ML20211J332
| ML20211J332 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 02/20/1987 |
| From: | Greenman E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20211J267 | List: |
| References | |
| 50-341-87-06, 50-341-87-6, NUDOCS 8702260417 | |
| Download: ML20211J332 (5) | |
See also: IR 05000341/1987006
Text
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U.S NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-341/87006(DRP)
Docket No. 50-341
Operating License No. NPF-43
Licensee:
Detroit Edison Company
2000 Second Avenue
Detroit, MI 48226
Facility Name:
Fermi 2
Inspection At:
Fermi Site, Newport, Michigan
Inspection Conducted:
December 29, 1986, through February 9, 1987
Inspectors:
W. G. Rogers
M. E. Par er
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Approved By:
E. G. Greenman, Deputy Director
DivisionofReactorProjects
Date
Inspection Summary
Inspection on December 29, 1986, through February 9, 1987 (Report No.
50-341/87006(DRP))
Areas Inspected:
Special unannounced inspection by two resident inspectors
of the events surrounding the discovery on December 26, 1986, of both
(24.409.01) divisions of hydrogen thermal recombiners being ino)erable.
Results:
Three violations were identified (failure to verify tie adequacy
of design, failure to preoperational test and surveillance test the hydrogen
recombiner system utilizing the designed cooling water system, and the plant
entered Operation Condition 2 on eleven occasions with both divisions of the
hydrogen recombiner system inoperable - Paragraph 2).
0702260417 B70220
ADOCK 05000341
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DETAILS
1.
Persons Contacted
a.
Detroit Edison Company
+* Frank Agosti, Vice President, Nuclear Operations
S. Becker, Maintenance
B. Catanese, Maintenance Staff
+*S. Catola, Chairman, Nuclear Safety Review Group
+0. K. Earle, Technical Engineer
- S. Frost, Licensing
S. Heard, Assistant Operations Engineer
+*J. Leman, Superintendent, Maintenance and Modification
+*R. Lenart, Plant Manager, Nuclear Production
+*R. May, Maintenance Engineer
+*G. Ohlemacher, I&C Assistant Maintenance Engineer
+*W. Orser, Vice President, Nuclear Engineering
- R. Poche, Licensing
+*E. Preston, Operations Engineer
+T. Randazzo, Director, Regulatory Affairs
- L. Simpkin, Nucleu Engineering Director
+*F. Sondgeroth, Licensing
+*B. R. Sylvia, Group Vice President, Nuclear Operations
+*G. Trahey, Director, Quality Assurance
+*W. Tucker, Acting Superintendent, Operations
b.
U.S. Nuclear Regulatory Commission
+*M. Parker, Resident Inspector
+*W. Rogers, Senior Resident Inspector
+M. Farber, Reg #cnal Inspector
- Der .es those attending exit meeting on January 15, 1987.
+ Denotes those attending exit meeting on February 3, 1987.
Other personnel were contacted as a matter of routine during
the inspection.
2.
Hydrogen Recombiner System
On December 26,fication required six month functional surveillance 1986, at 1
Technical Speci
(24.409.01) on the Division II hydrogen recombiner system.
The
surveillance was being performed using the Residual Heat Removal
keep-fill (demineralized water) system as a source of cooling water for
the hydrogen recombiner system.
During the surveillance, the licensee
initiated the Residual Heat Removal (RHR) system in the torus cooling
mode in preparation for HPCI testing.
At the same time the RHR system
was started, the air temperature of the hydrogen recombiner began
decreasing.
This prevented successful completion of the hydrogen
recombiner surveillance.
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Technical Specification 4.6.6.1 states, "Each drywell and suppression
chamber hydrogen recombiner system shall be demonstrated OPERABLE at
least once per six months by verifying during a recombiner system
functional tast that the heater outlet gas temperature increases to
greater than or equal to 1150 F within 75 minutes and is maintained
for at least one hour." The licensee was unable to satisfy these
requirements upon initiation of the RHR system and subsequently declared
both divisions of hydrogen recombiners inoperable and took appropriate
action to comply with the applicable Technical Spec'fication action
statements.
The licensee initially determined that the inability to achieve outlet
gas temperature was due to excessive cooling water flow.
The cooling
water flow to the hydrogen recombiners had been provided at about 60 psig
through the RHR keep-fill system. When the RHR system was started, the
cooling water pressure was increase'd to about 220 psig which resulted in
greater flow and thus more coeling.
This resulted in a decrease of the
thermal recombiner temperature.
The licensee subsecuently adjusted the
cooling water flow, repeated the surveillance, and ceclared both divisions
of the thermal recombiners operable on December 27, 1986.
In order to satisfy operability concerns addressed by the resident
inspectors, the licensee repeated the surveillance with the manual
isolation valve full open, simulating the original test conditions.
The
Division I thermal recombiner passed the surveillance on January 8,1987,
but Division II failed on January 9,1987.
After the second surveillance failure on the Division II thermal recombiner
system on January 9,1987, pressure gauges were installed on the cooling
water line.
The RHR pressure to the unit was measured at 190 psig and
the pressure to the blower seal was measured at 140 psig.
Rough flow
measurements determined that approximately three gpm were provided to
the seal with one and one-half gpm at the seal outlet.
The licensee
subsequently determined that the blower seal was leaking internally
at the higher RHR pressures.
