ML20148B301

Mit Research Reactor Annual Rept to NRC for Period Jul 1985 - June 1986

ML20148B301
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	06/30/1986
From:	Lisa Clark NUCLEAR REACTOR LABORATORY
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
NUDOCS 8803210432
Download: ML20148B301 (25)

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- MIT RESEARCH REACTOR ,

ANNUAL REPORT TO UNITED STATES NUCLEAR REGULATORY. COMMISSION FOR; THE PERIOD JULY '1, 1985' - JUNE . 30, 1986 BY e.

REACTOR STAFF August 29, 1986

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. TABLE OF CONTENTS Page Section Number Introduction..................................................'.. 1 A. Summ ar y o f Ope r a t in g Ex pe r ie nc e . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 B._ Re a c t or O p e r a t ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 C. Sh u t d o wn s and Sc r am s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 D. Ma j or Ma i n t e n a nc e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 E. Sec t io n 5 0. 5 9 Ch a ng e s , Te s t s and . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Experiments F. Env ir o nme n t a l Su rv e ys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 C. Rad i a t ion Ex po s u r e s a nd S u rv e ys . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 H. Rad io ac t iv e E f f l ue n t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 i

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MIT RESEARCH REACTOR ANNUAL REPORT 70 UNITED STATES NUCLEAR REGULATORY COMMISSION FOR THE PERIOD JULY 1, 1985 - JUNE 30, 1986 Introduction This report has been prepared by the staff of the Massachusetts Institute of Technology Research Reactor for submission to the Admin-istrator of Region 1, United States Nuclear Regulatory Commission, in compliance with the requirements of the Technical Specifications to Facility Operating License No. R-37 (Docket No. 50-20), Paragraph 7.13.5, which requires an annual report following the 30th of June of each year .

The MIT Research Reactor (MITR), as originally constructed, con-sisted of a core of MTR-type fuel, fully enriched in uranium-235 and cooled and moderated by heavy water in a four-foot diameter core tank, surrounded by a graphite reflector. After initial -criticality on July 21, 1958, the first year was devoted to startup experiments,- calibra-tion and a gradual rise to one megawatt , the initially licensed maxi-mtsa power. Routine three-shift operation (Monday-Friday) conusenced in f

July 1959. The authorized pwer level was increased to two megawatts in 1962 and five megawatts (the design power level) in 1965.

Studies of an improved design were first undertaken in 1967. The concept which was finally adopted consisted of a more compact core, cooled by light water, and surrounded laterally and at the bottom by a heavy water reflector. It is undermoderated for the purpose of maxi-mizing the peak of thermal neutrons in the heavy water at the ends of the bean port re-entrant thimbles and for enhancement of the neutron flux, particularly the fast componen t , at in-co re irradiation fac il i-l ties. The core is hexagonal in shape, 15 inches across, and utilizes i

fuel elements which are rhomboidal in cross section a .d which contain

! UALx intermetallic fuel in the fo rm of plates clad in aluminum and fully enriched in ur anium-235. Much of the original f ac ility , e.g.

graphite reflector, biological and thermal shields, secondary cooling systems, containment, etc., has been retained.

After Construction Permit No. CPRR-118 was issued by the former U.S. Atomic Energy Commission in April 1973, major components for the modified reactor were procured and the MITR-I was shut down on May 24, 1974, having logged 250,445 megawatt hours during nearly 16 years of operation.

The old core tank, associated piping, top shielding, control rods and drives , and some experimental facilities were disassembled, re-moved and subsequently replaced with new equipment . After pro pe r a-tional tests were conducted on all systems, the U.S. Nuclear

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Regulatory Commission is sued Amendment No. 10 to Facility Operating License No . R-37 on July 23, 1975. After initial criticality for MITR-II on August 14th, 1975, and several months of startup testing, power was raised to 2. 5 W in Dec ember . Rout ine 5 W operation was achieved in December 1976.

This is the eleventh annual report required by the Technic al Specifications, and it covers the period July 1, 1985 through June 30, 1986. Previous reports, along with the "MITR-II Startup Re po r t" (Report No. MITNE-198, February 14, 1977) have covered the startup testing period and the transition to routine reactor operation. This re por t covers the ninth full year of routine reactor operation at the 5W licensed power level. It was another year in which the safety and reliability of reactor operation met the requirements of reactor users.

A summary of operating experience and other activities and re-lated statistical data are provided in the following Sections A-H of this report, l

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A.

SUMMARY

OF OPERATING EXPERIENCE

1. General During the period covered by this report (July 1, 1985 - June 30, 1986), the MIT Research Reactor, MITR-II, was operated on a routine, five days per week schedule, normally at a nominal SMW. It was the ninth full year of normal operacion for MITR-II.

