ML20056H490
| ML20056H490 | |
| Person / Time | |
|---|---|
| Issue date: | 06/30/1993 |
| From: | Rossi C Office of Nuclear Reactor Regulation |
| To: | Malkmus M AFFILIATION NOT ASSIGNED |
| References | |
| NUDOCS 9309090423 | |
| Download: ML20056H490 (3) | |
Text
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NUCLEAR REGULATORY COT 6 MISSION g v h,F. E wasmNGTON, D. C. 20555 a
j JUN 3 01993 Mr. Michael V. Malkmus, Vice President Marketing and Sales Pathway Bellows, Inc.
P.O. Box 3027 Oak Ridge, Tennessee 37831
Dear Mr. Malkmus:
SUBJECT:
REPAIR AND REPLACEMENT INFORMATION FOR BELLOWS EXPANSION JOINTS In your letter of June 9,1993, you requested information regarding the number cf repairs or replacements required annually for bellows installed in nuclear power plants.
You indicated that in the past your company supplied bellows for use in nuclear power plants at various locations in the plant.
While the Nuclear Regulatory Comission (NRC) does not maintain records of detailed repairs and replacements of such components at individual nuclear I
plants, we are very concerned with the identification of component defects and failures that could have an adverse effect on public health and safety.
this context, we do require licensees to report such events to the NRC toIn facilitate an evaluation of safety significance of the defect / failure, its generic implications for other nuclear plants, root cause of the defect / failure, and corrective actions undertaken to resolve the problem and preclude its recurrence.
notification from the Commonwealth Edison Company on MarchIn this regard, the 27, 1991, l
describing the effect of two-ply expansion bellows, manufactured by your company and used in primary containment mechanical penetrations, on the performance of integrated and local leak rate testing of the Quad Cities Station Unit I containment structure.
The nature of the design and construction of the two plies can limit the flow of the leak rate test medium between the inner and outer plies thereby masking the true leakage rate.
NRC elected to issue an information notice describing this situation to allThe its licensees so that appropriate action could be taken.
Copies of the Part 21 notification from Comonwealth Edison and Information Notice 92-20 are enclosed for your use and information.
With regard to the availability of detailed repair and replacement actions taken by licensees for bellows installations at nuclear power plants, it is recommended that you contact licensees directly or nuclear industry oversight organizations including the Institute of Nuclear Power Operations (INPO) and MSG ME CENim C0i V p,uyw 6 ->
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Mr. Michael V. Malkmus the Nuclear Management and Resources Council (N') MARC). They can be reached at the following addresses:
Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, Georgia 30339-5957 Nuclear Management and Resources Council 1776 Eye Street, NW Suite 300 Washington, D.C.
20006-2496 Should you have any questions on the above, please contact W. Haass at 301-504-3219.
Sincerely, e
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harles Ro si, Director j j Division of Reactor Inspection and
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Licensee Performance Office of Nuclear Reactor Regulation
Enclosures:
As stated l
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Mr. Michael V. Malkmus,
the Nuclear Management and Resources Council (NUMARC).
They can be reached at the following addresses:
Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, Georgia 30339-5957 Nuclear Management and Resources Ccuncil 1776 Eye Street, NW Suite 300 Washington, D.C.
20006-2496 Should you have any questions on the above, please contact W. Haass at 301-504-3219.
Sincerely, ORIGl!lAL SIGtmp gy.
dlYi$k42 by E
Charles E. Rossi, Director Division of Reactor Inspection and Licensee Performance Office of Nuclear Reactor Regulation
Enclosures:
As stated DISTRIBUTION:
VIB R/F Central files / Docket files /PDR
- SEE PREVIOUS CONCURRANCE' s
OFFICE VIB/DRIL VIB/DRIL VIk/Dh!L bl/DD DRIL'/(
NAME WHASS UPOTAPOVS LNONLM RZIMkMAN d[NSYb DATE 6/24/93*
6/25/93*
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NO OFFICIAL RECORD COPY Document Name: G:\\ PATHWAY
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- Ih Commonwestth Edison 1@ Opus Place
- t Dos.ners Grove. Inmois 60515 March 27, 1991 Mr. A. Bert Davis Regional Administrator U.S. Nuclear Regulatory Ccmtssion 799 Roosevelt Road Glen Ellyn, IL 60137
Subject:
Quad Cities Nuclear Power Statlan Unit 1 and 2 10 CFR Part 21 Notification NRC Docket Jos, 50-254 and 50-265 Hr. Davls:
During the performance of the Quad Cities Station Unit I containment integrated leak rate test pursuant to 10 CFR 50 Appendt, J, increased air leakage was identified from containment penetration X-25.
