1

LA-601 6-SOPStandard Opwating Procedure

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UC-46Reporting Date: June 1975Issued: November 1975

CIC-14 fKPc)R-f COLLECTION

REPRODUCTION

Technical Specifications for the

Pajarito Site Critical Experiments Facility

by

H. C. Paxton

Ioswalamosscientific laboratory

of the University of CaliforniaLOS ALAMOS, NEW MEXICO 87545

An Affirmative Action/Equal Opportunity Emplayer

uNITED STATES

ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION

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CONTENTS

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ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...1

DEFINITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...1

SAFETY LIMIT AND OPERATING LIMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2Fission Product Limitation.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2

LIMITING SAFETY SYSTEM SETI’ING (LSSS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Scram-Setting Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..2

LIMITING CONDITIONS FOR OPERATION (LCO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2

Scram Interval Limit . . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..2Positive Period Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Reproducibility-Based Reactivity Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Reactivity Restrictions for Fast Neutron Bursts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Reactivity Restrictions for Kinglet Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Remote Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...4Communication System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Protection During Manual Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...5Neutron Source and Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...5Fission Power Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . ...5Scram Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...5Reactivity Addition Rate Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..6Scram and Vernier Control Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Power Loss Scram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...6Vernier Control and Safety Device Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...6Portable Radiation Monitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...6

SURVEILLANCE REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...7Test of New Controls and Safety Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...7Check of Scram System and Radiation Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...7Scram Internal Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..7Maintenance Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...7

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ADMINISTRATIVE CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .."..• 7Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Action if Technical Specification is Violated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...8Written Procedures and Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . . ...8Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..”. .”.8Audits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..”. .””..”8Procedural Matters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. s. . . . . . . . . . ..”8

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. O... O... OO... OO.OOO.".. "."" .""" """.9

AppPoved:

H--I+ IJ-JL’W4For A-5 Safety Committee

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TECHNICAL SPECIFICATIONS FOR THEPAJARITO SITE CRITICAL EXPERIMENTS FACILITY

by

H. C. Paxton

ABSTRACT

This document is to satisfy the requirement for technicalspecifications spelled out in ERDA Manual Chapter 0540, “Safetyof ERDA-Owned Reactors. ” Technical specifications are defined inSec. 0540-048, and the requirement for them appears in Sec. 0540-015. The following technical specifications replace the document,“Operating Limits for the Los Alamos Critical Assembly Facility,”revised May 27, 1971.

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DEFINITIONS

Pajarito Site Critical Experiments Facility: Thisfacility of the Los Alamos Scientific Laboratory isdescribed in “Safety Analysis for the Los AlamosCritical-Assembly Facility,” dated November 7,1969.1

Kiva: As pointed out in Ref. 1, this name is appliedto each of the three remote laboratory buildings inwhich critical experiments are performed.

Critical experiment (experiment): An experimentperformed with fissile material at or near criticality.

Critical assembly (assembly): The system con-taining fissile material with which critical ex-periments are performed.

Safety device: A mechanism designed to reduce thereactivity of a critical assembly.

*. Scram: A rapid reduction of reactivity to sub-criticality, by means of safety devices.

JScram setting: The minimum radiation monitorsignal that automatically triggers a scram.

Positive period: The time interval during which thepower of a supercritical assembly increases by thefact or e.

Dollar of reactivity: The reactivity incrementbetween delayed and prompt criticality.

Reproducibility-based reactivity limit: An upperlimit of reactivity that depends upon thereproducibility demonstrated by a series of dis-assembly and reassembly operations.

Reproducibility (of reactivity): The standarddeviation of at least six measurements of the reac-tivity at a given assembly configuration. “

Damage threshold: The excess reactivity at which aprompt critical burst produces a small crack in acomponent, but does not lead to complete rupture.

Neutron multiplication: For a subcriticalassembly, a neutron counting rate that is sensitive toreactivity change, normalized to a reference coun-ting rate (ideally that which would exist if there wereno fissions).

Vernier control (control device): A criticalassembly component intended for fine adjustment of

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react ivit y. Its function may be incorporated in theassembly and disassembly device used for final ap-proach to criticality.

