ML20196K019

Responds to Question 13 Noted in NRC Re TS Amend 32.Amend to TS 6.4 Requested.Provision to Conduct Patient Irradiation with Inoperable Minor Scram from Medical Control Panels Deleted

ML20196K019
Person / Time
Site:	MIT Nuclear Research Reactor
Issue date:	06/30/1999
From:	Bernard J, Hu L NUCLEAR REACTOR LABORATORY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20196K024	List: ML20196K019 ML20196K033
References
NUDOCS 9907080116
Download: ML20196K019 (17)

Text

I~ l

~

, s j%g 9'

h L NUCLEAR REACTOR LABORATORY c f' *d AN INTERDEPARTMENTAL CENTER OF MASSACHUSETTS INSTITUTE OF TECHNOLOGY

' ~[ '

JOHN A. DERNARD 138 Albany Street. Cambndge, MA 02139 4296 Activabon Analysis {

Director Telefan No. (617) 253 7300 Coolant Chemistry I e: rector of Reactor Operations "#**'**"*

Pnncipal Research Engineer Tel. No. (617) 253-4202 Reactor Engineering i

June 30,1999 l

Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Massachusetts Institute of Technology Research Reactor, Docket No. 50-20, ,

License No. R-37, Technical Specification Amendment 32 Gentlemen-In October 1997, the original fission converter SER and the associated Technical Specifications were submitted to the NRC. In July 1998, we received a lengthy series of questions on that submission. A response was prepared, discussed with the NRC during a two-day site visit, and submitted to the NRC. That action occurred in January 1999. A second set of thineen questions was received on May 13, 1999. Our response to the first eleven questions was submitted on June 24,1999. Question #12 was answered separately by request for an amendment that corrected a typographical error in Technical Specification 3.10. This letter addresses the last question (#13). An amendment is requested for Technical Specification 6.5.

The proposed changes for TS 6.5 have been modified from the original request.

These changes, except those which are directly the result of having two treatment facilities or neutron beams, are summarized as follows:

(a) 6.5.3: The provision to conduct patient irradiation with an inoperable /

minor scram from the medical control panels has been deleted. The MIT Committee on Reactor Safeguards recommended this change. We note that in the event that the minor scram is inoperable, a substitute could be

/[

installed and tested without significantly delaying the start of a patient irradiation. y (b) 6.5.5 (c) and 6.5.12 (d): Automatic shutter closure upon loss of electric power or low air pressure can be replaced with an alarm to alen the reactor operator to lower power when shutter closure is needed.

(

(c) Extensive changes were made to provision 14 of the specification. This provision originally consisted of three paragraphs that collectively defined

<3 T1 O V U 9907080116 990630 PDR ADOCK 05000020 P PDR

e .

requirements for functional checks, calibration checks, and characterizations. The language was further modified in paragraph 3(c) of the Quality Management Program. The provision is changed for two reasons: to improve clarity and to revise frequencies. Clarity is improved because there are now five paragraphs in place of the three, one each for functional checks, calibration checks, characterization, calibration requirements for the instruments that are used to perform both the calibration checks and the characterization, and one specifying the minimum number of beam monitors. The reason for changing frequencies is to reflect experience gained since 1994 as it impacts on ALARA considerations. The changes are:

(i) 6.5.14 (a): This paragraph now concerns only functional checks.

Also, " component replacement" is added to the items that require a functional check.

(ii) 6.5.14 (b): A new paragraph is created t- define a calibration check. Also, " component replacement" i., Lied to the items that require a calibration check. Finally, the cabbration check interval is changed to six months.

(iii) 6.5.14 (c): This is the c!d paragraph (b). The beam characterization interval is changed from six months to twelve months. This change is based on our past experience that shows that the beam characteristics have not changed since 1994. The characterization process requires two individuals to work in the medical room for five or six hours over a two-day period. This can involve radiation exposures that are unnecessag given the fact that the results of characterization are unchanged.

(iv) 6.514 (d): This is the old paragraph (c). The beam monitors are calibrated as part of the characterization. The effect of the original language in paragraph (c) together with the original defmition 5 was to require calibration of the instruments used for the characterization by a secondary calibration laboratory. The language has been revised to make this objective explicit. As a result, the original definition 5, " calibration of the beam monitors",

is no longer required. A two-year calibration cycle is retained.

(v) 6.5.14 (e): A new provision is added to specify a minimum number of beam monitors. We currently have five monitors. These are:

two epithermal neutron, two thermal neutron, and one gamma.

