**NRC INSPECTION MANUAL** IOLB

INSPECTION PROCEDURE 79702

CONTROL AND MONITORING OF RADIOLOGICAL SOURCE TERM

PROGRAM APPLICABILITY: 2515

79702‑01 INSPECTION OBJECTIVES

01.01 To determine whether the licensee is adequately controlling the
quality of plant primary and secondary systems and process water to
minimize out-of-core radiation buildup.

01.02 To evaluate ALARA planning and controls, and provide additional
guidance on evaluating licensee source term control programs.

79702‑02 INSPECTION REQUIREMENTS

This procedure is implemented to independently assess licensee
conclusions regarding extent of condition of issues, when selected as a
part of supplemental inspections using IP 95002, ASupplemental
Inspection For One Degraded Cornerstone or Any Three White Inputs in a
Strategic Performance Area.@

02.01 [Implementation of the Source Term Control Program]{.underline}

a.  Section 02.03 of the baseline inspection procedure for ALARA
    Planning and Controls, contains general guidance for assessing the
    status of the licensee=s overall source term.

b.  Determine if the licensee has developed an understanding of the
    plant source-term and whether there is a source-term control
    strategy. This strategy should consider:

    1.  The reduction of cobalt containing components.

    2.  An operating and shutdown chemistry control plan to minimize
        cobalt transport and crud bursts. This includes such activities
        as zinc injection (BWRs) or early boration (PWRs).

    3.  Industry technologies such as Zinc Injection (BWRs),Noble Metal
        Chemistry (BWR), Hydrogen Water Chemistry (BWRs), use of
        chromium coatings (PWRs) or Chemical Decontamination
        (PWRs/BWRs).

    4.  Preconditioning or electropolishing of reactor component
        surfaces to minimize the deposition of corrosion products.

    5.  System flushes to remove or reduce source term (e.g., hot
        spots).

c.  Interview selected individuals (e.g., Operations Manager,
    Maintenance Supervisor) to verify that responsible staff are aware
    of this strategy and that is supported by plant management.

    1.  Determine if the licensee has established reasonable criteria to
        evaluate if the strategy is effective and is being implemented
        in a timely manner.

    2.  Review several significant source term reduction actions taken
        by the licensee (such as chemical decontaminations, replacement
        of cobalt containing valves, etc) and determine:

        a.  If the action was performed in accordance with the overall
            strategy; and

        b.  Its effect (if any) on the radiological source term.

d.  Additionally, examine those actions proposed, but subsequently not
    approved by licensee management. Determine if these decisions were
    made within the strategy guidelines.

02.02 [Implementation of the Water Chemistry Control
Program]{.underline}

a.  Determine whether the water chemistry control program is being
    implemented in accordance with existing policies and procedures.
    This review may include the following:

    1.  Reviews and discussions of the trends of recorded water quality
        data and reviews of these data by plant chemistry personnel.

    2.  Reviews of investigative (diagnostic) and corrective actions
        taken when chemical variables have exceeded the established
        levels or limits, including consideration of the timeliness of
        these actions.

    3.  Review and discussion of the effectiveness of measures taken to
        prevent the introduction of chemical contaminants into primary
        and secondary coolant water and to detect the presence of these
        contaminants.

    4.  Discussions with individuals at all levels (including plant
        operating and maintenance personnel) who are involved with water
        chemistry controls to determine whether they understand the need
        for, and importance of these controls and whether individuals
        understand their roles in maintaining water quality. Corporate
        and plant management support and involvement are essential for
        success of the water chemistry control program.

    5.  Reviews and discussions of plant collective occupational dose
        (person‑rem) as it relates to plant water chemistry control.

b.  Determine if the licensee has established effective measures to
    control the potential increase of radiation fields from corrosion
    transport (i.e., crud bursts) occurring during plant shutdown and
    startup.

c.  For BWRs utilizing Hydrogen Water Chemistry (HWC) determine if the
    plant has evaluated the optimal hydrogen injection rate and has
    developed a policy for minimizing cycling.

79702‑03 INSPECTION GUIDANCE

[General Guidance]{.underline}

This procedure includes inspection of both regulatory requirements and
industry good practices, but emphasis is on the good practices that can
result in large reductions in occupational radiation exposure. EPRI and
industry research and infield trial/demonstrations is ongoing, and NRR
and the Regions will continue to monitor and keep abreast of the latest,
pertinent publications.

[Specific Guidance]{.underline}

03.01 [Implementation of the Source Term Control Program]{.underline}

The primary source of radiation fields in BWR and PWR nuclear power
plants is Co-60. In PWRs, Co-58 can also be a significant radiation
source early in plant life. However, after 10 effective full power
years, Co-60 accounts for the majority of the radiation fields in PWRs
due to its longer half-life.

Co-60 is formed as a result of neutron absorption by Co-59, the only
cobalt isotope present in naturally occurring cobalt. Co-59 constitutes
the major portion of many hardfacing materials (such as Stellite) used
in nuclear plants. Co-58 is formed by neutron bombardment of nickel-58.
Nickel is a major alloying constituent in many reactor coolant pressure
boundary materials, such as PWR steam generator tubing.