An investigation to identify the cause of the leakage was conducted. During that investigation, it was found that the two-ply bellows assembly had been successfully tested pursuant to the 10 CFR 50 Appendix J Type B test requirements. As a result of the inconsistent test data. Commonwealth Edison conducted various tests of the two-ply bellows and has concluded that a valid Type B test cannot be performed on the bellows assembly.
I On March 22, 1991 Correnwealth Edison nottfled B. Burgess, Branch Chief via telenhone of the evaluation of the two-ply bellows assembly, which was performec jursuant to 10 CFR Part 21. While the evaluation conclusions did not strictly meet the criterla which is contained in 10 CFR Part 21 Corronwealth Edison considered the evaluation conclusions to be significant and thereby warranted formal notification to the Ccm tssion. Enclosed are three (3) copies of the report which contains the information required by 10 CFR Part 21.21(b)(2).
If there are any questions regarding this notification, please direct i
them to R. Stols at (708) S15-7283 or H. Massin at (708) 515-7450.
Very truly yours, T.J. Kovach 80
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10 CFR 21 *)TIFICATION Type B Testability of Primary Containment Penetration Bellows 5
8211Cability This Notification is submitted in accordance with the requirements cf 10 i.
CFR 21, Section 21.1.(b), 21.3.a.(3), and 21.3.d.(4).
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D-y identificittien of Fat 111ty_EnLComponent This Notification concerns the local leak rate testing of primary 9:.
containment mechanical penetrations fitted with two-ply expansion bellows.
fz Recent integrated and local leak rate testing, which was conducted on an
'S, expanston bellows assembly at the Quad Cities Nuclear Power Station, Indicates i
that these bellow assemblies are not testable per the requirements of 10 CFR
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50 Appendix J (Type B testing only). The evaluation of information regarding the bellows testing discrepancy was completed on March 22, 1991.
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Identificatlen of Cce w nent ManufactuIII f}
The subject bellows assemblies were manufactured and supplied by:
Pathway Bellows Corporation 115 Franklin Road
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Oak Ridge, TN 37830 (615) 483-7444 These assemblies are ortgtnal plant equipment which were manufactured and installed in the late 1960's and early 1970's. It is believed that the bellows design has remained essentially unchanged; therefore, bellows which were manufactured in subsequent years would also be subject to the same concern regarding the abl11ty to perform a valid Type B test.
NAtuI1_QLDiftti The bellows assemblies which were supplied by Pathway Bellows Corporation 4
were in full compilance with the procurement specification. Commonwealth E'r.
Edison has determined that any potential leakage of the bellows durir.g the performance of a 10 CFR 50 Appendix J. Type B test cannot be properly F
quantified due to the construction of the bellows.
This testing deficiency is
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the subject of this Notification.
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The flexible metallic bellows are constructed with two plies of S
austenttic, type 300 series stainless steel which are formed together into a p-cylindrical corrugated element. This design configuration is typical of 7,
bellows penetrations that are installed at major piping penetrations and for g^
the drywell ventilation and purge lines (in-line bellows assemblies).
The bl forming process can bring the piles into contact, thus limiting flow of the local leak rate test medium (Inert gas or alr) between the inner and outer piles. Based upon our evaluation of the local leak rate test (LLRT) and i
integrated leak rate test (ILRT) results of this flexible metallic bellows k
assembly, the LLRT is capable of detecting leakage but cannot be relled upon to accurately quantify the actual leakage rate.
A Type B test was performed on the 18" Drywell Ventilation Penetration, 9
X-25.
The measured leatage rate was 6 scfh. Approximately two days after the y
LLRT, the primary containment ILRT was performed. While the containment was E
at pressure, application of a soap solution to the surface of the bellows d
revealed one large crack and over a hundred small indications.
Following the ILRT, a Type B test was again performed and the results duplicated the initial LLRT leakage rate. A soap solution was applied to the bellows during this LLRT and identlfled only a few small leaks.
A " local" ILRT was subsequently performed in an effort to Quantify actual leakage from the bellows. A steel plate was welded to the ventilation line inlet inside of the drywell. The bellows were pressurized from the inside through a threaded hole in the plate and a leakage rate test was performed on the entire ventilation penetration.