The reac tor averaged 75.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> per week at full power compared to 86.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> per week for the previous year and 90.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> per week two years age. The reactor is normally at power 90-100 hours / week, but holidays, major maintenance, long experiment changes, waste ship-ping, etc. , reduce the average. During the past year it was reduced more than usua L as the result of three week-long shutdowns for major maintenance activities (described later), two of them occurring at Christmas and New Ye ar ' s .

1 We reactor routinely operates from late Monday af ternx n until late Friday af ternoon, with maintenance sched-uled for Mondays and, as necessary, for Saturdays.

The reactor was operated throughout the year with 24 or 25 ele-ments in the core, he remaining positions were occupied by irradia-tion facilities used for saterials testing and the production of med ical isotopes and/or by a solid aluminum dummy. Compensation for reactivity lost due to burnup wcs achieved through five refuelings of several elements each. The fir st of these entailed the introduc tion of three fresh elements to the core's intermediate fuel ring (the B-ring), he others involved a continuation of the practice begun in previous years in which partially spent elements that had been origi-nally removed from the B-ring were gradually introduced to the C-ring to replace fully spent elements. These procedures were combined with many element rotations / inversions, the objective of which was to mini-mize the e f fects of r adial/ axial flux gradients and thus achieve higher average burnups.

The MITR-II fuel management program remains quite successful.

All but seven of the original MITR-II elements (445 grams U-235) have been permanently discharged. The average overall burnup for the dis-charged elements was 42%. Of the remaining seven elements with the 445 gram loading, six will reach maximum depletion within the next few months. Birty-six of the new elements (506 grams U-235) have been introduced to the core. Of enem, three have attained the maximum al-lowed fission density. However, these may be reused if that limit is increased as would seem warranted based on metallurgical studies by DOE. As for the other thirty-three new elements, they are either cur-rently in the reactor core or have been partially depleted and are awaiting reuse in the C-ring.

The continued delays in the availability of a licensed cask from DOE are of increasing conc e r n . Specifically, our inability to ship spent fuel is causing our total fuel inventory to approach our author-ized pas se s sion limit and is forc ing us to deviate from our normal fuel cycle in that:

(1) The inventory of partially spent elements is now substan-tially below normal. This is making it difficult to convert.

from one core configuration to another.

(2) Inability. to bring in fresh fuel and to place it in the A and B-Rings of the core may necessitate premature C-Ring re-fuelings in order to obtain sufficient reactivity for con-tinued operation. This will result in lower overall burnups and ultimately increase our need for additional fuel.

Finally, it should be recognized that if casks continue to be unavail-able, we will have to request a reinstatement of part or all of our previous license limit for possession of U-235 in order to continue o peration .

Protective system surveillance tests are conducted on Friday evenings af ter shutdown (about 1800), on Mondays, and on Saturdays as necessary.

As in previous years, the reactor was ope r ated throughout the period .without the fixed ha fnium absorbers, which were designed to achieve a maximum peaking of the thermal neutron flux in the heavy water reflector beneath the core. These had been removed in November 1976 in order to gain the reactivity necessary to support more in-core facilities.

2. Experiments The M ITR-II was used throughout the year for experiments and irradiations in support of research and training programs at MIT and elsewhere.

Experiments and irradiations of the following types were conducted:

a) Neutron dif fraction spectrometer alignment and studies (3 ports),

b) The production of MSasbauer sources by the irradiation of Gd-160 and Pt-196 for studies of nuclear relaxation of Dy-161 in Gd and for the investigation of the chemistry and structure of gold com-pounds.

c) Irradiation of biological, geological, oceanographic, and medical s pe'cimens for neutron activation analysis purposes.

d) Production of gold-198, dysprosium-165, and chlorine-38 for medi-cal research, diagnostic and therapeutic purposes, e) Irradiation (i) of tissue specimens on particle track detectors for plutonium radiobiology, and (ii) of geological s amples for fissile element distribution.

f) Irradiation of amorphous hydrogenated silicon (a-Si:H) to produce some phosphorous in order to study the ef fect of such donor atoms on the properties of a-Si:H.

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g) Use of the facility for reactor operator training.

h)  ; Irradiation damage studies of candidate fusion reactor materials.

i) Fault detection analysis of the output of control and process channels from the MIT Reactor as part of a study leading to control of reactors by use of fault-tolerant, digital computers.

