ML20235V660
| ML20235V660 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/11/1985 |
| From: | Andrews R OMAHA PUBLIC POWER DISTRICT |
| To: | Martin L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| LIC-85-465, NUDOCS 8710150260 | |
| Download: ML20235V660 (10) | |
Text
_ _ _
g I
Omaha Public Power District 1623 Harney Omaha. Nebraska 68102-2247 402/536 4000 October 11, 1985 L IC-85-465 j
Mr. Lawrence E. Martin, Chief l
'[}
Project Section B 9 I D0 l/
i U.S. Nuclear Regulatory Commission 1
bW.'-
Region IV 611 Ryan P1aza Drive, Suite 1000
' Ehik 0 '
Arlington, Texas 76011
' ~ ~
Reference:
Docket No. 50-285
Dear Mr. Martin:
Inspection Report 85-09 An inspection of the Omaha Public Power District's Fort Calhoun Station was conducted from April 29 to May 3,1985, to detennine canpliance wi th 10 CFR 50.49. The results of this inspection were documented in the subject inspec-tion report. Based upon telephone conversations between OPPD and the Region IV office, OPPD has provided in the attachment to this letter, information concerning the resolution and di sposition of each of the unresolved and open items relating to equipment.
It is our belief that this information is ade-quate to resolve the renaining concerns for each of the itens and demonstrate compliance with 10 CFR 50.49.
If you have further questions concerning any of these itens, please contact us.
Sincerely,
./!swl R. L. Andrews Division Manager Nuclear Production RLA/DJM/ rh cc:
LeBoeuf, Lamb, Leiby & MacRae 1333 New Hampshire Avenue, N.W.
Washington, DC 20036 4
Mr. E. G. Tourigny, NRC Project Manager j
Mr. P. A. Harrell, NRC Senior Resident Inspector f('I
.lb h8I B710150260 851011
~I DR ADOCK 0500 5
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L n4ou i opponunw assa4 tmmoumn
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4 g,7 ATTACHME NT 1.
Finding r
Contrary to paragraphs (d)(4) and (k) of 10 CFR 50.49, OPPD's documenta-tion did not establish that the harsh environment threshold total radia-4 tion dose of.10E5 Rads'was low enough to ensure that radiation damage to all potential Master List equipment was ' adequately considered.
(Para-graph 5. A.(1),( a), Item 50-285/85-09-01)
Disposition 1
As part of OPPD's Electrical Equipment Qualification effort, a screening l
criteria for radiation dose ef fect at which level eqaipment was con-I sidered for the qualification progran was established for those areas which see a change in radiation environment as a result of a Main Steam Line Break, Loss of Coolant Accident, or High Energy Line Break. A1x 5
10 R Total Integrated ' Dose (TID) was established.
5 OPPD has reviewed the 1 x 10 R screening criteria for electric equipment (cable, terminal blocks, motors, solenoids, control switches, electric /
. pneumatic converters and limit switches) and believes this to be an 5
acceptable value for use in the EEQ program. The 1.0 x 10 R screening criteria for electric equipment is supported by Appendix C of the 00R 4
Guidelines (not previously cited in the District's justification) which does not identify any materials other than electronics which have a
)
5 threshold less than 1 x 10 R.
This-threshold is further supported by EPRI report' NP-2129, Radiation Ef fects on Organic Materials in Nuclear P.ower Plants -(cited by OPPD), which demonstrates that a total dose of less than 105 Rads produces no significant degradation of mechanical or electrical properties. This was further confirmed in the EPRI Report NP4271M (not.previously cited in the District's justification).
The
~
EPRI research project did indicate that caution should be taken with ny-lons and epoxy resins since a minority of reports had thresholds in the 4
10 R to 10bR range.
It is the District's position that material perfonnance concerns are best addressed by-operating experience in which similar types of most equipment and materials have been exposed to 105 doses inside the bio-i 1ogical shield.
Performance concerns are also supported by the fact that similar devices have been qualified for much higher dose levels in other areas of the plant.
I To ensure the typical electrical equipment statement was correct and 3
that electronic equipment with a 10 R screening value was correctly addressed, a review was conducted to identify the equipment in the 103 to 105 range.
This review made use of a radiation study which more accurately reflects plant performance during a DBE.
Specifically, the Chemical and Volume-Control and Radioactive Waste Disposal Systens were removed as post accident sources since they are isolated within seconds of a DBE.
1 Based on this revised study and the equipment review, only cable, sole-noids, motors, limit switches, control switches, electric to pneumatic converters and tapes (splices) were identified. No electronic eqiupnent was identified.