The soap solution revealed a large leak along with many small leaks which were similar to the ILRT results. A leakage rate 137 scfh was measured.
With the validity of the Type B tests now in question, Station personnel examined the sensitivity of the LLRT procedure to detect and quantify new l
cracks. A 0.25" hole was drilled through the two bellows from the outside diameter to the inside diameter. A Type B test was perforced and resulted in a small increase in leakage to 7 scfh. A second 0.25" hole was drilled
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through each of the bellows. The subsequent Type B test resulted in a leakage of 8 scfh. It was concluded that air flow between the bellows through the area which contained the large crack was very restricted. The Type B test, therefore, can only detect additional through-wall leakage and cannot quantify the extent of the leakage.
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The bellows were subsequently sent offsite to Argonne National Laboratory (ANL) to conduct destructive testing of the bellows. Physical examination of the bellows cross-section revealed that a tight metal-to-metal contact occurs
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in the convolutions, at the inflection point between the inner and outer apezes.
The shape of the convolutions as-formed is such that the Inner and outer convolutions are tightly interlocked at the inflection point. A gap i
size of 0.002-0.010 was measured at the aperes, which is the maximum gap location.
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SLfety_SisnifJ cance The performance of an ILRT properly challenges the bellows elements.
Operability of the Primary Containment structure was, therefore, demonstrated through the ILRT performed at the end of the refueling outage. Bellows with high leakage rates which are undetected by the local leak test will result in a noticeable increase in ILRT results. Based upon an ILRT value adjusted for g
the X-25 leakage, it was determined that all other plant bellows collectively have a leakage rate sufficiently low such that the overall ILRT performance is not impacted.
Corre ttive_Acticos To ensure the acceptable performance of the penetration, the bellows assembly wrs replaced during the outage. The new bellows assembly was supplied by Parker-Metal Bellews Corporation. Six other penetration bellows with known positive leakage rates as established by recent LLRT's, were examined. Visual and penetrant examinations of these bellows showed no indication of flaws. Commonwealth Edison is currently investigating several leak rate testing rethods that would provide accurate LLRT results for bellows assembly penetrations.
Bellew toraticas Bellows assemblies of this design are installed at the Quad Cities Nuclear Power Station and the Dresden Nuclear Power Station. Attachments A and B list the locations of all bellows assembly penetrations for Quad Cities and Dresden, respectively.
ContLtts Questions pertaining to this Notification should be addressed to:
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Mr. H.L. Massin EHR Systems Design Superintendent Comonwealth Edison Company 1400 Opus Place. Suite 400 Downers Grove. IL 60515 (708) 515-7460 Mr. D. Fisher EHR Systems Design System Engineer Comonwealth Edison Company 1400 Opus Place. Suite 400 Downers Grove, IL 60515 (708) 515-7428 mw. m
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Attachment A Quad Citles Station Bellows locations Quad Cities Nuclear Power Station Penetration Unit 1 Unit 2 X-7A A Main Steam Line X
X X-7B B Hain Steam Line X
X X-7C C Main Steam Line X
X X-7D D Hain Steam Line X
X X-8 Main Steam Line Drain X
X X-9A A Feedwater Line X
X X-9B B Feedvater Line X
X X-10 RCIC Steam Supply X
X X-11 HPCI Steam Supply X
X X-12 SDC Supply X
X X-13A A LPCI Injection X
X X-13B B LPCI Injection X
X X-14 RHCU Suction X
X X-16A A Core Spray
(*)
X X-16B B Core Spray
(*)
(*)
X-17 Head Spray X
X X-23 RBCCW Supply X
X X-24 RBCCW Return X
X l
l X-25 Drywell Vent X
X X-26 Drywell Supply X
X X-36 CRD Return X
X X-47 Standby Liquid X
X 1
l X - Installed on this Unit.
(*) - Bellows replaced with claeshell design l
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10 CFR 21 Notification Attachment B
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Dresden Station Be11cvs Locations
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'l Dresden Nuclear Power Station Penetration Unit 1 Unit 2
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X-105A A Main Steam Line X
X X-105B B Hain Steam Line X
X X-105C C Main Steam Line X
X v.
