ML20137F872
| ML20137F872 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/14/1985 |
| From: | Gray E, Wiggins J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20137F842 | List: |
| References | |
| 50-245-85-20, NUDOCS 8508270112 | |
| Download: ML20137F872 (6) | |
See also: IR 05000245/1985020
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U.S. NUCLEAR REGULATORY COMMISSION
REGION I
Report No. 50-245/85-20
Docket No. 50-245
License No. DPR-21
Priority
Category
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Licensee:
Northeast Nuclear Energy Company
P.O. Box 270
Hartford, Connecticut 06141-0270
Facility Name: Millstone Nuclear Power Station, Unit 1
Inspection At: Waterford, Connecticut
Inspection Conducted: July 8-12, 1985
Inspector :
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E.'H. Gray, Lead Reactor Eng(fi@r
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Approved by:
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J. T. Wiggins, Chief
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Materials and Processes Section, DRS
Inspection Summary:
Inspection During July 8-12, 1985, (Report No. 50-245/85-12)
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Areas Inspected:
Routine unannounced inspection by one region based inspector.
The inspection included areas of the ISI Program, diesel generator interpolar
,
connecting straps, and licensee actions taken in response to GE SIL No. 402
ccncerning the potential for cracking of steel components (Torus Vent Header)
by Liquid Nitrogen. The inspection included 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> on site and three hours
of follow-up at the region office.
Results: No violations were identified.
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DETAILS
1.0 Persons Contacted
Northeast Nuclear Energy Company (NNECo)
D. Bergstrom, Senior Control Room Operator
G. Closius, QC/QA Manager-MS#1/2
E. Hernandez, Maintenance Department Planner
- J. Leason, MS #1, ISI Coordinator
G. Mathers, ISI Technician
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- R. Palmieri, OPS Supervisor
- W. Romberg, Station Superintendent
J. Summa, Assistant Engineering Supervisor (Electrical)
J. Quinn, Assistant Supervisory Engineer
- W. Varney, Maintenance Department Superintendent
Northeast 'y 111 ties Service Company (NUSCo)
P. Higgins, Engineer (Inerting System)
- R, West, ISI Coordinator
- Indicates presence at Exit Meeting of July 12, 1985.
2.0 Inservice Inspection (ISI) Program Activities
The present 10 year ISI program started on December 28, 1980.
It is in
accordance with the ASME Code Section XI, 1980 Edition through the winter
1980 addenda, except that the summer 1975 addenda is applicable to
categories BJ, BD,BF,B-G-1 and B-G-2 as stated in the ISI program,
Revision 1, dated August 31, 1984. The licensee's Nuclear Engineering and
Operations (NEO) procedure NEO 2.07 delineates responsibilities for
fulfilling the ISI requirements and is supplemented by procedure QRE 1.10-1.
This procedure prescribes the NUSCO ISI Coordinator responsibilities
including involvement in planning on-site ISI activities.
The present
NDE contractor is EBASCo, who works to the Northeast Utilities NDF.
procedures.
The inspector reviewed the aspects of the ISI program which include
tracking of required examinations, availability of records from the 1984
ISI outage, planning for the present 40 month period, preparation for the
ISI portion of the fall 1985 outage, status reporting format and process-
ing of Non Destructive Examination (NDE) findings as required by procedure
EN 1060G. The overall controls of the ISI program must meet plant
technical specification commitment to ASME Code Section XI and augmented
examination requirements including NUREG 1061. Millstone Unit.1 is in the
first part of the second forty month period of the second 10 year ISI
interval. This forty month period includes two planned refuel outages,
one in the fall of 1985 and the following in 1987. NUREG-1061, Volume 1
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outlines NDE requirements intended to determine the progress of Inter-
granular Stress Corrosion Cracking (IGSCC) in BWR piping with the NDE
scope being dependent on countermeasures taken to prevent or reduce the
IGSCC rate of attack. The outage plan for ISI during 1985 was presented
to the NRC by the licensee in the IGSCC augmented ISI plan memo dated
June 24, 1985.
This outage plan included identification of welds to be
examined to NUREG 1061 and those examinations applicable to meeting the
ASME Code Section XI requirements.
Dbservations were made of archived shop and field radiographs, the storage
area, ultrasonic test blocks, portions of the' ISI data base and of
previous ISI records and documentation.
The steps of review for approval
of NDE procedures and personnel certifications were also reviewed.
The inspector concluded that the administration of the ISI program is
under adequate control to provide for NDE cf the ASME Code Section XI and
the augmented ISI program requirements.
No violations were identified.
3.0 Independent Measurement - Diesel Generator Interpolar Connecting Straps
As a result of the diesel generator (Fairbanks Morse) defects that caused
interpolar connecting strap failure during overspeed at the Calvert Cliffs
Nuclear Plant on May 14, 1985, damage to the stator winding of one diesel
resulted. On May 29 and June 3, 1985, the diesel generator manufacturer
reported under 10 CFR Part 21 the defects of the specific model and
informed licensee's at other nuclear plants supplied the same model.
The
Millstone Unit #1 diesel generator was not identified as the affected
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Fairbanks Morse model.
However, the inspector performed independent
observations to verify that the diesel generator at Millstone Unit No. I
was indeed a different model.
Millstone Unit I has one diesel generator, Fairbanks Morse type TGZDJ,
FR-V-34 which has a gas turbine unit as a backup. Millstone Unit 2 has
,
two diesel generators, Fairbanks Morse type TGZDK. The unit 2 diesels
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were observed to not have interpolar connecting straps but does have
damper bars and shorting straps.