-- ---- J
OPPD believes this is adequate to ensure safe operation. OPPD will re-3 vise the EEQ manual to reflect the 10 R screening criteria for electron-ic components and to add a general statement that the screening should also. consider the equipment type and function as well as expected total integrated dose.
No equipment changes are planned. The revision to the EEQ manual is scheduled to be canpleted by restart fran the 1985 refuel-ing outage.
2.
Finding l
Contrary to paragraphs (d)(1) and (k) of 10 CFR 50.49 and paragraph 5.2.5 of the D0R Guidelines, CPPD did not document required accuracies for most postaccident monitoring transmitters nor conpare then with errors reported from qualification type tests.
(Paragraph 4. A.(1)(b),
Iten 50-285/85-09-02)
Disposition The District has reviewed the instrumentation within the scope of the EEQ program (see Table 1 of the EEQ Manual for the list of instruments) for accuracy.
Accuracy is based on each individual instrument's requirement as out-i lined in EP-5, 5A, SB, 29 and 36.
In cases where numerical data was clearly defined, these values were used in judging the adequacy of the instrument. Our review demonstrated that the existing instrumentation 1
is capable of fulfilling its post accident monitoring requirements.
More clearly defined accuracies have been developed which require proce-dure changes.
These changes will provide the accuracy of the readings.
Accuracy requirements will be specified in the next revision of the EEQ Ma nual.
These steps will be conpleted before startup fran the 1985 re-fueling outage.
3.
Finding Contrary to paragraph (g) of 10 CFR 50.49, OPPD did not adequately demon-strate and/or document qualification of Conax electrical penetration as-semblies modi fied by OPPD wi th RTV silicone rubber.
(Paragraph 4.D.(1),
item 50-285/85-09-03)
Disposition The District has elected to replace the electrical penetration assen-bites of concern with new fully qualified penetrations.
These modifica-tions will be cmpleted prior to restart fran the 1985 refueling outage.
4.
Finding l
Contrary to paragraph (g) of 10 CFR 50.49, OPPD did not adequately demon-strate and/or docunent qualification of States Company terminal blocks modified by 0 PPD with RTV silicone rubber.
(Paragraph 4.D.(2), Iten 50-285/85-09-04)
'l 1
Disposition l
1 OPPD has reviewed the use of tenninal blocks in the Fort Calhoun Station I
to assess their functional requirements and the circuit effect of a 2.4 x 104 ohms leakage resistance in that circuit.
It has been determined that the blocks are used in: 130 VDC ASCO pilot solenoid air operated valves and their associated NAMC0 limit switch indicating circuits; the four RPS/ESF pressurizer pressure Foxboro trans-mitters, the two pressurizer pressure control circuit Foxboro transmit-ters; and the four HPSI loop flow Foxboro transmitters.
Three concerns are addressed regarding the 130 VDC pilot solenoid and position indication:
{
1.
Improper Operation of a Deenergized Solenoid (solenoid pick up)
In the solenoid circuit, the design is such that for normally deen-l i
ergized circuits the solenoid is isolated from the positive DC bus by the position indication or the contact, and the block insula-tion resistance (see Figure 1, attached). This should ensure that a deenergized solenoid cannot be picked up.
In the worst case the current required for energization is 49.8ma (based on actual op-l erating voltage of 53%).
Leakage current is expected to be 11.6ma at the noninal high instrument bus voltage of 140 VDC. Based on l
this dif ference, no adverse operation is expected. NOTE: This i
does not take credit for the position indication or solenoid coil i
resistance which would further limit the current.
2.
Improper Operation of an Energized Solenoid (blown control fuse) l For the normally energized circuit, it must be ensured that the solenoid circuit fuse protection does not blow. For a nonnally j
energized coil, there are three leakage paths (solenoid worst case i
and two limit switches) producing a current of 206.5ma. This i
would have no effect on the 10 amp fuse circuit and would not result in a blown fuse and valve repositioning.
1 3.
Incorrect position indication (both open and closed lights on)
In both cases (energized and deenergized) inaccurate position indi-cation must not be given. The position indication leakage current would be limited to less than 5.4ma which is less than the 33ma re-quired to light the indicating lamp.
For the Foxboro transmitter circuits which use tenninal blocks, the sig-nal error was determined by current division between the block IR and the transmitter load, i
1.
For the four pressurizer pressure trip channels (PT-102A/B/C/0),
the calculated error from current leakage is - 0.9%.
This is con-servative for RPS TM/LP trip and ESF actuation both which operate on decreasing pressure.
Post accident use of these channels is bounded by the wide range channels where no tenninal blocks are used.
2.
The pressurizer pressure control channel calculated error fran cur--
rent leakage is -1.7%.
