ML20137G926

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Insp Rept 50-264/67-03 on 671025-26.No Noncompliance Noted. Major Areas Inspected:Reviews of Reactor post-critical Performance Data & Appropriate Log Books,Observation of Startup & Discussions W/Personnel
ML20137G926
Person / Time
Site: Dow Chemical Company, 05000000
Issue date: 11/07/1967
From: Fiorelli G, Thornburg H
US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML20136D183 List: ... further results
References
FOIA-85-256, FOIA-85-258, FOIA-85-259, FOIA-85-261 50-264-67-03, 50-264-67-3, NUDOCS 8508280018
Download: ML20137G926 (12)
v • d • e


Text

e U. S. ATOMIC ENERGY COMMISSION REGION III c DIVISION OF COMPLIANCE _

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- 3' Report of Inspection t' -w CO Report No. 50-264/67-3 ~

Licensee: Dow Chemical Company License No. CPPR-94 Category F Dates of Inspection: October 24 and 25, 1967 Date of Previous Inspection: July 5 and 6, 1967 Inspected By: G. Fiore111 Reactor Inspector Date of Report November 7, 1967 Reviewed By: H. D. Thornburg Sr. Reactor Inspector November 4, 1967 Proprietary Information: No SCOPE An announced visit was made to the 100 kw Triga Mark I research reactor located in Midland, Michigan.

The purpose of the visit was to conduct the first routine inspection of the operating facility following its initial loading to critical on July 6, 1967. Included were reviews of reactor post critical performance data and appropriate log books, observation of a startup, discussions with members of the reactor staff, and a tour of the facility.

SUMMARY

Safety Items - None.

Moncompliance Items - None.

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((~y{ Unusual Occurrences - None. *

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Status of Previously Reported Problems - No problems were reported in the 2~ "*

previous report. *(f s s 8508280018 850712

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PDR FOIA MOHN85-256 PDR

r-Other Significan Items -

1. Stuck Shim Rod Control Switch I
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hviI Two period scrams were experienced as a result'5f's sticking N tc. shim rod control switch button. Minor repairs had been made to

'. ~, the switch following the first scram. However, these repairs were not made until several days after the scram experience. (See Management Interview and Section F-8.)

2. Fuel Clad Failure The high airborne activities detected during the first rise to power operation following attainment of minimum critical was confirmed to be originating from a suspected fuel clad failure.

Air monitor readings returned to normal following the removal of the fuel element from core position F-28. Radioactivity releases did not exceed limits specified in 10 CFR 20. (See Section G-1.)

3. The post critical testing program outlined in the Technical Bulletin No. 116 Rev. A submitted to Dow by General Atomic was satisfactorily conducted following the initial loading of the reactor core. Results of the tests indicated operating characteristics were essentially as expected. (See Sections F-1 thru 7.)
4. Control of experiments was found to be adequate and in accordance with the provisions of the technical specifications. No problems associated with sample irradiations have been encountered to date. (See Section S.)
5. The radiation dose rates following equilibrium power operations
have been as expected. Radiation levels at full power within the facility are minimal except for the predicted 10 mr/hr exposure rate one foot above the pool water. (See Section P-2.)

Management Interview - Inspection results were discussed with Drs. W. H.

Beamer and O. U. Anders. The following items were covered:

1. The writer emphasized that in his opinion the delay in attempting to repair the stuck shim rod control switch did not constitute prudent or responsible action on the part of the licensee. Repairs to the switch should have been initiated prior to resuming opera-tion. The licensee did not challenge the position of the writer and agreed that immediate repair action would have been in order.

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Since the licensee has had only three months 'ef ' reactor operating i

experience, the writer indicated further that the' initiation of l immediate investigation and corrective action,use the proper course of action when operating problems are'emperienced with key systems which have a safety function.

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Management Interview (continued) i<

2. A discussion was held on the advantages associated with main-3 taining a separate accounting of scram and mensual occurrence f.; sy. experiences. Representatives of the licensee indicated that 7, all scram experience would be listed in a separate portion of j;f c; the operating log. The inspector was also informed that serious h consideration would be given to expanding the function of his maintenance log, which currently lists equipment problem experiences, to include all unusual operating experiences now covered in the operating log.
3. The inspector outlined the functions and organization of the Division of Compliance.

DETAILS A. Persons Contacted Dr. W. H. Beamer, Laboratory Director Dr. O. U. Anders, Reactor Supervisor Mr. L. G. Silverstein, Radiological Of ficer B. Administration and Organization

1. The organizational staff of the facility has not changed since the last visit. Since achieving minimum critical, six members of the laboratory staff have passed the senior reactor operator tests and have received their licenses. The total number of senior reactor operators at the facility is seven.
2. The minutes of the Reactor Operations Committee were reviewed.

The frequency and function of the meetings are in accordance with the intent of the provisions of the technical specifications.