The requirement -is that any two neutron-sensitive monitors be operable at the outset and that any one neutron-sensitive monitor remain operable. Our experience suggests that the gamma monitor, while useftd, should not be the primag means of indication.

1 i

)

)

(d) Provision 19 is added per NRC request in the guidance for relicensing document preparation (NUREG-1537).

(e)- Definition 5: The definition of " component' replacement" replaces the )

definition of" calibration of the beam monitors"  !

. (f) Paragraph 3 (c) of the QMP is modified to reflect the change to provision 14.

l We believe that the above changes substantially strengthen the Technical '

Specification. The above request was reviewed and approved by the MIT Committee on Reactor Safeguards on June 24,1999.

Sincerely,-

m Lin-Wen Hu, Ph.D.

Reactor Relicensing Engineer kT J hn A. Bernard, Ph. 4 Director JAB /lwh l

cc: USNRC -. Senior Project Manager,

_ NRR/ONDD USNRC -

Region I- Project Scientist Efiluents Radiation Protection Section (ERPS)

FRSSB/DRSS

fg ]

{

d 6.5 Generation of Medical Therapv Facility Beams for Human Therapy

. Applicability 1

This specification applies solely to the generation of medical therapy facility beams i

for the treatment of human patients. It does not apply to any other use of the medical therapy facilities and/or their beams. Surveillances listed in this specification am only required if human therapy is planned for the interval of the surveillance. However, in the event of a hiatus in the scheduled performance of any given surveillance, that surveillance shall be performed prior to the initiation of human therapy during the interval in question.

Obiective To pmvide for the protection of the public health and safety by ensuring that patients I

am treated in accordance with the tmatment _ plan established by the BNCT physician authorized user and that the ALARA principle is observed for all non-therapeutic radiation exposures.

Soecification

1. Patients accepted for treatment shall have been referred by written directive from a

. BNCT physician authorized user from a medical center with an NRC or Agreement State medical use license that contains BNCT specific conditions and commitments

' for BNCF treatment on humans conducted at the Massachusetts Institute of Technology Research Reactor's Medical Therapy Facilities.  !

2. All medical treatments, including iiradiations and analyses of the neutron capture agents in the patients, are the responsibility of the BNCT physician authorized user in charge of the therapy and the medical physicists from the NRC-licensed or Agreement State-licensed medical center. The Massachusetts Institute of Technology is only responsible for providing current and accurate beam characteristic parameters to the medical use licensee and for delivery of the desired radiation fluence as requested in the written directive. Before the start of a therapy, both the certified medical physicist and the Director of the Nuclear Reactor Laboratory, or his designate, must agree that the therapy can be initiated. The BNCT physician 6-21 1

. 4

~

authorized user is responsible for monitoring the therapy and for directing its termination. However, a radiation therapy can also be terminated at any time if either the BNCT physician authorized user or the NRL Director, or their designates, judge that the therapy should be terminated.

3. It shall be possible to initiate a minor scram of the reactor from a control panel located in each medical therapy facility area.

4. Access to each medical therapy facility shall be controlled by means of the shield i

door located at its entrance.

5. The following features and/or interlocks shall be operable:

(a) An interlock shall pmvent opening of the shutters that control beam delivery unless the medical therapy facility's shield door is closed.

(b) The shutters that control beam delivery shall be interlocked to close automatically upon opening of the medical therapy facility's shield door.

(c) The shutters that control beam delivery shall be designed to close automatically upon failure of either electric power or on low air pressure if the shutter is operated pneumatically. Alternatively, on loss of either electric or pneumatic power an alarm could sound which alerts the reactor operator to the need to lower power when shutter closure is needed.

(d) Shutters that control beam delivery and that are normally pneumatically-operated shall, in addition, be designed for manual closure.

(e) It shall be possible to close the shutters that control beam delivery from within the medical therapy facility.

6. Each of the shutters that controls beam delivery shall be equipped with a light that I indicates the status of the shutter. These lights shall be visible at each medical therapy facility's local control panel. In the event of a status light malfunction, it i

shall be acceptable to use the affected shutter provided that an attemate means of j verifying position is available. Use of this attemate means of shutter position verification is limited to seven consecutive working days.

l

~

6-22

F.

7. Each medical therapy facility shall be equipped with a monitor that provides a visual indication of the radiacion level within the facility, that indicates both within the facility and at the local control panel, and that provides an audible alarm both within j 1

the facility and at the local control panel, i

(a) .This radiation monitor shall be equipped with a backup power supply such as the reactor emergency power system or a battery.