Discussions with the seal manufacturer, Durametallic Corporation, concluded
that the springs in the blower seal will compress at 39 psid and could
allow water to enter the blower cavity.
Vendor drawings identified that
the blower seal was designed for a cooling water flow of one gpm at
10 psi 15 psi.
Rockwell International vendor drawing No. N019560002
provided for an RHR system pressure to the hydrogen recombiners of
100 psi minimum, while Rockwell internal letter to H. L. Yobs from
S. A. Itow dated January 13, 1987, indicates 100 psi.
Neither specified
the actual 220 psi to the unit.
The licensee specification 3071-107 dated
April 13, 1972, specifically identified a 250 psig(water source to the341/87006-01(DRP)) o
recombiner units.
This is considered a violation
10 CFR 50, Appendix B, Criterion III, Design Control, for failure to
appropriately verify the adequacy of design.
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A review of the preoperational test program identified that the thermal
T4804.001,"preoperational' test, "T4804 Thermal Recombiner System PRET
recombiner
Revision 2, allowed the use of the RHR system or an alternate
source if needed to supply cooling water.
The PRET identified that the RHR keep-fill system was utilized in the
-preoperational test and that no specific intent was made to utilize the
higher RHR pressures to verify proper system operation.
The system was
operated on nyeral occasions and each time the RHR keep-fill system was
used as a source of cooling water.
Through discussions with personnel
there were several reasons that the RHR was not utilized:
(1) RHR pump
availability; (2) economic factors, and (3) RHR keep-fill availability.
As a result, the hydrogen recombiner system was never tested utilizing the
higher RHR pressures. Additionally, functional surveillance Procedure
No. 24.409.01, " Post LOCA Thermal Recombiner Functional Test," Step
No. 5.3, allowed the RHR keep-fill system to be in service to provide
water to the blower and spray cooler during the test.
A temporary change
to this procedure, effective December 26, 1986, deleted the use of the
RHR kee)-fill system.
This is considered a violation (341/87006-02(DRP))
of 10 CFR 50, Appendix B, Criterion XI, Test Control, for failure to
preoperational test and surveillance test utilizing the designed cooling
water system.
On January 9, 1987, the licensee identified that while utilizing the RHR
systemasasourceofcoolingwater,theDivisionIIhydrogenrecombiner
system only heated up to 761 F within the required 75 minute time period.
Technical Specification 4.6.6.1 requires the outlet gas temperature to
increase to greater than or equal to 1150 F within 75 minutes.
The
inability to obtain the required gas temperature was due to excessive
internal cooling water seal leakage at the higher RHR pressures.
As a
result, the Division II hydrogen recombiner system was inoperable and
unable to satisfy the surveillance requirements of Technical Specification 4.6.6.1 utilizing the designated source of cooling water.
Ever since the last seal replacement on August 29, 1985, the licensee has
noticed external seal leakage with the Division II recombiner.
Therefore,
the Division II hydrogen recombiner system was considered inoperable since
the seal replacement on August 29, 1985.
Technical Specifications 3.6.6.1 states that "Two independent drywell
and suppression chamber hydrogen recombiner systems shall be OPERABLE
in Operational Conditions 1 (power operation) and 2 (startup).
Technical Specification 3.0.4 states in part, " Entry into an OPERATIONAL
CONDITION or other specified condition shall not be made unless the
conditions for the Limiting Condition for Operation are mb:, without
reliance on provisions contained in the ACTION requirements."
During the time period from August 29, 1985, to January 8, 1987, the
plant entered Operational Condition 2 (Startup) on eleven occasions
(October 3, 1985, August 4, 1986, August 11, 1986, August 30, 1986,
September 6, 1986, October 3, 1986, October 7, 1986, October 14, 1986,
October 19, 1986, October 29, 1986, and December 19,1986) with both
divisions of hydrogen recombiner systems inoperable.
This is considered
a violation of Technical Specifications 3.0.4 (341/87006-03(DRP)).
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During the troubleshooting effort to repair the thermal recombiners,
several problems were encountered which caused concern as to the
reliability of the recombiners.
They are as follows:
Division I heater breaker would not close in on several occasions
due to sticky door interlock.
Division I silicon controlled rectifiers (SCRs) failed to fire.
Division I SCRs fired continuously"fied as broken.
Division I pin connector was identi
Division II solenoid contact did not close in allowing closure at
heater breaker motor.
In order to address these concerns, the licensee has embarked upon a
program to ensure reliability of the thermal recombiners.
This program
consists of performing reliability runs in addition to the six-montfi
Technical Specification surveillance requirements.
In these runs the
heaters will be energized to approximately 400 F to ensure reliability of
the heaters, blowers, cooling water, and electrical circuits.
These runs
will be performed:
for one month, and then (3) y other day for one week; (2) once per week
(1) everonce per month for six months.
If these runs
are determined to be successful, the surveillance frequency will be
returned to the six-month Technical Specification required frequency.
3.
Exit Interview (30703)
The inspectors met with licensee representatives (denoted in Paragraph 1)
on January 15, 1987, February 3, 1987, and informally throughout the
activities. period and summarized the scope and findings of the inspection
inspection
The inspectors also discussed the likely informational
content of the inspection report with regard to documents or processes
reviewed by the inspectors during the inspection.
The. licensee did not
identify any such documents / processes as pro
The licensee
acknowledged the findings of the inspection.prietary.
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