SAFETY LIMIT AND OPERATING LIMIT

Fission Product Limitation

Applicability. The fission product limitationapplies to all Pajarito systems: Big Ten, Flattop,Godiva IV, Godiva IVA, Honeycomb, Jezebel,Kinglet, Parka, the Plasma Cavity Assembly (Marsmachine), and temporary assemblies on Comet,Venus, and Supercomet machines.

Objective. The purpose is to maintain the dis-tinguishing feature of a critical facility, that the fis-sion product inventory of each assembly be limitedso that there is no need for special containment. orfor auxiliary cooling to prevent damage as a result ofafterheat ing.

Specification.

Safety Limit. This limit corresponds to a Kivaoperation that generates a total of 1019 fissionswithin 1 h. A universal means of measurement isradiochemical analysis of a sample of fissile materialfrom the assembly involved.

Operating Limit. Operation shall be controlledso that the fission product power generation in anyassembly, when averaged over the first hour aftershutdown, does not exceed 600 W. Figure 1 gives theinformation required to translate any fission producthistory into fission product power at any later time.Note that the 600-W limit is the first-hour averagethat would be generated by a burst of 1018 fissions.

Bases. The effectiveness of the Pajarito facilityprotective features is demonstrated by extrapolationof dose rates measured immediately outside controlrooms (in line of sight to the Kiva) during normalcritical operations. Extrapolated yields that wouldgive the LASL “administrative” whole-body doselimit (3 rem) range from 1019 to 2 x 1020 fissions,depending on the type of assembly and the degree ofshielding by Kiva walls. 1!2Another factor of 8 wouldbe required to produce the emergency whole-bodydose limit prescribed by 10 CFR Part 100.3

Effects of fission product release from anyassembly may be related directly to the formalistic

trest ment in the “Kinglet Safety Analysis.”4 There,the release of all fission products from a 10-s run of1.3 x 1018 fissions (corresponding to the operatinglimit ) under the most adverse conditions is shown toproduce doses of less than 5 rad to the whole body or

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20 rad to the thyroid at 300 m. It is stated thatrealistic estimates would be about two orders of

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magnitude less, or approximately 0.05 and 0.2 rad,respect ivel y.

LIMITING SAFETY SYSTEM SETTING(LSSS)

Scram-Setting Limitation

Applicability. The scram setting limitationapplies to at least two radiation monitors in use dur-ing a critical experiment with any Pajarito assembly.

Objective. The purpose is to implement the abovefission product limitation.

Specification. Scram settings at each of tworadiation monitors shall not exceed 1 rem/s for anoperation in Kiva 1 or 2, and 3 remfs for an operationin Kiva 3.

Bases. Relative measurements in Kivas and out-side control rooms show that operation giving theabove rates would lead to no more than 0.3-rem dosein 1 h to a person outdoors. This is the upper doselimit that could be produced by attaining the fissionproduct operating limit in 1 h.

LIMITING CONDITIONS FOR OPERATION(LCO)

Scram Interval Limit

Applicability. The scram interval limit applies toall Pajarito assemblies.

Objective. The purpose is to supplement theabove scram LSSS so that the fission product safetylimit will not be exceeded during any accidentallyshort. positive period.

a

Specification. With all scrams acting, the timefrom a scram signal to decrease of fission power shall

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not exceed 0.5 s.

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-30

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Average fission-product power:per joule

during first hour after shutdown

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20 s60 S

200 s600 S

2000 s

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Basis. At an exceptionally short positive period of0.!5 s. the 0.5-s LCO allows only one uncontrolled e-folding of power beyond the scram setting, so itprevents escalation to the fission-product safetylimit as a result of scram delay.

Positive Period Limit

Applicability. The positive period limit applies toComet, Honeycomb, Parka, Plasma Cavity (Mars),Supercomet, and Venus assemblies.

Objective. The purpose is to provide a generoussafety margin below prompt criticality, in par-ticular, to avoid an uncontrolled excursion fromassemblies that lack a clearly demonstrated prompt-shutdown mechanism.

