ML20207L251

Rev 4 to Sequoyah Nuclear Plant Element Rept, Steam Generator Installation

ML20207L251
Person / Time
Site:	Sequoyah
Issue date:	12/30/1986
From:	Touchstone C TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20207K584	List: ML20207K581 ML20207K641 ML20207K723 ML20207K830 ML20207K861 ML20207K986 ML20207L046 ML20207L111 ML20207L128 ML20207L147 ML20207L204 ML20207L207 ML20207L213 ML20207L217 ML20207L222 ML20207L226 ML20207L229 ML20207L251 ML20207L268 ML20207L273 ML20207L280
References
301.08-SQN, 301.08-SQN-R04, 301.08-SQN-R4, NUDOCS 8701120055
Download: ML20207L251 (12)

Text

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TVA EMPIAYEE CONCERNS REPORT NUMBER: 301.08-SQN SPECIAL PROGRAN REPORT TYPE: Sequoyah Nuclear Plant Element REVISION NUMBER: 4 TITLE: S/G Nanway Installation REASON FOR REVISION:

Incorporation of TAS/SRP comments. Revision 1 Addition of new concern IN-85-872-001 and incorporation of Revision 2 SRP comments.

Documentation of SQN corrective action response and incorporation Revision 3 of SRP comments.

Incorporation of TAS conunents Eeneral revision. Revision 4 PREPARATION PREPARED BY:

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lE */S*SN SIGNATURE DATE

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REVIEWS N If // /7l}$ W-

/ 5IGNATURE ' DATE 7

TAS*

bo0Y / l3 b Yb SIGNATURE DATE CONCURRENCES 8701120055 870102

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.-CEG-H.i am M SRP:01lntri b N$$/. ]Z/50/f6 DATE SIGNATURE SIGNATURFg [/

APPROVED BY:

'1N M ik(61)~ \E[31/8{o N/A 4\ECSP MANAGER DATE 3 NAGER OF NUCLEAR POWER DATE

(' CONCURRENCE (FINAL REPORT ONLY) i *SRP Secretary's signature denotes SRP concurrences are in files.

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TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT EMPLOYEE CONCERNS TASK GROUP OPERATIONS CEG Subcategory: Mechanical Equipment Reliability / Design Element: S/G Nanway Installation Report Number: 301.08 - SQN, Revision 4 IN-85-869-001 XI-85-052-001 IN-85-872-001 Evaluator: M 7M6 M Ib C. W. Touchstone Date Reviewed by: D L . Vlf t i1-16-86 IPS CEG Member ' Date Approved by: ( [eN /1/M/8(,

W. R. Lagergren Bate 1465T

' R3visica 4 I. S/G MANWAY INSTALLATION This report documents partial closure of the investigation of steam I generator primary manway installation concerns at Sequoyah Nuclear l Plant (SQN). Element 311.05 addresses ALARA aspects of manway concerns. l NSRS report I-85-558-SQN (attachment 1) evaluated concern II-85-052-001 l

in October 1985. A review of the report's findings indicates adequacy lR4 of the investigation. This report also addresses a new concern, i 1 IN-85-872-001, with respect to the steam generators. The pressurizer l aspect of this concern is addressed in Element 313.09, " Plant l Improvement / Suggestions." l II. SPECIFIC EVALUATION NETHODOLOGY 4 The NSRS report (attachment 1), was reviewed for adequacy and determined to fully address the scope of the concerns. A follow-up interview was conducted to determine status of the report's recommendation. The concerns considered for applicability to SQN are: ,

i IN-85-869-001: "Nanway Door at the botton Steam Generator takes i approximately 20 minutes to open and 3-4 hours to close due to a complicated process necessitated by poor

design. If the come along slips, it is most likely that

' personnel would be pinned between the swing-arm and hand rail. There are 5 rems / hour escaping while this door is i

open.- A way to open/close this door must be found that would take only 20 minutes total. Construction i department concern. Units 1 and 2. CI has no further

, information."

i i XX-85-052-001: "Sequoyah-Nanway Door at the bottom of Steam Generator

takes approximately 20 minutes to cpen and 3-4 hours to l close due to complicated process necessitated by poor

! design. If a come along slips, it is most likely that j personnel would be pinned between the swing-arm and hand rail. There are 5 rems / hour escaping while this door is i open. A way to open/close this door must be found that  ;

would take only 20 minutes total. Units 1 and 2. CI

! has no further information."

