IE Circular 77-14, Separation of Contaminated Water Systems from Noncontaminated Plant Systems


                               UNITED STATES 
                         WASHINGTON, D. C. 20555 

                            November 22, 1977 

MEMORANDUM FOR:     B. H. Grier, Director, Region I 
                    J. P. O'Reilly, Director Region II 
                    J. G. Keppler, Director, Region III 
                    E. M. Howard, Director, Region IV 
                    R. H. Engelken, Director, Region V 

FROM:               H. D. Thornburg, Director, DROI, IE 


The subject circular should be dispatched for information to all power and 
test reactor, fuel cycle, and major by-product material processor facilities
with an operating license or a construction permit on November 28, 1977. 

The circular and a draft of the letter to licensees are enclosed for this 

                                        Harold D. Thornburg, Director 
                                        Division of Reactor Operations 
                                        Office of Inspection and 

1. Draft Transmittal Letter 
2. IE Circular 77-14 

CONTACT:  R. W. Woodruff, IE 

IE Circular No. 77-14 

(Transmittal letter for IE Circular 77-14 to all power and test reactor, 
fuel cycle and major by-product material processor facilities with an 
Operating License or a Construction Permit.) 


The enclosed IE Circular 77-14 is forwarded to you for information. No 
written response is required. Should you have any questions related to your 
understanding of this matter, please contact this office. 

                                        (Regional Director) 

1. IE Circular 77-14 
2. List of IE Circulars 
     Issued in 1977 

                         WASHINGTON, D. C. 20555 

                            November 22, 1977  

                                                     IE Circular No. 77-14 


This circular describes an event which occurred at a nuclear power facility;
however, the generic implications may be applicable to test reactors, fuel 
cycle facilities, and major by-product material processors. 

In June, 1977, the licensee for Beaver Valley 1 reported that make up water 
from a primary water storage tank (PWST) contaminated the plant water 
treatment system, which in turn supplies the in-plant domestic (Potable) 
water system. The plant domestic water became contaminated with a tritium 
concentration of 7xE(-3) uCi/ml. The domestic water was contaminated for 
approximately six hours before the condition was detected by the licensee 
and controls were established over the use of in-house water. No significant
expo!ure of plant personnel resulted from the event; however, five 
individuals showed positive levels of tritium by urinalysis. No release to 
the offsite environment above maximum permissible occurred. 

The PWST receives processed reactor coolant water from the Boron Recovery 
System which has been purified through evaporation, degasification and 
demineralization to remove radioisotopes other than tritium. The PWST is 
used to supply primary grade water to the reactor coolant system and is 
normally kept separated from the water treatment system. The cross 
connection between the primary grade water system and the water treatment 
system occurred when an isolation valve was inadvertently left open during 
valve line-up operations to recirculate the PWST. The procedure which 
specified the required line-up was being used for the first time since 
preoperational testing and did not list the subject valve. 

In addition to the valving error, however, a design error resulted in 
connecting a line from the PWST to a water treatment system line at a 
position upstream of two series stop-check valves in the proper 
configuration, the line would have been connected downstream of the 
stop-check valves, which would have prevented back flow of water from the 
primary grade water system to the water treatment system even with the 
isolation valve left open. Corrective actions taken 

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IE Circular No. 77.14                                   November 22, 1977 

by the licensee were to: (1) correct identified procedural deficiencies 
which led to the valving error; (2) modify the piping installation to the 
intended configuration; and (3) add two series isolation valves upstream of 
the stop-check valves in a "tell-tale" arrangement to provide an air break 
between the primary water and water treatment lines. The above corrective 
actions are being reviewed for suitability with design separation criteria. 

Section 10.5.3 of the National Standard Plumbing Code requires double check 
valves or siphon breaker between potable and nonpotable systems. Section 
9.2.4 of the Standard Review Plan (NUREG-75/087) states that the acceptance 
criteria for design of the potable and sanitary water systems (PSWS) is 
acceptable if there are no interconnections between the PSWS and systems 
having the potential for containing radioactive materials. 

A somewhat similar incident had previously occurred in March, 1975, at 
Millstone Units 1 and 2, when an improperly wired conductivity cell 
instrument permitted the return of high activity water to the house heating 
boiler makeup system. Overflow from the deaerating feed tank and surge tank,
which are components of the house heating boiler makeup system, resulted in 
an unfiltered and unmonitored release of contaminated water. 

It is recommended that you review your systems and as-built (or design) 
drawings, identify all interconnections between contaminated and 
noncontaminated water systems, and review the interconnection design to 
assure that separation has been provided. Operating procedures which could 
lead to inadvertent contamination of domestic water systems should be 
reviewed to verify that proper valve lineup and administrative controls are 
provided to prevent contamination of the domestic water supply and the 
subsequent intake of radioisotopes by plant personnel. 

No written response to this Circular is required. Your review of this matter
to determine its applicability to your facility and any corrective and 
preventive actions taken or planned, as appropriate, will be reviewed during
a subsequent NRC inspection. If you desire additional information regarding 
this matter, contact the Director of the appropriate NRC Regional Office. 

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