Specification. The excess reactivity, includingeffects of add-on experiments, shall be limited sothat m) positive period will be less than 5 s.

Basis. The 5-s minimum positive period providesa margin of more than 0.3!$ below prompt criticalityand is adequate for operator response 5 to preventescalation to the fission product safety limit.

Reproducibility-Based Reactivity Limit

Applicability. This limit applies to ,Jezebel, Flat-top. and Big Ten, and to Godiva IV and IVA during anew approach to prompt criticality, providedreproducibility has been established experimentally.

Objective. The purpose is to provide an adequatebut not excessive margin below prompt criticality, inshort-period experiments with an assembly forwhich the effectiveness of a prompt shutdownmechanism is clear.

Specification. The excess reactivity, includingeffects of add-on experiments, shall be limited tomaintain a margin below prompt criticality which isat least three times the reproducibilitydemonstrated by a series of disassembles andreassemblies.

Bases. With a margin of three times the ex-perimental reproducibility, prompt criticality is un-likely to be reached; the still greater margin below

the damage threshold protects against exceeding thefiesion product safety limit.

Reactivity Restrictions for Fast Neutron Bursts

Applicability. These rest rictions apply to GodivaIV and lVA.

Objective. The purpose is to prevent a severelydamaging excursion.

Specification. The demonstrated reproducibility(adjusted to constant temperature) shall be within*0.002$, and any reactivity increase beyond a valuepreviously attained shall not exceed 0.01$ or pass anobservable damage threshold.

Bases. According to computations of kineticenergy as a function of excess reactivity,6 a stepincrease of 0.02$ beyond the damage thresholdwould produce less than 0.1 oz HE equivalent ex-plosive energy, and the above LCO guards againsthalf that increase.

Reactivity Restrictions for KingIet Operation

Applicability. These restrictions apply toKinglet.

Objective. The purpose is to prevent rupture ofthe solution cent airier.

Specification. The demonstrated reproducibility(adjusted to constant temperature) shall be within*0.OM. and any reactivity increase beyond a valuepreviously attained shall not exceed 0.1$ or pass 5.0$superpmmpt critical.

Bases. KEWB dynamic experiments attainedexcess react ivit ies more than 6$ above promptcrit icaiity wit bout damage, and the above I,CO ismore conservative. Even escape of Kinglet solutionunder this condition would not constitute an un-acceptable public hazard. ~ Note that the reactivityscale in dollars is calibrated with stationary fuel.

Remote Operation

Applicability. The requirement for remote opera-t ifm applies to crit ical experiments with any Pajaritoassembly (p. 2).

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Objective. The purpose is to protect people fromradiation resulting from normal operation or an ac-cidental excursion.

Specification. Critical operations, and subcriticaloperations beyond the provisions of ANSI StandardN16.3-1974,8 shall be performed in a Kiva with theexclusion area cleared and secured.

Bases. This is required by “Operating Proceduresfor the Pajarito Site Critical Assembly Facility”(Procedures),g and it implements parts of items 3.6and 3.7 of ANSI Standard N405-1975. 1°

Communication System

Applicability. This system must be activewhenever people may be in a Kiva to prepare for acritical experiment.

Objective. The purpose is to maintain coordina-tion of activities in the control room and the Kiva.

Specification. There shall be a system for com-munication between personnel at the control consoleand those in the Kiva.

Basis. This is required by ANSI N405 item 4.2.10

Protection During Manual Operations

Applicability. This requirement applies to anymanual operation that is beyond the scope of ANSIStandard N16.1-1975, 11 such as building up the,active parts of an assembly.

Objective. The purpose is to indicate effects ofreactivity changes for the protection of those presentduring addition of reactivity to an assembly.

Specification. All provisions of ANSI N16.3-19748 shall be satisfied during manual reactivity ad-ditions.

Bases. This is required by Procedures,g and itimplements ANSI N405 item 4.3 and parts of items3.5 and 4.4.10

Neutron Source and Counters

Applicability. This requirement applies. duringany new approach to criticality with any Pajaritoassembly (p. 2).