The channels (PT-103X and PT-103Y) perform monitoring only and are bounded by the wide range channels.
Adding the -1.7% error to the LOCA error of 18.6% gives -10.2% to
+6.9% which is acceptable. These transmitters have a 1500 psia low reading and are of limited value in a LOCA or MSLB.
3.
The HPSI flow calculated error from current leakage is -0.46%.
Thi s is acceptable since fl ows (FT-313, FT-316, FT-319, FT-322) are balanced and long tenn core cooling requires equal flow in all four irdection legs.
Since it is always negative, balanced equal flows should not be af fected.
The assessment of the functional requirements and the circuit effect of g
leakage resistance are acceptable.
In order to completely alleviate any 1
concern about the use of these tenninal blocks, the tenninal blocks for PT-103X, PT-103Y, FT-313, FT-316, FT-319, and FT-322 will be changed out prior to restart from the 1985 refueling outage.
5.
Finding Contrary to paragraph (g) of 10 CFR 50.49, OPPD did not adequately demon-strate and/or document qualification of Rockbestos Pyrotrol III PT-102A/
B/C/D cable.
(Paragraph 4.D.(3), Item 50-285/85-09-05)
Disposition OPPD has an additional quali fication report not presented during the in-spection in which Rockbestos Pyrotrol III was used as part of the system used to quali fy the original Fort Calhoun Station containment penetra-tion splices (which are no longer installed). This test, F-C 3348, com-pleted in April of 1972 was conducted by the Franklin Research Institute for the Commonwealth Electric Company (the Fort Calhoun Station electri-cal contractor) using acceptance criteria established by Gibbs, Hill, Durham and Richardson, Inc., the Architect Engineer. The test record includes copies of the laboratory measurements and strip chart record-ings. The cables tested are identified with the Fort Calhoun Station identifier.
The cable was subjected to five 60 psig LOCA transients with peak tenper-i atures of 302*F, 296*F, 296'F, 296"F and 295 F for twenty minutes fol-lowed by a 30 minute ramp down to 30 psig, 240*F, followed by a 110 min-l ute ramp down to 150*F.
This envelopes the District's LOCA profile with the exception of the peak of 305"F.
It is the District's judgement that I
the 5 LOCA profiles provide adequate material str.ess to ensure qualifi-cation at 305*F.
The cable was exposed to 1900 ppm boron chemical spray at a pH of 9.5.
l The District specification is 2000 ppm boron pH 5.2 to 7.2.
It is the District's judgement that although the test spray was slightly alkaline and the District's containment spray is slightly acidic for the first 20 minutes, the chemical resistance of high-density cross-linked polyethy-lene is considered good for mild acid and mild alkaline solution.
Using analysis pennitted under the 00R Guidelines for radiation, general 8
l infonnation indicates XLPE to be suitable for 1 x 10 R (EPRJ Report NP 7
2129).
The expected exposure is 6.26 x 10 R - Beta (2 x 10 R) plus 7
Gamma (3.2 x 10 R) plus background.
The (1.06 x 107) neoprene jacket is
[
1 b
l l
i 8
.o'nly credited for 30 mils of Beta shield or a factor of 10 fran 2 x 10 R 7
to 2 x 10 R, for those cables exposed to beta radiation.
Aging was accounted for using the Arrhenius methodology with an activa-l tion energy of 1.13.
The Pyrotrol III Speci fication (supported by mea-I surements) is 121*C for 168 hours0.00194 days <br />0.0467 hours <br />2.777778e-4 weeks <br />6.3924e-5 months <br /> for 70% elongation. Using actual ambient temperature and calculations for heat rise due to loading, a 40 year life was demonstrated for all applications.
I Although under D0R Guidelines an MSLB analysis is not required due to the presence of a redundant spray systen, the District judges the cable to be quali fied. The MSLB profile renains above the LOCA profile for 35 seconds with a 355"F peak. This brief temperature excursion is not expected to cause significant heating beyond the LOCA value. MSLB degradation of the material is considered bounded by the five test LOCA transients.
The only test ananalies were a failure of the splices.
Expected insula-7 tion resistances are greater than 5 x 10 n.per foot.
It should be noted 3
that lower readings were measured, however, these were on cables where splice problems were noted. These splices have been replaced with qual-ified Raychem Splices.
OPPD believes that there is sufficient infonnation at this time to ade-i quately demonstrate' quali fication.
We further believe that adequate l
quali fication has always been demonstrated and no further steps are necessary.
6.