IN-85-872-001: "The floor grating needs to be extended in the area near the steam generator manways and between the top and bottom of the pressurizer. This increased work space would benefit the crafts and Health Physics. It would 1 also create a much safer working area."

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-III. FINDINGS Findings for XX-85-052-001 are detailed in the attached NSRS report.

Conclusions in that report are summarized below, as well as results of a follow-up interview (1) The concern was substantiated based on the issues raised.

(2) Plant maintenance records indicate that closing operations have historically taken approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for each manway cover.

(3) Safety hazards are present during manwe.y cover handling activities. However, these are appropriately emphasized in plant procedures and personnel training. Involved personnel should be aware of them and take the necessary precautions to prevent possible injury.

(4) Recommendation: The plant should complete the evaluation of proposed new manway cover tensioning systems that is underway 1

and make a decision as to what new equipment, if any, will be purchased.

Follow-up A follow-up interview was conducted to determine the status of the recommendation in item (4) above. An individual in SQN Site Services Branch responsible for coordination of the S/G outage program at WBN and SQN stated that a stud-nut tensioner has been selected for use at both sites. The system requires complex modification and technical analysis; hence. Westinghouse will i supply a " package" to provide a S/G stud-nut configuration J

compatible with the vendor's stud-nut tensioner. SQN has plans to implement the new system during the unit 2, cycle 3 outage.

The individual also commented on the ALARA program with respect to S/G outsge work at SQN. He said SQN has an excellent program which has experienced much success. An example stated was a comparison between radiation dose received during present and previous S/G eddy current and tube plugging efforts. Combustion Engineering (CE) employees had received 17 man-rems during earlier eddy current inspection; however, during more recent inspections, a total of 4.3 man-rems was received. Tube plugging in the past had resulted in 71 man-rems for all involved employees for one S/G; however, use of the GENESIS Robot resulted in only 13.2 man-rems for 3 S/Gs. The Site Services individual noted that since he will be coordinating l l

with WBN for S/G outage preparation WBN should see similar results in the future. t l

IN-85-872-001-Findings

! SQN Site Services confirmed that the floor grating (platform) in the vicinity of the S/G primary manways will be extended in accordance with Design Change Request (DCR) SQ-DCR-2247.

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R3visien 4 III. FINDINGS (continued)

Conclusion The concerns were substantiated based on the need for reduction in exposure time. The plant recognized the need to improve manway handling operations and has already made some improvements to reduce closing time. Implementation of the new stud-nut tensioning system will further reduce exposure times; however, a 20 minute closure time may or may not be achievable. The ALARA aspects of this concern are more thoroughly treated in ECTG Report No. 311.05-SQN. Also, extension of the platform at the base of lR4 S/Gs will benefit manway cover removal and replacement operations. l IV. ROOT CAUSE Manway cover operations have been a learning experier.ce. Earlier tools and methods used during removal and replacement of covers resulted in mechanical problems such as galling of bolt threads, difficulty in achieving proper bolt torque, and longer exposure times than now possible. Complicating the process was limited work space.

From the experience gained in these manway cover operations, continual improvement of equipment and procedure has occurred.

V. GENERIC APPLICABILITY Subcategory report 30100 addresses these concerns for WBN. Element 311.05 l addresses ALARA aspects of these concerns. No applicability was lR4

, identified for Bellefonte Nuclear Plant. I VI. REFERENCE

1. NSRS Investigation Report I-85-558-SQN, " Potential Hazards Associated with Removing and Replacing S/G Primary Manway Covers,"

November 26, 1985.

VII. IMMEDIATE OR LONG-TERM CORRECTIVE ACTIONS Westinghouse Electric Corporation has been selected to provide steam generator primary manway closure equipment. Installation should occur at U2C3 and UIC4 refueling outages. SQN DCR-2247 is now in the DNE review cycle. It has been categorized as a post restart activity, hence review completion and ECN issue will occur in the summer, 1987.

CATD NO. OP-30108-SQN-01 has been issued to track the above corrective actions.