This effort recently resulted in the demonstration of techniques for reconfigurable control.

j) Closed-loop direct digital control of reactor power using a shim blade as well as the regulating rod during some steady-state e.nd transient conditions. A new relation, . the alternate dynonic period equation, was developed and used as the basis of a reactor controller, k) Experimental studies of various closed-loop control t e'..hni que s including rule-based control and the use of reactivity con-straints.

1) Development and experimental evaluation of several new techniques for the measurement of reactivity, m) Measurements of the energy spectrum of leakage neutrons using a mechanical chopper in a radial beam port (4DHl). Measurements of the neutron wavelength by Bragg reflection then perm tt s demon-stration of the DeBroglie relationship for physics courses at MIT and other universities, o) Detection of trace quantities of fissile nuclides using a delayed neutron detector.

3. Changes to Facility Design As indic ated in past reports the uranium loading of MITR-II fuel has been increased from 29.7 grams of U-235 per plate and 445 grams pe r element to a nominal 34 and 510 grams respectively. With the ex-ce ption of three elements that were found to be out gassing exces-sively per formance has been good. (Please see Reportable Occurrence Reports Nos. 50-20/79-4, 50-20/83-2 and 50-20/85-2.) The heavier loading results in 41. 2 w/ o U in the core, based on 7% voids, and corres ponds to the maximum loading in Advanced Test Reactor (ATR) fuel. The most recent fuel fabricator , Atomics International Division of Rockwell International, completed the production of 41 of the more highly loaded elements, 36 of which have been used to some degree.

Three with about 37% burnup were in operation in the core starring in January 1980 and we r e discharged last year, since they had at t a ir.ed the burnup limit. Additional elements are now being f abr icated by Babcock & Wilcox, Navy Nuclear Fuel Division.

The MITR staf f has been following with interest the work of the Reduced Enrichment for Research and Test Reac tor s (RERTR) Program at Argonne National Laboratory, particularly the development of advanced fuels that will permit uranium loadings up to several times the sv = -- . . _ . , _ .

current upper limit of 1.6 grams total uranium / cub ic centimeter.

Consideration of the thermal-hydraulics and reactor physics of the MITR-II core design show that conversion of MITR-II fuel to lower enrichment must await the successful demonstration of the proposed advanced fuels.

Other changes in' the facility are reported in Section E.

4. Changes in Performance Characteristics Pe r formanc e characteristics of the MITR-II were reported in the "MITR-II Scartup Repor t". Minor changes have been described in pre-vious reports. There were no changes during the past year.

5. Changes in Operating Procedures Related to Safety There were no mendments to the Facility Operating License during the last year.

MIT has received approval of its application for renewal of License No. SNM-986. This license covers kilogram quantities of slightly snriched U-235, normal and depleted U. and gram quantities of Pu. Other licenses covering smaller quantities of similar material have been combinea with License SNM-986. The MIT Reac tor is involved, because most of the SNM is stored on the reactor site, and much of it is used on the reactor in accordance with authorized experiment review and approval procedures.

Quality Assurance Program Approvak for Radioactive Material Pack-ages No. 164, Rev. 1, was renewed on June 20, 1986 (Rev. 3). This Ap-proval is required for the shipment of (1) Type B quantitier, of radio-active material and (2) fissile material above exempt quantities. In order to renew the Approval, it was necessary to update SAR Chapter 11, "Quality Assurance Program", which supports Approval No. 164.

Chapter 11 was changed as follows (SR #0-86-4):

1) References to igraphs in 10 CFR, Part 71, "?ackaging and Tr an s por ta t ioit (. Radioactive Material, were updated to re-flect changes in that Part since Chapter 11 was submitted five years earlier.

2) References to the Co-Director for Reactor Modification were deleted, since they are no longer applicable.

3) In paragraph 11.15, "Non-Conforming Mater ial, Parts or Com-ponents", the granting of waivers from material or fab r ic a-tion specifications is explicitly recognized.

4) Fig. 11.1-1 was updated to reflect the fac t t h a t. the Machine Shop foreman now re por t s to the Director, Nuclear Reactor Laboratory.

5) Editorial improvements were made.

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With respect to operating procedures subject only to MITR inter-nal review and approval, a summary of those related to safety is given below:

a) In order to satisfy the surveillance requirements established by the new Technical Specification #6.4 (Amendment No. 24 to Facility Operating License No. R-37, April 2, 1985), Procedure 6.7.1, "Shim Blade Digital Control System Surveillance", was prepared and approved.