Objective. The purpose is to provide an orderlyapproach to criticality.

Specification. Neutron counters and a source ofneut mns sufficient to produce a valid indication ofmult implicationshall be present during any approachto criticality, except that the neutron source may beomitted for special experiments in which reactivityeffects have been measured. Each neutron count in-dicative of multiplication shall have a standarddeviation no greater than *5%.

Bases. This is required byANSI N405 item 4.4.10

Fission Power Instruments

Proceduresg and by

Applicability. This requirement applies to anycritical experiment with any Pajarito assembly (p.2).

Objective. The purpose is to provide indication offission power.

Specification. During critical experiments, atleast two instruments shall indicate the neutronlevel within the assembly; these may be scrammonitors,

Basis. This implements ANSI N405 item 4.9.10

Scram Monitors

Applicability. This requirement applies to anycritical experiment with any Pajarito assembly (p.2).

Objective. The purpose is to provide scramsignals if fission power exceeds a preset value.

Specification. At least two radiation monitorsshall each be capable of initiating a scram at a presetradiation level.

5I

Bases. This is required by Proceduresg and byANSI N405 item 4;6. 10

Power Loss Scram

Applicability. This requirement applies to allPajarito assemblies (p. 2). .

Reactivity Addition Rate Limit

Applicability. The reactivity addition rate limitapplies to Comet, Honeycomb, Parka, Plasma Cavi-ty (Mars), Supercomet, and Venus assemblies. Italso applies to Godiva IV, Godiva IVA, and Kingletduring initial approaches to criticality.

Objective. The purpose is to provide adequatetime for operator response in case of a loading error.

Specification. The final rate of assembly of majorparts shall be limited so that reactivity cannot beadded faster than 0.05$/s when the neutron mul-tiplication is greater than 100.

Bases. This LCO is required by Procedures.g Itdoes not apply to components that can add no reac-tivity greater than 0.5$.

Scram and Vernier Control Devices

Applicability. These requirements apply to allPajarito assemblies (p. 2).

Objective. The purpose is to provide for orderlyapproaches to criticality while preventing unplan-ned excursions.

Specification. Any assembly intended for criticaloperation shall have at least two independent safetydevices that can be scrammed automatically ormanually, and a vernier control. The safety devicesshall be capable of removing reactivity faster than itcan be added. Shutdown shall be at least 5$ totaland greater than 1$ with any single safety device in-operative.

Any subcritical assembly shall have at least onesafety device capable of at least 5$ shutdown.

Bases. This augments ANSI N405 item 4.5,10 andis required by Procedures.g Note that an assemblythat does not satisfy the requirement for criticaloperation must be kept subcritical by a marginspecified in the experimental plan.g

Objective. The purpose is to establish a safe con-dition upon loss of actuating power. “

Specification. Loss of actuating power or energysupply to the safety system shall produce a scram.

Bases. This is required by Proceduresg and byANSI N405 item 4.7.10

Vernier Control and Safety Device Indication

Applicability. This requirement applies to allPajarito assemblies (p. 2).

Objective. The purpose is to provide a convenientreactivity index.

Specification. The status of any vernier reactivitycent ml shall be displayed continuously at the con-trol console; “in” and “out” conditions of safetydevices shall also be displayed.

Basis. This is required by ANSI N405 item 4.10.10

Portable Radiation Monitors

Applicability. This requirement applies to allcritical experiments.

Objective. The purpose is to minimize normaland accident al exposure to radiation from criticalassemblies and to guide rescue operations if requiredbecause of an accident.

Specification. A portable gamma meter (0-500R/h) and a portable alpha meter shall be in eachKiva, and at least one each of these and one high-range gamma meter (0-10 000 R/h) shall be near thecontrol moms.

Basis. This implements ANSI N405 item 3.11.10 .

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SURVEILLANCE REQUIREMENTS

Test of New Controls and Safety Devices

Applicability. This requirement applies to allnewly installed or significantly altered controlequipment and safety devices.

