United States Nuclear Regulatory Commission - Protecting People and the Environment

IE Circular No. 80-18, 10 CFR 50.59 Safety Evaluations for Changes to Radioactive Waste Treatment Systems

                                                           SSINS No.: 6830 
                                                           Accession No.: 
                                                           IEC 80-18

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                               August 22, 1980


Description of Circumstances: 

Recent inspection efforts at operating power reactors have revealed numerous
instances in which licensees have failed to perform adequate safety 
evaluations to support changes made to the design and/or operation of 
facility radioactive waste treatment systems.  These safety evaluations are 
required by the regulations of 10 CFR 50.59 whenever changes are made in the 
facility as described in the Safety Analysis Report (SAR). 

The inadequacies of the evaluations have caused radiological safety hazards 
to occur unidentified and therefore to remain unevaluated and uncorrected.  
In two particular cases, the inadequately evaluated system changes resulted 
in system failures that caused an uncontrolled release of radioactivity to 
the environment.  In each of these situations, a proper 10 CFR 50.59 safety 
evaluation should have identified and corrected deficiencies in the system 
modification and/or operation and would have prevented the inadvertent 
release of radioactivity. 

NRC followup examination of the situation indicates that the inconsistency 
and/or inadequacy of licensee safety evaluations may be widespread.  A wide 
range of opinions seems to exist among licensees as to what constitutes an 
appropriate 10 CFR 50.59 safety evaluation, particularly for radwaste 
systems. Therefore, the following discussion and/or guidance is provided for 
licensee use in preparing future 10 CFR 50.59 safety evaluations to support 
changes in the design and/or operation of the radioactive waste treatment 
systems of licensed facilities. 

Although the contents of this guidance are specifically directed to the 
radioactive waste systems, the general principles and philosophy of the 10 
CFR 50.59 safety evaluation guidance are also applicable to the facility 
design and operation as a whole; thus, the application of 10 CFR 50.59 
should reflect a consistent approach. 


The requirements of 10 CFR 50.59 are composed of three essential parts. 
First, paragraph (a)(1) is permissive in that it allows the licensee to make
changes to the facility and its operation as described in the Safety 
Analysis Report without prior approval, provided that a changes in Technical
Specifications is not involved or an "unreviewed safety question" does not 

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exist.  Criteria for determining whether an "unreviewed safety question" 
exists are defined in paragraph (a)(2).  Second, paragraph (b) requires that
records of changes made under the authority of paragraph (a)(1) be 
maintained. These records are required to include a written safety 
evaluation that provides the basis for determining whether an "unreviewed 
safety question" exists.  Paragraph (b) also requires a report (at least 
annually) of such changes to the NRC.  Third, paragraph (c) requires that 
proposed changes in Technical Specifications be submitted to the NRC as an 
application for license amendment.  Likewise, proposed changes to the 
facility or procedures and the proposed conduct of tests that involve an 
"unreviewed safety question" are required to be submitted to the NRC as an 
application for license amendment. 

Any proposed change to a system or procedures described in the SAR, either 
by text or drawings, should be reviewed by the licensee to determine whether 
it involves an "unreviewed safety question."  Maintenance activities that do 
not result in a change to a system (permanent or temporary), or that replace
components with replacement parts procured with the same (or equivalent) 
purchase specification, do not require a written safety evaluation to meet 
the 10 CFR 50.59 requirements.  However, a safety evaluation is required to 
meet the provisions of 10 CFR 50.59 and any change must be reported to the 
NRC as required by 10 CFR 50.59(b) if the following circumstances occur:  
(1) components described in the SAR are removed; (2) component functions are
altered; (3) substitute components are utilized; or (4) changes remain 
following completion of a maintenance activity. 

Notice to Licensees: 

For all cases requiring a written safety evaluation, the safety evaluation 
must set forth the bases and criteria used to determine that the proposed 
change does or does not involve an "unreviewed safety question."  a simple 
statement of conclusion in itself is not sufficient.  However, depending 
upon the significance of the change, the safety evaluation may be brief.  
The scope of the evaluation must be commensurate with the potential safety 
significance of the proposed change or test.  The depth of the evaluation 
must be sufficient to determine whether or not an "unreviewed safety 
question" is involved.  These evaluations and analyses should be reviewed 
and approved by an appropriate level of management before the proposed 
changed is made. 

An important part of the "unreviewed safety question" determination is the 
evaluation and analysis of the proposed change by the licensee to assure 
that (1) potential safety hazards are identified, and (2) corrective actions 
are taken to eliminate, mitigate,or control the hazards to an acceptable 
level. All realistic failure modes and/or malfunctions must be considered 
and protection provided commensurate with the potential consequences.  All 
applicable regulatory requirements, including Technical Specifications, must
be complied with so that the proposed change shall not represent an 
"unreviewed safety question."  Also, the margin of safety as defined in the 
bases of the Technical Specifications shall not be reduced by the proposed 

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                                                            August 22, 1980 
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For radioactive waste systems, the appropriate portions of 10 CFR 20, 30, 
50, 71, and 100, the facility Technical Specifications, and 40 CFR 190 
(Environmental Dose Standard) are applicable. 

Additional specific criteria that should be reviewed prior to the 
modification of radioactive waste systems are presented below. 

(1)   System modifications should be evaluated against the seismic, quality 
      group and quality assurance criteria in Regulatory Guide 1.143.  
      Design provisions for controlling releases of radioactive liquids, as 
      presented in Regulatory Guide 1.143, should also be evaluated. 

(2)   Radiological controls should be evaluated against the criteria in 
      Regulatory Guide 1.21 and Standard Review Plant Section 11.5, "Process
      and Effluent Radiological Monitoring and Sampling Systems." 

(3)   Systems involving potentially explosive mixtures should be evaluated 
      against the criteria in Standard Review Plan Section 11.3, "Gaseous 
      Waste Management System," subsection II, item 6. 

(4)   System design and operation should be evaluated to assure that the 
      radiological consequences of unexpected and uncontrolled releases of 
      radioactivity that is stored or transferred in a waste system are a 
      small fraction of the 10 CFR 100 guidelines; i.e., less than 0.5 rem 
      whole body dose, 1.5 rem thyroid from gaseous releases, and less than 
      the radionuclide concentrations of 10 CFR 20, Appendix B, Table II, 
      Column 2 from liquid releases at the nearest water supplies.  (See 
      Standard Review Plan Sections 15.7.1, 15.7.2, and 15.7.3 for more 

The evaluation must include an analysis encompassing the above criteria to 
the extent that the criteria are applicable to the proposed changes; i.e., 
if the modifications involve a change addressed by the above regulations and
criteria, then the modifications must be evaluated in terms of these 
regulations and criteria.  

In conclusion, for any change in a facility radioactive waste system as 
described in the SAR, a safety evaluation is required in accordance with 10 
CFR 50.59.  In this safety evaluation and the "unreviewed safety question" 
determination, the evaluation criteria in Items 1-4 above should be used.  
If the proposed modification (design, operation, or test) represents a 
departure from this evaluation criteria, one of the following actions should 
be taken: 

(1)   The proposal should be modified to meet the intent of the criteria; 

(2)   The evaluation/determination must present sufficient analyses to 
      demonstrate the acceptability of the departure; or, 

(3)   Commission approval must be received prior to implementing the 
      modification (i.e., an unreviewed safety issue may be involved). 

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No written response to this circular is required.  If additional information
regarding this subject is required, contact the Director of this office.

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