1 (b)- This radiation monitor shall be checked for proper operation by means of a check source on the calendar day of and prior to any patient irradiation.

(c) This radiation monitor shall be calibrated quarterly.

1 (d) The audible alarm shall be set at or below 50 mR/hr. This monitor and/or its 1

alarm may be disabled once the medical therapy room has been searched and 1

secured, such as is done immediately prior to initiation of patient therapy. If this is done, the monitor and/or its alarm shall be interlocked so that they become functional upon opening of the medical therapy facility's shield door.

i l (e) In the event that this monitor is inoperable, personnel entering the medical therapy facility shall use either portable survey instmments or audible alarm l personal dosimeters as a temporary means of satisfying this provision. These i

l instruments / dosimeters shall be in calibration as defined by the MIT Research l

l Reactor's radiation protection program and shall be source-checked daily l prior to use on any day that they are used to satisfy this provision. Use of l these instruments / dosimeters as a temporary means of satisfying this provision is limited to seven consecutive working days.

8. An intercom or other means of two-way communication shall be operable both 1

betveel tach medical therapy facility control panel and the reactor control room, and also bei een each medical therapy facility control panel and the interior of the facility. The latter is for the monitoring of patients.

9. It shall be possible for personnel monitoring a patient to open each medical therapy facility's shield door manually.

l 6-23 l

l'

g, e

~

10. It shall be possible to observe the patient through both a viewing port and by means of a closed-circuit TV camera. Both methods of patient visualization shall be operable at the outset of any patient irradiation. Should either fail during the irradiation, the treatment may be continued at the discretion of the BNCT physician authorized user. Adequate lighting to permit such viewing shall be assured by the provision of emergencylighting.

I1. The total radiation fluence delivered by the medical therapy facility beam as measured by on-line beam monitors shall not exceed that prescribed in the patien! treatment plan

! by more than 20%. The tmatment is normally delivered in fractions in accordance with standard practice for human therapy. The 20% criterion applies to the sum of I

l the radiation fluences associated with all fractions in a given tmatment plan. A l criterion of 30% applies to the difference between the administtred and prescribed l

fluence for any given week (seven consecutive days). Finally, if the treatment consists of three or fewer fractions, then a criterion of 10% shall apply. '

12. The following interlocks or channels shall be tested at least montidy and prior to treatment of human patients if the interlock or channel has been repaired or 1

deenergized:

Interlock or Channel Sgrveillance a) Medical therapy facility minor scram Scram test b) Shutters will not open unless Operational test shield dooris closed -

c). Shutters close upon both manual and Operational test automatic opening of shield door d) Shutters close and/or alarm on loss Operational test of electrical power and reduction of pressure in pneumatic operators, if spplicable c) Manual closure of pneumatic shutters Operational test f) Shutters can be closed manually Operational test from within the facility i

)

6-24  !

4 g) Shutter status lights Operational test h) Radiation monitor alarm Operational test i) Radiation monitor and/or alarm Operational test enabled upon opening of shield door j) Inten: oms Operational test In addition to the above, each medical therapy facility minor scram shall be tested prior to reactor startup if the reactor has been shut down for more than sixteen hours.

13. Manual operation of each medical therapy facility's shield door in which the door is opened fully shall be verified semi-annually.

I

14. Use of the medical therapy facility beams shall be subject to the following:

a) A functional check of the beam monitors that are described in provision 11 of this specification shall be made weekly for any week that the beam will be used for human therapy. This check shall be made prior to any patient irradiation for a given week. In addition, a functional check shall be performed prior to any patient irradiation in the event of a component replacement or a design i

modification. 1 b) A calibration check of the beam shall be performed every six months for any six-month interval that the beam will be used for human therapy. This six-month calibratior, check shall be made prior to any patient irradiation for a given six-month iaterval. In addition, a calibration check shall be performed prior to any patient irradiation in the event of a component replacement or a design rnodifiiation.

c) A characterization of the beam shall be performed every twelve months for any twelve-month interval that the beam will be used for human therapy. This twelve-month characterization shall be made prior to any patient irradiation for a given twelve-month interval. A characterization shall also be performed prior to any patient irradiation in the event of a design modification. As part of the l

l 6-25

~

characterization process, the proper response of the beam monitors that are described in provision 11 of this specification shall be established.