Finding Contrary to paragraphs (e)(5) and (f) of 10 CFR 50.49, Omaha Public Power District (0 PPD) had not established nor performed a maintenance program to preserve Allis Chalmers canponent cooling water pump motors in a qualified state, nor was an analysis performed to demonstrate the extended life of replacanent windings.
(Paragraph 4.D.(4), Iten i
50-285/85-09-06) i Disposition OPPD has canpleted its review of the Allis Chalmers component cooling l'
water pump motors AC-3A, AC-3B and AC-3C. The results of the review are summarized here along wi th the planned di sposition of these motors wi th respect to the Electrical Equipment Qualification Program and action l
OPPD plans regardi ng the motors thenselves.
l The review consisted of an investigation into three areas; bearing lubri-l cation practices, operating history and its impact on preventive mainten-i ance, and the rewound motor life.
i The vendor was contacted to obtain the latest instruction manual and lubrication recommendations. The vendor recommends the use of shielded bearings (the same type as presently installed), and lubrication every a
6000 hours0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br /> of operation for continuous duty motors using a number 2 l
grease and yearly bearing cleaning. A review of maintenance records indicates that Lubriplate #930-2, which is a #2 grease, is in use on notors AC-3 A and AC-30. The exact type of grease in AC-3C is u.known, however, AC-3C has been operating since 1979 with no problem (as non-1
.__-__-_-___________O
itored by OPPD's ST-ISI-CC-3 quarterly vibration testing).
This indi-cates that the grease is acceptable and that lubrication on installation of the bearings provides adequate bearing reliability.
A ruiew of maintenance history indicates that AC-3A required new bear-ings and balancing due to high vibration in 1979,1982 and 1983, AC-3B required rewinding in 1983, and AC-3C required new bearings in 1975 and a new bearing and balancing in 1979.
Further investigation indicates that the higher frequency of repair required on AC-3A is a result of high vibration induced by the inlet piping on AC-3A.
The only motor failure was AC-38 on 4/10/83.
This is considered an isolated incident of apparent winding failure af ter i hour and 40 minutes of service time af ter being placed in operation.
The last area of investigation was the AC-3B rewind motor life based on the rewind material in the insulation. The phase insulation was changed l
frcm glass fiber fabric with an 18 year life to Fiberglass Polyester with a life of:
t = exp(Ea + Intercept)
KgT l
Intercept = -15.973894 Where l
t = Li fe 97*F - Worst Case Ambient Ea = activation energy =.95 (actual ranges from 80*F Kn = Boltzmann's Constant to 97*F)
T = Operating Temperature *K = 97*F ambient + 40*C temp. rise
+ 273 = 349.1*K t = exp (
.95
- 15.973894) i l
8.617 x 10-5 x 349.1 l
= 6 x 106 hours0.00123 days <br />0.0294 hours <br />1.752645e-4 weeks <br />4.0333e-5 months <br />
= 685 years Thus, a 40 year quali fied 11 fe is demonstrated for continuous operation.
Actual operation is significantly less.
Based on actual motor operation, operating history, and manufacturer's recommendations, the following actions will be taken:
1.
The bearings in AC-3C with the unknown lubricant have been changed l
I and a Texaco Marfak Multi Purpose 2 grease with a radiation with-7 stand capabili ty of 2.3 x 10 R installed.
It should be noted that the Lubriplate in the other motors and the unknown grease would be expected to perfonn in a similar manner since composition of grease for this general application are very similar in nature.
2.
Grease zerts will be installed and greasing on an 18 month basis (6000 hours0.0694 days <br />1.667 hours <br />0.00992 weeks <br />0.00228 months <br /> operation) will begin. After approximately three years of operation, from April 1983 either AC-3A or AC-3b will be inspected to detennine the bearing cleaning frequency.
In addi-tion, OPPD will continue to monitor vibration on a quarterly
T-
[,
basis.- OPPD believes-this is the best preventive maintenance and can indicate problems ~ prior to failure. The. quarterly frequency -
is considered adequate to account for flow induced vibration which-may result in. accelerated degradation.
3.
OPPD will check the. motor ' air intake screens quarterly, and will-clean them as required..
'4.
The rmaining two motors -AC-3A.and AC-3C will be rewound on an 18 year frequency unless the materials are -improved during rewind.=
-l Any future hardware additions to the EEQ progran are'done through the-1 station Standing Order which requires the preventive maintenance be
- addressed.
3 J
These actions will be in place before startup fran the 1985 refueli%
l outage.
7.
Finding f
Containment ambient temperature. During review of the qualification l
files for a replacement transmitter the inspector discovered that a contaiment ambient temperature of 85'F ~ was used in the thennal aging l
calculation. Documentation in support of this value was requested, but the. item renained open at the close of the inspection. Contaiment i
Ambient Temperature is an Open Item, 50-285/85-09-08.