It provides for (1) the periodic measurement of dif ferential- and inte-(2) functional check of the auxiliary per-gral control iod trip blade prior to worths, use of .the closed-loop digital control system for shim blades, (3) annual calibration of the digital system so f tware 's recording of blade position against the actual blade position, and (4) preparation of a quarterly procedure to check the speed limiter on a variable speed motor if one is installed and used on a shim blade as part of the digital control. (SRf0-85-15) b) As the result of a recommendation contained in the independent audit of MITR operations and endorsed by the MITR Safeguards Cotanit-tee, Procedure 1.14.3, "Equipment Tagout Proc ed ur e" , was revised to incorporate a lockout procedure in a new "Equipment Tagout and Lockout Procedure". (SRf0-85-17) c) The original conductance probe that provides a scram signal for a low level in the core tank was replaced by a float-type switch. A description of the switch was prepared for inclusion in section 6.5.1 of the Reactor Systems Manual, and a precedure was written for inclu-sion in FM 3.1.1.1.2, the reactor in s trumen t a t ion startup checklist.

(SRf0-85-18) d) Procedure 7.1.5, "Damper Accumulators Charging and Actuator In-spection Procedure, Main Dampe r - Auxiliary Damper In s pe c t io n" , was revised to require annual replacement of the hydraulic oil filter.

This requirement was adopted following failure of the isolation valve to close on demand, as reported in Reportable Occurrence Report #85-3.

(SRf0-85-19) e) The "Schedule of Surveillance Tests and Calibrations", Procedure 7.3.1, was revised to include Procedure 6.5.13, "Shield Storage Tank Level Calibration" (established by SRf0-85-5 last year) and Procedure 6.7.1, "Shim Blade Digital Con t rol System Surveillance" (item (a) ab ov e) . (SRf0-85-21) f) Procedure 4.4.4.16, "Instructions to the MIT Campus Police During MIT Reactor Radiological Emergencies", was revised to clarify the in-structions (no substantive changes). (SR #0-85-22) g) The emergency operating plans and procedures were updated to make explicit the requirement to identi fy the class of emergency and to delete the now redundant correlation in Table 4. 7. 3.4-1. In Pl an Y ,

PM 4.4.4.14, the list of area occupants is updated. (SRf0-85-23) l

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h) Procedure 1.10, "Experiment Review and Approval", was revised to require ' explicitly the review of criticality considerations for in-reacter s amples , and Procedure 1.18, "Audits", was revised to require an administrative audit of SNM criticality safety. (SRf0-86-1) i) In Procedure 5.8.9, "Malfunction of a Shim Blade / Regulating Rod",

the discussion of possible blade / rod malfunctions was clarified, and the erroneous operation of a blade drive motor was specifically listed as a reason for scramming the reactor along with a requirement to fol-low the approved restart procedure. (SRf0-86-2) j) In Procedure 6.1.1, "Emergency Cooling System", the revalving necessary to check the operability of the system and to measure its discharge rate was clarified, and explic it pr ec aut i'o ns were added to preclude the possibility of flowing city waster into the core tank.

(SRf0-86-3) k) The Emergency Plan (PM 4.7.2), three Emergency Procedures (PM 4.4.4.14, ?;t 4.4.4.15 and PM 4.4.4.16) and an Abnormal Operating Pro-cedure (PM 5.6.2) were revised to implement changes requested by the MIT Reactor Safeguards Committee at its Dec ember 1985 meeting (SRf0-86-6):

1) The ef fluent release criterion for determining action levels was clarified.

2) Cambridge Civil Authority titles were up-dated.

3) Operating instructions for the survey air sampler were clar-i fied .

1) In accordance with a requirement of SNM License No. 986, as renewed on November 13, 1985, that the MIT Reactor Sa feguard s Committee membership collectively have the capability to review criticality safety including non-reactor applications, the MITRSC Charter was revised accordingly. (SRf0-86-7) m) Procedure 2. 7.1, "Receipt of Reactor Fuel", was clarified to make clear that the shipper of fuel is res ponsible for providing in-transit security. (SRf0-86-8) n) The checklist used fo Procedure 6.1.2.1, "Building Pressure Test", was revised so that both phases of the test were conducted with the truck lock inner door sealed. Both because of a sus-pected leak in the truck lack itself and because the outer door was there fore not tested, che inner door must be sealed during reactor oper ation until the leak is repaired and the lock and outer door tested. (QAf0-86-1) o) Miscellaneous minor changes to operating procedures and to equip-ment were approved and implemented throughout the year.

6. Surveillance Tests and Inspections There are many written procedures in use for surveillance tests and inspections required by the Technical Specifications. These pco-cedures provide a detailed method for conducting each test or in s pec-tion and specify an acceptance criterion which must be met in order for the equi pmen t or system to comply with' the requirements of the Technical S pec i fic a t ions . The tests and ins pec tions are scheduled throughout the year with a frequency at least equal to that required by the Technical Specifications. Twenty-seven such tests and calibra-tions are conducted on an annual, semi-annual or quarterly basis.