Objective. The pu;p~se is to reduce the chance ofmalfunction during critical experiments.

Specification. The satisfactory performance ofnew m altered control and safety equipment shall beestablished, and adherence to the reactivity additionrate limit shall be confirmed before initial criticaloperation.

Basis. We consider this requirement of ANSIN405 item 5.110 to be good practice.

Check of Scram System and Radiation Detectors

Applicability. This requirement applies to eachday’s operation of any critical assembly (p. 2).

Objective. The purpose is to verify the operabilityof scram systems and of instrumentation aspreliminaries to each critical experiment.

Specification. The proper functioning of the safe-ty system shall be checked before each day’s opera-tion; operability of any vernier control, and theresponse of scram monitors and radiation detectorsto a change of radiation level shall be noted early ineach day’s operation.

Basis. This is to confirm effectiveness of the safe-ty system; it is called for by Proceduresg and byANSI N405 item 5.2.10

Scram Interval Measurement

Applicability. This requirement applies to eachactive assembly.

Objective. The purpose is to determine whetherthe scram interval limitation is satisfied, and tomake corrections if necessary.

Specification. The interval from scram signal todecrease of fission power in each active assemblyshall be measured at least annually.

Basis. This requirement is related to the effec-tiveness of excess reactivity (positive period)limitations.

Maintenance Program

Applicability. This requirement applies to eachactive assembly machine.

Objective. The purpose is to maintain goodoperating conditions.

Specification. Actuating features related tocriticality shall be inspected and maintained as re-quired, at least quarterly.

Basis. These routine inspections follow check listsfor the individual machines and supplementcustomary visual checks before each operation.

ADMINISTRATIVE CONTROLS

Organization

The administrative chain extends from the LASLDirector, down through the A-Division Leader, tothe A-5 Group Leader. The LASL Reactor SafetyCommittee (RSC) represents the Director in reactorsafety administration. The A-5 Safety Committeereviews proposed documentation and advises theGroup Leader about technical nuclear safetymatters.

Each operating crew that performs experiments isappoint ed by the Group Leader and consists of acrew chief and at least one crew member. The crewchief is responsible for all aspects of the operationand is instructed to consider personnel safety ofparamount importance. A crew chief must be a StaffMember. Both crew chief and crew member shall bein the control room during any approach to criticali-ty or supercritical operation.

Training for crew chief or crew member consists ofserving as an extra member of operating crews untiljudged by the Group Leader to be capable of formalparticipation, and attending a formal session on

each machine to be operated and sessions onemergency procedures. All technical members of theGroup participate in such training sessions, in-cluding one session on emergency procedures, atleast twice a year. Qualifications for either crew chiefor crew member include examinations in accordancewit h ERDA Immediate Action Directive (IAD) 8401-6, “Retraining and Requalification of ReactorOperators and Supervisors,” April 22, 1970.

Action if Technical Specification is Violated

A violation of any technical specification will bereported immediately to the A-Division Leader, theRSC Chairman, and, through the Chairman, to theLASL Director and a member of the ALOOperational Safety Division.

If the safety limit is violated, the assembly inquestion will be secured pending ERDA approval offurther operation.

If any technical specification other than the safetylimit is violated, the RSC Chairman will determinethe appropriate action.

Written Procedures and Approvals

Pajarito critical operations are governed generallyby the operating procedures of LA-4037-SOP, Rev.,gand by the emergency procedures of LA-4037-SOP,Rev., Suppl. 1. 12 In addition, each critical (or near-critical) experiment shall be covered by a written ex-perimental plan approved by the A-5 Safety Com-mittee, the A-5 Group Leader, and the A-DivisionLeader. Experimental plans shall include the follow-ing items as applicable: operational limits, purpose,materials, description, procedures, and safetyevaluation. If the experimental plan introduces a un-ique, significant safety question, RSC approval isalso required; any experiment with explosives shallbe considered to be in this category. Any departurefrom the procedures of LA-4037-SOP, Rev., shall bespelled out in the experimental plan.