Disposition
-l Part 1 - Verify 85'F j
The use.of the 85"F ambient temperature is based on environmental tenper-ature measurements and analysis of the heat sources and heat sinks which i
ef fect the contaiment atmospheric ambient temperature.
The containment is considered to be a closed system with the heat sources being the NSSS (primary and ' secondary) and the reactor coolant pump motors. The heat sinks are considered to be the containment air cooling and-filtering units and the heat transfer through the contain-ment building walls to the outside atnosphere, i
' The containment wall heat transfer is considered a secondary effect.
The containment wall thickness prevents large heat transfers and mini-mizes.the ef fect of hot summr days. Also, not including this heat
~
transfer is conservative. The average mean. temperature of 51.9'F (Taken fra USAR Table 2.5-6) would indicate a general heat transfer out of the buil di ng.
l The contaiment building enviroment is controlled by containment cool-i ing, and filtering units of which two of four are in service during 1
nonnal plant operation, with reduced cooling water flow (full flow is used only during a DBE). These cooling and filtering units use compo-nent cooling water (CCW) which is cooled through heat exchangers by the Raw Water (RW) system pumps which take suction from the river. D uri ng l
the hot summer months two of four raw water punps are run to provide additional CCW cooling.
I
i 4
n
- To verify the adequacy of 85*F, a nodel was used. This model assumes that the containment temperature responds to changes with river tempera-ture.
In this model the CCW low temperature control of 55 F is used, and the use of two raw water pumps in the summer is also used. On May 23,1985 an 87.4*F ambient was measured with a CCW temperature of 70*F and a river water temperature of 68.7*F.
This measured temperature can then be factored into the heat source 'and heat sink analysis.
During j
the two months of July and August when two raw water pumps are used, a 19*F rise over river water was assuned, more closely modeling the actual measurements. This projects a profile as follows:
6 months 7 5*F Nonnal Operation 1 month 81*F October Equivalent 1 month 86 F May Equivalent 1 month 91*F June Equivalent 1 month 93*F Septenber Equivalent 1 month 96*F 2 Hottest Months Assuming 2 Raw Water Pumps in 1 month 97*F Operation.
Using the Arrhenius methodology, a calculation was made to determine the equivalent aging of the temperature profile to days at 85*F on a per
. year basis. The.61 eV for Target Rock Solenoids was selected as it is the lowest activation energy and provides the highest degree of sensi-tivity to temperature excursions over 85*F.
Based on the calculations attached in Table 1, an equivalent life of 351.4 days was detennined, which is less than the 360 day (1 year) criteria. That is, for each year of operation the profile provides less degradation than would be expected if the material were aged at a constant 85*F, the assumed tempe rature.
Based on this, the 85 F average temperature is considered adequate for qualified li fe aging.
)
Part 2 - Effect on Aging Each type of equipment in containment was reviewed to detennine the actual maximum equivalent containment aging temperature which is possi-ble without any change in maintenance frequency to demonstrate the con-servatism used in the EEQ program qualified life.
Each b pe of equipment was converted fron time margin at 85*F to re-quired life plus ten percent at an increased ambient aging temperature.
New calculations were done if the equipment aging was done at 85*F, no calculations were done if the demonstrated aging temperature was in excess of 85'F (e.g., the Limitorques were quali fied for 40 years in Room 81 at 114"F).
These calculations demonstrate sufficient aging margin such that util-izing an ambient temperature of 90 F would cause no increase in rebuild f reque ncy.
i
?
Table 1 85*F Equivalent Use Activation Energy of.61 eV Arrhenius Equation 1
h.
t< = te I
t< = Equivalent Li fe t = Time at Temperature T2 AE = Activation Energy KA = Boltzman's Constant T1 = 85*F converted to *K T2 =. Profile Temperature in *K
.61
[
1 1
]
8.617x10-5 302.444 296.888 75*F 180e
= 117 day s
.61
[
1 1
]
8.617x10-5 302.444 300.222 81*F 30e 25 days
=
.61
[
1 1
]
8.617x10-5 302.444 303 31 days 86*F 300
=
.61
[
1 1
]
8.617x10-5 302.444 305.778 3
39 days j
91*F 30e
=
.61
[
1 1
]
8.617x10-5 302.444 306.889 42 days 93*F 30e
=
.61
[
1 1
]
8.617x10-5 302.444 308.55 47.7 days 96 F 30e
=
.61
[
1 1
]
8.617x10-5 302.444 309.111 I
49.7 days 97"F 30e
=
Equivalent days age at 85*F per year of operation 351.4 days l
l