ML17321A367
| ML17321A367 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/18/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17321A366 | List: |
| References | |
| NUDOCS 8501070415 | |
| Download: ML17321A367 (9) | |
Text
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~ gr UNITiDSTAT""S iVUCLEAn REGULATORY CCiMi>II8SIC"I IVASMINGTON.O. C. 2G=ss SAFET
( EVALUAT ciI 3Y TH= CFF >C= 0=
HUCLE.'~2
? i CTCR
'":UL:
REVIEW OF INSERVICE INSPECTION CORRESPONDENCE AND SAFETY EVALUATION ON INSERVICE AND INSERVICE TESTING REQUIREMENTS INDIANA 8 MICHIGAN ELECTRIC Q)MPAHY DONALD C.
COOK NUCLEAR PLANT UNITS HO.
1 8
2 DOCKET NOS.
50-315 AND 50-316
References:
(1)
Letter Dated April 5,
- 1982, S.
A. Varga to J.
Dolan (IMEC)
(2)
Letter Dated July 2", 1982, R.
S.
Hunter (IMEC) to H.
R.
Denton (3)
Letter Dated September 2,
- 1982, R.
S.
Hunter (IMEC) to Harold R.
Denton (4)
Letter Dated December 20,
- 1982, R.
F. Hering (IMEC) to H.
R.
Denton (5)
Letter Dated March 31,
- 1983, R.
F. Hering (IMEC) to H.
R.
Denton (6)
Letter Dated April 15,
- 1983, S.
A. Varga to John Dol an (7)
Letter Dated March 8, 1984,,M.
P. Alexich (IMEC) to Harold R.
Denton (8)
Letter Dated March 15,
- 1984, R.
F.
Hering (IMEC) to Harold R.
Denton (9 ) Letter Dated May ll, 1984, R.
F. Hering (IMEC) to Harold R.
Denton I.
BACKGROUND INFORMATION As required by 10 CFR 50.55a, Indiana and Michigan Electric Company (IMEC) submitted Inservice Inspection (ISI) Programs for the Donald C.
Cook Nuclear Plant Units 1 and 2 to the NRC on September 22, 1978 and November 18, 1977, respectively.
The programs were revised and resubmitted on September ll, 1979 and August 25, 1978 for Units 1
8 2, respectively.
8501070415 841218 PDR ADOCK 05000315 PDR
I ll
2-The revised programs were reviewed, resulting in requests for additional information which were transmitted to IMEC by Reference 1.
Reference 2
transmitted to the NRC a partial response to the requests and the remaining information was transmitted to the NRC by references 3, 4, and 5.
Reference 6
transmitted the Safety Evaluation and Technical Evaluation Report (SER/TER) to IMEC covering the revised programs and the additional information provided in References 2,
3 and 4.
The additional information transmitted by Reference 5
was not reviewed prior to issuance of the SER/TER because of the scheduled completion date of the TER and IMEC's late submission of the information.
This information as well as the requests for relief from certain Section XI Code requirements and the request for a corimon Inservice Inspection ten-year interval start date for D.
C.
Cook Units 1
& 2 transmitted to the NRC by References 5, 7, 8, and 9 will be reviewed and evaluated in this report.
II.
INSERVICE INSPECTION PROGRAM - ADDITIONAL INFORMATION REFERENCES 4
AND 5)
The additional information contained in Reference 4 provided (1) a complete and updated list of Class 2 welds being examined in accordance with Code requirements, (2) a revised list of welds for which relief is requested, and (3) the addition of systems which had been exempted from examination by "chemistry control" under IWC-1220 (c).
Reference 4 pertained to Unit 1
only and Reference 5 included the same information for Unit 2 in a combined package for both Units.
The information contained in References 4 and 5
answered the requests of Reference 1 and satisfied the requirements for compliance with 10 CFR 50.55a (g).
No changes to the SER/TER of Reference 6 are necessary because of the additional information submitted.
This information, which was informally transmitted to the NRC on September 23,
- 1982, was included in the review and evaluation (SER/TER) of the ISI Program, and was formally transmitted by References 4 and 5.
