IE Circular 77-14, Separation of Contaminated Water Systems from Noncontaminated Plant Systems
CR77014
UNITED STATES
NUCLEAR REGULATORY COMMISSION
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
SUBJECT: IE CIRCULAR 77-14; SEPARATION OF CONTAMINATED WATER
SYSTEMS FROM NONCONTAMINATED PLANT SYSTEMS
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
purpose.
Harold D. Thornburg, Director
Division of Reactor Operations
Inspection
Office of Inspection and
Enforcement
Enclosures:
1. Draft Transmittal Letter
2. IE Circular 77-14
CONTACT: R. W. Woodruff, IE
49-28180
.
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.)
Addressee:
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.
Signature
(Regional Director)
Enclosures:
1. IE Circular 77-14
2. List of IE Circulars
Issued in 1977
.
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D. C. 20555
November 22, 1977
IE Circular No. 77-14
SEPARATION OF CONTAMINATED WATER SYSTEMS FROM NON-CONTAMINATED PLANT SYSTEM
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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