 18 850221 83.4 850414 111.9 28.5 1 21 850220 105.0 850415 114.3 9.3 2 22 850516 91.2 850521 124.5 33.3 2 23 850320 88.8 850408 112.6 23.8 1 24 850504 96.1 850614 121.3 25.2 1 26 850308 129.2 850314 130.4 1.2 2 28 850421 81.6 850429 126.0 44.4 1 29 850519 88.0 850526 125.7 37.7 1 30 850423 110.9 850614 120.5 9.6 1 31 850501 115.5 850528 119.2 3.7 1 32 850429 108.2 850614 124.8 16.6 1 33' 850525 97.6 850602 128.4 30.8 1 34 850503 93.2 850620 123.6 30.4 1 35 850425 84.7 850504 127.3 42.6 1 36 850316 79.8 850410 124.1 44.3 1 37 850506 84.9 850614 129.8 44.9 1 38 850322 117.9 850407 119.9 2.0 1 39 850415 80.0 850428 120.8 40.8 1 40 850523 89.3 850530 126.3 37.0 1 41 850529 91.3 850620 121.4 30.1 1 42 850407 81.4 850614 125.5 44.1 1 44 850518 92.4 850615 121.2 28.8 1 Comments:

1,5-Based on shots in the core before and after refurbishement.

2-Orig, in Equip. Stor. Well. No pre-refurb, in-core shot available.

3-CRD did not have a motor. No pre-refurb, in-core shot available.

4-No valid post-refurbishment, in-core shot available.

5-Post shot with old DAS system due to noise problems.

ATTACIDfENT 2 (cont.)

The effect of the refurbishment process on Front End (F.E.) Acceleration varied considerably from CRDOA (Control Rod Drive and Orifice Assembly) to CRDOA. The following tables sumarize the results:

CRDOA Lowest Pre-Returb F.E. Accel. 17 63.5 rads /seca2 Highest Pre-Refurb F.E. Accel. 26 129.2 rads /seca2 Lowest Post-Refurb F.E. Accel 14 101 1 rads /seca2 Highest Post-Refurb F.E. Accel. 7 131.2 rads /sec^2 Highest Gain in F.E. Accel. 17 54.0 rads /sec^2 Highest Loss in F.E. Accel 14 -2.1 rads /seca2 CRDOAs SHOWING A NET F.E. ACCEL. LOSS AFTER REFURBISHMENT CRDOA PRE-REFURB POST-REFURB NET EFFECT 2 128.0 127.9 .1 4 124.5 123.2 -1.3 14 103.2 101.1 -2.1 CRDOAs WITH COMPARATIVELY LOW F.E. ACCEL.

CRDOA PRE-REFURB POST-REFURB NET EFFECT 13 104.2 111.1 6.9 14 103.2 101 1 -2.1 17 63.5 117.5 54.0 18 83.4 111.9 28.5 21 105.0 114.3 9.3 23 88.8 112.6 23.8 AVERAGE PRE-REFURB F.E. ACCEL.

97.77 AVERAGE POST-REFURB F.E. ACCEL. '

122.49 AVERAGE F.E. ACCEL. GAIN 20.18 %

REFURBISHMENT CRITERIA F.E. ACCEL. FAILURE LEVEL 98.83 NOTE: All acceleration values are expressed in cad,/sec^2.

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ATTACHMENT 3 T-260 Shim Motor Torque Maximum Breakaway Torque Shim Motor No. TORQUE (in.oz.)

Pre-Refurb. Post-Refurb 1 6 4 2 42 6 3 20 3 4 13 4 5 20 4 6 22 2 7 Bearing Test Motor 9 6 9 18 2 10 26 2 11 36 2 12 24 2 13 7 2 14 16 3 15 18 2 16 3 18 26 3 20 7 2 21 4 22 5 1 23 15 4 24 19 2 26 5 2 28 8 6 29 32 2 30 6 3 31 15 4 32 18 8 33 10 2 34 3 35 8 2 36 10 4 37 22 2 38 43 3 39 42 2 40 11 2 41 8 5 42 9 4 43 2 1A 13 3 100 4 101 5 3

ATTACHMENT 4 T-261 Shim Motor / Gear Train Torque Maximum System Breakaway Torque.

(Post Refurbishment)

TORQUE (in. oz.)

CRD N0. Holding Breakaway 1 22 28 2 24 32 3 22 24 4 22 32 5 22 24 6 18 26 7 24 32 8 22 28 9 22 34 10 22 30 11 20 30 12 23 25 13 18 26 14 19 33 15 18 25 16 20 28 17 19 31 18 24 36 19 22 27 21 22 27 22 22 28 23 22 30 24 21 31 26 22 28 28 20 30 29 22 28 30 20 30 31 22 34 32 20 30 33 21 28 34 22 26 35 20 32 36 19 33 37 21 29 38 22 28 39 21 30 40 22 27 41 24 28 42 18 26 44 20 32 u