III. REACTOR COOLANT PUMP CASING FIELDS REFERENCE 7'y letter dated March 8, 1984 {Reference 7),
IHEC requested relief fiom the examination requirements for the reactor coolant pump.
The Code requirements, IHEC's justification, alternative examination, and our evaluation are given bel ow.
CODE RE UIREHENTS l974 EDITION OF SECTION XI EXAMINATION)
ITEM B5.6, Examination Category B-L-1:
Yolumetr ic examination performed during each inspection inter val shal 1
include 100% of the pressure-retaining welds in at least one pump in each group of pumps performing similar functions in a system.
The areas examined shall include the weld metal and the base metal for one wall thickness beyond the edge of the weld.
The examination may be performed at or near the end ot'he inspection interval.
ITEM B5.7, Examination Category 8-L-2:
Yisual examination of one pump in each group of pumps performing similar functions in the system shall be performed during each inspection, interval.
This examination may be performed on the same pump selected for the Category B-L-1 examinations.
The examinations shall include the internal pressure boundary surfaces.
The examinations may be performed at or near the end of the inspection interval.
LICENSEE'S BASIS FOR RE VESTING RELIEF The basis for requesting code relief is that the substantial radiation exposure that the inspection personnel will incur and the substantial costs involved do not justify the possible information that might be gained about the weld and adjacent base metal.
The pump casing is made from ASME SA-351, Grade CF-SM, a cast austenitic stainless steel that has a long history of satisfactory service in handling fluids.
The casting was made in two sections to facilitate the casting process and the two sections are welded together with a matching fillets material.
Welding cast CF-SM material to repair imperfections is a
routine practice for almost all CF-BM castings, except those of simple configuration and small size.
The material has good fracture toughness.
and unlike ferritic steels, is not subject to fracture prevention criteria.
Volumetric examination will require a substantial number of radiographic exposures that will require complete disassembly of the pump.
Oisassembly of the pump, storage of the internals, and placement of film will expose personnel to substantial radiation.
From experience at othe~
nuclear plants examining reactor coolant
- pumps, personnel exposure could be in the range of between 35 to 100 man-rem.
Based on costs incurred by other nuclear plants, this pump examination cost is estimated to be about
$500,000, which does not include costs associated with unit unavailability should this examination require extending an outage.
The examination will require disassembly of a pump under adverse conditions where there is a possibility of causing damage to the pumps internals.
There is no other reason to disassemble any of these pumps other than to perform these examinations.
This examination will also require additional time for handling the reactor vessel upper internal
- assembly, as the upper internals wi 11 have to be put back into the reactor vessel to minimize airborne radiation while the pump examination is performed.
Radiographic examination of similar welded reactor coolant pumps has been performed at a number of plants.
The radiography has been acceptable and the volumetric examination has not shown any deterioration in the welds.
We understand that code relief has been granted by the NRC from volumetric examination. for other reactor coolant
- pumps, and that this examination and its frequency are being studied by EPRI and the ASME 88PV Code groups.
LICENESS' PROPOSEO ALTERNATIVE EKAMINATION As an alternate to the 8-L-1 and 8-L-2 examination, a visual examination will be performed on the external surfaces of one pump during the hydrostatic pressure tests.
In addition, a surface examination will be performed on this pump on the accessible external surface of the weld.
If a pump has to be disassembled for maintenance, a visual examination will be made of the internal surfaces to satisfy the 8-L-2 code require-ment and the volumetric examination of the 8-L-I requirement reevaluated at that time.
STAFF EVALUATION The Code required visual inspection of the internal surfaces and volumetric examination of the casing welds of a reactor coolant.
pump utilizing radio-graphy necessitate complete disassembly of the pump.
Volumetric examination of the casing weld by ultrasonics would produce questionable results because of the high ultrasound attenuation characteristics of the cast casing material.
Disassembly of 'a reactor coolant pump for the required examination would expose the examination personnel to relatively high levels of radiation.
Considering the pump design, materials of construction, and the radiation levels associated with performing the required examinations, the staff finds the examinations impractical to perform.