d) The instruments (e.g., tissue-equivalent chamber or graphite-magnesium wall ionization' chamber or the equivalent) that are to be used to perform both calibration checks and characterization of the beam shall be calibrated by a secondary calibration laboratory. This calibration shall be performed at least once every two years for any two-year interval that the beam will be used for human therapy. The two-year calibration shall be made prior to any patient irradiation during any given two-year interval. (Note: If a method (e.g., foil activation) other than these checks is used for the calibration and or the characterization, then the devices (e.g., foils) used in that method shall either be traceable to the National Institute of Standards and Technology or be selected in accordance with the relevant ANSI /ANS standards.

e) There shall be a minimum of two neutron-sensitive beam monitors to initiate a patient irradiation. Once initiated, a patient irradiation may be continued at the discretion of both the certified medical physicist and the Director of the Nuclear Reactor Laboratory, or his designate, provided that at least one neutron-sensitive beam monitoris operable.

15. Maintenance, repair, and modification of the medical therapy facilities shall be performed under the supervision of a senior reactor operator who is licensed by the U.S. Nuclear Regulatory Commission to operate the MIT Research Reactor. The

' medical therapy facility' includes the beam, beam shutters, beam monitoring equipment, medical therapy facility shielding, shield door, and patient viewing equipment. All modifications will be reviewed pursuant to the requirements of 10 CFR 50.59. The operating couch, patient positioning equipment, medical instruments, and other equipment used for the direct medical support of the patient are not considered part of the medical therapy facility for purposes of this provision, except insofar as radiation safety (i.e., activation and/or contamination) is concerned.

6-26

]

j

, 4 1

16. Personnel who are not licensed to operate the MIT Research Reactor but who are responsible for either the medical therapy or the beam's design including construction and/or modification may operate the controls for the corresponding medical therapy facility beam provided that:

(a) Training has been provided and proficiency satisfactorily demonstrated on the design of the facility,its controls, and the use of those controls. Proficiency shall be demonstrated annually.

.. (b) Instmetions are posted at the medical therapy facility's local control panel that specify the procedure to be followed:

(i) to ensum that only the patient is in the treatment room before turning the primary beam of radiation on to begin a treatment; l

(ii) if the operator is unable to turn the primary beam of radiation off with controls outside the medical therapy facility, or if any other abnormal condition occurs. A directive shall be included with these instructions to notify the reactor console operator in the event of any abnormality.

(c) In the event that a shutter affects reactivity (e.g., the D2 0 shutter for the medical room below the reactor and the converter control shutter for the fission converter beam), personnel who are not licensed on the MIT Research Reactor but who have been trained under this provision may operate that shutter provided that verbal permission is requested and received from the reactor console operator immediately prior to such action. Emergency closures are an exception and may be made without first requesting permission.

Records of the training provided under subparagraph (a) above shall be retained in i

accordance with the MIT Research Reactor's training program or at least for thme  !

years. A list of personnel so qualified shall be maintained in the reactor control room.

6-27

17. Events defined as ' recordable' under definition 8 of this specification shall be recorded and the record maintained for five years. Events defined as

'misadministrations' under definition 9 of this specification shall be reported to the U.S. Nuclear Regulatory Commission (24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> verbal,15 day written report). The 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> verbal reports will be made to the Regional Administrator, Region I, or his designate. The 15 day written reports will be sent to the NRC Document Control Desk with a copy to the Regional Administrator, Region I, or his designate.

I 8. The requirements of the Quality Management Program (QMP) for the Generation of Medical Therapy Facility Beams for Human Therapy at the Massachusetts Institute of Technology Research Reactor shall be observed for any human therapy. (Note: The presence of this commitment to observe the QMP in these specifications does not preclude modifying the QMP as provided in that document. Any such modifications are not considered to be a change to the MITR Technical Specifications.)

19. Rextor facilities (e.g., prompt gamma for the determination of boron concentration in blood or tissue) that are used to perform measurements associated with the conduct i 1

of medical therapy J.L..I be calibrated every twelve months for any twelve-month interval that the beam will be used for human therapy. This twelve-month calibration <

shall be made prior to any patient irradiation for a given twelve-month interval. This calibration could be done by measuring a series of standards that span the anticipated range of boron in blood or tissue. In addition, a single point check, (e.g.,

verification that a single standard is measured i10% of its true value) shall be performed prior to any patient irradiation.

s i

i 6-28 i

n

c

• . j j

Definitions

1. The medical therapy facilities are equipped with shutters that are used (i) to control beam delivery and (ii) to adjust the neutron energy spectrum of the beam. The former currently include lead, boral, and light water shutters as described in p Reference 6.5-1. The heavy water blister tank, which is'also described in Reference L 1 i 6.5-1, is an example of the latter. It is conceivable that these designations may j 1

change should it be found desirable to alter the beam configuration. Accordingly, the phrase " shutters that control beam delivery" refers either to the aforementioned three 4 existing shutters or to any future shutter or group thereof that provides an equivalent or greater reduction in beam intensity. Shutter-effect analyses shall be documented l through the standard safety review process including, where appropriate, an SAR l

revision and submission to NRC under 10 CFR 50.59.