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TENNESSEE VALLEY AUTilORITY NUCLEAR SAFETY REVIEW STAFF 5' NSRS INVESTIGATION REPORT NO. I-85-558-SQN i

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EMPLOYEE CONCERN: XX-85-052-001 b

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SUBJECT:

POTENTIAL HAZARDS ASSOCIATED WITH REMOVING AND REPLACINC f, STEAM GENERATOR PRIMARY MANWAY COVERS ti l . .

DATES OF INVESTIGATION: OCTOBER 18-23, 1985

.I INVESTIGATOR: //#((! / /4')dId //

DATE f/M M. W. ALEXANDER '

v REVIEWED BY: .. (W '8[EkOS ,

R. C. SAUER DATE APPROVED BY: 2 N!44[8 M. S. KIDD DA'fE /

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eh I. BACKGROUND ,

A tiuclear Safety Review Staff (tiSRS) investigation was conducted to determine the validity of an expressed employee concern as roccived by Quality Technology Company (QTC)/Employeo Response Team (ERT). The concern of record, as summarized on the Employeo Concern Assignment Request Form from QTC and identified as XX-85-052-001, stated:

"Sequoyah - Manway door at the bottom of steam generator takes approximately 20 minutos to open and 3-4 hours to close due to complicated process necessitated by poor design. If a comcalong slips, it is most likely that personnel would be pinned between the swing-arm and hand rail. There are 5 rems / hour escaping while this door is open. A way to open/close this door must be found that would take only 20 minutes total."

II. SCOPE A. The scope of the investigation was determined from the concern of record to be that of four specific issues requiring investigation.

1. Closing the steam generator primary manway cover takes f approximately 3-4 hours.

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2. If a hoist were to slip, it is possible that personnel could be pinned between the swing-arm and hand rail. -

3. Radiation icvcis of 5 Rem / hour are present at the open manways.

4. A way to open and close the manway covers must be found that would take only 20 minutes total.

B. The investigation required interviewing plant personnel who were directly involved in the industrial safety, health physics, technical services, and operational aspects of primary side steam generator opening and closing. Plant and vendor procedures were also reviewed for similarity comparisons in the steam generator

. opening and closing process.

III.

SUMMARY

OF FINDINGS A. Requirements and Comitments

1. Titic 10 Code of Federal Regulations, part 20. " Standards for Protection Against Radiation."

2. TVA Code VIII, " Occupational Radiation Exposure."

3. Westinghouse Technical Manual 1440-C228, September 1971,

" Vertical Steam Generators for Tennessee Valley Authority Sequoyah Nuclear Plant."

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B. Findings ,

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1. The Sequoyah steam generator primary manway cover handling system was designed by Westinghouse and is similar to that found on other Westinghouse plants of Sequoyah vintasc. Removal is accomplished by attaching a swing-arm assembly to the cover and lowering the cover by means of a hoisting device (come-along).

Reinstallation is the reverse sequence with manual torquing of hold-down bolts. The manway covers weigh about 650 pounds cach, and tho work space is somewhat limited. Plant procedures for the removal and reinstallation of +he covers are provided in MaintenanceInstruction(MI)-3.1kref.1)andarebasedon Westinghouse Technical Manual 1440-C228. During the U2C2 refueling outage recorded closing times were approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per generator (2 manway covers). This included scaling surface preparation and inspection and other activities in addition to bolt torquing.

2. HI-3.1 includes safety precautions to be observed during handling of the manway covers. Personnel involved in opening and closing the steam generators are briefed on these procedures' and are made aware of the safety aspects of this activity prior to beginning work.

3. During the recent Environmental Qualification (U1C3) outage, the unit 1 steam generators were opened for oddy current testing and

' tube plugging. Radiation levels inside the primary heads were

- measured to be 15-25 R/hr. At the manway openings, levels were 4-10 R/hr; and in work areas outside the primary heads, .

radiation icvels were 500 HR/hr and loss. HI-3.1 contains l

several cautionary notes which emphasize the need to minimize

% personnel exposure at all times. Projob ALARA plans are also prepared for each primary sido entry to identify exposure estimates and any specini health physics controls that may be required. All work in this area is controlled by a Radiation 1

f Work Permit (RWP). Each employeo is assigned an allowablo work time and must leave the arca when his time expiros. Health

. physics personnel are on duty continuously to monitor personnel j and working conditions. There have been no recorded incidences j

• of radiation over-exposure during primary side work. Plant

procedures RCI-1 (ref. 6) and IP-15 (ref. 7) specify that if,

,- for any reason, an employee were to become incapacitated while 3 participating in steam generator primary side work, an emergency 9

situation would be declared and the employec's safety would take l

immediato peccedence over all other activitics and requirements.