A special meeting of the Radiation Hazards Committee is scheduled during the month of November. According to Dr. Beamer, the agenda will include a presentation on reactor operating per-formance to date.

I C. Operations l The reactor has been operated to check the performance characteris* ics of the core, to train reactor operating personnel and produce small quan-tities of radioisotopes. The reactor normally operates at its maximum dI"'

l ' licensed power level of 100 kw with operating runs conducted on the

<- average of four days per week. 5-

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DETAILS (continued)

Twenty-fiveunintentionalscrasswereexperiencedjemedagthe3hmonth c

, period. A breakdown of the shutdown causes is as follous:

Range switching errors 5 -

- Defective tube in the high voltage ion chamber supply 4 (See Section F-Sa)

Power overshoots due to operator error during training period 4 Log N channel electronic noise 10 (See Section F-9b)

Period scram 2 (See Section F-8)

Instrument technician error 1 Total 26 On October 25, 1967 the inspector observed a startup of the reactor.

The significant observations made during the demonstration are summarized below:

1. The daily startup check sheet was completed and initialed prior to startup.
2. The run was being made to irradiate special samples. It was noted that the samples were handled properly and a completed and properly approved activation request form was used.
3. The linear compensated ion chamber came on scale at about 1 milliwatt and the log N about a decade later. The fission counter was observed to indicate from source level to approximately 1 watt (saturation level). The fission counter detection position is fixed mechanically.
4. There was no detectable difference in power indications between the log N and linear recorder when the reactor operated at 100 kw.
5. When placed on servo-control, the reactor power level did not

" hunt" above 100 kw.

l Facility Procedures D.

I

,q , Not inspected.

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  • E. Primary System '

j, A review of pool water chemistry records indicated hba water conduc- -

tivity to be less than 1 umho/cm and the ph to range between 6.4 and 7.2.

Activity measurements of evaporated water samples indicated background readings.

l l

s DETAILS (continued)

F. Reactor Control and Core Phyaica

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1. Excess Reactivity .

7 Following initial criticality, which was achieved with 72 elements, ~

? TI[l ' the core size was increased to 76 elements. With this core configuration (shown on Attachment Nog 1), the maximum excess reactivity was measured to be 1.48% st 28 C. This is the maximumvaguenotedintheoperating{logbookandiswithin the 1.5% k limit specified in the technical specifications.

2. Control Rod Calibrations After final fuel loading, each control rod was calibrated by the rising period method as described in Technical Bulletin 116A Rev.

A furnished to the Dou Chemical Compnny by General Atomic.

According to the licensee the following measured values were essentially in agreement with the predicted worths.

Safety $2.34 Shim 3.26 Regulating 0.71 Total $6.81

3. Shutdown Margin The minimum shutdown margin based on the stuck rod concept was determined as follows:

Total Rod Worth $6.81 Most Reactive Rod 3.26 Difference 3.55 Excess Reactivity 2.11 7,,

Shutdown Margin $ 1.44 (1.0% gE -)

This is in e mpliance with the technical specifications limit o f '>. 35% (k .

4. Period Meter Calibration

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The period meter was calibrated by inserting predetermined amounts r.u 47%. of excess reactivity. Using the In-hour curve, the periods l

  • ;; b. ,C corresponding to the insertions were determiaod and the period meter was adjusted accordingly. yl

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r DETAILS (continued)

5. Power Calibration i

J *y The reactor power instrumentation was calibrede by operating L the reactor at an indicated power level of 10 kw on the linear

channel. The rate of temperature rise of the water was normalized to the rate of rise for a known kilowatt heat input (determined by electric heaters in other standard Triga reactor tanks). The measured power level was 9.75 kw. The power level channels were adjusted accordingly.
6. Fuel Element Worths The fuel element worths versus water were determined for positions in the B, D and F rings of the core. According to the licensee the following terresentative measured worths were in close agreement with expected values.

F ring $0.46 D ring 0.86 B ring 1.48

7. Rod Drop Times Rod drop times have been measured several times since achieving critical. The times are measured with a stop watch and represent

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the time from magnet release to rod extreme down position. All times were within the one second specified by technical specifica-tions. According to the licensee, no problems have been encountered with rod drop performance.

8. Stuck Control Rod Up-position Button During the reactor operator training period, a reactor scram was incurred from a period trip (7 second setting) when the shim rod "up" control switch button stuck in the depressed position.

According to the licensee the cause of the sticking problem was a minimal clearance condition between the button and the console cut out. Application of force, which was not normal to the direction of button movement, caused it to bind.

The licensee stated that repairs to increase the switch button df clearance were not initiated until a few days after the

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occurrence in order that reactor operator troiming operation

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[g_ TAILS (continued)

A i A second period scram occurred several weeks after the initial switch repairs were made. This trip was aleh[ caused by a stuck

. $2 , shim rod "up" control switch. Repairs were again made to in-(j, crease the control button clearance and no Surther similarly P'> initiated scrams have occurred.