2. The term ' calibration check' refers to the process of checking the beam intensity and l l quality via one or more of the following: foil activation; use of a fission chamber; I

l use of an ion chamber; or an equivalent process. The purpose of a calibration check l '

is to ensure that the beam has not ' changed in a significant way (e.g., energy spectrum or intensity) from the beam that was characterized. l l

3. The term ' functional check of the beam monitors' shall consist of verifying that l system output is consistent (i 10%) with previously measured values upon normalization to a common reactor neutronic power level.

4. The term ' characterization' refers to the process of obtaining the dose-versus-depth profile in phantoms as described in Reference 6.5-2 or an equivalent process. The dose-versus-depth profile from the surface of the phantom to a depth at least equivalent to the total thickness of the body part to be treated on a central axis is deemed adequate for a characterization. Fast neutron, thermal neutron, and gamma l

ray components are determined in a characterization and monitors are normalized by this characterization.

6-29

~.

o

5. The term ' component replacement' means the mplacement of a component in the

. beam with an identical unit or the re-installation of a component in the beam for l

l which a characterization has already been performed. For example, the latter may be.

a change of collimators.

i

6. - - The term ' design modification' as applied to a medical therapy facility beam refers (a) to a change that is shown to alter the dose-versus-depth profile of the fast neutrons, l

l thermal neutrons, or gamma rays in the beam as sensed by the calibration check and l (b) to a change that has the potential to increase significantly the amount of activation i products in the medical therapy facility when the beam is to be used for the treatment of human patients.

7. The term ' radiation fluence' means the total fluence of neutrons and gamma radiation that is emitted in a medical therapy facility beam. The determination of the ratios of I gamma, fast neutron, and thermal neutron fluences is part of the beam characterization. Knowledge of these ratios allows the total radiation fluence to be monitored by the on-line detectors, which are neutron-sensitive. Compliance with the limits specified on radiation fluence by this specification is determined by reference to the fluence monitored by these detectors.

l

8. The term ' recordable event' means the administration of:

(a) A radiation treatment without a written directive; or (b) A radiation treatment where a written directive is required without reporting to l the medical use licensee in writing each fluence given within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the treatment; or

! (c) A tmatment delivery for which the administered radiation fluence for any given fraction is 15% greater than prescribed.

6-30 l'

F.

9. The term ' misadministration' means the administration of a radiation therapy:

(a) Involving the wrong patient, wrong mode of treatment, or wrong treatment site; or (b) When the treatment delivery is not in accordance with provision 11 of this

.- _ _ specification. _

10. The term ' written directive' means an order in writing for a specific patient, dated and signed by a BNCT physician authorized user prior to the administration of radiation and which specifies the treatment site, the total radiation fluence, radiation fluence per fraction, and overall treatment period.

I 1. The tenn ' human therapy' means radiation tmatments that am of dimet therapeutic benefit to the patient and/or part of investigatory studies that involve humans.

12. The term 'BNCT physician authorized user' means a medical physician authorized by the medical use licensee's radiation safety committee to act as an authorized user for BNCI' on humans.

13. The tenn ' certified medical physicist' means a medical physicist certified in either radiological physics or therapeutic radiation physics by the American Board of Radiology, or in therapeutic radiation physics by the American Board of Medical Physics and who also has specific training in neutron dosimetry and neutron beam capture therapy.

Basis The stipulation that patients only be accepted from a medical use licensee that has an NRC or an Agreement State medical use license that contains BNCT specific conditions and commitments for BNCT treatment of humans conducted at the Massachusetts Institute of Technology Research Reactor's Medical Therapy Facilities ensures that medical criteria

-imposed by NRC or the Agreement State on such licensees for the use of the MIT Research Reactor's medical therapy facility beams for human therapy will be fulfilled. The second provision delineates the division of responsibilities between the Massachusetts Institute of 6-31

c.

, 4 j.

Technology and the medical licensee that refers the patient. Also, it establishes administrative authority and protocol for initiating and terminating a radiation therapy.