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, 4 During the recent unit 1 steam generator entry, an improved manway cover closing technique was introduced by plant maintenance personnel. To resolve previously experienced

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j mechanical problems (galling of bolt threads and difficulty in

- achieving proper bolt torque) and reduco the time required to j close the manways a new hydraulic torque wrench and specially hardened steel washers for the bolts were used. The hydraulic a

t torque wrench is much faster than previous manual bolting techniques and the hardened steel washers reduce torquing N{ . friction between the bolts and covers. Maintenance records ui indicato closing timas were reduced considerably (11-19 hours

/ per generator) over past experience (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> per generator)

$ resulting in reduced personnel exposure. This technique is j planned for use on all future manway cover handling operations.

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5. The Sequoyah Site Services group is investigating further M improvements in cover handling techniques. Several stud r 3 tensioning devices especially tailored for application to steam

? generator manway covers are now available. They involve the i replacement of the cover bolts with studs and nuts which are tt designed to fit a stud tensioner. Reports indicate these 3 devices could further improve opening and closing times and d solve other technical problems that have been experienced.

$ Studies are underway at Sequoyah and Watts Bar to determine tho' best app' roach for TVA application. Site Services has made N) .

i. recommendations,to plant management on this new concept (reff '

$ b 2). A final decision has not been made.)

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• g IV. CONCLUSIONS AND RECOMMENDATIONS h

y A. Conclusions 1p, The concern of record was substantiated based only on the issues

' raised, not on any technical or administrative deficiencies.

b. plant maintenanco records indicate that closing operations have

! 1 iI historically taken aproximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for each manway cover.

b 2. Safety hazards are present during manway cover handling

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?g- activities. However, these are appropriately emphasized in 1 plant procedures and personnel training. Involved personnel should be aware of them and take the necessary precautions to

'[i prevent possible injury. If, for any reason, an employee were

}3 to become incapacitated while participating in steam generator primary side work, an emergency situation would be dociated and

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N the employco's safety would take immediate precedence over all other activitics and requirements.

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3. Radiation surveys taker,during the recent UIC3 steam generator work show levels in th6 range of 4-10 R/hr at the manway openings. However, it is recognized by plant perconnel that high radiation levels exist in the vicinity of the steam generator primary heads. From reviewing plant maintenance procedures and projob ALARA planning documents and interviewing maintenance and health physics personnel, it appears that an appropriate level of attention has been given the health physics aspects of working in this area.

4. Hanway closing time is excessive; howaver, the plant recognizes the need to improve manway handling operations and has already made some improvements to reduce closing time. These were used recently in the UIC3 steam generator work. In addition the plant has underway studies which could further improve those operations.

B. Recommendations

1. I-85-558-SQN-01, Plant Evaluation of Improved S/G Primary Hanway Cover Handlinr. Fixtures _

The plant should complete the evaluation of proposed new manway cover tensioning systems that is underway and make a decision as to what new equipment, if any, will be purchased. This is an NSRS tracking item only. [P3]

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DOCUMENTS REVIEWED IN INVESTICATION 1-85-558-SQN O. AND REFERENCE 3'

1. Maintenance Instruction 3.1, Revision 15. " Removal and Installation of Steam Generator Primary Manway Cover."

2. Undated notes, " Proposed Project for Replacement of Steam Generator Primary Manway Bolts with Studs and Nuts and Tensioning System,"

Prepared by Mike Hodge (Site Services) and used in June 1985 Presentation to site management.

3. Prejob ALARA Planning Report No.85-063, dated September 2,1985, covering eddy current testing of unit I steam generator during the recent outage. .

4. Westinghouse Technical Manual 1440-C228, September 1971, " Vertical Steam Generator for Tennesseo Valloy Authority Sequoyah Nuclear Plant."