A departure from an experimental plan oroperating procedure that presents no unique, signifi-cant safety problem requires the Group Leader’s ap-proval. Other departures or modifications requireapproval by the RSC.

Records

A log of the operation of each assembly, withreference to safety features, shall be maintained. Atthe end of each day’s record, the status of the

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assembly shall be noted. Safety features to be notedroutinely are results of scram testa, instrument bresponse, and scram monitor settings. There shallalso be a log of maintenance and modification ofassembly machines.

Other records shall include material covered inGroup training sessions, attendance at thosesessions, minutes of the A-5 Nuclear Safety Com-mittee, and dates and results of examinations.

Audits

Independent review of documentation, facilities,and operations, in accordance with ERDA Appendix8401 and IAD 8401-7, falls within the province of theRSC. Such review is supplemented by technicalreviews requested of the A-5 Safety Committee orundertaken voluntarily. This committee meets atleast four times a year.

Procedural Matters

Manual operations with fissionable material, suchas storage and transfer, shall be conducted in accor-dance with ANSI Standard N16.1-1975. 11

Before a critical experiment begins, all membersof the operating crew shall review the experimentalplan.

During nonoperating periods, the key that controlsthe operational power switch at the console shall belocked in a safe file or be in the custody of a persondesignated to control entry to the Kiva area whenthe radiation field is significant.

The crew chief’s approval is required for any entryinto the Kiva area during an operational period.

Any unexpected behavior of equipment during acritical experiment should be evaluated and resolvedbefore further operation; if a participant is notsatisfied with the safety of a proposed action, the ex-periment shall be suspended until the doubt isresolved.

Additions of reactivity (beyond those permitted A

by ANSI N16.1-197511 ) shall be guided by neutron

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detector response. During an initial approach tocriticality, effects of reactivity additions shall beplotted and each step should be understood before asubsequent addition is made.

No reactivity additions shall be madesimultaneously by two or more distinct methods orby two or more persons unless the effect of each addi-tion has been measured.

REFERENCES

1. W. U. Geer, P. G. Koontz, J. D. Omdoff, and H.C. Paxton, “Safety Analysis for the Los AlamosCritical-Assembly Facility,” Los Alamos ScientificLaboratory report LA-4273 (1969).

2. W, U. Geer, P. G. Koontz, J. D. Orndoff, and H.C. Paxton, “Hazards Evaluation for the Lm AlamosCritical Assembly Facility,” Los Alamos ScientificLaboratory report LAMS-2698 Rev. (1962).

3. Code of Federal Regulations, Title 10, Part 100,“Reactor Site Criteria,” see Sec. 100.11.

4. T. F. Wimett, R. H. White, H. C. Paxton, and J.D. Orndoff, “Kinglet Safety Analysis,” LAXAlamosScientific Laboratory report LA-4797-MS (1971).

5. G. R. Keepin, Physics of Nuclear Kinetics(Addison-Wesley, Reading, MA, 1965).

6. T. F. Wimett, R. H. White, W. R. Stratton, andD. P. Wood, “Godiva II-An Unmoderated Pulse-Irradiation Reactor,” Nucl. Sci. Eng. 8, 691-708(1960).

7. M. S. Dunenfeld and R. K. Stitt, “SummaryReview of the Kinetics Experiments on WaterBoilers, ” Atomics International report NAA-SR-7087 (1963).

8. American National Standard, “Safety in Con-ducting Subcritical Neutron-MultiplicationMeasurements In Situ,” ANSI N16.3-1974.

9. J. D. Omdoff, and H. C. Paxton, “OperatingProcedures for the Pajarito Site Critical AssemblyFacility,” Los Alamos Scientific Laboratory reportLA-4037-SOP, Rev. (1973).

10. American National Standard, “A Code of GoodPractices for the Performance of Critical Ex-periments,” ANSI N405-1975.

11. American National Standard, “NuclearCriticality Safety in Operations with FissionableMaterials Outside Reactors,” ANSI N16.1-1975.

12. H. C. Paxton, “Pajarito Site Plan for RadiationEmergency,” LA-4037-SOP, Rev., Suppl. 1 (1973).

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