X-105D D Main Steam Line X
X X-106 Main Steam Line Drain X
X X-107A A Feedwater Line X
X X-107B B Feedwater Line X
X X-108A Iso. Cond. Steam X
X X-109A Iso. Cond. Return (N/A)
X X-109B Iso. Cond. Return X
(N/A)
X-111A A Shutdown Cooling X
X X-111B B Shutdown Cooling X
X X-113 RRCU X
X X-116A A LPCI Injection X
X
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X-116B B LPCI Injection X
X X-123 RSCCH Supply X
X X-124 RBCCH Return X
X i.
X-125 Drywell Vent X
X
- j X-126 Drywell Supply X
X f
X-115A HPCI Steam Supply X
(N/A)
X-12B HPCI Steam Supply (N/A)
X X-130 Standby liquid Inlet X
(N/A)
X-138 Standby Liquld Inlet (N/A)
X X-144 CRD Return X
(H/A)
X-147 Head Spray X
X X-149A A Core Spray X
X X-14SB B Core Spray X
X X
- Installed on this Unit.
(N/A) - Not applicable to this Unit.
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UNITED STATES NUCLEAR REGULATORY COMMISSION
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0FFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C.
20555 March 3, 1992 1
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NRC INr0RMATION NOTICE 92-20:
INADEQUATE LOCAL LEAK RATE TESTING Addressees All holders of operating licenses or construction permits for nuclear pcwer reactors.
Purpose h
The U.S. Nuclear Regulatory Comission (NRC) is issuing this information i
notice to alert addressees to problems involving local leak rate testing (LLRT) of containment penetrations under Part 50 of Title 10 of the Code of Federal Regulations (10 CFR 50), Appendix J.
It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.
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Description of Circumstances Quad Cities Station, Unit 1
((
u On February 26, 1991, the Commonwealth Edison Company (the licensee) performed a Type B LLRT on the containment penetration bellows for penetration X-25 at Quad Cities Station, Unit 1, and found an acceptable measured leakage rate of 6 standard cubic feet per hour (scfh). The licensee perfonned this LLRT by i
pressurizing the volume between the two plies of the bellows through a test i
connection. On February 28, while performing the primary containment inte-grated leak rate test (ILRT) under 10 CFR 50, Appendix J, the licensee found i
excessive air leakage from the penetration. The licensee recognized the inconsistencies between the LLRT data for the penetration and the ILRT results and began a test program to determine the source of the error. Using a blank flange on the containment side of the bellows, the license pressurized the bellows for a " local ILRT," which yielded a leak rate of 137 scfh. The licensee l
also repeated the Type B LLRT with holes drilled in the bellows. This LLRT result (8 scfh) was only slightly higher than the previous LLRT result. The results of this test program led the licensee to conclude that it is not possible to perform a valid Type B LLRT on this type of bellows assembly. The licensee replaced the bellows for penetration X-25 due to cracks identified by the tests. Comonwealth Edison is also investigating alternative test methods that would provide accurate LLRT results for bellows penetration assemblies.
This problem was reported to the NRC under Title 10 of the Code of Federal Regulations, Part 21 (10 CFR 21).
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March 3, 1992 Page 2 of 3 Dresden Nuclear Power Station, Unit 2 i
On December 17, 1990, the Commonwealth Edison Company (the licensee) found a leakage rete significantly greater than the maximum allowed during the pressur-ization phase of its ILRT.
4 The licensee identified the source of the leak as the inboard flange of the torus purge exhaust inner isolation valve with an l
estimated leakage rate of approximately 25 weight percent per day at 15 psig.
l The licensee had last performed maintenance on this valve during the previous
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outage. Although a LLRT had been performed on the valve following the mainte-nance, the test did not challenge the inboard flange.
Perry Nuclear Power Plant, Unit 1 4
On July 7,1989, the Cleveland Electric Illuminating Company (the licensee) discovered a leak through the inboard flange of the seal leakoff line on a relief valve for the residual heat removal system during the plant's first periodic ILRT.
The licensee had performed maintenance on the valve three times from 1986 to 1989.
i In each case, the licensee had performed a LLRT following the maintenance.
However, the LLRT did not challenge the inboard flange.
i Clinton Power Station, Unit 1 5
On December 18, 1990, the Illinois Power Corporation (the licensee) found that lines from the residual heat removal system relief valves were not water-sealed under post-accident conditions as previously indicated in its safety analysis l
These lines were intended to terminate below the suppression pool report.
minimum drawdown level, allowing the water to maintain a seal on the contain-ment isolation valves under accident conditions.