Other surveillance tests are done each time before startup of the reactor if shut down for more than 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, before startup if a chan-nel has been repaired or de-energized, and at least monthly; a few are on different schedules. Procedures for such surveillance are incor-porated into daily or weekly startup, shutdown or other checklists.

During the reporting period , the surveillance frequency has been at least equal to that required by the Technical Specifications, and the results of tests and inspections were satisf actory throughout the year for Facility Operating License No. R-37. The truck lock is out of commission as of this writing due to a suspected leak and is iso-lated by the inner truck lock door from the reactor containment build-ing.

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B. -REACTOR OPERATION Information on energy generated and on reactor operating hours is tabulated below:

Quarter Total 1 2 3 4

1. Energy Generated (MWD):

a) MITR-II (MIT FY86) 171.9 173.1 159.4 162.7 667.1 (normally at 4.9 MW) b) MITR-II (MIT FY76-85) 7,763.7 c) MITR-I (MIT FY59-74) 10,435.2 d) Cumulative, MITR-I 18,866.0 6 MITR-II

2. Hours of Operation MIT FY1986, MITR-II a) At Power (>0. 5 MW) 1,021.9 932.9 978.2 9R5.7 3,918.7 for research b) Low Power (< MW) 55.6 54.2 55.6 30.4 195.8 for training and test c) Total critical 1,077.5 987.1 1,033.8 1,016.1 4,114.5 Note (1): These hours do not include reactor operator and other training conducted while the reactor is at full power fo r research purposes (spectrometer, etc.) or for isotope production. Such hours are included in pravious line.

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_11 C. SHUTDOWN AND SCRAMS During the period of this report there were 14 inadvertent scrams and 13 unscheduled power reductions.

The term "scram" refers to shutting down of the reactor through protective s ys t em action when the reactor is at power or at least critical, while the term "reduction" or "shutdown" refers to an unscheduled power reduction to low power or to suberitic al by the reactor operator in response to an abnormal condition indication. Rod drops and electric power loss without protective system action are included in shutdowns.

The following summary of sc r ams and shutdowns is provided in approximately the same fo rmat as for previous years in order to facilitate a comparison.

I. Nuclear Safety System Scrams Total a) Chan. 6 scram due to failure to raise trip before opening thermal column steel doors 1 b) Blado 6 dropped off while magnet current was being adjusted 1 c) Blade 3 dropped off while being calibrated due to dirty contacts on the period simulator receptacle 1 d) Withdraw permit open on relay failure 1 e) Withdraw permit open for no apparent cause 1 f) Dump valve relay failure 2 g) Low voltage on detector power supply 2 Subtotal 9 II. Process Systems Scrams a) High Temperature Reactor Outlet scram while operating too close to trip point 2 b) Failure of relay associated with secondary coolant pumps 1 c) Loose connection in secondary flow scram circuit 1 d) Simultaneous deflation of both gaskets on main personnel lock due to interlock malfuction 1

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III. Unscheduled Shutdowns or Power Reductions a) Shutdowns due to Electric Company power loss 4 b) Operator shut reactor down due to:

i) Imminent arrival of Hurricane Gloria 1 ii) Failure of-plenum gas #2 monitor 2' iii) Reduction in compressed air pressure for main personnel lock I c) Operator lowered power to investigate:

i) Low pressure in the helium supply at an irradiation thimble 2 ii) Malfunction of plenum particulate monitor 1 iii) Trip of secondary booster pump caused by defective controller contacts 1 d) Operated at 2.5 NW to permit repair of broken drain line for cooling tower riser pipe 1 Subtotal 13 Total 27 The scrams and _ shutdowns during FY 86 compare with the 10, 19, 25, and 28 experienced in FY 85, FY 84, FY 83 and FY 82 respectively.

The inc rease in FY 86 is due both to outside sources (power loses and hurricane) and to component aging. Relay failures have been a fre-quent cause, and selective replacements are now being made in an e f fort to reduce the number of such failures.

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D. MMOR MAINTENANCE Major maintenance projects during FY86, including the effect, if any, on safe operation of the reactor, are described in this section.

FY86 saw a continuation of the ef fort s in restoring the cooling towers closer to their original per formance levels. The underground valves to the cooling tower basins had ceased to operate due to ag e .