Since the safety circuit functioned as designed and the licensee has analyzed " pulsed" transienta involving greater amounts of reactivity ($3.00 excess) in the safety analysis report, the experienced period trips did not constitute an unsafe condition.

The delay in repairs to the switch was a topic for discussion during the exit interview.

9. Instrumentation Repairs
a. During the post critical testing period, scrams were occurring from a drop in the HV to the ion chambers. Replacement of a defective tube in the power supply corrected the problem,
b. The log N detector required replacement after causing 10 spurious scrams. Sudden drops in reading to hard zero and then up scale spikes caused false fast period induced scrams.

The installation of a new detector corrected the condition.

10. Instrument Linearity The linear and log N console instrumentation was compared with the referenced Keithley micromicroammeter readings taken during the post critical testing period. The results indicated that the readings were linear and compatible.

G. Core and Internals Fuel Failure Upon reaching 90 kw during the first rise to power operation following attainment of minimum critical, it was noted that the continuous air monitor reading had increased above its normal 200 cpm background.

Following a determination that the airborne activity was not associated with normal activation products, a systematic air sipping procedure

, was initiated to locate what was suspected to be a defective feel SF element. The cladding failure was located in position F-28. Prior f h J, 7 to resuming post critical testing, the element was removed into the MY-l s '

shipping cask and returned to General Atomic.  ; J:

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r l DETAILS (continued) i No isotopes except those associated with water impurities were detected

,, ,,, . from the gamma ray spectrometer analysis of the peellsamples. Fission d .

products (Rb-87 Rb-88, Cs-137, Cs-138) were detected,11a the air )

' c ,' samples only when the reactor power level approached full power of

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' ,? :' 100 kw. The maximum concentration of airborne activity in reactor i

3414 room during the 4 day period required to locate the defective fuel element was calculated to be 0.2% of the permissible concentrations specified in 10 CFR 20 to unrestricted areas.

Since the stainless steel clad fuel elements had been previously used at General Atomic reactor facility, each element was inspected for dimension and surface defect before delivery to Dow. It is suspected that the fuel element was damaged during the pre-shipment loading operation at the General Atomic facilities.

H. Power Conversion System Not applicable.

I, Auxiliary Systems Not inspected.

J. Electrical Systems Not inspected.

K. Containment Not inspected.

L. Emergency Core Cooling Systems Not applicable.

M. Other Engineered _ Safeguards Not applicable.

N. Emergency Power

[n Not inspected.

h' ' ' O. Fuel Handling a

Not inspected. ,.

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DETAILS (continued) -

P. Radiation Protection ,; .; ~c

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Radiation experience since initial startup was reviewed with Dr. Beamer 3-- . and Mr. Silverstein. To date they have experienced nolproblems with t+ '. :

contamination control or irradiated sample handling procedures. The '

significant points of the discussion and observations are summarized as follows:

l. Personnel Expocures Dasimetry reports from the Landauer Company showed that exposure to radiation of each person working at the reactor facility. has o'cen below the minimum detectable.
2. Radiation Levels Except for the area immediately above the pool water, the radiation levels have been minimal in other reactor areas. With the reactor power at 100 kw the radiation dose rate 1 foot above the tool uac measured to be 10 mr/hr (B & P). No detectable dose rate due to neutrons could be measured from an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> film badge exiosure at this location. The reactor control room, lab.,

and demineralizer area dose rates were less than 1 mr/hr.

3. Contamination Control No contaminatiou control problema have been experienced according to the licensee. The writer observed that smears have been taken on sample capsules removed from the reactor.
4. Posting and Labelinn Radiation areas and radioactive material storage locations lo-cated at the facility were observed to be adequately posted in l accordance with 10 CFR 20.203.

l Q. Radioactive Waste Systems Not inspected.

R. Environment Not applicable. .

- L 8. Experiments and Tests '

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( The writer reviewed numerous activation request forms which are pre-  !

! pared and approved prior to sample insertion into the reactor. In each l

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e DETt.ILS (continued) 7 '. ,

case all information required by the torm (see Attachment)#2):was observed 3., to have been entered. In every form, ocasured radiation' levels were

" significantly below the estimated values. The range of experiment worths

[ was noted to be between $0.08 and $0.12 which is in compliance with the

l* . technical specificationu requirement of $2.cu maximum. According to the licensee, no problems have been encountered with the operation of the lazy Susan or rabbit transfer facilitica.

The reactor operation committee meeting minutes disclosed 4 meetings devoted to special sample irradiation reviews.

T. Facility Modification The licensee stated that the carryover items listed in C0 Report No.

264/67-1 will be covered in a letter to DRL in the very near future.

U. Miscellaneous Not applicable.

V. Reliability Information The inspector observed that the daily, weekly and monthly component and operational checks required by Sections F and G of the technical specifications are being made at the required frequency. No failures or malfunctions were noted.

Attachments:

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f.5 requirci ;c cei cc :s 200 ::Irc::i/hr on con:cet

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