The problem was first identi-1 fied when it was discovered that a liie, considered to be water-sealed, included a vacuum breaker.
dent, bypassing the water seal.The vacuum breaker would open following an acci-i The licensee investigated this condition and found that a number of other lines that empty into the suppression pool either 4
contained flanges or terminated above the pool minimum drawdown level.
Since l
these lines would have been open to the containment atmosphere following an accident, the associated! isolation valves should have been tested for leakage using Type C air tests.
To correct this problem, the licensee removed the vacuum breaker connections and the flanges and extended the pipes to ensure that a water seal would be maintained.
Discussion
~
Steel expansion bellows are used on piping penetrations in many plants as part 1
of the containment isolation scheme. A Type B LLRT is performed on the bellows
't periodically to verify that containment integrity is being maintained.
The could not be used to accurately measure the leakage rate that 4
through the bellows under accident conditions. The two plies of the bellows were in contact with each other, restricting the flow of the test medium to the crack locations.
The NRC staff investigated and found that this problem is not isolated to the bellows manufactured by the vendor involved at Quad Cities.
Any two-ply bellows of similar construction may be susceptible to this problem.
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O IN 92-20 March 3, 1992 Page 3 of 3 The NRC granted an exemption from the Type B testing requirements of 10 CFR 50, Appendix J, to Connonwealth Edison for Quad Cities and Dresden on February 6,1992. The exemption covers the testing of the two-ply bellows i
discussed in th h information notice because no valid Type B LLRT can be perf omed on thest bellows.
The exemption specifies an alternative program of beilows testing anJ replacement that involves testing with air at a reduced leakage limit, testing any leaking bellows with helium (sniffer testing),
replacing bellows that are unacceptable, and performing an ILRT each refueling outage until all of the bellows have been replaced with testable bellows.
The two events invalving leaking flanges occurred because the licensees failed to consider all possible leakage paths when they established their leak rate test programs.
Both licensees identified the valves involved in the events as containment isolation barriers, but they failed to consider the gasketed flanges as leakage paths.
i Both licensees tested the isolation v:lves in the reverse direction which did not challenge the flanges properly. Any contain-ment isolation valve could have this problem, particularly if the valve is tested in the reverse direction or if both valves on a penetration are outside of containment.
Appendix J to 10 CFR Part 50 requires all licensees to perform local leak rate testing on containment isolation valves.
The licensees for some plants, including Clinton, have received credit from the NRC for maintaining a water seal on the valves instead of performing local leak rate testing using air as the test medium.
One requirerant for a valid water seal is that the pene-tration have no potential air leakage paths, such as flanges or vacuum breakers.
For those lines that depend on the minimum water level in the suppression pool to prevent leakage, it is expected that the lines terminate below the minimum suppression pool level in the actual plant configuration.
This information notice requires no specific action or written response.
If you have any questions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) p sject manager.
n aresE.RY1, Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical contacts:
M. P. Phillips, RIII A. J. Kugler, NRR (708) 790-5530 (301) 504-2828 F. A. Maura, RIII J. C. Pulsipher, NRR (708)790-5596 (301) 504-2811
Attachment:
List of Recently Issued NRC Information Notices
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h0M tn K 92-19 Misappittetton of Potter 8 03/02/92 All holders of Ots or CDs
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sete Shutdown tapability for nuclear power reactors.
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92-1 T NRC Inspections of Pro-02/26/92 All holders of CLs or cps grams beln9 Developed et for nuclese power reetters.
Nuclear Power Plants in Pesponse to Generic letter 89 10 92-16 toss of flow from the 02/25/92 All holders of Ots or its Bestdval Nest Removal for nuclear power reacters.
Pvec during Refuelteg Cavity Drotadown f
92-15 Fettere of Prtnery Systee 02/24/92 All holders of Ots or cps r
Cogression Fitting for evcleer power reactors.
P feelresterchenddevelopmentl 92 14 Urselve Ostde Fires et feel 07/21/92 All feel cycle sad eventue Cycle Factittles licensees.
92-02, telep5/ Nod 3 Cemester Code 02/18/92 All holders of Ots or cps Supp. I trror associated with the for aveleer pnwer reactoes.
Conservetten of Energy Equetton 92-13 Inedeguate Control Over 02/19/92 All holders of Ots or cps Vehiculer traffic et for nuclear power roectors.
Nucteer Power Plent Sites 92-12 fffects of Cable testete 02/10/92 All holders of Ots or cps Currents on lastrument for nucleer power reactors.
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