Reducing the amount of cobalt available for irradiation is the soundest
and most cost-effective means of controlling radiation fields. This is
typically accomplished by:

a.  Minimizing the amount of cobalt in system components, such as system
    valves, that can potentially reach the core. Typically, this is
    accomplished by identifying those components having the highest
    cobalt contribution potential and prioritizing them for replacement.
    For example, industry studies have shown that a significant
    reduction in BWR cobalt inventory can be achieved by replacing the
    control rod pins and rollers (typically containing high cobalt
    alloys) with low cobalt replacements.

b.  Minimizing the amount of cobalt escaping to plant piping systems in
    the course of in-situ maintenance (e.g., valve maintenance), which
    some industry studies concluded accounts for about 10-30 percent of
    the cobalt entering the reactor system annually.

c.  For BWRs, minimizing the amount of feedwater corrosion products by
    improving condensate polisher efficiencies, installing condensate
    filters, improving plant lay-up requirements, and/or eliminating
    corrosion product input into the condensate system.

> The industry has developed several alloys (such as EPRI=s NOREM) that
> are suitable replacements for hardfacing alloys such as Stellite.

d.  Use of sub-micron filtration of the reactor coolant system at power
    is a proven, effective way to minimize corrosion product deposition
    on primary plant component and piping surfaces.

03.02 [Implementation of the Water Chemistry Control
Program]{.underline}

Standard LWR Technical Specifications include limits and associated
surveillance requirements on certain chemical variables in the primary
coolant. The standard administrative controls section also contains a
requirement that written procedures be established as recommended in
Appendix A of Regulatory Guide 1.33, \"Quality Assurance Program
Requirements (Operation).\" Regulatory Guide 1.33 includes \"Chemical
and Radiochemical Control Procedures\" among the typical safety‑related
activities that should be covered by written procedures.

Compliance with NRC requirements will not ensure that water chemistry is
adequately controlled (from an ALARA perspective) to reduce out‑of‑core
radiation field buildup that may result in high occupational radiation
exposures. The nuclear power industry, through its BWR and PWR owners
groups and the Electric Power Research Institute (EPRI), has recognized
the need for improved LWR water chemistry controls and has developed
consensus guidelines for PWR and BWR primary and secondary water
chemistry.

Control of PWR primary coolant water chemistry is essential if crud
formation on the fuel and subsequent redeposition of radioactive oxides
outside the core are to be minimized. The formation and stability of
colloidal corrosion products are strongly affected by pH, and adsorption
of cobalt on colloidal iron oxides is greatly increased at high pH.
Cobalt solubility is greatest at low pH values (high boron, low lithium)
and increases above the minimum at very high pH values (low boron, high
lithium).

Industry experience has shown that for PWRs, the release of radioactive
corrosion products during plant shutdown has been a significant
contributor to radiation field buildup. The negative effects of these
releases can be diminished by controlling the coolant chemistry to
maximize the decomposition and solubilization of corrosion products. The
[PWR Primary Shutdown and Startup Chemistry Guidelines]{.underline} were
developed by EPRI to provide an optimal strategy to minimize the
radiological consequences, from the release of corrosion products.

Examples of some effective measures to reduce post-shutdown dose rates
at PWRs are:

-   Early boration at shutdown to promote corrosion product solubility
    and aid in the release of corrosion products.

-   Slow plant cooldown rates with specific temperature hold points to
    maintain solubility of corrosion products, thus aiding in their
    removal via filtration and ion exchange.

-   Use of hydrogen peroxide to create an oxygenation crud burst,
    liberating corrosion products early on it the shutdown clean up
    process.

-   Use maximum primary clean-up purification flow to enhance corrosion
    product removal.

Radiation buildup in the BWR primary system occurs as the result of both
soluble phase and particulate phase transport and deposition of
activated species. Several industry initiatives have been developed,
such as HWC, depleted zinc injection, noble metal chemistry, and control
of feedwater iron, to reduce the transport of radioactive corrosion
products. Guidelines for each of these topics can be found in the BWR
Water Chemistry Guidelines and other related EPRI documents.

Frequently identified problems that resulted in poor water chemistry in
operating BWRs include:

a.  Improper operation of the condensate treatment system.

b.  Improper operation of the reactor water cleanup system.

c.  Leakage of condenser cooling water or air.

d.  Inadequate design or maintenance of equipment.

e.  Insufficient training or experience of plant personnel.

IonBexchange resin ingress and condenser tube leaks have been found to
be the principal recurring causes of off‑standard water chemistry in
BWRs. Ingress of resins into the reactor coolant system has caused more
severe water chemistry transients than any other source. Transients
resulting from ingress of resins or other organic materials been
attributed, erroneously, to ingress of air (see memorandum from J.
Wigginton to Regional Branch Chiefs, 04‑15‑83).

79702-04 RESOURCE ESTIMATE

It is estimated that 25-30 on-site inspector hours will be needed to
complete this instruction. Multi-unit sites require the same amount of
time.

79702 REFERENCES

EPRI TR-107991,ARadiation-Field Control Manual - 1997 Revision

EPRI TR-105714, APWR Primary Water Chemistry Guidelines, Revision 3\"
1995

EPRI RS-103515-R1, ABWR Water Chemistry Guidelines- 1996 Revision,@ 1996

NCRP report no. 120, ADose Control at Nuclear Power Plants,@ (issued
December 30, 1994).

END