Replacement of these valves was initiated in FY85 and comple t ed in FY86. Ther e were a total of 2 eight inch, 2 six inch, and 2 three inch butter fly valves. New screens were fabricated and installed to cover openings at the bottom of the cooling tower s and around the basins. The screens prevent debris and large objects from falling in-to the basins and fouling the system. The coupling on the shaft of cooling tower fan number one failed and was replaced. The sprinkler system fo r pro tec t ion again s t fire on both cooling towers had devel-oped an air leak. Due to old age, the entire system, including the piping and nozzles that are exposed to weather, was replaced. As a means of improving the heat rejection capability, both basins were drained and cleaned, the entire secondary system was drained, and all three main heat-exchangers were chemically flushed with hydrogen per-oxide so as to remove the build-up of bio ~ deposits and other pollu-tants in the secondary system.

One of the main heat exchangers, HE-1 A which developed a leak in FY85, was completely decoupled from the primary system and isolated on the secondary system side. Leak testing on the heat exchanger was in-itiated and is still in progress. Heat exchanger integrity is neces-sary to prevent po ten t ial fission products or other radioactivity from entering the secondary system.

The gaskets on the main intake damper , main exhaust damper, and the auxiliary exhaust damper were replaced as the result of conditions noted during a semi-annual damper in s pec t ion. The pillar block bear-ings on the main shaft of the exhaust fan developed noise and ccused abnormal vib r at ion . They were replaced. The intake fan motor was also replaced when it showed signs of bearing failure. The flexible expansion joints of the intake air plenum at both the suction and dis-charge of the intake f an had deteriorated and were replaced. An oil filter, similar to the one in the in take damper system for cleaning the hydraulic oil, was added to the exhaust damper hydraulic system so as to remove the debris which may have accumulated in the system over time and which might prevent closure of the damper, as happened with the intake d ampe r (see Repor t abl e Occurrence Re por t No. 85-3). The hydraulic system for the main personnel outer door was disassembled and rebuilt after seeing signs of sluggish performance during normal usage.

A compensated ion chamber (Channel 7 of the nuclear in s t r umen t a-tion) which is used for power level indication throughout the source range and the pawer range showed signs of breakdown at voltages above the operating value. The chamber was replaced with another three inch compen sa ted ion chamber. The po r t plug fo r this chamber was rede-signed to allow easy repositioning of the chamber within the shielding

.. af ter installation. The new design also incorporates a lead shield in front of the chamber so as to compensate for som: af the effects due to gamma radiation. Neutron shields were add ed to some of the beam por t s on the reactor floor in an e f for t to reduce further the background level for the spectrometers used for physics experiments.

While performing the on going preventive maintenance procedure on the control blade magnets, the magnet on control blade number 5 was identified as weak and was replaced. Preventive maintenance was also performed on the exterior of the containment shell. The paint on the the to p section of the shell was mechanically removed and repainted with coats of red lead and the finishing paint. The wind s peed and wind direction indicators were damaged in a hurricane during the year.

The wind vane and the wind velocity indicator were replaced.

Many other routine maintenance and preventive maintenance jobs were done throughout the year.

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9 E. SECTION 50.59 CHANGES, TESTS AND EXPERIMENTS This section contains a description of each change to the facili-ty or procedures and of the conduct of tests and experiments carried out under the conditions of Section 50.59 of 10 CFR 50, together with a summary of the safety evaluation in each case.

The review and approval of changes in the facility and in the procedures as described in the SAR are documented in the MITR records by means of "Safety Review Fo rm s" . These have been paraphr ased for this report and are identified on the following pages for ready refer-ence if further information should be required with regard to any item. Pertinent pages in the SAR have been or are being revised to reflect these changes, and they will be forwarded to the Chief, Stan-dardization and Special Projects Branch, Division of Licensing, USNRC.

The conduct of tests and experiments on the reactor are normally documented in the experiments and irradiation files. For experiments carried out under the provisions of 10 CFR 50. 59, the review and ap-proval is documented by means of the Safety Review Form. All other experiments have been done in accord anc e with the descriptions pro-vided in Section 10 of the SAR, "Experimental Facilities".

For the past year the only facility changes and experiments car-ried out under Section 50.59 were in connection with the digital closed-loop computer control project described on the following pages:

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l Digital Computer Control of Reactors Under Steady-State and Transient Conditions SRf-M-81-3 (11/17/81), M-81-4 (12/10/81), E-82-2 (01/08/82),

E-82-3 (02/24/82), E-82-4 (03/03/82), E-82-5 (04/14/82), E-82-6 (07/13/82), 0-83-5 (02/03/83), E-83-1 (02/08/83), 0-83-12 (04/23/83),

0-83-20 (07/20/83), 0-84-11 (06/25/84), 0-84-12 (07/12/84), 0-84-16 (12/6/84), 0-84-21 (11/1/84), 0-85-11 (5/9/85), 0-85-13 (6/28/85),

0-85-16 (7/12/85), 0-85-20 (8/16/85), 0-85-25 (12/1/85), 0-85-26 12/1/85).