The unit I diesel was observed to not
have a visible damper bar circuit but does have a bolted design
interpolar connecting strap.
The interpolar connecting strap is
perpendicular to the generator centerline and is not subject to fatigue
loading similar to that of the Calvert Cliffs TGZDJ generator.
No evidence of degradation was visible on either the Millstone Unit #1 or
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- 2 diesel generator interpolar connector areas as visible through the
generator screens.
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4.0 TI 2500/12 Actions Taken By The Licensee To Prevent Damage To Plant
Components By Liquid Nitrogen. - Response To GE SIL No. 402.
The boiling water reactor (BWR) Mark I and II containments operate with a
nitrogen drywell atmosphere of less than 4% oxygen.
The nitrogen is
generally provided by vaporizing liquid nitrogen (LN2) from a storage tank
located outside the reactor building. One of the important aspects of
operation of the nitrogen inerting system is to have adequate vaporization
and heating of the LN2 to prevent cooling of carbon steel components
including piping and drywell or Torus components to a temperature below
that where the material will not behave in a ductile manner. The General
Electric Service Information letter (SIL) No. 402 dated February 14, 1984,
outlines this problem and provides the recommendations listed below as
actions to prevent material damage by the nitrogen inerting system.
1.
Evaluate inerting system design
2.
Evaluate inerting system operation
3.
Test for Drywell/Wetwell bypass leakage
4.
Inspect nitrogen injection line
5.
Inspect containment
The region based inspector reviewed NRC inspection reports (50-254/84-02
and 50-254/84-11) which discuss previous activity by the licensee in
meeting the SIL 402 recommendations.
It was noted that the licensee
originally modified the nitrogen supply system in 1973 to prevent damage
by liquid nittogen. The inspector reviewed the drawings (25202-29134-7
and 26009), operations procedure (0P) #311 and engineering correspondence
(GMB-85-R-066 and 059) as applicable to the Nitrogen System. The
inspector also observed the LN2 system including temperature / pressure
interlocks, the steam vaporizer and walked down the nitrogen lines to the
points of entry into the drywell and torus.
The memo GMB-85-R-066
documents licensee review of the nitrogen inerting system design,
potential for injecting low temperature nitrogen into the containment,
orientation of the nitrogen discharge port, operating experience of the
N2 inert.ing system, plant calibration and maintenance schedules, plant
operating procedure, by pass leakage test and visual inspection of the
vent header and downcommer.
Safety features preventing discharge of LN2
into the carbon steel piping include (1) a pressure switch on the steam
vaporizer that prevents LN2 flow if low steam pressure, (2)
temperature
switches preventing LN2 flow if N2 as vaporized is not above approximately
50*F, (3) a flow switch preventing gaseous N2 flow if its temperature is
below 50*F.
On the basis of documents reviewed, discussions with operat-
ing and engineering personnel and observations of the N2 supply system the
inspector concluded that the recommendations of GESIL 402 had been
addressed such that the licensee response to the is considered to be
complete.
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System improvement is planned by providing recycling of a portion of the
N2 gas, reducing the amount needed to be vaporized and thereby further
reducing the risk of having LN2 exposed to those carbon steel components
susceptible to damage.
No violations were identified during evaluation of the licensee actions
pertaining to GESIL 402.
5.0 QA/QC Interactions in Areas Inspected
During inspection of the LN2 vaporizing systeh a tag (trouble report
number 29MI145946, dated 6/29/85) was noted on 7/9/85 identifying a crack
in a copper flange to a 2 inch diameter LN2 supply tube.
To evaluate
control of the identified problems and QA/QC involvement in the mainte-
nance process, the inspector reviewed the trouble report (TR) and the
administrative ccitrol procedure ACP-QA-2.02 C Revision 4.
The procedure
was found to provide for the designation of a lead department, in this
case QC, responsible for activities preceding actual work; however, the
procedure and personnel assignments do not provide for advising the lead
department of the TR.
In this case, the maintenance department PMMS
Planner was aware of the TR and had planned to initiate a work order. The
priority level required that work of the assigned priority generally be
initiated within one week of the date of the TR.
The NRC inspector observed that the procedure (ACP-QA-202-C) permitted a
condition where a designated lead department would not be aware of the
writing of a TR and would not meet the responsibilities of a lead depart-
ment as defined in paragraph 5.0 of the procedure. While a regulatory
violation was not identified in this area, the licensee agreed to review
ACP-QA-2.02C to determine if a revision is required to prevent unnecessary
delay between TR writing and initiation of a work order where a designated
lead department does not monitor TRs.
This item is unresolved
(245/85-20-01).
In the area of ISI, the site QA is involved by audit on a preoutage basis,
review and signoff of the ISI work order, presence during contractor
review by the ISI coordinator and review of NDE procedures and personnel
certifications.
No violation was identified.
6.0 Unresolved Itesm
Unresolved Items are matters about which more information is required
in order to ascertain if they are violations or deviation. An unresolved
item is discussed in paragraph 5.0.
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7.0 Exit Interview
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The inspector met with licensee representatives (denoted in paragraph 1)
at the conclusion of the inspection on July 12, 1985. The purpose,
scope and findings of the inspection were summarized and discussed. At
no time during this inspection was written material provided to the
licensee by the inspector.
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