The requirement tha'. it be possible to initiate a minor scram from control panels located in the medical therapy facility areas assures the attending physician and/or medical

.- . physicist of the capability to terminate the treatment immediately should the need arise. _ The ___

provision that access to each medical therapy facility be limited to a single door ensures that there will be no wjvertent entries. The various interlocks for the shutters that control beam delivery ensure that exposure levels in the medical therapy facility will be minimal prior to entry by personnel who are attending the patient. The shutter-indication lights serve to notify personnel of the beam's status. The provision for a radiation monitor ensures that personnel will have information available on radiation levels in the mcdical therapy facility prior to entry. ' The purpose of this monitor's audible alarm is to alert personnel to the presence of .

l elevated radiation levels, such as exist when the shutters that control beam delivery am open. 1 1

This monitor and/or its alarm may be disabled once the medical therapy facility has been searched and secured so that it will (1) not disturb a patient and (2) not distract attending j personnel. The monitor and/or its alarm are interlocked with the shield door so that they are made functional upon opening that door, and hence prior to any possible entry to the medical therapy facility. One intercom provides a means for the prompt exchange of information '

l between medical personnel and the reactor operator (s). The second intercom is for  ;

r L monitoring the patient. l The provision for manual operation of each medical therapy facility's shield door ensures access to any patient in the event of a loss of electrical power. The presence of a viewing window and a closed-circuit TV camera provide the attending BNCT physician authorized user and/or medical physicist with the opportunity to monitor the patient visually as well as through the use of various instruments. The viewing window will function even during an electric power failure because of the provision for emergency lighting.

The sexification that the total radiation fluence for a therapy (i.e., the radiation fluences for the sum of all fractions specified in a given treatment plan) not exceed that prescribed in the 6-32

l:

% ~ '

patient treatment plan by 20% establishes a trigger limit on the delivered fluence above which NRC has to be notified of a misadministration. The 20% criterion is based on the definition of misadministration (clause 4(iv)) as given in 10 CFR 35.2. The criterion that the difference between the administered and prescribed fluence for any seven consecutive days is

_._ . . _ . set at 30%. His is also in accordance_with the. definition of misadministration.(clause 4(iii))

as given in 10 CFR 35.2. ' Finally, if a treatment involves three or fewer fractions, then a more stringent criterion,10%, applies to the difference between the total radiation fluence for a therapy and that prescribed in the treatment plan (10 CFR 35.2(4ii)). The surveillance requirements for the functional checks as well as those for the beam calibration checks and I

characterizations provide a mechanism for ensuring that each medical therapy facility and its i

beam will perform as originally designed. Similarly, the surveillance requirements on the instruments used to perform these checks and characterizations ensure that these instruments -

are calibrated by a means traceable to the National Institute of Standards and Technology.

The chambers specified (tissue-equivalent, and graphite or magnesium-wall) were chosen j _ because they measure dose as opposed to fluence. Finally, the requirement on the number of beam monitors is in keeping with standard practice for gamma-ray sources.

The specification on maintenance and repair of the medical therapy facilities ensures that all such activities are performed under the supervision of personnel cognizant of quality assurance and other requirements such as radiation safety. The provision on the training and proficiency of non-licensed personnel ensures that all such personnel will receive instruction I

equivalent to that given to licensed reactor operators as regards use of the medical therapy facility beams. (Note: Licensed reactor operators may, of course, operate the medical therapy facility beams.) Also, this provision provides for the posting of instructions to be followed in the event of an abnormality.

The specification on ' recordable events' and 'misadministrations' provides for the documentation ~and reporting to the U.S. Nuclear Regulatory Commission of improper l events regarding the generation and use of medical therapy facility beams. The requirement L

that the Quality Management Program (QMP) be observed ensures that radiation treatments l

6-33

c provided by a medical therapy facility beam will be administered as directed by the BNCT l physician authorized user.

l The specification on calibration of reactor facilities that are used to measure the l

l concentration of boron in blood or tissue ensures that these measurements are accurate.

1 References 6.5-l' MITR Staff, " Safety Analysis Report for the MIT Research Reactor (MITR-II),"

Report No. MITNE-115,22 Oct.- 1970, Section 10.1.3.

6.5-2 Choi, R.J., " Development and Characterization of an Epithermal Beam for Boron

, Neutron Capture Therapy at the MITR-II Research Reactor," Ph.D. Thesis, Nuclear l

l Engineering Department, Massachusetts Institute of Technology, April 1991.

l l

i 1

l l

i 6-34 l