A joint proj ec t involving computer analysis, signal validation of data from reactor instruments, and closed-loop control of the MIT Re-actor by digital computer was continued with the Charles Stark Draper Laboratory in Cambridge. A non-linear supervisory algorithm has been developed and demonstrated. It functions by restricting the net reac-tivity so that the reactor period can be rapidly made infinite by re-versing the direction of control rod mo t io n . It , combined with the signal validation procedures, insures that there will not be any chal-lenge to the reactor safety system while testing closed-loop control me t h od s . Several such methods, including decision analysis, rule-based control, and modern control theory, continue to be experimental-ly evaluated. The eventual goal of this progr am is to use fault-tolerant computers coupled with closed-loop digital control and signal validation methods to demonstrate the improvements that can be achieved in reactor control.

Each new step in the progr an is evaluated for safety in accor-dance with standard review procedures (Safety Review numbers listed above) and approved as necessary by the MIT Reactor Safeguards Commit-tee.

Initial tests of this digital closed-loop controller were con-d uc ted in 1983-1984 using the facility's regulating rod which was of relatively low reactivity worth (0.2% AK/K). Following the successful completion of these tests, a facility operating license amendment was submitted to NRC (January 11, 1985) that would:

(1) pe rmit closed-loop control of one or more 8him blades and/or the regulating rod provided that no more than 1.8% AK/K could be inserted were all the connected con-trol elements to be withdrawn, (2) permit closed-loop control of one or more shim blades and/or the regulating rod provided that the overall controller is designed so that reactivity is con-strained sufficiently to permit control of reactor i power within desired or authorized limits.

, _17 knendment No. 24 authorizing the above activities was issued by NRC on April 2, 1985. Pertinent pages of the SAR that concern the reactor control system have been updated *.hrough submission with the January 11, 1985 letter of SAR Revision t'o. 32.

A successful experimentation program is now in progress under the provisions of this license amendment, he test program that was originally per formed using the regulating rod was repeated using s shim blads which was of considerably greater reactivity (1.4% AK/K).

Also a protocol has been developed in which this controller is used to monitor, and if necesaary override, other novel controllers that are still in development. One series of tests is being conduc t ed under the conditions of 10 CFR 50.59. It was found that the observation of controller performance could be maximized if the speed of the associ-ated shim blade were reduced (i.e., made more conservative because the available rate of reactivity addicion is reduced). Accordingly, the timing chain sprocket of one of the reactor's six shim blades was changed so that this one blade could only be moved at hal f-s peed ,

his is a temporary change that will be removed once the test program is question is completed. It was concluded that no unreviewed safety questions were involved in this change.

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18 F. ENVIRONMENTAL SURVEYS Environmental surveys , outside the facility, were performed using area monitors. The systems (loca ted approximately in a 1/4-mile

-radius from the reactor site) consist of calibrated G.M. detectors with associated electronice and recorders.

The detectable radiation levels due to argon-41 are listed below:

Site July 1,1985 - June 30,1986 North O'.4 mR/ year South 2.1 mR/ year East 6.0 mR/ year West 0.4 mR/ year Green (East) 0.2 mR/ year Fiscal Yearly Averages:

1978 1.9 mR/ year 1979 1.5 mR/ year 1980 1. 9 mR/ year 1981 1.9 mR/ year 1982 2. 5 mR/ year 1983 2.3 mR/ tear 1984 2.1 mR/ year 1985 2.2 mR/ year 1986 1. 8 mR/ yea r

o' G. RADIATION EXPOSURES AND SURVEYS WITHIN THE FACILITY A summary of radiation exposures received by facility personnel and experimenters is given below:

Period 7/01/85 - 6/30/86 Whole Body Exposure Range (Rems) No. of Personnel No ;4e a s u r ab l e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 Measurable - Exposure less than 0.1. . . . . . . . . . . 68 0.1-0.25......................................6 0.25 - 0.5..................................... 10 0.5 - 0.75...................................... 2 0.75-1.0......................................2 Total Personnel - 161 Total Man Rem - 10.3 Summary of the results of radiation and contamination surveys from July 1985 to June 1986:

During the 1985-1986 per iod , the Reactor Radiat ion Protection Office continued to provide radiation protection services for full power (5 megawatts) opera *. ion of the reactor. Such services

( per formed on a daily, weekly, or monthly schedule) include the following:

1. Collection and analysis of air samples taken within the containment shell, and in the exhaust-ventilation system.

2. Collec tion and analysis of air samples taken from the cooling towers, D0 2 system, vaste storage tanks, shield coolant, heat exchangers, fuel storage facility, and the primary system.