5. TVA Radiation Protection Plan, Section A. "Nuc1 car Power Plants," dated August 18, 1983.

6. Sequoyah Radiological Control Instruction (RCI)-1, Revision 27, dated September 12, 1985. .

7. Sequoyah Radiological Emergency Plan (REP) Implementing Procedur'es

- Document (IP)-15. Revision 4, December 27, 1984.

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Ef F[EUTE - ECPS120J-ECPS12IC TENNESSEE VALLEY CUTHORITY CUN TIME - ', I

- REGUEST OFFICE OF NUCLEAR PCHER RUN DATE -

) l'aiat%CY EMPLOYEE CONCERN PROGRAM SYSTEM (ECPS)

• C .7 - ILLS - E::M LIST OF EMPLOYEE CONCERN INFORMATISN

• CaiEGORY: CP PLANT OPER. SUPPORT SUBCATEGORY: 30108 S/G MANHAY INSTALLATION (ALARA)

D KEYHCRD A S GENERIC KEYHORD B APPL QTC/MSRS P H

S CONCERN KEYHORD C CcNCERN SUS R PLT BBSH INVESTIGATION R DESCRIPTION" KEYHORD I rnn3ER CAT CAT D LOC FLQB REPORT NS MANHAY DOOR AT THE BOTTOM STEAM GENE HEALTH PHYSICS IN 369-001 CP 301C3 S H5N NNYY SAFETY CONDIl K-FORM RATOR TAKES APPROX. 20 MINUTES TO OP T50155 CP 31105 EN AND 3-4 HOURS TO CLOSE DUE TO A C CPERATIONS 3 OMPLICATED PROCESS NECESSITATED BY P RADIATIOf 00R DESIGN. IF THE COMEALONG SLIPS, IT IS MOST LIKELY THAT PERSONNEL H0 ULD BE PINNED BETHEEN THE SIDING ARM a AND HAND RAIL. THERE ARE 5 REMS /HO UR EXCAPING HHILE THIS DOOR IS OPEN.

A HAY TO CPEN/CLOSE THIS DOOR MUST BE FOUND THAT HOULD TAKE ONLY 20 MI a NUTES TOTAL. CONSTR. DEPT. CONCERN.

UNITS I AND 2. CI HAS NO FURTHER INF0RMATION. NO FOLLOHUP REQUIR THE FLOOR GRATING HEEDS TO BE EXTEND SAFETY PROGRAM 3

IN 172-001 CP 33IC3 S H3N IN-85-872-001 SAFETY CONDI' K-FCRM ED IN THE AREA NEAR THE STEAM GENERA T50:17 0? 31309 TOR MANHAYS AND BETHEEN THE TOP AND CONSTRUCTI SF 90906 BOTTOM OF THE PRESSURIZER. THIS INC EMPLOYEE 3 REASED HORK SPACE HOULD BENEFIT THE CRAFTS AND HEALTH PHYSICS. IT HOULD ALSO CREATE A MUCH SAFER HORKING AR EA.

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NS SEQUDYAH-MANHAY DOOR AT THE BOTTOM 0 HEALTH PHYSICS Ir 052-03I CP 3010! S SQN NNNY I-85-558-SQN - SAFETY CONDI K-FORM F STEAM GENERATOR TAKES APPROX. 20

• T50155 CD 31105 MINUTES TO OPEN AND 3-4 HOURS TO CLO OPERATIONS SE DUE TO COMPLICATED PROCESS NECESS RADIATIO ITATED BY PCOR DESIGN. IF A COMEALO NG SLIPS, IT IS MOST LIKELY THAT PE".

s SONNEL HOULD BE PINNED BETHEEN THE S HING-ARM AND HAND RAIL. THERE ARE 5 REMS / HOUR ESCAPING HHILE THIS DOOR IS OPEN. A HAY TO CPEN/CLOSE THIS D o 00R MUST BE $UND THAT HOULD TAKE ON LY 20 MINUTES TOTAL. UNITS I AND 2.

CI HAS NO FURTHER INFORMATION. NO FOLLCHUP REQUIRED.

t 4 CONCERNS FCR CATEGORY CP SUBCATEGORY 30I08 7 .

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