In lieu of the volumetric examination of the pump casing weld and visual inspection of the internal surfaces, the licensee has committed to perform a surface examination of the accessible external surface" of the weld.
In addition, if a pump has to be disassembled
"6-for maintenance a visual examination will be made of the internal surfaces and the volumetric examination will be reevaluated at that time.
The Staff finds the alternative examination acceptable for determining the structural integrity of the pump casing and concludes that relief from the Code requirements may be granted.
IV.
RE VEST FOR A COMMON INSERVICE INSPECTION INTERVAL START OATE FOR 0.
C.
COOK UNITS 1
8 2
Section XI of the ASME Code define's the ten-year inspection interval as that. period of time in calendar years commencing with the date of commercial operation of the facility.
For 0.
C.
Cook Units 1
8 2, the second ten-year intervals should begin on August 28, 1985 and July 2, 1988, respectively.
By letter dated March 15, 1984 (REFERENCE 8 ), Indiana and Michigan E lect'c Company requested to begin the second ten-year interval on the same date for 0.
C.
Cook Units 1 and 2.
The reasons stated for the request were (1) use of the same Code Edition and Addenda in preparing and implementing the Inservice Inspection Program for both Units, (2) submission of a combined program which significantly decreases preparation and review time for IMEC and the NRC, and (3) more efficient and uniform use of personnel in implementing the requirements.
The common start date requested was July 1, 1987 and was changed to July 1, 1986 in REFERENCE 9.
The change of date resulted after discussions between IMEC personnel and members of the staff and made it necessary for IMEC to request the following:
1.
The Unit 2 reactor vessel beltline examination for the first ten-yeai inspection interval will be conducted during the mid-1987 refueling outage as presently scheduled, maintaining the 1974 Edition with Addenda through Summer 1975 of the ASME 88PV Code Section Xl as the governing code.
2.
Because the Unit 2 first ten-year interval is being shortened by two
- years, the scheduled examination of some Class 1 and'2 welds'will not be completed by July 1, 1986 requiring code relief'or the first interval.
These welds will be examined at, or near the beginning oi the second ten-year interval to the code edition in effect at that time.
These examinations will be credited toward the second inspect,ion interval.
I 3.
The system pressure tests for Unit 2 for the first ten-year inte~ val ei11 be conducted during the mid-1987 refueling outage as present.ly scheduled, maintaining the 1974 Edition with Addenda through Summei 1975 of the ASME B8PV Code Section XI as the governing code.
The Staff has reviewed the requests and determined that the change to a
common inservice inspection interval start. date will not change t,he numb~'i or frequency of examinations required by Section Xl.
The sequence of examinations of Class 1 8 2 welds established during the first interval must be repeated during each successive interval for 0.
C.
Cook Units 1
8 2.
The Staff also agrees with the licensee that a combined program is advantageous to both the NRC and IHEC.
The staff has also reviewed the licensee's proposal with respect to inservice testing (IST) of pumps and value and has determined that the utilization of July 1, 1986 as a
common start date will constitute a
one year delay in updating the Unit 1
IST program and voluntary update for Unct 2 two years sooner than it would normally be required.
Because of the common start date for Unit 1
and Unit 2, the Unit 1 program for the.revised inspection interval will be structured to a one year newer code than would have been required by the Regulations (10 CfR 50.55) and the Un)t 2 program for the revised inspection interval will be structured to a two year older code than would have been required.
Based on the consideration discussed herein, the staff agrees with the licensee's proposal and feels that the utilization of a common start date for both units wi 11 result in a net overall increase in olant safety.
We
- conclude, therefore, that the requested exemption to 10 CFR 50.55 to allow a common start date should be approved an.d
'ihe reliefs to accomodate this action be qranted.
The granting of this exemption will not endanger the health and safety of the oublic.
V.
Environmental Consideration Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this relief and exemption with relief will have no signif-icant impact on the environment (49 FR 47666 ).
VI. Conclusion We have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed ma'nner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these reliefs and exemption will not be inimical to the common defense and security or to the health and safety of the public.
pated:
December 18, 1984 Princi al Contributors:
G. Johnson J.
Page D. Wigginton