3. '

Per formance of radiation and contamination surveys, r adioac tive waste collection, calibration of reactor radiation monitoring systems, and servicing of radiation survey meters.

4. The providing of radiation protec tion services for control rod removal, spent-fuel element transfers, ion column removal, etc.

The results of all surveys described above have been within the guidelines established for the facility.

-20 H. RADIOACTIVE EFFLUENTS This section summarizes the nature and amoent of liquid, gaseous and solid radioactive wastes released or discharged from the facility.

1. Liquid Wasy Liquid radioac tive wastea generated at the facility are dis-charged enly. to the sanitary sewer serving the facility. There were three sources of such wastes during the year: the cooling tower blow-downs; the liquid waste storage tanks ; and laboratory drains. All of the liquid volumes are measured,- by far the largest being the 3,970,000 liters discharged during FY 1986 fro.ra the cooling tovers.

(Larger quantities of non-radioactive waste water are discharged to the sanitary sewer system by other parts o f MIT, but no credit for such dilution is taken since the volume is not routinely measured.)

All releases were in accordance with Technical Specification 3.8-1, including Part 20, Title 10, Code of Federal Regulations.

There are no reportable radionuclides inasmuch as all activities were substantially below the limi.ts specified in 10 CFR 20.303 and 10 CFR 20, Appendix B, Note 5.

2. Gaseous Waste Gaseous rad ioac tivity is discharged to the atmosphere from the containment building exhaust stack and by evaporation frarr the cooling to we r s . All gaseous releases likewise were in accord anc e with the Technical Specifications and Part 20, and all nuclides were below the limits of 10 CFR 20.106 after the authorized dilution factor of 3000.

Also, all were substantially below the limits of 10 CPR 20, Appendix B, Note 5, with the exception of argon-41, which is reported in the following Table H-l. The 3797 Ci of Ar-41 were released at an average concentration of 1.05 x 10-8 pCi/ml for the year. This represents 26%

of MPC (4 x 10-8 pCi/ml) and is about the same as the previous year's release.

3. Solid Waste Only one shipment of solid waste was made during the year, infor-mation on which is provided in the following Table H-2.

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?ll < ~ -. .,.-a 21-TABLE H-1 ARCON-41 STACK RELEASES FISCAL YEAR 1986 Ar-41 Average Discharged. Concentr ation(l)

(Curies) (pCi/ml)

July 1985 384 1.03 x 10-8 August 314 1.05 September 337 1.19 October 477 1.28 November. 306 1.03' December 274 1.23 January 1986 -297 1.00 February 303 1.02 March 343 1.15 April 281 0.76 May 242 0.81 June 239 0.80 12 months 3797 1.05 x 10-8 MPC (Table II, Column I) 4 x 10-8

% MPC 26%

Note: (1) Af ter authorized dilution factor (3000).

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~s' TABLE H-2

SUMMARY

OF MITR RADIOACTIVE' SOLID WASTE SHIPMENTS FISCAL YEAR 1986 Units Shipment #1 Total

1. Solid waste packaged Cub ic . 75 75 Fee t

2. Weight Pounds 2336 2336

3. Total activity (Ci) 0.097 0.097 (irradiated components,

'c-)

is", si;;s ssit!;;

6s Zn, etc.

4. (a) Dates of Shipment 5/22/86 (b) Disposition to Rad iac Licensee for burial l

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?7  ; l NUCLEAR REACTOR LABORATORY r ti .%

b AN INTERDEPARTMENTAL CENTER OF %Q';g/

MASSACHUSETTS INSTITUTE OF TECHNOLOGY O K HARLING 138 Albany Street Cambridge, Mass. 02133 L. CLARK, JR.

Director (617)253- 4 2 0 2 Director of Reactor Operations August 29, 1986 Dr. Thomas E. Murley, Administrator U.S. Nuclear Regulatory Cournission Region #1 631 Park Avenue King of Prussia, PA 19406

Subject:

Annual Report, License R-37, Docket No. 50-20

Dear Dr . Mur ley :

Forwarded herewith are t wo (2) copies of the Annual Report for the MIT Research Reactor for the period July 1, 1985 to June 30 1986, in compliance with paragraph 7.13.5 of the Technical Specifications for Facility Operating License R-37.

Sincerely, L J Ok~f Lincoln Clark, Jr.

Director of Reactor Operations LC/gw Enclosu e: As stated cc: MITRSC USNRC-01&E USNRC-DMB USNRC-0MIPC

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